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Proceedings of the Symposium on the Ecology, Management, and Utilization of California Oaks

Proceedings of the Symposium on the Ecology, Management, and Utilization of California Oaks

United States Proceedings of the Symposium on the Department of Agriculture Service Ecology, Manage ent, an Pacific Southwest Forest and Range Experiment Station ilization of Ca ifornia

P.O. Box 245 Berkeley 94701

General Technical Report PSW-44 June 26-28, I 979, Claremont, California The views expressed in the papers included in this volume are those of the authors. Trade names of commercial products are used solely for information and no endorsement by the U.S. Department of Agriculture or other organizations is im- plied. This volume includes reports involving pesticides. It does not make recommendations for their use, nor does it imply that any uses described have been registered. All uses of pesticides must be registered by appropriate State or Federal agencies or both before they can be recommended.

Publisher:

Pacific Southwest Forest and Range Experiment Station P.O. Box 245, Berkeley, California 94701

November 1980 Proceedings of the Symposium on the Ecology, Management, and Utilization of California Oaks

June 26-28, 1979, Claremont, Callifornia

Timothy R. Plumb Technical ~oordinhtor

CONTENTS

Opening Remarks ...... 1 Canyon Live Vegetation in the Sierra Robert Z. Callaham ...... 86 Ecological Relationships Rodney G. Myatt Neogene History of the California Oaks ...... 3 Inventory and Quantification of Central Coast Jack Wolfe Hardwood Resources in California ...... 92 History of Cultural Influences on the Distribution and Norman H. Pillsbury Reproduction of Oaks in California...... 7 Oaks in California's Commercial -Volume, Randall S. Rossi Stand Structure, and Defect Characteristics ..... 101 of California Oaks ...... 19 Charles L. Bolsinger John M. Tucker Silviculture and Management Natural Hybridization Between Two Evergreen Black Preliminary Recommendations for Managing Oaks in the North Central Coast Ranges of California Black Oak in the ...... 107 California ...... 30 John Tappeiner and Philip M. McDonald Michael C. Vasey An Approach to Managing California Black Oak and Tanoak (Lithocarpus densijlorus) Surface Hardwoods on a Deer Winter Range in Central Characteristics...... 36 California ...... 112 M.G. King and S.R. Radosevitch Donald Potter and Barbara Johnston Adaptations of Mediterranean-Climate Oaks to Oak Management Harvest A: An Experimental Environmental Stress ...... 43 Management and Utilization Project on Southern Phil@ W. Rundel California Private Ownership ...... 117 Wildfire and the Geographic Relationships Between James E. Asher Canyon Live Oak, Coulter Pine, and Bigcone Growth of Thinned and Unthinned Hardwood Stands in Douglas-fir Forests ...... 55 the Northern Sierra Nevada. ..Preliminary Richard A. Minnich Findings ...... 119 The Fire Resistance of Engelmann and Coast Live Oak Philip M. McDonald Seedlings...... 62 Radial Growth of California Black Oak in the San Gerald E. Snow Bernardino Mountains ...... 128 Inventory and Distribution Records of Oaks in Barbara Gemmill California ...... 67 Prescribed Burning in California Oak Timothy E. Paysen Management ...... 136 Quercus sadleriana, R. Br. Campst., Its Distribution, Lisle R. Green Ecology, and Relationships to Other Oaks ...... 75 Nursery Propagation of California Oaks ...... 143 Gilbert J. Muth Suzanne Schettler and Michael Smith Change in Vegetative Cover of Oak Stands in Southern Nutrient-Microbial Considerations in Oak San Diego County: 1928-1970...... 81 Management ...... 149 Carla R. Scheidlinger and Paul H. Zedler Paul H. Dunn Oaks and the California Landscape ...... 161 Storage by Acorn Woodpeckers in an Oak R. Burton Litton Jr. Woodland: An Energetics Analysis ...... 265 Measures That Can Help Offset the Detrimental Effects Walter D. Koenig That Urban Development Has on Oak .... 167 Annual Oak Mast Yields from Visual Estimates ... 270 Paul A. Rogers Walter C. Graves Aspects of Water Relations in Coast Live Oaks and of California Oak -Management Valley Oaks Subjected to Root Damage from Land Implications...... 275 Development Operations ...... 171 Reginald A. Barrett Stephen W. Roberts and Robin L. Smith Ecological Relationships Between Southern Oak Banks and Relocation ...... 176 and California Black Oak...... 292 Richard D. Cross R. Terry Bowyer and Vernon C. Bleich Characteristics of Root Systems: California Oaks . . 178 Trends in oak Utilization-Fuelwood, Mast W.D. Thomas Production, Use ...... 297 California Oaks and Outdoor Recreation ...... 180 John W. Menke and Michael E. Fry Sam S. Ayano Livestock Utilization of California's Oak Damage Factors Woodlands ...... 306 Feeding on California Oak Trees ...... 184 D.A. Duncan and W.J. Clawson Leland R. Brown Effect of Blue Oak on Rangeland Forage Production in Diseases of Oaks in California ...... 195 Central California ...... 314 Robert D. Raabe V.L. Holland Response of Oaks to Fire ...... 202 Effect of Blue Oak on Nutritional Quality of Rangeland Timothy R. Plumb Forage in Central California ...... 319 Sprouting in Fire-Damaged Valley Oaks, Chews V.L. Holland and Jimmy Morton Ridge, California ...... 216 Effect of Blue Oak Removal on Herbaceous Forage James R. Griffin Production in the North Sierra Foothills ...... 323 Effect of Chronic Oxidant Air Pollution Exposure on Burgess L. Kay and O.A. Leonard California Black Oak in the San Bernardino Oak Trees and Livestock-Management Options . . 329 Mountains ...... 220 Alfied H. Murphy Paul R. Miller, Gail J. Longbotham, Robert E. Van Energy Yield Potentials of California Oaks and Other Doren, and Maureen A. Thomas Wood Biomass ...... 333 Sea-Salt Aerosol Damage to and A1 Groncki in the , Economics of Utilizing Oak for Energy ...... 345 California ...... 230 Raymond Stine Gary L. Ogden Obse~ationson Abundance in Several Tolerance of Oaks to Flooding ...... 238 California Black Oak Habitats in Northern Richard W. Harris, Andrew T.Leiser, andRobert E. California ...... 354 Fissell Steven J. Kerns Animal Damage to Valley Oak and Seedlings, Acorns-Food for Modem Man ...... 360 Camel Valley, California ...... 242 Jeanine A. Derby James R. Griffin Wood Products from California Oaks, Cal Oak Lumber Products Company Style ...... 362 Guy Hall of California Oak Habitats-Management Implications...... 246 Jared Verner PREFACE Grateful recognition is due the members of the Coordinating Committee, who provided technical support and encourage- In June 1979, more than 200 people met on the campus of ment: Scripps College in Claremont to share information about our native oaks, one of California's most important natural re- Leland R. Brown, University of California, Riverside sources. Historical records show that the beauty and value of Reginald Barrett, University of California, Berkeley the arborescent oaks were readily apparent to the early settlers, James R. Griffin, Hastings Natural History Reservation, but during the last 200 years, probably more effort has been University of California, Carmel Valley spent to remove and kiil oaks than to grow and manage them. Philip M. McDonald, Pacific Southwest Station, Redding Efforts by concerned individuals and public resource organi- Nonnan H. Pillsbury, California Polytechnic State Uni- zations to manage oaks have generally been ineffective. versity, San Luis Obispo Because of the "poor" stem form and the relatively slow Jared Verner, Pacific Southwest Station, Fresno growth of most oak trees, professional foresters have generally Herbert Hahn, Pacific Southwest Region (R-5), Forest concentrated their efforts on managing other trees, mainly Service, representing the Society of American Foresters. conifers. Recently, however, broad-scale interest in oaks has developed. The public has become aware of the limitations of The chairmen of the four sections of the meeting contributed our natural resources. The potential of the oak woodlands in greatly to the success of the symposium, and their work is meeting energy shortages and wildlife needs, as well as the sincerely appreciated: great immediate value of these woodlands to recreation, are Ecological Relationships, James R. Griffin now being recognized. This recognition, and the intense con- Silviculture and Management, Philip M. McDonald cern now felt about the urbanization of California's wood- Damage Factors, Leland R. Brown lands, have contributed to the success of the symposium. Products, Jared Verner The symposium was sponsored by Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Depart- We also thank the many individuals who took care of the ment of Agriculture, and the Society of American Foresters. multitude of jobs to be done, in particular, DiAnne Broussard, The background for the symposium and its general tenor was Pacific Southwest Station, Riverside, who served as sym- set in the opening address by Dr. Robert Z. Callaham, Director posium coordinating assistant. The Research and of Pacific Southwest Station, who emphasized that the sym- Development Program and the Chaparral Research Work posium was a joint effort by scientists, land managers, and Unit, both of Pacific Southwest Station, Riverside, supported practitioners representing many different points of view. the symposium from its inception.

Timothy R. Plumb Forest Service, U.S. Department of Agriculture Chairman, Coordinating Committee Opening Remarks1

Robert Z. callaham?'

I am particularly happy to be here to open Although one of California's largest this meeting because I know it is needed. natural resources, oaks are almost unmanaged. Expressions of need for information about oaks Utilization is low, nonexistent, and even in California have been numerous and frequent designed to reduce the oak resources in many in recent years. Responding to this need, the areas. Most foresters either ignore oaks or Forest Service, specifically our Chaparral consider them as weeds. For many years, oaks Research and Development Program, has organized have been looked upon as a detriment to range this Symposium dealing with oaks in California. management. Currently, where urbanization is invading the oak-woodlands, the oaks are mixed You are about to participate in the first blessings. Some people look upon them as a meeting ever designed to collect all facets of nuisance impeding progress; and others value information about oaks and related in them very highly for their individual beauty, California. This Symposium is going to make for the shade they cast, and for other available a great deal of information, much of environmental benefits. it heretofore unpublished. People seem to know more about oaks than they have ever bothered to Tremendous interest in oak has developed publish. In some disciplines, such as taxonomy in the past few years. Some of this interest and entomology, there is quite a bit of informa- is undoubtedly generated by the rapid loss of tion~veryspecific and technical. In some native oaks in urban-range environments. The other disciplines, such as silviculture and recent emphasis on renewable energy resources , we lack information but hope this has rekindled interest in the use of oak wood, Symposium will provide the occasion to pull particularly to replace fuels. There together what is known. is growing recognition by more than the wild- life professionals that oaks are tremendously One primary purpose of this meeting is to important to wildlife . Most of us identify the information gaps. Some people have at least a subconscious, latent affection talk about the state-of-the-art, but I have for stately oaks and recognize their come to reject that phrase. I have learned to environmental and social values. distinguish between the state-of-science and the state-of-practice. These are two impor- Oaks obviously have more value than just tant and different subjects. Scientists want being nice to have around. Traditional uses of to know about frontiers of knowledge and the oaks for lumber or other wood products (ex- gaps for further exploration. Practitioners cluding fuel) have been extremely limited in have very little interest inthe state-of- California. This limitation is due partially science; they are only interested in what is to poor tree form, problems is seasoning lum- known that can be put into practice today, at ber, and high levels of defect found in our what costs, and with what benefits. This meet- native trees. But some innovative milling ing strives to describe both the state-of- techniques have overcome many of these past science and state-of-practice relating to oaks problems. Utilization of native oaks for lumber in California. is increasing. Modern laminating techniques and seasoning procedures have made it practical to use small and otherwise unusable wood resources.

But oaks have many values other than being 1 just a source of wood products. Their value -Presented at the Symposium on the Ecology for watershed protection, wildlife habitat, Management and Utilization of California Oaks, recreational enjoyment, and general esthetics June 26-28, 1979, Claremont, California. far exceed their potential value as wood products. With these other values in mind, -~irector,Pacific Southwest Forest and Range crooked, branchy trees with a high incidence of Experiment Station, Forest Service, U.S. defect may not be valueless. But what are their Department of Agriculture, Berkeley, California. values? One accomplishment I would like to have from this meeting is an expression of how we success. Obviously, the technology for might quantify the nonwood values of oaks. management is lacking.

Fire, the constant threat to all forest The Chaparral R&D Program, launched by trees in California, may cause extensive the Forest Service in in damage and reduced lumber values, but it may November 1977, sent out a questionnaire ask- not seriously affect the nonlumber values of ing about interest in oak management. oaks. In almost every location where condi- Responses evidenced a very high level of in- tions permit tree growth, one or more species terest. Eighty percent of the respondees of oak can be found. They are a component of indicated a mild to intense interest in oaks. the major vegetation types. For example, here This response caused us to bring together 70 in Southern California, they grow in the people a year ago to plan for this Symposium. valleys below the chaparral, in the chaparral Consequently, this meeting is the result of itself, as fingers in the riparian draws and a joint effort by many different institutions drainages that dissect the chaparral, and then and by people having diverse interests, on up into the conifer forest above. organizational affiliations, and professional backgrounds. Unfortunately, we do not have an accurate estimate of California's oak resource. Oaks Here we are at the fruition of our are estimated to grow on about 15 to 20 million planning. More than 50 papers provide a cross acres in California. That acreage forms 15 to section of many interests and viewpoints about 20 percent of the entire state. This estimate oaks. Papers range from highly technical. to includes only about 5 million acres of conuner- very practical. There should be something of cia1 forest land. Estimates of the volume of interest for everyone in the audience. We want oak resource are traditionally based only on your active participation. You are a small trees that grow on these commercial forest enough group that your inquiry and dialogue as lands. So we really have no idea of the cur- a committee-of-the-whole will be meaningful and rent volume and value of oak in California. rather easy to manage. Please join in, ask Certainly, the current growth of oaks greatly questions, and seek out people having interests exceeds their utilization for any products or related to yours. Whoever knows about oaks values. should be in this room. You should be able to find the people that have some information on The Forest Service, other organizations, almost any question. I know that you will and individuals have attempted to manage oaks. benefit from this meeting, and I wish you These efforts have met with little or no success. Thank you for coming. Ecological Relationships

Neogene History of the California Oaks1 Jack A. wolfe2

Quercus wislizenii Abstract: The Neogene oaks of California and adjacent states represent groups that have survived in California to- day. The Agrifoliae, Lobatae, and have a history largely in the summer-wet Miocene forests of the Pacific Northwest. The white scrub oaks and Q. tomentella apparently originated in California or in areas to the southwest. The associations and geographic ranges of the California oaks were probably greatly a1 tered during the climatic fluctuations of the Pleistocene.

The fossil record has only a limited A review of the Neogene (Miocene and contribution at this time relative to the Pliocene) oaks of western North America phylogenetic relationships within Quercus. indicates that almost a1 1 of the species This is partially because of the difficulty groups extant in California had evolved by in working with foliage in a polymorphic sometime in the Miocene. In the Pacific , concomitant with the problems of Northwest during the early to middle Miocene, fol iar convergence and para1 lel ism such as the flora included at least three species of discussed by Tucker (1974). Even more Agrifol iae; one of these represents the significantly, fossil assemblages ancestor of Quercus kel loggi i. During the older than 22 to 23 million years--that is, Neogene this lineage undergoes progressive pre-Miocene and pre-Neogene--are unknown in foliar evolutionary trends such as 1) an the low1 and areas of southwestern North increase in number of lobes, 2) an increase America, except for Paleocene and older in the degree of dissection of the lamina, assemblages, which probably predate the and 3) an increase in the frequency of of oaks. secondary teeth on the lobes. This lineage includes variously ref erred to Q.

Fol iaae of soecies di solavi" na.# characters pseudolyrata Lesq., Q. merriami Knowlt., and of ~epid~balanu~,~r~throbalanus, and Proto- Q. deflexiloba H. v. Sm. A closely related balanus occurs in the Florissant flora of species is Q. cognata Know1 t. and its unde- (MacGinitie. 1953). which is of scribed descendant species; this 1ineage late ~oceneage. he relationships of any maintained the presumably primitive shallow of the Florissant oaks to any extant species and few-lobed conditions and became extinct or species groups are, in my opinion, highly by the end of the Miocene. An undescribed conjectural. Not until the Miocene can many oak from the Latah flora of Washington is be confidently relegated to particular allied to Q. agrifolia and Q. wislizenii, species groups of extant oaks. although the fossil may not be directly ancestral to either species. The next- youngest record of this type is Q. cedrusensis Wolfe from the late Miocene of Nevada (Wolfe, 1964). Also represented in the early to middle Miocene of the Pacific Northwest is a species -'submitted to the Symposium on the Ecology, of Protobalanus closely a1 1ied, and probably Management, and Utilization of California Oaks, ancestral, to Quercus chrysolepis Liebm. By Claremont, California, June 26-28, 1979. the middle to late Miocene, foliage apparently indistinguishable from Q. chrysolepis is of L'~eol ogist, Geological Survey, U.S. Depart- wide occurrence in the Pacific Northwest, as ment of Interior, 345 Middl efield Road, Menlo well as in more southern areas (Wolfe, 1964, Park, Calif. 1969). Lobed species of Lepidobalanus occur in The known Neogene floras from Nevada the Neogene of the Pacific Northwest. The appear to represent vegetation that grew at a earl iest of these--Q. col umbiana Chan.--is considerable altitude and that is floristically typically simple-lobed, although some specimens closely allied to the Neogene floras of the possess rare teeth on the lobes. Some of Pacific Northwest (Wolfe, 1969). All the the specimens have decidedly rounded lobes, oaks now known represent the Agrifoliae, but some have very sharp-almost spinose- Quercus simulata, or Protobalanus allied to lobes, indicating a possible relationship to Q. chrysolepis. The one specimen attributed the bristle-tipped Asian species of Lepido- to the Lobatae (Axel rod, 1958) is a fragmentary balanus. Several specimens of the early and lobe of the & macrophyl lum type. middle Miocene Alaskan Q. furuh'elmi Heer are definitely bristle-tipped"; and In California, the early to middle Miocene Tanai, in press), and thus the Pacific flora is known from only two assemblages: Northwest species could conceivably include the undescribed Valley Springs flora from the some genetic influence from Q. furuhjelmi. early Miocene in the western foothills of the In any case, one descendant of this probable central Sierra Nevada and the Tehachapi flora plexus--Q. winstanleyi Chan.--represents an from the middle Miocene of the Mojave desert extinct and simple-lobed lineage. By the (Axelrod, 1939). The oaks in the latter late part of the middle Miocene, a second flora are in great need of work with modern lineage is consistently compound-lobed and techniques of foliar analysis. Members of is clearly leading to Q. garryana and Q. Protobalanus are probably present in the lobata. Tehachapi, but whether the scrub oak type of Lepidobalanus is a1 so present remains to be Yet another group is represented in the demonstrated. The only oak in the Val ley Neogene of the Pacific Northwest. The rela- Springs assemblage is closely related to tionships of the species known as Quercus of Protobalanus. simulata Know1t. have been much discussed. Some workers (e.g., Chaney and Axelrod, 1959) During the late Miocene--5 to 13 million have favored a relationship to certain Asian years ago~relativesof most of the extant species that are segregated by many system- California oaks were represented in California. atists into the genus Cyclobalanopsis. A Some of these, however, first appear in the recent chemical analysis of leaves of Q. latest Miocene, that is, younger than 10 simulata (invalidly referred to Q. consimilis) million years. For example, the group now by Niklas and Gianassi (1978), however, represented by the blue oak, Quercus douglassii, indicates that the fossil is closely related is not known until the latest Miocene in to Asian oaks such as Q. acutissima and Q. California (Condit, 1944), and possibly a1 1 chenii but not to any of the cyclobalanopsid the Dumosae also appear at about this time. oaks. Unfortunately, Ni klas and Gi anassi did Considering the general excellence of the not include in their analysis of extant Neogene record in the Pacific Northwest and species the west American Q. sadleriana; this Nevada, I think it reasonable to conclude species has several critical morphological that oaks such as the white scrub oaks were similarities in foliage to Q. simulata and Q. either present in California lowland areas in acutissima. It seems most probable that 0. the early Neogene or entered the state from simulata represents the same species group as the southwest. does the extant Q. sadleriana. It would, however, be highly conjectural at this time One point that the fossil record clearly to derive Q. sadleriana directly from Q. indicates is that there has been little simulata. Also included in this species interchange of oaks between North America and group is Q. bockei Dorf from the Pliocene of Eurasia. Only in Lepidobalanus can some . interchange be documented, and even this was very 1imi ted. No oaks referable to Erythro- The species known as Quercus dayana Knowlt. balanus or to Protobalanus are known in has been likened to the eastern American Q. Eurasia or even at high latitudes in North virginiana (Chaney and Axel rod, 1959) ; in America. The most northern occurrence of marginal and ultimate venation, however, the Erythrobalanus is in northern Washington fossils represent . A second during the middle Miocene. For Protobalanus species known as Q. eoprinus H. v. Sm. has, the most northern occurrence is at latitude as the epithet indicates, been compared to 54O in central British Columbia, also during another eastern American oak; in several the middle Miocene. critical characters, the fossils can be demonstrated to represent Fagus. Thus, a1 1 What is perhaps of more pertinence to this the Neogene oaks now known in the Pacific symposium is to learn from the fossil record Northwest appear to represent species groups the general climatic-ecologic background of that are still extant in western United the California oaks. That is. have certain States. 1ineages been confined to a particular climatic in the northern Sierran foothills during the regime for millions of years, which would latest Miocene. The blue oak may well be a indicate little adaptive ability? Or, have late Neogene derivative in California of the some lineages shown considerable tolerance of Lobatae. various clirnatic regimes? The Quercus chrysolepis lineage appears If paleobotanists re1 ied strictly on since the middle Miocene to have been primarily present climatic tolerances of extant relatives a member of Mixed Coniferous forest--that is, of fossil species to determine the climates to areas of moderate summer temperatures. under which various assemblages lived, I This lineage appears to have been more would certainly run the risk of circuitous common in late Miocene assemblages that, reasoning. However, paleobotanists also use a1 though existing under summer , were data based on the physiognomy of fossil somewhat dry. Thus the lineage appears to assemblages; for example, types of leaf have occupied areas that were climatically margins, leaf sizes, proportions of conifers, similar to areas in the present range of Q. broadleaved , and broadleaved ever- chrysolepis. green , etc. Such physiognomic analyses are independent of the taxonomic composition In regard to the lepidobalanid scrub oaks of a fossil assemblage and thus allow an and tree species such as Quercus engelmannii evaluation of the various climates under and the protobalanid Q. tomentella, the which various 1i neages and species groups oldest occurrences of these are in subhumid have lived (Wolfe, 1971). assemblages. The presumption is that such 1ineages have a long history in dry environ- In regard to the Agrifoliae, the fossil ments. However, the evolutionary and ecologic record strongly indicates that the evolution history of these oaks will await future of the group was centered in the Pacific paleobotanical work. Northwest. During most of the Miocene, this region was characterized by summer rainfall; One point that must be emphasized is that by the late Miocene, however, the amount of the geographic ranges of the California oaks summer precipitation was decl ining. Summer were drastically a1 tered during the Pleistocene, temperatures were general ly higher than now, and such alterations occurred several times. and, during the early and middle Miocene, the During an early Pleistocene glacial, for mean of the wannest month was certainly 20 to example, the lowland vegetation near San 24T. The known records of the Agrifoliae Jacinto included both uercus chrysolepis and during the early and middle Miocene are in wislizenii (Axelrod,51966 . During the vegetation that was a diverse broadleaved ?Âater Pleistocene I1linoisan glacial, the forest. A1 though the Quercus kel loggi i lowland area around Clear Lake in the North lineage also occurred in lowland broadleaved Coast Ranges was occupied by a Mixed Coniferous forest during the late Miocene, many occur- forest that contained Q. chrysolepis; this rences are also in upland Mixed Coniferous area is now a woodland of blue, California forest. In such forest, warm month means are white, and interior live oaks. During the consistently less than 20°C By the late Y annouthian interglacial, the blue and interior Miocene, therefore, the Q. kel loggi i 1ineage live oaks occurred abundantly at Clear Lake, had adapted to approximately its present but no California white oak has been found. temperature range, but the lineage has shown Not only have the geographic ranges of the a progressive adaptation to drier summer California oaks been repeatedly altered regimes. during the Pleistocene, the particular communities may have undergone Quercus agrifol ia and Q. wisl izeni i have significant floristic change. somewhat problematic records. Related fossils occurred in summer-wet assemblages in the Pacific Northwest in the middle Miocene and in drier but probably still summer-wet assem- blages in Nevada during the late Miocene. LITERATURE CITED Both lineages became abundant by the latest Miocene in California under even drier Axelrod, D. I. conditions. 1939. A Miocene flora from the western border of the Mohave Desert. Carnegie The climatic history of the Lobatae paral- Inst. Washington Pub. 516, 129 p. lels that of the Q. kel loggii lineage: adapting from summer-wet to summer-dry climates Axelrod, D. I. during the Neogene. It may be significant 1958. The Pliocene Verdi flora of western that the oldest occurrence of the Q. douglassii Nevada. California Univ. Pubs. Geol. lineage is in a mesic summer-wet assemblage Sci., V. 34, p. 91-160. Axelrod, D. I. Tucker, J. M. 1966. The Pleistocene Soboba flora of 1974. Patterns of parallel evolution of southern California. California Univ. leaf form in New World oaks. Taxon, v. Pubs. Geol. Sci., v. 60, 79 p. 23, p. 129-154.

Chaney, R. W., and D. I. Axelrod Wolfe, J. A. 1959. Miocene floras of the Columbia 1964. Miocene floras from Fingerrock Plateau, Part 11. Systematic Wash, southwestern Nevada. U.S. Geol . considerations. Carnegie Inst. Washington Survey Prof. Paper 454-N, p. N1-N36. Pub. 617, p. 135-237. Wolfe, J. A. Condi t, Carl ton 1969. Neogene floristic and vegetational 1944. The Remington Hill flora. Carnegie history of the Pacific Northwest. Inst. Washington Pub. 553, p. 21-55. Madrono, v. 20, no. 3, p. 83-110.

Mac initie, H. D. Wolfe, J. A. 953. Fossil plants of the Florissant 1971. Tertiary climatic fluctuations and beds, Colorado. Carnegie Inst. Washington methods of analysis of Tertiary floras. Pub. 599, 198 p. Palaeogr., Palaeocl im., Palaeoecol ., v. 9, p. 27-57. Nik as, K. J., and D. E. Giannasi 978. Angiosperm paleobiochemistry of the Wolfe, J. A., and T. Tanai Succor Creek flora (Miocene), , in press. The Miocene Seldovia Point USA. Am. Jour. , v. 65, p. 943- flora from the Kenai Group, Alaska. 952. U.S. Geol. Survey Prof. Paper 1105. History of Cultural Influences on the Distribution and Reproduction of Oaks in California1

Randall S. Rossi-2'

Abstract: Prior to the advent of European colonization, the California Indians' impact on oaks was confined to acorn collecting and the occasional use of fire. Since 1769 oaks have been vulnerable to six human activities: stock raising, wood cutting, agriculture, flood control, fire supression, and urbanization. Specific research concerning human impacts on the distribution and reproduction of oaks has been meager. In this survey of cultural influences, grazing activity is identified as the most persistent pressure on oak reproduction. Charcoal production consumed a significant amount of oak until the 1960's; incomplete data suggest that cordwood sales con- tinue to account for much wood cutting. Agricultural clearing, initially for orchards, and later for row and field crops, has greatly reduced the range of some species, e.g. valley oak (Quercus-- lobata). Extensive clearing of blue oak (Q. douglasii) from foothill range in the late 1950's and 1960's was partially supported by federal payments. Riparian oak in the have been disappearing since early American occupance and today only a fraction of the original woodland remains. Be- cause of fire suppressionefforts since 1900, the build up of fuels and the invasion of woody plants in oak communities make lethal, high-intensity fires more likely. Finally, urban and suburban land uses continually displace native oaks and condemn remnant stands to slow decline without replacement.

INTRODUCTION

Human activities of the last two hundred This paper surveys the state of our years have greatly reduced the range of many knowledge about human impacts on California's California oaks and adversely affected their oaks. Historically, oaks have been vulnerable reproduction. While we are aware of the gen- to at least six human activities: stock raising, eral course of this demise, the actual losses wood cutting, agriculture, flood control, fire have been incremental, unchallenged,~and unre- supression, and urbanization. The biggest corded. Further, we are only beginning to ask: change of the last two hundred years, of course, What are the consequences of this impoverish- is that the foothills and valley floors, once ment of the landscape? occupied by many species of oaks, are largely covered by the farms, cities, and freeways of twenty-two million people.

Ñ'presente at the Symposium on the Ecology, Four major oak communities, covering about Management, and Utilization of California Oaks, 10 percent of the state, have been recognized as Claremont, California, June 26-28, 1979 part of California's original landscape. These are: 1) Northern Oak Woodland of the North Coast Ranges and valleys, (, 2'~h. D. Candidate, Geography Department, University of California, Berkeley. -Q. kelloggii, Q. chrysolepis, and Q. wislizenii); 2) Foothill Woodland of the alluvial terraces Oaks are part of what we define and iden- tify as typically Californian. Attention nat- urally focuses on the California endemics, --Quercus lobata (valley oak) and Q. douglasii (blue oak) which are widely distributed in and around the Central Valley and Coast Ranges. The valley oak, largest of the North American oaks, grows on deep alluvial soils and up onto broad ridge tops. It often forms strikingly beautiful , having a parklike appear- ance. The blue oak grows on rolling hills and drier sites, singly or in clumps, and is common on thousands of acres throughout the state.

The task of reconstructing how our oak woodlands have changed is a difficult one, and there will always be great gaps in our knowledge. Only a handful of studies have been concerned with landscape changes in the oak woodland (Thompson 1961; Brooks 1967; Vankat 1970; Griffin 1971, 1976; Snow 1972; Dutzi 1979; Rossi 1979). While university and government personnel have advocated and aided in the clear- ing of thousands of acres of oaks, no state or federal agencyhas monitored or inventoried the extent or cumulative effects of the activity. Figure 1 - Areas of Oak and Today we find we lack any accurate estimates Woodland in California of even the most recent clearing. Further, with notable exceptions (Griffin 1971, 1976; Snow 1972), the conspicuous lack of oak regeneration, and surrounding hills of the Central Valley perhaps the most important issue in oak manage- and Inner Coast Ranges, (Q. douglasii, Q. lobata, ment, has received virtually no study. In strong -Q. chrysolepis, Q. agrifoiia~wislizenii); contrast to the long history of conservation 3) Southern Oak Woodland of the coastal valleys and land stewardship examined by Parsons (1962) of Southern California, (2. agrifolia, and (5. in Spain's oak woodlands, California oaks have enge1manngi);and 4) Riparian Woodlands espec- been disregarded as a natural resource. ially on the Central Valley river margins, where valley oaks (Q. lobata) were locally abundant (Munz and Keck 1963; Griffin 1977). ABORIGINAL INFLUENCES

Each species and certain associations The extensive, almost continuous oak wood- have sustained different kinds of impacts at lands and savannas of California provided the different times. While some areas are relatively staple food of the native Indians for centuries. unchanged,in others some species have been elim- The acorn and the oak were worshipped by these inated over wide areas, or exist only as remnant hunter-gatherers (Pages 1937). The extent of stands. And where individual trees or woodland their adverse impact on oaks was confined to tracts remain there may be a false sense of well- acorn collecting and the occasional use of fire. being, since few, if any seedlings are becoming established. An estimated 500 pounds (230 kg) of acorns were consumed each year (Hoover 1977). In poor The nature and extent of human impacts on seed years it is likely that nearly all of the oaks before 1930 is not comparable to that of crop from some species was collected and stored. the last fifty years. Pressures on oaks have The preference for acorns of tan oak (Lithocarpus increased due to the rapid increase and spread densiflora) and California black oak, ( ,Q. kello- of population, increasing land values, the ggii) and the accessibility of acorns from valley lengthy periods of firesuppression, the devel- oak must have created a considerable pressure on opment of practices and machinery for clear- these species ( 1902; Baumhoff 1963). ing range land, channelizing , and build- In the Central and Southern Coast Ranges, coast ing roads and cities. The oaks, which were the live oak (Q. agrifolia) sustained California's single most important plants in the lives of densest Indian population. The effects on repro- the Indians, are valued by modern man only as duction of acorn collecting should not be ig- amenities in real estate. nored, but the extent to which it may have altered oak distribution is not known. droughts, and the introduction of Mediterranean annual plants contributed to the rapid replace- The use of fire to clear the ground be- ment of the original bunchgrass vegetation fore acorn harvesting has been noted in North- (Hendry 1931; Burcham 1957). There is evidence ern California and Yosemite Valley (Baxley that this change resulted in greater competi- 1865; Harrington 1932; Schenck and Gifford) tion for oak seedlings in the thick annual cover 1952). Fire was used to drive game, aid in (Holland 1976).?/ Further, poisoning and trap- collecting food, and make clearings for grow- ping of.predators, coupled with the increasein ing tobacco (Kroeber 1925). Any such fire seed-bearing plants, has brought an increase could kill oak seedlings, but light ground in seed-eating rodents and birds, putting added fires would not harm established trees. Cap- pressures on the acorn crop (Holland 1976). tain Belcher observed on the Sacramento River in 1837 that during the dry season the natives When a mission was established, it would burned the annual growth, "and probably by customarily receive from other missions gifts such means destroy many oak plantations which of livestock to begin new herds. In 1827,four otherwise would flourish" (Belcher 1969, p.48). years after the founding of the last mission, Hinds, a botanist on Belcherls expedition re- Thomas Coulter reported that collectively they ported Sacramento Valley nativesf practice of had 210,000 branded and 100,000 unbranded cat- lighting their fires at the bases of valley tle (Coulter 1951). oaks. He continued, "and as they naturally select the largest, it was really a sorrowful Grazing continued to be the most wide- sightto behold numbers of the finest trees spread pressure on oaks throughout the Rancho prematurely and wantonly destroyed" (Hinds era that followed mission secularization in 1844, p. 3). From this brief description the 1833. Most of the land grants and grazing death of the trees must be interpreted as ac- activity were in the Southern and Central Coast cidental, since they represented a perennial Ranges where huge herds roamed the grasslands food resource. and the woodlands alike (Cleland 1941). Burcham (1957) in his history of California range land Regarding the valley oaks, Jepson felt considers the foothill woodland a grazing re- "it is clear that the singular spacing of the source second only to the grasslands. In the trees is a result of the periodic firing of woodlands, grazing impacts are highly selective, the country - an aboriginal practice of which since cattle seek out the shade, devouring the there is ample historical evidence" (Jepson oak seedlings and acorns. Further, repeated 1923, p. 167). Lewis (1973) has argued that trampling of clay soils makes germination of the California native had an active role in woody plants more difficult (Wells 1962). The manipulating vegetation with fire. Sampson acorn crop suffers doubly because of its pal- (1944). Burcham (1957). and Clar (1959) have ability and the time of its ripening at the suggested the influence was more benign. Per- end of the dry season when forage is scarce. iodic burning by the California Indians may Bryant (1848) observed in the Central Valley have thinned oak stands or caused certain that "during the period of transition from areas to remain open, but probably was not a the dry grass to fresh growth, horses, mules, significant factor in altering the overall and even horned cattle, mostly subsist and abundance or distribution of oaks. fatten upon these large and oleginous nuts" (p. 351). Jepson (1910)called the acornsofblue oak in the Sierra foothills "one of the ranch- EARLY STOCK RAISING man's assets for stock feed" (p. 216.).

Before European contact, California oaks Beginning in the late 1700's swine fed were principally a food resource, and had on acorns at Mission San Antonio and other evolved in the absence of grazing, agriculture, missions (Bolton 1926; Engelhardt 1929). Dur- or commercial uses. However, this changed for- ing the 19th century hogs were driven to oak ever when the Spaniards brought their faith, groves for mast feeding in the Coast Ranges agriculture, and grazing to Alta Cal- (Q. agrifolia) , Central Valley (Q. lobata) , ifornia in 1769. Cattle and sheep certainly and Sierra foothills (Q. douglasii), and the consumed acorns and many seedling oaks in the acorns were also collected and fed to the an- vicinity of the missions. The grazing tracts, imals in lieu of grain (Bryant 1848; Sudworth or ranchos, of many missions were in oak stud- 1908; Jepson 1923; Fages 1937). In the 1920's ded lands, for example Mission Santa Clara, hogs were still being fattened on acorns in San Jose, San Antonio, San Miguel, Santa Ines, the Santa Lucia Mountains for shipment to San and San Juan Capistrano. Jepson (1910) obser- Francisco (Coulter 1926). ved that the chain of missions corresponded roughly to the range of the coast live oak, and that Spanish land grants encompassed most 2'~ersonal communication, C. B. Hardham, of the valley oak forests. Local overgrazing, Botanist, Paso Robles, California. In 1834 the number of cattle held by the County (Watts 1959). Oak wood was used to missions alone was estimated to be 400,000 fuel the quicksilver (mercury) retorts at New (Bolton 1917). As private ranchos replaced Almaden (Santa Clara Co.) and New Idria (San the mission holdings, stock raising spread Benito Co.), as well as at mines in Napa, Lake, throughout the state. Cattle numbers burgeoned and San Luis Obispo Counties (Yale 1904) .A/ in response to the Gold Rush influx, until an estimated one million roamed the land in 1860 Fire wood cutting was incidental to land (Burcham 1957). From 1849 on, month-long cat- clearing in some instances, but in others a tle drives were regularly made from Southern profitable activity in itself. Sudworth (1908) California ranchos to San Francisco. Treks noted that valley oak from the river banks, and involving herds of several thousand were made interior live oak (Q. wislizenii) from thesierra through the Central Coast Ranges and San foothills were "highly prized for domestic use" Joaquin Valley in the fall as the acorns ripen- in the Sacramento Valley. In 1914-1916, as part ed (Cleland 1951). The drought of 1862-64 of an orchard development, 20,000 cords of oak brought cattle numbersplummeting, but the oaks (valley oak, blue oak, coast live oak) were continued to suffer. During the droughts of cleared from 12,000 acres (4800 ha) on the 1862-64 and 1897-98, small trees and branches Salinas River near Atascadero in San Luis Obispo from larger ones, especially Q. agrifolia in County (Rossi 1979). The wood was shipped by the South Coast Ranges, were cut to provide rail to San Francisco and Los Angeles. Thereare, browse in the path of starving cattle and no doubt, numerous examples such as these from sheep (Jepson 1910; Lynch 1935). The recur- all over the state. ring droughts, while temporarily reducing the cattle population, actually heightened the im- For more than a century oak has been the mediate grazing pressures, and seedling oaks preferred wood for manufacture of charcoal in stood little chance of survival. California. Bancroft (1890) says that charcoal from oak had been burned in California since the In the 1870's and 1880's the livestock early 1850's. Oak was cut around San Francisco industry began recovering with sheep numbers Bay to supply charcoal burners in the 1850's reaching over four million in 1880, and cattle and 1860's (May 1957). In 1855, 11,000 bags of one million again by 1890 (Burcham 1957). Dur- charcoal, the equivalent of 110 tons made from ing the wheat "bonanza" decades at the end of "red", white, and live oak, was consumed in and the 18001s, grazing land was pushed out to the about San Francisco. In the 1860's powder mills margins of the cropland, and into the oak wood- in Santa Cruz and Marin Counties used charcoal land and foothills (Hutchinson 1946). The poor as a major constituent of their product. In the natural reproduction in California's oak wood- 1880's the Clipper Gap Iron Company annually lands since that time has been generally attri- burned 10,000 to 15,000 tons of charcoal in its buted to grazing-related influences (Sudworth furnace near Auburn, requiring as much as 30,000 1908; Jepson 1910). cords of wood each year (May 1956).

In the early 1900's charcoal from oak was WOOD CUTTING made in large quantities throughout the state, especially in Sacramento, Shasta and Sonoma In 1793 on Vancouver's voyage down the Counties. Between 1905 and 1910 California's California coast,parties were landed near Santa annual charcoal production averaged 160,000 Barbara to secure water and fuel. Menzies re- sacks from 3200 cords of wood. Sonoma County ported in his journal wood "was easily procured was the top producer then, with about 100,000 at no great distance from the beach as there sacks annually, or about 1,000 tons of charcoal were some large trees of a kind of ever green per year. In 1914 at Heroult on the Pit River, Oak, which they were suffered to cut down for a site now under Shasta Lake, 50 cords a day of the purpose" (Menzies 1924 ). California black oak were distilled to charcoal for the Noble Electric Steel Company (May 1956). During the 19th century, oak wood was a primary source of fuel, but it is impossible In the decades from 1920 to 1940 therewere to know how much was cut for this purpose. It only a few charcoal plants of substantial size was reported that mission padres in the San in operation. During the early 1920's a char- Gabriel Valley had instructed the Indians to coal plant near Templeton in San Luis Obispo cut only oak tree limbs for fuel "preserving County was making charcoal out of coast live the trunks with sacred care" (Clar 1957). Oak wood was used for heating and cooking through- out the mission and rancho period. Fuel and timber demands were locally heavy during the T'~ossi, R.S. (1975) The quicksilver mines of mining era. Blue oak and pine were used as the Santa Lucia Mountains in northwestern San fuel and mine timbers in the Mother Lode mines, Luis Obispo County, California. Unpublished with forest removal greatest in El Dorado manuscript. 40 p. oak and valley oak, and one near Ukiah in Men- Statistics point out that 7.8 million docino County was using canyon live oak ((5. board-feet ofhardwoods were cut in 1976, vir- chrysolepis). In 1939 about 1400 tons were tually all of it California black oak. At the produced, but eight years later only a few state's largest hardwood mill, Cal Oak, locat- small kilns in San Luis Obispo County were ed at Oroville, the wood is used primarily for operating (May 1956). However, ten years pallet stock, with a small volume entering later, following World War 11, the increasing furniture manufacturing in Los ~ngeles.z/ A popularity of "outdoor living" sustained the smaller amount of white oak, mostly (5. lobata operation of over forty charcoal plants once is cut annually, and estimated to be between again in the state. A 1955-56 survey found one and two million board-feet (Dost and 30 wood charcoal kilns in San Luis Obispo Gorvad 1977). Recently riparian oaks (Q. County, seven in the Sierra foothills, and lobata) have been cut and sold for wood chips four in Southern California. In that year (McGill 1975). Additionally, each year thou- San Luis Obispo accounted for more than 80 sands of cords of oak firewood are sold in percent of the 4,650 tons produced (May 1957). metropolitan areas, but the sales reported are Questionnaires determined that 99 percent of only a fraction of the actual volume involved. the wood burned was oak. Coast live oak was In 1977 California Department of Forestry re- the most commonly used in San Luis Obispo ported 18,500 cords of fuelwood cut in the County, cut from the Santa Lucia foothills in state (California Dept. of Forestry 1977). For the Upper . Oregon white oak the last three quarters of 1977 the State Board (Q. garryana) was used in Sonoma and Yolo of Equalization reported 6,000 cords of oak counties; blue oak and to a lesser extent firewood sold in California (three million California black oak in the Sierra foothills board-feet).?/ but this may reflect as little (May 1957). By 1961 twenty producers in Cal- as 10 percent of the total. ifornia were making 5,400 tons of charcoal from 10,000 cords of oak; eleven of these were in San Luis Obispo County (USDA 1963). In the AGRICULTURE last 15 years, production in the state has dwindled as inexpensive imported charcoal has Throughout California's history, agricul- become available from Mexico. ture has displaced extensive tracts of native oaks, and eventually much of the land has be- Use of California oaks for manufactured come sprawling suburbs. Agricultural opera- products has always been limited. Jepson tions have made reproduction virtually impos- (1923) thought when the name "Mush Oak" was sible even when mature trees have been left applied to valley oak it was a contemptuous in the cropland. reference to its failure to meet the require- ments of a strong, straight wood. He says The earliest agricultural clearing af- that the most valuable oak, canyon live oak, fecting oaks was for orchards. Following the was used for shipbuilding, wheels, axles, plow early Gold Rush immigration, orchards were beams, tool handles, and furniture in the early planted where blue oak, black oak and interior days of the state (Jepson 1910). Coast live live oak had been cleared from the Sierra oak and blue oak were utilized to a lesser ex- foothills (Hutchinson 1946). Between 1900 tent for tools and wagon parts. In the 1870 - and 1920 orchards expanded greatly in the 1880's in Mendocino County, the, forks of open Sierra foothills, and in the 1930's Placer, grown California black oak were used as "nat- El Dorado, and Nevada Counties were still urally assembled" ship keels and ribs (McDonald among the top four counties in pear acreage 1969). Wood from valley oak was used in Cal- (Hutchinson 1946; Watts 1959). Early orchards ifornia shipyards during World War I1 for keel planted on the broad natural levees of the blocks, and a very limited use has been made Sacramento River were at the expense of ripar- of it for wine barrels (Schniewind and Bryan ian valley oak groves, especially between Rio 1959; Dost and Gorvad 1977). Vista and Marysville.

Generally oaks have not been managed for In the , the expansion commercial uses in California, and in conifer of orchards in the early 1900's led Broek stands have been considered undesirable forest (1932) to observe: "Once a grassland dotted components. California black oak in particu- lar has been removed from softwood stands on state and national forest land, where experi- ments have shown trees as large as 24" dbh can be poisoned by herbicides (Otter 1960). How- ?'Personal communication, Brian Barrette, ever, California black oak remains the most California Department of Forestry. important commercial hardwood species in the Ñ'~ersona communication J.C. Denny Chief, state. Resource Management, ~he'~esourceAgency, State of California. with evergreen oaks, a large portion of the Even where mature trees remain in the fields, valley is now covered by a veritable forest of reproduction is precluded by recurring plant- deciduous trees" (p.137). In the Coast Ranges ing and harvest operations, and the practice around Paso Robles, a huge promotional develop- of grazing animals on the crop stubble, where ment from 1915 to 1925 converted 8,000 acres they eat both the acorns and any seedling (3200 ha) of dense coast live oak woodlands trees. Characterizing the plight of valley oak, and 6,000 (2400 ha) acres of valley oak and Griffin (1973) observed: "... the scene is now blue oak savanna to almond orchards.z/ When one of tired relics towering over an intensive- most of the acreage proved unprofitable due to ly cultivated system" (p. 6). Very often the marginal rainfall, early frosts and increasing only areas where oaks become established is in competition from irrigated plantings, the trees waste places, abandoned fields, and along road- were removed in favor of dry farming uses. At sides, between the asphalt and the fences. least from 1910 on it was recognized that oaks Ironically, one place in San Luis Obispo County are host to the Armillaria mellea, which where thickets of valley oak saplings have be- may subsequently attack the roots of orchard come established is on the freeway borders and trees (Smith 1909). After 1925 fewer oaks were median. cleared specifically for orchards.

For cropland, however, as Jepson (1910) STOCK RAISING observed, early settlers knew well that the presence of valley oaks was a "sign of the Over a large area, particularly in the richest ". Being flat and accessible, foothill woodland, grazing activities have these parklike, often pure stands of valley caused the same impacts on oak reproduction. oak, developed on deep alluvial soils, have The results of predator control and overgrazing continually been under the greatest pressure included explosive ground squirrel numbers, from agriculture. Land cleared of valley oaks which in at least one instance, at Fort Hunter includes huge tracts on the east side of the Liggett, received national attention.!!' San Joaquin Valley, where today scattered in- dividual trees on the Kaweah River plain attest Oak reproduction also has been found ab- to the report of 400 square miles (104,000 ha) sent in areas protected from grazing (White of valley oaks there in 1910 (Jepson 1910). 1966). Mice, wild pigs, and especially deer Valley oaks have been removed or isolated-by consume acorns and oak seedlings, and agricultural uses in the Sacramento Valley, kill many seedlings by girdling and chewing oak Livermore Valley, Napa Valley, Santa Clara roots (White 1966; Griffin 1970, 1977). Valley, parts of the Santa Ynez Valley, and the upper Salinas Valley. Round Valley in Mendocino Fifty years ago, Bauer (1930) observed County and San Antonio Valley in the Santa Lucia in the , "grazing explains Range are examples of a few locations where siz- the openness of the understory and ... absence able valley oak savannas remain. of young growth generally in oak communities ... the very young oaks being readily grazed" In 1861 William Brewer traveling through (p. 279). Studying the vegetation of the San northern San Luis Obispo County remarked: Luis Obispo quadrangle, Wells (1962) found oak . in these valleys are trees every few rods - seedlings everywhere absent, except occasional- great oaks, often of immense size, ten, twelve, ly outside fences, and pointed to heavy cattle eighteen, and more feet in circumference ... stocking to account for the poverty of oak re- In passing over this country, every hill pre- production. In the Santa Ana Mountains, Snow sents a new view of these trees - here a park, (1972) found that browsing and trampling by there a vista with the blue mountains ahead" cattle destroyed all unprotected seedlings of (Brewer 1864, p. 93). Today, in this area where coast live oak and Engelmann oak (Q. engelmannii) I have examined the extent of clearing, over 70 in open habitats. He observed that the absence percent of the valley oak parkland has been elim- of grazing in the area between 1895 and 1905 inated to facilitate agriculture. Of the trees corresponded to a period of successful repro- that remain, nowhere is there a reproductively duction of these species. Observing oak repro- viable tract of 9. lobata (Rossi 1979). duction on 50,000 acres (20,000 ha) at heavily grazed Hunter Liggett, Fieblekorn found seed- Clearing, however, is not the only activ- lings of valley oak and blue oak exceedingly ity affecting the survival of oak savanna. More rare, and those of coast live oak present on important is the widespread lack of reproduction.

!!Isan Francisco Examiner-Chronicle, z~ossi,R.S. (1974) Paso Robles area almond September 12, 1976. orchard promotion 1910-1925. Unpublished manuscript. 45 p. only about 2,000 acres (800 ha) .2/ Over an area about 5,000 acres (2,000 ha), but in these as large as the Santa Lucia Mountains, Griffin areas subsequent resprouting has reversed the (1976) found a general absence of valley oak clearing effort .g/ seedlings more than one year old and saplings less than 50 years old. Holland (1976) has It was not until 1973 that the practice of made the same observation about blueoak through- clearing oaks from rangeland was seriously ques- out its range. tioned. Holland (1973) working in oak savanna sites near Madera, in the Temblor Range, in In the blue oak foothill woodlands, ranch- Kern County, and at Hastings Reservation in ers have been clearing oaks and digger pine Carmel Valley, showed that forage production () for range improvement since and nutritional quality are greater under the about 1940. It was assumed that the removal blue oaks than between them. Further, the for- of these "weed" trees would improve the forage age has greater nutritional value and remains production and therefore the output of meat. greener into the dry season; the trees also The practice became widespread on the east and modify the micro-climate and improve range land west side of the Sacramento Valley when inex- soils. Further details of this blue oak canopy pensive methods of killing the oaks were dev- effect and its implications for oak clearing eloped. The practice was advocated and direct- appear in Holland (1980) and Holland and Morton ed by the Agricultural Extension Service and (1980). Where oaks form a nearly closed canopy university advisors (Leonard 1956; Leonard and (120-200 trees per acre) tree removal has re- Harvey 1956; Johnson et al. 1959; Murphy and portedly not affected forage value in some Crampton 1964; Dal Porto 1965; Brown 1973). areas (Murphy and Crampton 1964) and enhanced Extensive clearing was done in the period 1945- it in others (Johnson et al. 1959). 1960, especially of blue oak and live oak in the Sierra foothills and North and Central Coast Ranges. Methods have included bulldozing, RIPARIAN OAKS burning, girdling, cutting, and chemical treat- ment with 2,4-D and 2,4,5-T applied in axe cuts, The riparian forestsof the Central Valley, and even broadcast spraying from aircraft. in which valley oaks were a conspicuous element, have undergone a complete transformation, most From 1945 to 1953 some of the clearing having disappeared without description. Cap- was paid for through matching funds by federal tain Sir Edward Belcher, visiting the Sacramento programs of the Agricultural Adjustment Admin- Valley about 1840, said of the forests lining istration (now the Agricultural Stabilization the river: "Within, and at the verge of the and Conservation Service, A.S.C.S.). Beginning banks, oaks of immense size were plentiful. in 1945 the A.A.A. offered payments for clear- These appeared to form a band on each side, ing land for tillage, and in 1947 payments were about three hundred yards in depth, and within extended to clearing land for pasture. Though (on the immense park-like extent, which we gen- the statistics reflect only the total clearing erally explored when landing for positions) it appears that counties with large areas of they were seen to be disposed in clumps, which oak woodland were the most active participants. served to relieve the eye, wandering over what For instance, in 1947, Amador, Calaveras, and might otherwise be described as one level plain El Dorado counties accounted for one-third of or sea of grass" (Belcher 1843). Based on his- the 1,500 acres (600 ha) cleared for pasture torical accounts of the Sacramento Valley there (U.S. Ag. Adj. Adm. Annual Reports 1944-53). were about 775,000 acres (310,000 ha) of rip- From 1948 to 1952 six central Sierra counties arian woodland in 1850. By 1952 only about (Amador, Calaveras, El Dorado, Placer, Tuolomne, 20,000 acres (8,000 ha) remained. Today the and Mariposa) accounted for over 50 percent of estimate is 12,000 acres (McGill 1975; Dutzi the 110,000 (44,000 ha) acres cleared for range. 1979). Thompson (1961) in his study of the San Luis Obispo Co. lostover6500acres (2600 ha) Sacramento Valley concluded that the riparian of oak savanna and woodland under these programs. forests were effaced during the first two or In Tehama County, where clearing was most ex- three decades of Anglo-American occupance. tensive, the A.S.C.S. Director estimates that Cronise (1868) recognized large-scale destruc- during the last half of the 1950's through the tion of riparian forests by 1868 in Colusa, 19601s, blue oak trees were removed from 90,000 acres (36,000 ha). Herbicides were used on

g'~ersona1 communication, A. Cornell, Agricul- tural Stabilization and Conservation Service, Davis, California. ?/~ieblekorn, C. (1972) Interim report on oak regeneration study. Unpublished report on file, Ñ~ersonacommunication, R. Christianson, Natural Resources Conservation Office, Fort Agricultural Stabilization and Conservation Hunter Liggett, Jolon, California, 23 p. Service Advisor, Tehama County, California. Yuba, Solano, and Sacramento Counties. At the effect of converting oak woodlands to pure Knight's Landing, huge quantities of cordwood chaparral stands. In the 1977 Marble Cone fire, were loaded onto the numerous steamboats nav- the valley oaks in the area of Chews Ridge which igating the Central Valley rivers during the had not burned in almost fifty years, were great- mining days (Thompson 1961). Agricultural ly damaged where Coulter pines (Pinus coulteri) land uses, especially orchards on the broad had invaded. Griffin (1980) found 47 percent natural levees, displaced further miles of of the valley oaks were killed in the areas of gallery forests. crown fire and that the thicket of pine saplings and litter had greatly increased the fire hazard Tree removal was also incidental to to the oaks. flood control projects and levee construction. The construction of Shasta Dam by the U.S. Bureau of Reclamation in the mid 1940's caused URBANIZATION landowners to respond to dramatically reduced flood and erosion dangers on low lying alluvial Since 1945 the most conspicuous impact soils. Moving onto the floodplain, they con- on California's oaks has resulted from the verted much riparian vegetation to permanent growth of cities and suburbs. At both ends of cropland and orchards (McGill 1975) . During "El Camino Real" huge population centers have the period 1952-1972 over 50 percent of the grown up. In the Los Angeles basin where high terrace riparian vegetation on the margins Engelmann oak used to be extensive between of the Sacramento River was converted to other Pasadena and Claremont, no intact woodland re- uses, especially new orchards (13,100 acres mains in the path of suburban growth (Griffin (5,240 ha) ) (McGill 1975). 1977). Cities named for their oaks, such as Thousand Oaks, Sherman Oaks and Encino, are Valley oaks have been killed indirectly often left only with token examples of their in some areas by greatly lowered water tables natural heritage in order toaccommodategrowth created by water impoundment in the foothills and development. Around San Francisco Bay, and local ground water pumping; in other areas there are few oaks in Oakland, very few left the accumulation of saline irrigation runoff among the suburbs filling in the Livermore has been equally destructive. Valley, and even fewer in the Santa Clara Valley. Between San Jose and Redwood City, In the Sacramento Valley, local concern Cooper (1926) found a "more or less skeleton- for the continuing loss of riparian habitat ?zed form" of what was "originally a continuous has been manifested in a workshop and several belt of oak forest" on the alluvial fans that conferences (e.g., Sands 1977). At the state reach the bay. Observing this same area in level, the Secretary for Resources has estab- 1798, Captain George Vancouver compared it to lished the Upper Sacramento River Task Force a well kept park planted with huge oaks, and whose work includes specific interest in dim- added prophetically, it "required only to be inishing riparian vegetation. adorned with the neat habitations of an indus- trious people" (Vancouver 1798). These people certainly have come; the area today numbers FIRE SUPPRESSION over one million people in ten cities and end- less suburbs, shopping centers and freeways. Fire suppression policies of the last 50 years have resulted in the unnatural build up Very often, of course, where urban areas of fuels in oak woodland communities. The have developed, oaks were originally cleared absence of frequent low intensity fires has for agriculture. Yet, where they were spared permitted the invasion of chaparral species, it is paradoxical that now in large and small or highly flammable conifers into the under- cities alike, they fare so poorly and are so story (Dodge 1975; Griffin 1976). Overgrazing little revered. However susceptible oaks are has aggravated the situation by eliminating to cutting, grazing and other rural pressures, ground cover to carry low intensity burns. they succumb just as quickly to overwatering, When fires do start, the oaks are consumed in blankets of asphalt, grade changes and pruning. the conflagration unless they are protected As parcel sizes become smaller, and the land in a canyon bottom or by rocky outcroppings. uses intensify, it becomes less likely that In San Diego County, Dodge (1975) noted that viable oak communities will persist on the an oak woodland between Pine Valley and Corte metropolitan fringes. Often, in fact, the Madera that was "fairly openw in 1931 had be- new suburban residential uses put greater pres- come covered with a dense understory of brush. sures on the native plants than did the previous When the 1970 Laguna Fire burned through, ap- agricultural uses. Horses and cattle in "back- proximately 50 percent of the oaks were killed, yard" corrals are typically overstocked. Home and the remainder extensively damaged. He con- owners cut and disk weed from their property cluded that high intensity fires are having and also often from the roadsides. In the foothill woodland, land for residential uses likely to become extinct, human use has frag- includes areas that were too steep or inacces- mented the handsome oak landscape, and the sible for farming; now even these waste places unique character of many oak communities is have lost their protected status. Seedling already gone or frozen in premature senescence. oaks are treated as weeds, and the heavily man- icured gardens and public parks are filled with non-native plants. REFERENCES CITED

Many cities have adopted tree ordinances Bancroft, H. H. primarily intended to save their remaining oaks, 1890. History of California. Vol. 7. The as for example in Visalia, Men10 Park and San History Co., San Francisco. Luis Obispo. Unfortunately, the fine for cut- ting a two-hundred-year-old oak is generally Bauer, H. L. far less than the value of the cordwood from 1930. Vegetation of the Tehachapi Mountains, the tree.=/ County-wide tree ordinances per- California. Ecology 11:263-280. tain only to incorporated cities, and there- fore exempt the vast rural areas and unincor- Baumhoff, M. A. porated suburbs. Steinhart (1978) observed 1963. Ecological determinants of aboriginal that the luxury of fine healthy groves of oak California populations. her. Arch. and seem to be the sole possession of the most ex- Ethn. XLIX:155-235. clusive and expensive communities, such as Brentwood, Beverly Hills, Montecito, Atherton, Baxley, H. W. Woodside and Piedmont. 1865. What I saw on the west coast of South and North America. D. Appleton and Co., New York, N. Y. 632 p. SUMMARY Belcher, Sir E. In a brief span of time, modern man has 1843. Narrative of a voyage around the world. made impacts on California oaks which will af- Vol. 1. Henry Colburn, London. fect their distribution and abundance for cen- turies to come. This stands in contrast to Belcher, Cap,t. E. the gentle tenancy of the native Indians. 1969. H.M.S. Sulphur at California, 1837 and 1839. R. A. Pierce and J. H. Winslow,(Eds.) The oaks in the riparian woodlands have Book Club of Calif., San Francisco, Calif. suffered the most extensive losses. Almost everywhere, the range of valley oaks has been Bolton, H. E. seriously reduced and the remaining tracks are 1917. The mission as a frontier institution largely barren of seedlings. In the foothills, in the Spanish-American colonies. Amer. hundreds of thousands of acres of blue oak have Hist. Rev. 23(1) :42-61. been converted to grassland and crops, and grazing activity inhibits oak regeneration in Bolton, H. E. (Ed.) the remaining woodland. Until recently, oaks 1926. Historical Memoirs of New California were cut in the state for charcoal production, by Fray Francisco Palou. Vol. 13. Univ. but currently fuelwood accounts for the bulk of Calif. Press, Berkeley. of cutting. In Southern California Engelmann oak and coast live oak have been displaced by Broek, J. 0. suburban growth. Approximately 10 million 1932. The Santa Clara Valley, California: board feet of oaks are cut each year for man- A study in landscape changes. Utrecht, ufactured products, most of it being California N. V. A. Oosthoek's vitg. maatij. 184 p. black oak from Northern California. Brooks, W. H. The clearing of oaks and the impairment 1967. Some quantitative ecological aspects of reproduction indirectly affects wildlife of the grass oak woodland in Sequoia Nat- populations, soil development, and the ecosys- ional Park, California. Sequoia and Kings tem in general. The landscape is impoverished National Park files. both in a visual sense and in terms of its natural diversity. It is slowly losing its Brown, R. D. appeal, its distinction,it~uniqueness. Al- 1973. Pre-burn treatment of oaks with the though the individual species of oak are not ball and chain. Calif. Div. of Forestry, Range Improvement Studies No. 21.

E'~isalia Times-Delta, December 16, 1976. Bryant, Edwin Wtzi, E. J. 1848. What I saw in California (Journal 1979. Reduction of valley oak (Quercus of 1846 and 1847). D. Appleton and Co., lobata) range in the Sacramento Valley, New York, N. Y. 480 p. California. Master's Thesis in Geography, Univ. of Calif., Davis. Burcham, L. T. 1959. California Range Land. State of Engelhardt (Fr.) Zephyrin California, Div. of Forestry. 261 p. 1929. Mission San Antonio de Padua. James H. Barry Co. San Francisco. 140 p. Chestnut, V. K. 1902. Plants used by the Indians of Fages, Pedro Mendocino County, California. Contrib. 1937. A historical, political, and natural U. S. Natl. Herb. 7(3):295-408. description of California. Translated by H. I. Priestley. Univ. of Calif. Press, Cleland, R. G. Berkeley. 83 p. 1941. The cattle on a thousand hills. Huntington Library. San Marino, Fieblekorn, C. California. 327 p. 1972. Interim report on oak regeneration study. Unpub. report on file. Nat. Re- Cooper, W. S. sources Conservation Office, Hunter Liggett 1926. Vegetational development upon allu- Military Res., Jolon, Calif. 23 p. vial fans in the vicinity of Pa10 Alto California. Ecology 7:l-30. Griffin, J. R. 1971. Oak regeneration in the Upper Carmel Coulter, J. W. Valley, California. Ecology 52(5):862-868. 1926. A geography of the Santa Lucia Mountain Region, California. Ph.D. Griffin, J,. R. Dissertation, Univ. of Chicago. 286 p. 1973. Valley oaks - the end of an era? Fremontia l(1):S-9. Coulter, Thomas 1951. Notes on Upper California. Glen Griffin, J. R. Dawson, Los Angeles, California. 40 p. 1976. Regeneration in Quercus lobata savan- nas, Santa Lucia Mountains, California. Crespi, F. J. Amer. Midland Naturalist 95(2):422-435. 1971. Fray Juan Crespi Missionary Explorer on the Pacific Coast, 1769-1774. E. H. Griffin, J. R. Bolton (Ed.). AMS Press, New York, 1977. Oak woodland, p. 383-415. In: Barbour, N. Y. 402 p. M. G., and J. Major, Eds., Terrestrial Vegetation of California. John Wiley and Cronise, T. F. Sons. New York. 1002 p. 1868. The natural wealth of California. H. H. Bancroft, San Francisco. Griffin, J. R. 1980. Sprouting in fire damaged valley oaks Dal Port, N. J., and C. E. Carlson Chews Ridge, California. In: Symposium 1965. Blue oak cordwood from foothill range on Ecology, Management, and Utilization land. Calif. Div. of Forestry, Range Im- of California Oaks. provement Studies No. 15. 4 p. Harrington, J. P. Dobbie, J. F. 1932. Tobacco among the Karok Indians of 1939. The first cattle in and the California. Bureau of Amer. Ethnology, southwest progenitors of the longhorns. Bull. 94: 1-284. The Southwestern Historical Quarterly 52 (3) :171-1973. Hendry, G. W. 1931. The adobe brick as a historical source. Dodge, J. M. Agricultural History S(3):llO-127. 1975. Vegetational changes associated with land use and fire history in San Diego Hinds, R. B. County. Ph. D. Dissertation, Univ. of 1844. The botany of the voyage of the H.M.S. Calif., Riverside. 216 p. Sulphur, under command of Captain Sir Edward Belcher during 1836-42. Smith, Dost, W. A., and M. Gorvad Elder, and Co., London. 195 p. 1977. California oak tanks for California wine. California Agriculture 31(2):8-9. Holland, V. L. Leonard, 0. A., and W. A. Harvey 1973. A study of soil and vegetation under 1956. Chemical control of woody plants H & A compared to open in California. Calif. Agr. Exp. Sta. grassland. Ph.D. Dissertation in Botany, Bull. 755. University of Calif., Berkeley. 369 p. Lewis, H. T. Holland, V. L. 1973. Patterns of Indian burning in Califor- 1976. In defense of Blue Oaks. Fremontia nia: Ecology and Ethnohistory. Balena 4(l) :3-8. Press Anthropological Papers No. 1. Lowell John Bean (Ed.). Balena Press, Ramona, Ca. Holland, V. L. 1980. Effect of blue oak on rangeland forage Lynch', A. C. production in Central California. In 1935. The Kennedy Clan and Tierra Redonda. Proceedings of Symposium on Ecology Manage- Marnell and Co., San Francisco. 264 p. ment and Utilization of California Oaks, Claremont, California, June 26-28, 1979. May, R. H. 1956. Notes on the history of charcoal pro- Holland, V. L. and J. Morton duction and use in California. Calif. 1980. Effect of blue oak on nutritional Forest and Range Exp. Sta. Pamphlet on Misc. quality in rangeland forage in Central Products. October 1956. 6 p. California. In Proceedings of Symposium on Ecology, ~zagementand Utilization May, R. H. of California Oaks, Claremont, California, 1957. Wood charcoal in California. USDA, June 26-28, 1979. Forest Service, Forest Survey Release No. 28. 12 p. Hoover, R. L. 1977. California Indians uses of native McDonald, P. M. plants, p. 131-162. In: Native Plants: 1969. Silvical characteristics of California A Viable Option (D. R. Walters et al., Eds .) . black oak (Quercus kelloggii , Newb. ) . Calif. Native Plant Society Special Pub. Berkeley, Calif., Pacific SW. Forest and No. 3, Berkeley, Ca. Range Exp. Sta. USDA Forest Serv. Res. Paper PSW-53. 20 p. Hutchinson, C. B. (Ed.) 1946. California agriculture. Univ. of McGill, R. R. Calif. Press, Berkeley. 444 p. 1975. Land use changes in the Sacramento River riparian zone, Redding to Colusa. Jepson, W. L. State of Calif., The Resources Agency, 1910.~The silva of California. Univ. of Dept. of Water Resources, April 1975. California. Univ. of Calif. Memoirs. Vol. 23 p. 2. 480p. Munz, P.A., and D.D. Keck Jepson, W. L. 1963. A California Flora. Univ. of Calif. 1923. The trees of California. Second Press, Berkeley, Ca. 1681 p. Edition. Sather Gate Bookshop,'Berkeley, Ca. 240p. Murphy, A. H., and B. Crampton 1964. Quality and yield of forage as Kroeber, A. L. affected by chemical removal of blue 1925. Handbook of the Indians of California. oak (g. douglassi) . J . Range Man age. Bureau of American Ethnol. Bull. 78:l-995. 17~142-144.

Johnson, W. C., C. M. McKell, R.A. Evans and Otter, F. L. L. J. Berry 1960. Timber stand improvement by poisoning 1959. Yield and quality of annual range black oak on Mountain Home State Forest. forage following 2, 4-D application on Calif. Dept. Nat. Resources, Div. of blue oak trees. J. Range Mar.age. 12:lS-20, Forestry, State Forest Note 2. 4 p.

Leonard, 0. A. Parsons, James J. 1956. Effect on blue oak (Quercus douglasii) 1962. The acorn-hog economy of the oak of 2, 4-D and 2, 4, 5-T concentrates applied woodlands of Southwestern Spain. Geog. to cuts in trunks. J. Range Manage. 9 (1) : Rev. 52(2): 211-35. 15-19. Rossi, R. S. Thompson, K. 1979. The history of cultural influences 1961. Riparian forests of the Sacramento on the distribution and reproduction of Valley, California. Ann. Assoc. her. oaks, north San Luis Obispo County, Geographers 51(3):294-315. California. Ph.D. Dissertation in Geography, Univ. of California, Berkeley. U.S. Agricultural Adjustment Administration 1944-53. Annual Report. Participation in Sands, Anne (Ed.) Agricultural and Range Conservation Programs, 1977. Riparian forests in California, their California. ecology and conservation. Univ. of Calif., Davis, Institute of Ecology Pub. No. 15. U.S.D.A., Forest Service Div. of Forest Econmics 122 p. 1963. Charcoal and charcoal briquette pro- duction in the United states, 1961. Feb. Schenck, S. M. and E. W. Gifford 1963. 33 p. 1952. Karok Ethnobotany. University of California Anthropolitkcal Records Vancouver, George 13:377-92. 1978. A voyage of discovery to the north Pacific Ocean and round the world. London. Schniewind, A. P.. and E. L. Bryan 3 Vols. 1959. Some strength and related properties of California White Oak. Univ. of Calif., Watts, David Sch. of Forestry, Forest Products Lab., 1959. Human occupance as a factor in the Calif. Forestry and Forest Products No. 13. distribution of California digger pine (Pinus sabiniana). M.S. Thesis in Smith, R. E. Geography, Univ. of Calif., Berkeley 1909. Report on the Plant Pathologist, Univ. 222 p. of Calif. Agric. Exp. Sta. Bull. N0.203. Univ. of Calif. Press. Wells, P. 1962. Vegetation in the San Luis Obispo Snow, G. E. quadrange in relation to geologic sub- 1972. Some factors controlling the estab- strate and fire. Ecological Monographs, lishment and distribution of Quercus Wntr. 1962, pp. 79-103. agrifolia and Q. Engelmannii in certain Southern California oak woodlands. Ph.D. White, K. L. Dissertation in Botany, Oregon State Univ., 1966. Structure and composition of foothill Corvallis. 105 p. woodlands in central coastal California. Ecology 47~229-237. Steinhart, D. 1979. As the old oaks fall. Aud~boil Wieslander, A. E., and C. H. Gleason Magazine, Sept. 1978, pp. 31-40. 1954. Major brushland areas of the Coast Ranges and Sierra-Cascade foothills in Sudworth, G. B. California. USDA, Forest Service, Calif. 1908. Forest trees of the Pacific slope. Forest and Range Exp. Sta. Misc. Paper 15. USDA, Forest Service. 441 p. 9 P. Yale, C. G. 1905. California mines and minerals. Calif. State Min. Bureau, Bull. No. 44. 7 Taxonomy of California Oaks1 engelrnannii

John M. Tucker2

Abstract: The indigenous oaks of California belong to two genera: Lithocarpus and Quercus. The main differences are tabulated. The Californian species of Quercus belong to three subgenera: the white oaks (suJzJgenusQuercus), the black or red oaks (subgenus Erythrobalanus), and the intermediate oaks (subgenus Protobalanus). The major differences are given in a table. Emphasis in this paper is not on identifi- cation, but on hybridization between species, which sometimes complicates identification. Three hybrid complexes are dis- cussed: Quercus douqlasii X Q. turbinella subsp. californica, --Q. dumosa X Q. lobata, and 2. dumosa X 9. engelmannii. An annotated list of species, varieties, and hybrids is included.

INTRODUCTION

Separating tanoak and other oaks

The oaks indigenous to California repre- appearance. However, this is not a generic sent two different genera in the family difference. Their principal generic differ- E'agaceae. The tanoak, or tanbark-oak, Litho- ences are summarized below: carpus densiflorus, is the only North American member of its genus which is represented in Lithocarpus Quercus eastern and southeastern Asia by about 300 c? and 9 flowers borne dand $ flowers borne species. All the other Californian oaks either in separate only in separate belong to the genus Quercus. inflorescencesr or . often in the same To the casual observer the tanoak looks -- quite oak-like, and in fact botanically it was with the Q at the first named as a species of Quercus--2. base, and' the 8 above. densiflora. The two are, neverthelessr very the inflorescence is inflorescence is distinct genera. As a practical field charac- 8 a stiff spike, or a slender, ter, the acorn cup of Lithocarpus densiflorus E- in some species a dulous . is unmistakably different from any of our panicle. native species of Quercus, having long, re- curved cup scales that give the cup a bur-like flowers usually arranged flowers arranged in small clusters (3 singly along to 7 in a cluster) the axis of the along the spike, in inflorescence, Alpresented at the Symposium on the Ecology, axils of small the bracts soon Management and Utilization of California Oaks, c- sistent bracts. deciduous. Claremont, California, June 26-28, 1979. geographic distribution: world-wide in the eastern and south- Northern Hemis- 2'Professor of Botany, University of Califor- phere. nia, Davis, California 95616 eastern Asiar from Japan to the Hima- laya~~ with 1 species in western North America. Oak subgenera to rely on a single difference. For examplel in the white oaks the acorns mature in 1 year, Considering the "true oaks" -- the genus while in the other two subgenera 2 years are Quercus -- our Californian species fall into required -- i.e. the acorns do not mature till three distinct groups, which are classified as the end of the second growing season. The three subgenera. (European botanists, however, coast live oak (Q. agrifolia) -- one of the classify them somewhat differently, as does three native California black oaks -- is one Rehder, in his well-known "Manual of Culti- of the very few exceptions, maturing its vated Trees and ", 1947). These are (1) acorns in only one season. the white oaks (subgenus Quercus, or synonym Lepidobalanus), (2) the black or red oaks In addition to the differences listed in ( subgenus Erythrobalanus) and ( 3 the inter- table ll others could be mentioned in chemical mediate oaks (subgenus Protobalanus). The constituents of acornsl and host preferences white oaks occur around the world in the of oak gall wasps (Family Cynipidae). Al- Northern Hemisphere; the black oaks occur though these are hardly useful as field only in the New World -- North and Central characters, they follow a similar pattern to America, and extreme northern South America; the characters in table 1, and thus reinforce and the intermediate oaks -- a small group of the validity of dividing the New World oaks only five species -- are restricted to western into three distinct subgenera. North America.

The black oaks and white oaks have long Objectives been recognized as very distinct groups. The intermediate oaks, however, have usually been My objectives in the remainder of this placed (as a small group of closely related paper are (1) to point out a problem that species) in the white oaks, especially in sometimes makes field indentification diffi- older classifications. They are not really cult -- namely, hybridization between species, intermediate in most morphological characters; (2) to indicate the species, varieties, and rather, in some features they resemble the hybrids I recognize (in an annotated list), white oaks, but in others they are more like and (3) to give explanations for several names the black oaks. The characteristics that that have been sources of confusion. Regard- distinguish the three groups are presented in ing interspecific hybridization, although it table 1. may be a rather infrequentl or even rare, phenomenon in many parts of California, in The most reliable difference for distin- certain areas it has been so extensive as to guishing the white oaks from the black create a major problem in identification. I oaks is the character of the inner surface of will discuss several such examples. The the acorn shell. In the white oaks this is problematic names to be explained are either glabrous or essentially so, while in the black cases of synonymy (e.g., an older manual using oaks it is conspicuously tomentose. The a name no longer considered valid), or names condition in the intermediate oaks varies from not often seen in manuals (valid or otherwise) one species to another. In 2. dunnii it is by virtue of their obscurity, or uncertainty densely tomentose; in Q. vaccinifolia it is on the part of the author. only very lightly so; and in 2. chrysolepis, the most common and widely distributed species It is not my objective to provide a ready in the group, it varies from moderately to means of identification of the oaks of Cali- densely tomentose. Mature acorns are not fornia -- hence, I have not included a key, or found till late summer or fall, of course, detailed descriptions or illustrations of which to some extent limits the usefulness of individual species. Either of two well-known this character for making field distinctions. manuals should be adequate for purposes of Also, it is a character of less importance.in identification: "A California Flora" (Munz the intermediate oaks because of its vari- 1959, and supplement 1968) and "A Flora of ability. Nevertheless for distinguishing the Southern California" (Munz 1974). Also, where black oaks from the white oaks, this is the I have discussed the distributions of indi- most constant difference one can find. vidual species, this has been only in general terms. For detailed statements of geographic In most of the other differences listed ranges, and excellent distribution maps (for in table 1, occasional exceptions may be at least the arborescent oaks), the reader is found. Hence it is always safer to check referred to "The Distribution of Forest several of these characters rather than try Trees in California" (Griffin and Critchfield 1972). ences Between the 3 Subgenera of New World Oaks

Morphological White oaks Black, or Red Oaks "Intermediate" Oaks Character (Subgenus Quercus) (Subgenus Erythrobalanus) (Subgenus Protobalanus)

trunk bark of mature trees usually light gray or brown usually dark brown or black- light grayish-brown ish -wood heartwood light brown or yellowish reddish-brown light brown brown

tyloses in vessels tyloses present in the tyloses usually absent in tyloses present summer wood vessels summer wood vessels

leaves lobes or teeth usually lobes or teeth usually teeth pointed, not rounded, and without pointed, and often bristle-tipped but bristle tips bristle-tipped spinose to mucronate

9 flowers styles short, with broad styles elongated, narrow styles short, with broad stigmas stigmas t^J 8 flowers perianth deeply parted; perianth cup-shaped, with perianth deeply lobed; stamens ca. 6-9; united parts; stamens ca. stamens ca. 8-10; anthers notched at 6; anthers usually mucro- anthers pointed at tip apex nate at tip

acorns acorn shell glabrous on inner surface densely tomentose on inner from densely tomentose to surface almost glabrous (depend- ing on the species)

abortive ovules at the base of the mature apical (rarely lateral, or lateral seed (within the acorn) even basal)

maturation annual mostly biennial biennial

cup scales corky-thickened at base (to thin and flat mostly thickened to some some degree) degree HYBRIDIZATION IN CALIFORNIA their identity, therefore, they ordinarily pose no real taxonomic problems. Infrequent hybrids

People familiar with the oaks are aware Examples of extensive regional hybridization that natural hybrids, between certain species at least, are fairly common. Nevertheless, Another series of hybrids do, however, only species in the same subgenus are involved pose a more important taxonomic problem. in natural crosses. No authentic instances These are cases at the other extreme in which are known of natural crosses between members hybridization has been so extensive that over of different subgenera. Thus, they are sizeable areas the populations consist mainly clearly three distinct groups genetically. of highly variable intermediate types, with Over the country in general, many differ- only an occasional individual identifiable as ent natural hybrids are known -- sometimes one or the other parental species. When the between very different species (but always differences between the species are "blurred" members of the same subgenus). The hybrids in this way, botanists have sometimes classi- are usually quite infrequent and occur as fied them as mere varieties of a single spe- single, isolated trees growing with the parent cies -- especially when the species involved species. In California, also, this is the are quite similar anyhow. Quercus dumosa and usual pattern. Several examples could be -Q. turbinella provide an example of this cited; the most widely distributed, and sort. probably the most widely known is the oracle oak (2. X morehus), a cross between the One botanist has coined the term "semi- California black oak (Q. kelloggii) and species" for groups of this sort. Unfortu- interior live oak (Q. wislizenii). It has nately, there is no simple taxonomic solution been known the longest of any of the Califor- for all such cases. The degree of difference nian hybrids, having been first described and between the species involved,and the extent of named in 1863. Other hybrids known only as hybridization between them, can vary consider- rare, isolated individuals are the following: ably from one example to another.

California black oak (Q. kelloggii) X coast 1. Quercus douglasii X Q. turbinella live oak (Q. agrifolia) subsp. californica valley oak (2. lobata) X Engelmann oak (2. engelmannii) The most extensive hybrid complex in valley oak (2. lobata) X Oregon oak (2. California, percus X alvordiana, involves the garryana) blue oak (Q. douglasii) and desert scrub oak valley oak (2. lobata) X desert scrub oak (2. turbinella subsp. californica). These (2. turbinella subsp. californica) oaks are quite different morphologically and Oregon oak (Q. garryana) X scrub oak (Q. ecologically, and in large part have different

dumosal - geographical ranges. Oregon oak (Q. yarryana) X leather oak (Q. duratal The blue oak is a small to medium-sized Brewer oak (Q. zarryana var. breweri) X deer deciduous tree, 20-30 ft. (6-10 m.) in height. oak (Q. sadleriana) The leaves are dull bluish-green, 1-2 1/2 in. (2.5-6 cm.) long, shallowly lobed or coarsely These are usually found growing with the toothed (or entire), with rounded or obtuse parental species, and, to the critical lobes or teeth. It is common on dry interior eye, are morphologically intermediate. They foothills and lower mountain slopes from the are often demonstrably fertile, setting Tehachapi Mountains northward, forming an open sizeable crops of viable acorns. Neverthe- woodland sometimes in pure stands, but com- less, back-crosses or F'S are not commonly monly associated with digger pine (Pinus found. Usually it is just the single, iso- sabiniana) and often with interior live oak lated first-generation (F) hybrid. They are (2. wislizenii). often puzzling to the non-taxonomist, however, because of their unusual characteristics and The desert scrub oak is commonly a , their rarity. But once they have been criti- 6-15 ft. (2-5 m.) in height, or sometimes a cally compared with the species with which small shrubby tree. Evergreen in habit, the they are growing -- and perhaps others in the small grayish-green leaves are 1/2-1 1/2 in. area -- their true identity can usually be (1.5-4 cam.) long, with spinose or mucronate determined. Beyond this initial question of teeth on the margins. It occurs in pinyon- juniper woodland or in pure stands forming an 1950, 1952). And more recently, a very de- open chaparral on arid mountain slopes along tailed study was made of a series of variable the southwestern border of the Mohave Desert, populations on hillslopes facing different and northwestward to northern Ventura and directions at a single general location Santa Barbara counties and southeastern San (Benson, et al. 1967). This showed that on Luis Obispo County. the dry southwest-facing hillslope the ppula- tion, although variable, was composed mainly , in common with a of shrubby turbinella-like types, while number of other Mohavean species, extends on the more protected northeast-facing slope, northwestward through the very dry Inner South types more similar to Q. douglasii predomi- Coast Ranges as far as southern San Benito nated. Thus, each microsite was selecting in County. Throughout this region it hybridizes a very sensitive fashion the best adapted freely with blue oak,forming variable popula- types from the genetically variable popula- tions,with most individuals being intermediate tion. in varying degrees between the parents. More localized hybridization has also occurred in 2. guercus lobata X Q. dumosa areas on the west side of the upper Salinas Valley and in the northeastern Tehachapi's, The highly variable oak on the southern e.g., along Oak Creek. California islands called Quercus macdonaldii is generally recognized today as a complex The well-known botanist of the early derived from hybridization between the valley 1900ms, Alice Eastwood, was the first to oak (9. lobata) and scrub oak (Q. dumosa). It make collections from any of these variable was originally described as a species, how- populations. In 1894, in San Ernigdio Canyon, ever, by E. L. Greene (1889), from Santa Cruz Kern County, to the north of Mt. Pinos, she Island. It is also known from the neighboring made a series of collections ranging from Santa Rosa Island, and from Santa Catalina small-leaved shrubs to larger-leaved trees. Island; also from several mainland localities, And she may have surmised that the extreme from Santa Barbara County (Smith 1976) to local variation was the result of hybridiza- Orange County (Boughey 1968). tion. Nevertheless, a few years later she described a "new species" based on one of her Quercus macdonaldii was described by collections, naming it Quercus alvordiana Greene as "a small deciduous tree, from (Eastwood 1905). fifteen to thirty-five feet high", but later botanists noted that it sometimes intergraded For many years afterward this name was a with the shrubby evergreen scrub oak, common source of confusion to California botanists, both on Santa Catalina and on the Norrhern doubtless because of the extreme variation at Channel Islands. Accordingly, Jepson (1925) the type locality and elsewhere in that region. reduced Q. macdonaldii to a variety of Q. Every one of several manuals or floras in use dumosa. Others (Sargent 1895, Sudworth 1908) prior to 1959 (when Munz published "A Flora of had considered it merely a form of Q. duiiosa, California") interpreted guercus alvordiana not worthy of taxonomic recognition. differently. One treated it as a distinct species (Abrams, "Illustrated Flora of the On the other hand, the similarity of Q. Pacific States"); one reduced it to a variety macdonaldii to 2. lobata apparently went of Q. dumosa (Jepson, "A Manual of the Flower- unnoticed until Hoffmann (19321, who botanized ing Plants of California"); a third was extensively on the islands off Santa Barbara, reluctant to express any opinion (Sudworth, took exception to Jepson's treatment: "....if "Trees of the Pacific Slope"); and a fourth it [Q. macdonaldii] is not a distinct species, felt it was not worthy of recognition at all it seems to the writer to be much more closely (McMinn, "Illustrated Manual of California related to Q. lobata than to Q. dumosa." With Shrubs"). McMinn noted, however, that blue increased botanical interest in the southern oak hybridizes with scrub oak in the Inner California islands in recent years, the Q. South Coast Fanqes. (He considered Q. turbi- macdonaldii complex has been brought into nella merely a form of Q. dumosa). sharper focus: "Quercus lobata ~&eoccurs on Santa Cruz and Santa Catalina islands and I made a study of the "guercus alvordiana is genetically represented on Santa Rosa, problem", as a Ph.D. research project and Santa Cruz, and Santa Catalina where it has concluded that this whole complex was the hybridized freely with 2. dumosa to produce a result of long-continued hybridization be- variable population to which Greene applied tween Q. douglasii and Q. turbinella (Tucker the name Q. macdonaldii" (Muller 1967). One complicating factor is the fact that fornia has favored chaparral species, and Q. douglasii also occurs in a few small groves some former stands of oak woodland have dis- on Santa Cruz and Santa Catalina islands appeared. Thus, although percus engelmannii (Muller, 1967), and a single tree of Q. is no longer present, its genes remain in the engelmannii on Santa Catalina (Thorne 1967). remnants of hybrid swarms which are now being These oaks apparently have also hybridized absorbed by repeated backcrossing to QÃ with Q. dumosa, and their backcrosses to the dumosa. scrub oak may be difficult to distinguish from macdonaldii backcrosses. As so often happens with oak hybrids, those between Q. engelmannii and Q. dumosa The infrequent mainland occurrences of have been a source of some taxonomic confu- hybrids have usually been isolated F s. How- sion. The names, Quercus dumosa var. elegan- ever, in at least one location known1 to the -tula (Greene) Jepson and Quercus grandidentata writer in the Santa Barbara area, an F occurs Ewan, both apply to such hybrids. In each with Q. dumosa and a number of vhriable case, of course, the botanist who first dumosa-like intermediates. Interestingly published the name thought he had discovered a enough, most of the known occurrences on the "new", previously unnamed, oak. mainland are at -- or even beyond -- the southern limits of the range of Q. lobata. In the case of Q. dumosa var. elegantula (originally described by E. L. Greene as Q. 3. Quercus engelmannii X Q. dumosa macdonaldii var. elegantula), Greene realized his error when he re-visited his type locality In southern California (aside from the (Temecula Canyon) at a later date. He noted insular Q. X macdonaldii) the most frequent that Q. engelmannii and Q. dumosa were abun- and conspicuous examples of hybridization are dant in the area and hybridizing freely, and those involving Q. engelmannii and Q. dumosa. acknowledged that he had described one of the These are very different species: Q. engel- hybrids. Quercus yrandidentata, similarly, mannii is a tree 25-35 ft. (7-10 m.) in was described from a tree in a hybrid swarm -- height, with semipersistent leaves oblong to this one in Monrovia Canyon -- a1though oblong-ovate, with margins entire or nearly this fact was not realized originally. How- so, bluish-green and often glaucous, up to ever, later study by Prof. Lyman Benson about 2-2 112 in. (5-6 cm.) long. Quercus and his students, of Pomona College, demon- dumosa is an evergreen shrub with usually strated this beyond any doubt. In 1949, mucronate-dentate leaves quite variable and again in 1951, students planted acorns in shape, but green and slightly to moderately from the type tree. In both groups of glossy above, and mostly about 1/2-1 in. seedlings scarcely any two were alike, and (1.5-2.5 cm.) long. Engelmann oak is a individuals ranged in leaf characters from dominant tree in the southern oak woodland, those resembling Q. engelmannii to those occurring on deeper soils along the base of resembling Q. dumosa (Benson, 1962). the San Gabriel Mountains in the Pasadena area, and extending southeastward into north- ern . The scrub oak is a ANNOTATED LIST OF SPECIES AND HYBRIDS wide-ranging chaparral shrub common on the drier, more shallow soils of lower mountain The following list includes the species slopes. of Quercus native to California, and their natural hybrids. When a hybrid has been Where stands of oak woodland occur formally named with a binomial, this is also adjacent to chaparral, the two oaks have listed. Synonyms are included, and occasional hybridized freely,producing "hybrid swarms", nomenclatural notes in an attempt to clarify the members of which show varying combinations obscure or questionable names. of the parental characters. Also, in this general region stands of scrub oak often have White Oaks (Subgenus Quercus) leaves distinctly suggestive of Engelmann oak, i.e., somewhat larger and more oblong than 1. Quercus douglasii Hook. & Arn. (Q.ran- usual, with more nearly entire margins, etc. -somi Kell.; Q. oblongifolia brevilobata In such stands one may see larger, more arbor- Torr.) escent shrubs 10 to 15 ft. (3 to 5 m.) in height, rising above the surrounding chap- Blue Oak arral. As Benson (1962) has pointed out, the trend toward a drier climate in southern Cali- Hybrids: Hybrids:

Q. douglasii X Q. dumosa engelmannii X Q. dumosa : Q. egylasii X Q. yarryana : Quercus X gandidentata ban Quercus X eplingi C.H. Muller (Q. macdonaldii var elegan- -- - . Q. douglasii X Q. lobata : Quercus -tula Greene; Q. dumosa var. X jolonensis Sarg. elegantula (Greene) Jeps.) Q. douylasii X Q. turbinella ssp. (See detailed discussion in californica : Quercus X =- preceding section.) diana Eastwood (2. dumosa Q. engelmannii X Q. lobata var. eordiana (Eastw.) Jeps.) (See detailed discus- 5. Quercus garryana Eougl. (Q. neaei sion in preceding section.) Liebm. )

2. Quercus dumosa Nutt- (2. berberidifolia Oregon Oak Liebm.; Q. acutidens Torr.; Q. dumosa var acutidens S. Wats.) Hybrids:

Scrub Oak Q. garryana X Q. douglasii : e- -cus X eplingi C.H. Muller Hybrids: Q. yarryana X Q. dimosa : Quercus X howellii Tucker - -- Q. dunosa X Q. douglasii Q. garryana X Q. durata : Quercus 2. dumosa X Q. durata X subconvexa Tucker Q. dumosa X Q. engelmannii : Q. garryana X Q. lobata Quercus X yrandidentata Ewan (Q. macdonaldii var . elegan- Varieties: -tula Greene; Q. dumosa var. elegantula (Greene) Jeps.) var. breweri (Engelm. in Wats.) (See detailed discussion in Jeps. (2. breweri Engelm.; Q. preceding section.) lobata fruticosa Engelm.; Q. Q. dunosa X Q. garryana : Quercus oerstediana R. Br. Campst.; Q. X howellii Tucker yarryana var. semota Jeps. ) Q. dumosa X Q. lobata : Quercus X macdonaldii Greene (Q. X Brewer Oak townei Palmer; Q. dumosa var. kinselae C.H. Muller) (See Hybrids: detailed discussion in preced- ing section.) Q. garryana var. e- Q. dumosa X Q. -eri X Q. sadleriana californica The shrubby forms of Q. yarryana of the 3. Quercus durata Jeps. (Q. dumosa var. southern Sierra Nevada, Greenhorn Range, and bullata Engelm.; Q. dumosa var. revoluta the Tehachapi's, were called var. semota by Sarg. ) Jepson, supposedly having less tuberculate cup scales than in typical var. breweri of the Leather Oak high North Coast Ranges. However, there seems to be no significant morphological difference Hybrids: between the populations of these different regions. Q. durata X Q. dumosa Q. durata X Q. yarryana : Quercus 6. Quercus lobata ~&e(Q. hindsii Benth.; X subconvexa Tucker Q. longiglanda Torr. & Frem.)

4. Quercus engelmannii Greene Valley Oak

Mesa Oak, Engelmann Oak Hybrids:

Q. lobata X douglasii : Quercus x jolonensis Sargent Q. lobata X dumosa : Quercus X Hybrids: macdonaldii Greene (Q. X townei Palmer; Q. dumosa var. Q. chrysolepis X Q. tomentella kinselae C.H. Muller) (See detailed discussion in Q. chrysolepis X Q. vaccinifolia preceding section.) Q. lobata X Q. engelmannii In the mountains of central and 2. lobata X Q. garryana southeastern , Q. chrysolepis Q. lobata X Q. turbinella ssp. hybridizes freely with Q. dunnii. californica : Quercus X munzii In California, however, they are Tucker completely isolated ecoloqically.

7. Quercus sadleriana R. Br. Campst. Varieties:

Deer Oak var. Jeps.

Hybrids: This name has been applied to almost any shrubby form of Q. Q. sadleriana X Q. garryana var. chrysolepis throughout its ranq<. breweri Munz' (1959) suggestion that this variety is "possibly a hybrid with 8. Quercus turbinella Greene (Q. dumosa Q. vaccinifolia" may well apply to var. turbinella (Greene) Jeps; Q. shrubby forms found at higher subturbinella Trel.) elevations in the Sierra Nevada, but not to the numerous chaparral Desert Scrub Oak forms throughout the Coast Ranqes and the mountains of southern subsp. californica Tucker California (Myatt 1975).

Hybrids: 10. Quercus dunnii Kell. (2. chrysolepis subsp. palmeri Engelm.; Q. palmeri Q. L. californica X 2. a- Engelm. ) lasii : Quercus X =- diana Eastwood (Q. dumosa Dunn Oak (Palmer Oak) var. alvordiana (Eastw.) Jeps. ) (See detailed Hybrids: See comment under Q. discussion in preceding chrysolepis. section. ) Q. L. californica X Q. dumosa The name Quercus palmeri Engelm. Q. 2. californica X Q. is used for this oak by some authors; lobata : Quercus X munzii however, strict adherence to the Tucker rule of priority (Article 11, International Code of Botanical Intermediate Oaks (Subgenus Protobalanus) Nomenclature, 1972) dictates the use ---- of the name Quercus dunnii Kell. 9. Quercus chrysolepis Liebm. (2. fulve- scens Kell.; Q. crassipocula Torr.) Kellogq published the name and Canyon Live Oak, Maul Oak original description of Q. dunnii in the Pacific Rural Press (a weekly Jepson named a number of forms farm newspaper!) in June, 1879. (later elevating them to varieties) that Engelmann, however, had previously supposedly differ in one way or another named another collection of this oak from typical Q. *solepis: forma Quercus palmeri in 1877; but in grandis (var. grandis), forma hansenii doing so, he designated it a sub- (var. hansenii), forma (var. species of Q. chrysolepis -- not a -nana), forma pendula (var. pendula). distinct species. Although he did Aside from the var. E, however, elevate it to full specific rank in these are scarcely worthy of taxonomic a later publication (October, 1879), recognition. this was 4 months after Kellogg published Q. dunnii. Quercus tomentella Enqelm. Varieties:

Island Oak var. frutescens Enqelm. var. oxyadenia (Torr.) J. T. Hybrids: Howell

Q. tomentella X Q. chrysolepis Hybrids:

guercus vaccinifolia Kell. (2. chryso- Q. aqrifolia. var. oxyadenia pis subsp. vaccinifolia Engelm.) X Q. kelloqgii: Quercus Huckleberry Oak X ganderi C. B. Wolf Hybrids: Q. vaccinifolia X Q. *- solepis 14. Quercus kellogqii Newb. (Q. tinctoria var. californica Torr.; Q. califor- Black or Red Oaks (Subgenus Erythrobalanus) nica Cooper; Q. sonomensis Benth.)

13. Quercus agrifolia ~6e(Q. acutiglandis California Black Oak Kell.; Q. pricei Sudw.) Coast Live Oak Shrubby forms, mostly at higher elevations, were named forma cibata The name Quercus pricei Sudworth by Jepson. has long been a source of confusion to Californian botanists. In my Hybrids: judgment it is best considered a synonym of Q. agrifolia. Q. kelloqgii X Q. agrifolia: percus X chasei McMinn, The type specimen of Quercus Babcock & Riqhter pricei (Geo. B. Sudworth Aug. 20, Q. kelloqqii X Q. agrifolia 1904, U. S. National Herbarium No. var. oxyadenia: Quercus 1583367) is clearly Q. agrifolia in X ganderi C. B. Wolf most characteristics: the acorns are 0. kelloggii X Q. wislizenii: annual in maturation -- not bien- Quercus X morehus Kell. nial, as stated by Sudworth (1907, l908), the leaves are slightly to 15. puercus wislizenii A. DC. (Q. parvula moderately convex above, and on the Greene; Q. shrevei C. H. Muller) under side usually bear tufts of Interior Live Oak pubescence in the axils of the secondary veins. Some of the Quercus wislizenii is characteris- leaves, however, are slightly more tic of the woodland association pointed apically than is typical for of interior foothills and lower Q. agrifolia -- in this character mountain slopes in California, as they are slightly suggestive of Q. its common name implies. The wislizenii. species as a whole is rather diverse ecoloqically, however, and several A series of 4 collections recent- generally recognizable forms, noted ly made at the type locality, Dani's below, are often correlated with Ranch, Monterey County (N.H. Cheat- specific habitats. These may merit ham, 29 Sept., 1978) are all Q. taxonomic recognition, as varieties agrifolia. None of them showed any or subspecies; in fact, names have indication of hybridity with Q. been applied to some of them. ------wislizenii, although Cheatham reported that the latter species was 1. The most prevalent form is in the general area. the commonly spreading, round- headed tree of interior foothill Hybrids: woodland.

Q. aqrifolia X Q. kellogqii: Quercus X chasei McMinn, Babcock, & Righter Q. agrifolia X Q. wislizenii 2. A shrubby form is common ACKNOWLEDGEMENTS in chaparral areas and is the prevalent form in the mountains of I wish to express my thanks to Mr. Tim R. southern California (var. frute- Plumb and Dr. James R. Griffin for helpful scens Engelm. ) . suggestions in preparing this paper, and to them, and Mr. Kevin C. Nixon and Dr. Ralph N. 3. A form with unusually Philbrick, for reviewing the manuscript. large, oblong leaves, which may be a tall tree on the borders of My thanks are due, also, to the curator redwood groves, is frequent in the of the U.S. National Herbarium for the loan of Santa Cruz and Santa Lucia Moun- the type specimen of Quercus pricei. tains. The name Quercus shrevei C. H. Muller was applied to a similar form of Q. wislizenii from LITERATURE CITED the Santa Lucia's (Palo Colorado Canyon, Monterey Co., about four Abrams, L. miles from the ocean) although it 1923, 1940. (2nd printing) Illustrated was described as a small tree 4-6 flora of the Pacific States. Vol. 1. 557 m. tall, with small, evergreen p., illus., Stanford Univ. Press. leaves growing scattered in the chaparral of ridgetops (Muller Benson, L. 1938). 1962. Plant taxonomy, methods and princi- ples. 494 p., illus., Ronald Press Co., 4. A shrubby form on Santa New York. Cruz Island was described as Quercus parvula Greene. Munz Benson, L., E. A. Phillips, P. A. Wilder, et (1959) treated this name as a al. synonym of var. frutescens Engelm., 1967. Evolutionary sorting of characters in the chaparral form of the main- a hybrid swarm, I. Direction of slope. land; but shrubs of this insular Am. J. Bot. 54:1017-1026, illus. form, growing in the University of California Arboretum at Davis, Boughey, A. S. seem distinctly different, having 1968. A checklist of Orange County flower- larger, less spiny leaves, larger ing plants. Univ. Calif ., Irvine, and more pubescent buds, and more Mus. Syst. Biol. Res. Ser. 1. 89 p., blunt and pubescent acorns. illus. Quercus parvula probably merits recognition as a variety distinct Eastwood, A. from the var. frutescens. 1905. A handbook of the trees of California. Occas. Papers Calif. Acad. Sci. 9:l-86, Mr. Kevin C. Nixon, a graduate illus. student at the University of California, Santa Barbara, is Greene, E. L. currently making a detailed study 1889-90. Illustrations of west American of Quercus wislizenii (sensu oaks. 84 p., illus., Bosqui Engrav- lato). His views are quite simi- ing and Printing Co., San Francisco. lar to those expressed above. Griffin, J. R. and W. B. Critchfield. Hybrids: 1972. The distribution of forest trees in California. USDA, For. Serv. Res. Q. wislizenii X Q. agrifolia Paper, PSW-82/1972. 114 p., illus. -Q. wislizenii X Q. kelloggii: Quercus morehus Kell. Hoffmann, R. 1932. Notes on the flora of the Channel Islands off Santa Barbara, California. Bull. So. Calif. Acad. Sci. 31:46-60.

Jepson, W. L. 1925. A manual of the flowering plants of California. 1238 p., illus., Assoc. Students Store, Univ. Calif., Berkeley. McMinn, H. E. Rehder, A. 1939. An illustrated manual of California 1947 (2nd ed.1. Manual of cultivated trees shrubs. 689 p., illus., J. W. Stacey, and shrubs. 996 p., illus., Macmillan Inc., San Francisco. Co., New York.

Muller, C. H. Sargent, C. S. 1938. Further studies in southwesternoaks. 1895. The silva of North America, Vol. Am. Midi. Nat. 19:582-588. VIII. Cupuliferae. 190 p., illus., Houghton, Mifflin & Co., Boston. Muller, C. H. 1967. Relictual origins of insular endemics Smith, C. F. in Quercus. pp. 73-77, illus. &: R. N. 1976. A flora of the Santa Barbara region, Philbrick (ed.), Proceedings of the California. 331 p., illus. S. B. symposium on the biology of the California Mus. Natural History. islands. Santa Barbara Bot. Gard. Sudworth, G. B. Munz, P. A. 1907. A new California oak (Quercus pricei). 1959. A California flora. 1681 p., illus., For. and Irrig. 13:157-158, illus. Univ. Calif. Press, Berkeley and Los Angeles. Sudworth, G. B. 1908. Forest trees of the Pacific slope. Munz, P. A. 441 p., illus. USDA, For. Serv., Washing- 1968. Supplement to a California flora. 224 ton, D. C. p., Univ. Calif. Press, Berkeley and Los Thorne, R. F. Angeles. 1967. A flora of Santa Catalina Island, California. Aliso 6:l-77, illus. Munz, P. A. 1974. flora of southern California. 1086 A Tucker, J. M. p., illus., Univ. Calif. Press, Berkeley 1950. Interrelationships within the puercus and Los Angeles. dumosa complex. Ph.D. dissertation, Univ. Calif. Library, Berkeley. 246 p., illus. Myatt, R. G. 1975. Geographical and ecological variation Tucker, J. M. in Quercus chrysolepis Liebm. Ph.D. 1952. Evolution of the Californian oak dissertation. Univ. Calif. Library, Quercus alvordiana. Evolution 6~162- Davis. 220 p., illus. 180, illus. Quercus Natural Hybridization Between Two Evergreen aqrifolia Black Oaks in the North Central Coast Ranges of

Michael C. Vasey -2/

Abstract: Hybridization between coast and interior live oaks is recognized and appears to be concentrated in the northern portion of their overlapping ranges. A hybrid index analysis of selected populations of these species along a 175- mile north/south gradient confirms this observation,and an examination of the fossil record suggests a reason for this pattern of concentration. After a long period of isolation, ancestors of these two oaks converged during the Middle Pliocene and dramatic oscillations of climate in California since that time provided ample opportunity for hybrid estab- lishment particularly at their range extremes in the north central Coast Ranges. It is suggested that this study could be improved by incorporating Quercus kelloggii into a com- puterized hybrid analysis of all three species.

INTRODUCTION

Although California's two evergreen black Critchfield (1972) mention a senior thesis oaks, ~uerc&agrifolia ~6eand Q. kslizenii which focuses on such hybridization in the A. D.C.. are well recomized suedes, the Santa Cruz Mountains (Thomas 1970), I could possibility of naturalhybridizationbetween not obtain a copy. the two has been minimally investigated and This study was motivated by the long-term found to exist. Griffin and Critchfield (1972) observations of Dr. G. L. Stebbins,who noted reported that in Mendocino County, at the the apparent extensive hybridization in northern extreme of 0. agrifolia's distribution, Mendocino and was impressed by the lack of this species seems to hybridize readily with such hybridization in more southerly regions Q. wisiizenii so that it is difficult to tell of the Coast Ranges where the two species are where the coast live oak distribution ends. sympatric. As Visiting Professor at San Well-documented evidence of hybridization Francisco State University, Dr. Stebbins con- between these two species was first published ducted a graduate seminar in which he and nine by Brophy and Parnell (1974). By means of a students attempted to (1) analyse and document hybrid index analysis, they discovered signi- the extent of hybridization between selected ficant degrees of hybrid activity between four populations of the two species along an approx- sympatric populations of the two live oaks in imate 175 mile transect from southern Mendocino Contra Costa County. Although Griffin and Co. to the San Mateo/Santa Cruz Co. line and (2) investigate the possible causes for greater hybridization in the north than in the south. à Presented at the Symposium on the Ecology, Management and Utilization of California Oaks, Claremont, California, June 26-28, 1979. METHOD OF STUDY 2' 2' Graduate student, Department of Ecology and Two control populations were selected upon Systematic Biology, San Francisco State Univer- which the subsequent hybrid studies were based. sity, 1600 Holloway Avenue, San Francisco, The Q. agrifolia controls came from a presumably California 94132. pure population near San Bruno on the San data, Dr. Stebbins selected eight of these Francisco Peninsula and the Q. wislizenii con- characters that provided the most legitimate trols from a stand in the Sierra Nevada foot- contrast between the two controls. In view hills near Ione. Two sympatric localities of the small number of characters developed, were sampled, Saratoga Gap and Phoenix Lake, we analysed the results by means of an and two less distinct sympatric populations Andersonian hybrid index. Three of the char- near Hopland in Mendocino Co. were incorporated. acters were deemed of sufficient distinction These four sympatric populations covered as to merit weighting. Hence a total of eleven much of a north to south gradient as was pos- values were assigned to each specimen. Table sible within the scope of the survey. Finally, 2 lists the final characters, those weighted, two additional allopatric populations were and the values involved in scoring each selected, Q. a rifolia from Hamilton Base and individual. Q. wislizenii-jÑÃrom Lake Co. Table 1 provides The question of geographically differ- pertinent data regarding these eight popula- ential hybridization was approached by inves- tions. tigating the possibility of more effective We collected population samples in early reproductive isolation in the south due to February, 1978, removing one typical branch different timing mechanisms and from ca. thirty mature trees per locality. by examining the evolutionary history of the These were labeled, sealed, and stored in two species. The efforts expended in exploring large plastic bags in a cold storage chamber. the former did not prove to be particularly We initially evaluated the control samples in fruitful. However, this possibility was not terms of the best morphological distinctions ruled out. Some evidence suggested that the between the two species and determined only timing of Q. wislizeniils pollination is cued thirteen characters of potential significance. by photoperiod response whereas 0. agrifolials Each member of our group then scored an equal is not, and this may be a contributing factor share of specimens. Concerted efforts were in keeping the two species apart in the south made to unify the group's evaluation of each where Q. agrifolia may bloomearlier due to of the characters. Based upon the accumulated thermal response.

Table I--Population locality data.

Population Locat ion Elevation Plant ~ssociations-I1 Habit

San Bruno Junipero Serra Co. Park, off 60 m Mixed Hardwood F., spreading trees, 1-280, San Bruno, San Mateo Co. Q. agrifolia-Arbutus 10-16 m high Ione Off Hwy 88 ca. .8 km east of 90 m Foothill Woodland small trees, junction Rte 124, Amador Co. ca. 10 m high Saratoga Gap Along Hwy 9, .3-1.8 km SW of 670 m Mixed Hardwood F., varied trees, Hwy 35, San Mateo/Santa Cruz Arbutus-Lithocarpus 3-12 m high Co. line

Phoenix Lake AlongPhoenix~CrownRds., .8 180m Mixed Hardwood F., varied trees, km SE of Phoenix Lake, Marin Co. Q. agrifolia-Arbutus 3-10 m high & Chaparral Hamilton Base Ca. .4 km SW of Hamilton AFB at 60 m Mixed Hardwood F. spreading trees, entrance to Pacheco Valley Ave, Q. agrifolia-Arbutus 10-14 m high Marin Co. Lake County Along Hwy 175 ca. 16 km E of 720 m Chaparral shrubby trees, U.S. 101, Lake Co. 2-4 m high Hopland Entrance Ca. .3 km from junction Hwy 175 240 m Foothill Woodland/ medium trees, & rd. to UCD Field Sta., Northern Oak Woodland 4-10 m high Hopland, Mendocino Co.

Hopland Headquarters Vicinity of Bunkhouse, UCD Field 240 m Foothill Woodland/ spreading trees, 1Sta., Hopland, Mendocino Co. Northern Oak Woodland 6-16 m high Ñ Plant associations according to Barber and Major (1977). Table 2--Index values of character states.

-- -- Q. agrifolia Q. wislizenii Character Index Value (1) Index Value (2)

Length to width leaf ratio .57 - .79 .33 - .56 Number of secon ary veins 6 - 11 12 - 22 Leaf concavityL7 + +/- and - Leaf concavit +/- and + - Abaxial hairs/? + +/- and - Abaxial hairs +/- and + - Number of trichome rays 8 - 14 5-7 Max. width of lateral veins&/ .19 - .40 mm .07 - .18 mm Max. width of lateral veins .27 - .40 nun .07 - .26 INII 10. Mean size ultimate areoles .020 - .046 imn .047 - .080 mm 11. Length terminal bud scales 1 - 3.9 mm 4-7mm Maximum Hybrid Index Values 22 I I/ Indicates the characters weighted to give double values.

The evolutionary analysis took place in from the less adapted species into the gene three stages: (1) Dr. Stebbins visited Dr. pool of the most highly adapted species for D. I. Axelrod at U.C. Davis, who provided the particular environment (Anderson 1949). data regarding all known localities of the This process results in progeny which favor presumed fossil antecedents of the two subject the dominant species in a majority of char- species and the approximate dates of the fossil acters but nevertheless reveal a small number floras in which they were located; (2) all of features characteristic of the other parent. available literature regarding these fossils, As anticipated, of the four sympatric their floras and their photographs was reviewed; populations, Saratoga Gap presented the fewest and (3) Dr. Stebbins and I visited the Depart- intermediates (16 percent), this number in- ment of Paleontology at U.C. Berkeley and con- creased dramatically further north at Phoenix sulted with Dr. Howard Schorn and examined key Lake (54 percent), and the Mendocino popula- fossils pertaining to the study. tions were nearly bereft of pure species, possessing 87 percent and 80 percent inter- mediates at, respectively, Hopland Entrance RESULTS and Hopland H.Q. In reality, the Hopland H.Q. population did not consist of two sympatric The results of the hybridization analysis species since none of the individuals scored are graphically portrayed by histograms (fig. as pure Q. agrifolia. On the other hand, the 1) which plot the frequency distribution of Hopland Entrance population, which was nearer the total hybrid index values obtained for to the large valley in which the town of Hop- each individual sampled per population. The land is located, included sympatric individuals great majority of individuals from San Bruno of both parental species and appeared to (86 percent) scored between 11-13 and those constitute a classic hybrid swarm with few from lone (97 percent) scored from 20-22. pure species, a large percentage of intro- These two sets of values were interpreted to gressive types varying in each direction (47 represent, respectively, the ranges of varia- percent) and a significant number (40 percent) tion for pure Q. agrifolia and pure Q. *- of Fi hybrid types. These findings correlated lizenii. Individuals possessing scores midway well with field observations and tend to con- between these two extremes (16-17) were con- firm the suspected north to south hybridization strued to represent Fl generation hybrid types. gradient. Finally, specimens which scored between the The findings with respect to the two allo- extreme and mean values (14-15 and 18-19) were patric populations (Hamilton Base and Lake Co.) interpreted to represent, respectively, intro- were, on the contrary, quite surprising. Al- grossed Q. agrifolia types and introgressed Q. though the habitat and physiognomy of the wislizenii types. trees at Hamilton Base strongly resembled the Briefly stated, introgression represents control population at San Bruno, only 33 per- the repeated backcrossing of a natural hybrid cent of the population scored in the range of to an ecologically dominant parent which re- pure Q. agrifolia whereas 23 percent scored sults in the introduction of the germ plasm as introgressive Q. agrifolia types and a 18 16 14 12 210 8 v 6 .d > 4 '-'2 2 11 12 13 14 15 16 17 18 19 20 21 22 - - Index Values Index Values SAN BRUNO (29) IOKE (28) SARATOGA GAP (30)

.> 4 -3 2 T- ! ' T i - ?-'"I 1 1 1 : L l I l l H 1 1 - 1 1 11 12 13 14 15 16 17 18 19 20 21 22 Index Values Index Values PHOENIX LAKE (30) HAMILTON BASE (30)

Index Values Index Values LAKE COUNTY (30) HOPLAND ENTRANCE (30) 2101

Index Values HOPLAKD HEADQUARTERS (30)

Figure I--Frequency distribution of hybrid index values with extremes of 11 for Q. agrifolia and 22 for 9. wislizenii.

remarkable 40 percent appeared to represent the Eocene Chalk Bluffs Flora, has been inter- Fl hybrid types. Similary, although the Lake preted to represent an ancestor of Q. agrifolia Co. population looked like the typical shrubby (MacGinitie 1941). This fossil is ca. 55 Q. wislizenii frequently associated with high million years (m.y.) old^/ and, according to chaparral throughout the Coast Ranges, the MacGinitie, was part of a humid, subtropical hybrid index values reveal that less than half flora which now finds its closest modern of the population scored as pure. Since hy- counterpart in the tierra templada of the brid individuals occur in these populations eastern Sierra Madre Mnts. of Mexico. Thus, in spite of the present absence of one of the a plausible ancestor to Q. agrifolia is docu- putative parent species, either these trees mented in the early Tertiary of California, a represent progeny derived from ancestors distinction shared by few other modern ele- which once existed in more sympatric popula- ments of California's vegetation. tions and produced fertile hybrids, or some Over the next thirty-plus million years other factor not considered in the present the fossil record is silent with respect to study must account for these results. These these species. When evidence of their exis- two possibilities will be discussed below. tence resurfaces in the Miocene, a clear Although the fossil record of Q. a~&- pattern emerges with respect to their status -folia and Q. wislizenii is not extensive, it and distribution. The oldest known locality does provide certain key insights into the evolutionary history of the two species. A very ancient fossil, Q. distincta Lesq. from 31 Personal communication, H. Schorn. for Q. wislizenii's fossil antecedent, Q. cularly in their northern sympatric range wislizenoides, is the Middlegate Flora of where approximately 65 percent of the individ- western Nevada and the fossils found there uals which were sampled from populations north clearly demonstrate that Q. wislizenii had of San Francisco Bay demonstrated some degree completely differentiated by this time and of hybridity. Muller (1952) proposed that superficially did not differ from the modern speciation in Quercus is primarily a function species. This fossil flora has been dated at of geographic isolation, paleoecology, con- ca. 18 m.y. of age and included many deciduous temporary ecology (accompanied by convergence) hardwoods, conifers, and other sclerophyllous and hybridization. The evolutionary analysis trees typical of a mild continental climate. described above follows this pattern and sug- As is demonstrated by the west Sierra Nevadan gests that the underlying cause for the north/ Remington Hill Flora (ca. 9 m.y. old) and the south hybridization gradient relates to the central Coast Range Mulholland Flora (ca. 7 interaction of two ecologically dissimilar m.y. old), Q. wislizenoides and several of its species capable of exchanging genes which Middlegate associates were forced to retreat came into contact at least 5 m.y. ago and from the interior west as a result of Sierran which, in a region of mutual stress at range uplift and a warmer and drier climate. By extremes, produced hybrid derivatives more the Middle Pliocene, this western migration highly adapted to habitats created by the resulted in Q. wislizenoides being well es- vicissitudes of the recent Pleistocene than tablished in California's Coast Ranges. either of the parent species. Muller (1952) Q. agrifolia's recent fossil record is and Tucker (1952) also reached similar con- less satisfactory but, as indicated by the clusions in studies involving hybridization reported existence of its fossil relative, Q. in uercus and Nobs (1963) cites fossil evi- lakevillensis, in the 12 m.y. old Mint Canyon dence+ w ich suggests that a similar conver- and the 7.5 m.y. old Mt. Eden Floras, it then gence of maritime and continental species of apparently existed in a frostless, subhumid Ceanothus during the Middle Pliocene in the association which prevailed over much of same geographic region, the north central southern California. Axelrod (1977) has com- Coast Ranges, resulted in an explosion of pared this association, characterized by speciation in that genus. avocado, palm, laurel and other sclerophylls, This interpretation may account for the to the so-called hammock flora of Florida. surprising percentage of hybrids found in the The fossil record suggests that this flora, allopatric populations at Hamilton Base and and a contemporaneous coastal closed-cone Lake Co. An alternative explanation, however, conifer forest of which Q. lakevillensis was relates to one of the drawbacks to this study - most likely a member, moved up along Califor- i.e., the fact that a third member of the nia's coast during the Lower Pliocene, reach- black oak subgenus in California, Q. kelloggii ing its most northerly distribution in the Newb., was not considered in the hybridization Middle Pliocene. By 6.5 m.y. ago, as is in- analysis. Q. kelloggii is a deciduous oak of dicated by the Petaluma Flora, Q. lakevillen- northern affinities with deeply lobed leaves -sis was also present in the central Coast which, because of its distinctiveness in con- Range and, at least by this time, had the trast to the two evergreen black oaks, was soon recognized as a hybridizing parent in opportunity to exist in sympatric. - populations- - with Q. wislizenoides. crosses with both Q. wislizenii (Q. X morehus Hence, after an extended period of geo- Kell.) and Q. agrifolia (2.X chaseii McMinn). graphic isolation during which these two- Although this species was not observed at the species differentiated into their modern forms, Lake Co. site, there are several individuals they came together by the Middle Pliocene as in the Hamilton Base vicinity. Therefore, climatic and physiographic changes favored a this species may have influenced the results convergence of their two respective vegetation from that locality as well as elsewhere by types. Since that time, a gradual cooling contributing genes to the individuals sampled. and at least four major glacial advances and Another drawback to this study was our retreats have had a dramatic affect on the inability to utilize fruiting characteristics evolution of California's flora (Raven and because of the extremely poor acorn set in the Axelrod 1978) and, undoubtedly as well, on populations sampled, possibly due to the two the opportunity for sucessful establishment year drought preceding the study. Q. a~&- of hybrids between these two live oaks. folia is unique amongst all other black oaks in its ability to set mature acorns in one year, whereas the remainder of black oaks re- DISCUSSION quire two years, and consideration of this character would undoubtedly have helped in This limited survey suggests that a sub- recognizing hybrids. stantial amount of hybridization has occurred Jensen and Eshbaugh (1976) demonstrated between Q. agrifolia and Q. wislizenii, parti- the value of computerized cluster and principal component analysis in distinguishing the inter- Axelrod, D. I. relations between three sympatric species of 1977. Outline history of California vegeta- black oaks in the eastern U.S. and they were tion. Barbour, M.; Major, J. (eds.) critical of studies in which all possible Terrestrial vegetation of California. putative parents are not considered for the John Wiley Interscience, New York, pp. chief reason, as suggested above, that such 139-220. studies preclude an evaluation of the impact Barbour, M.; Major, J. (eds.) of potential contributors to the gene systems Terrestrial vegetation of California. John of the individuals sampled. This computerized Wiley Interscience, New York, 1002 pp. approach requires a large number of characters in order to be accurate and, if acorn char- Brophy, W. B.; Parnell, D. R. acteristics and the distinctive features of 9. 1974. Hybridization between Q. agrifolia kelloggii were included, it is likely that the and Q. wislizenii (). Madrono 22: Jensen and Eshbaugh techniques could be suc- 291-302. cessfully applied to a study of the precise relationships between the three California Griffin, J. R.; Critchfield, W. B. black oaks and such a study could conceivably 1972. The distribution of forest trees in be of great value in clarifying these relation- California. U.S. Dept. Agric. Forest ships. Service Research Paper PSW-82, 114 pp. In the absence of such a study, however, the evidence of hybridization between Q. s- Jensen, R. J.; Eshbaugh, W. H. folia and Q. wislizenii will presumably con- 1976. Numerical taxonomic studies of tinue to accumulate and the question of accord- hybridization in Quercus. Systematic ing taxonomic status to their recognizable Botany 1: 1-10. progeny must ultimately be considered. The chief argument in favor of such recognition MacGinitie, H. D. is that the taxonomic identity Is incorporated 1941. A Middle Eocene Flora from the into regional floras and, thus, communicates central Sierra Nevada. Carnegie Insti- the existence of recognizable hybrids to the tute of Washington Publication 534, greatest number of field observers. Perhaps Washington, D.C., 178 pp. the best argument against this alternative is that it may be literally impossible to provide Muller, C. H. andequate description of a type hybrid and 1952. Ecological control of hybridization the attempt might actually create more con- in Quercus: a factor in the mechanism fusion than vice versa. In any case, it is of evolution. Evolution 6: 147-161. reasonably clear that further attention should be devoted to this subject. Nobs, M. A. 1963. Experimental studies on species relationships in Ceanothus. Carnegie ACKNOWLEDGEMENT Inst. of Wash. Publication 623, 94 pp. Without the inspiration and dedication Raven, P. H.; Axelrod, D. I. of Dr. G. L. Stebbins, this paper would not 1978. Origin and relationships of the have been possible, and I would also like to California flora. U.C. Publ. Bot. 72, thank Dr. Axelrod and Dr. Schorn for their 134 pp. contributions to the evolutionary analysis and Drs. J. R. Griffin and J. R. Sweeney for con- Thomas, D. structive comments regarding this presentation. 1970. Hybridization and interpopulation The following graduate students at S.F. State variation in the California live oaks, were also instrumental in accomplishing this Quercus agrifolia and Quercus wislizenii. study: C. Bern, H. Chapot, K. Culligan, M. Senior Thesis, U.C. Santa Cruz, 40 pp. Elliott, E. Gerry, M. Hewlett, P. Sheldon, and D. Showers. Tucker, J. M. 1952. Evolution of the California oak. Quercus alvordiana. Evolution 6: 162-180. LITERATURE CITED Anderson, E. 1949. Introgressive hybridization. Wiley and Sons, New York, 109 pp. Tanoak (Lithocarpus densiflorus) Leaf Surface Characteristics1 M.G. King and S.R. Radosevich-11

Abstract: Abaxial (lower) and adaxial (upper) surfaces of densiflorus mature and immature tanoak leaves were characterized. Three types of trichomes (stellate, glandular, and uniseriate) are found on each surface of both mature and immature leaves. Tanoak leaves have stomata only on lower surfaces and the stomata1 complex lacks distinct subsidiary cells. Stomata morphology, wax ultrasturcture and cuticular membrane mor- phology are described.

INTRODUCTION results in substantial increases in conifer stem enlargement (Radosevich et al., 1976). Tanoak (~ithocarpusdensiflorus (H. & A.) On heavily infested sites, tanoak control is ~ehd.) is a hardwood, evergreen tree species. considered necessary prior to establishing It attains a height of 65to 130 ft. (20 to conifers. 40 m) but often occurs in a large shrub-like form as a result of sprouting (usually after Foliar herbicide applications are often fire or other disturbance) and subsequent limited in effectiveness on old tanoak growth, growth of the dominant stems. It ranges from possibly because of poor absorption through southwestern Oregon to Santa Barbara, Cali- the foliage. Leaf surface features influence fornia. Tanoak also occurs in the northern wetting, retention, and absorption of foliar Sierra Nevada, principally between the Feather applied chemicals (Hull, 1970). King and and American rivers (Fowells, 1965). In the Radosevich,(1979) found that enhanced absorp- Coast Ranges of California, tanoak is the most tion of C-triclopyr ( a promising brush abundant hardwood present in timber stands. control herbicide) was associated with greater In Mendocino and Sonoma counties an estimated stomata densities, lesser amounts of surface 169,000 ha (27 percent of the total commercial wax, greater stellate trichome densities and forest land) is occupied by tanoak (Oswald, thinner, more permeable cuticular membranes. 1972). Most (97 ~ercent)of the hardwood type is on land capable of producing conifers A knowledge of leaf surface characteris- (Oswald, 1972). tics has ~otentialuses for taxonomic studies. Some leaf surface structures can be considered McDonald (1977) has described the poten- as adaptive plant responses to the environ- tial economic uses of tanoak. However, in ment. In this paper, we describe thoroughly many areas tanoak is considered a problem weed both adaxial and abaxial surfaces of mature tree. Tanoak can completely dominate a site and immature tanoak leaves. after logging or fire. Vigorous sprouting, prolific seed product ion, and rapid early seedling growth enable tanoak to successfully MATERIALS AND METHODS compete with conifers such as Douglas-fir and redwood. Removing hardwood tree competition Plant Material

1 Tanoak acorns were collected in the North -'presented at the Symposium on the Ecology, Coast Range, Mendocino County, California. Managment, and Utilization of California After germination, the seedlings were grown in Oaks, Pomona, CA. June 25-27, 1979. a lath house. To maintain active growth during the winter, all plants were moved to a 2'~es. Asst. and Assoc. Prof., Dept. of controlled environment growth chamber. Botany, Univ. of California, Davis, CA Leaf material was collected near Laytonville, 95616. California,ana at the Blodgett Forest Research Figure 1. Scanning electron micrograph (SEM) Figure 3. SEM of a base of stellate trichome of a cross section of a mature tanoak leaf on the adaxial surface of an immature tanoak (~lod~ett),critical point dried, gold-coated. leaf (growth chamber), gold-coated, critical Adaxial surface (ad), and abaxial surface point dried. Wax globules (g). X2480. (ab). X300.

Figure 2. SEM of asymetrically-shaped stel- Figure 4. Light micrograph of a stellate late trichomes on the abaxial surface of trichome (It). X310. a mature tanoak leaf (~aytonville),oven- dried, gold-coated. X230. St ation near Georgetown, California. The surfaces of tanoak leaves, regardless of age. methods used to store and preserve both growth In figures 2 and 4, the asymetrical stellate chamber and field collected material have been trichome is shown. Many specialized epidermal described by King (1978). cells form a base upon which the stellate trichome sits (fig. 3). The arms of this In all studies mature leaves were a dark trichome are thick walled and have no septa green color, glabrate, fully expanded and (fig. 4). Stellate trichome density is averaged 2.4 in. (6.0 cm) in length. Immature significantly greater on immature than mature leaves were a pale green color, densely leaves and on abaxial rather than adaxial pubescent, averaged .8 in (2.0 cm) in length surfaces (table 1). Neither cellular contents and were neither fully expanded nor hardened. nor cytoplasmic streaming were observed in cells comprising stellate trichomes. None of Surface Investigation the component cells gave a positive reaction fliuoresced) to fluorescein diacetate even on The methods used for determining epicuti- the youngest leaves observed. cular wax quantities and ultrastructure, stomata densities, trichome types and distri- Table 1.' Surface characteristics of tanoak bution and cuticular membrane thickness and leaves.- morphology have been described (~ing, 1978 ; King and Radosevich, 1979). Epidermal anatomy and stomata1 morphology were investigated by viewing leaf cross sections under a scanning electron microscope (SEM). Cross sections were cut free-hand from fresh leaves from axial 890 growth chamber grown plants. They were Immature fixed in FAA (Sass, 19581, dehydrated in a Adaxial --- 33.5b l.Oa graded ethanol series (50 to loo%), trans- ferred to amyl acetate, critical point dried Abaxial 555 12.1~ 3.7b (Anderson, 19511, and gold-coated. Viability Mature of the cells comprising the various trichome Adaxial --- 2.Id 4.4~ types was determined by staining fresh leaf 1 -'~aken from King and Radosevich (1979). cross sections with fluorescein diacetate (Widholm, 1972). Cells which were viable 2'~eans differ significantly at t .05' fluoresced a bright yellow-green color. Ñ~eanfollowed by the same letter do not Embedded waxes in the cuticular membrane were differ significantly at the 5% level, observed using the polarized light microscopic Duncan's Multiple Range test. technique of Norris and Bukovac (1968). Figure 5 shows the glandular trichome RESULTS AND DISCUSSION found on tanoak leaf surfaces. Glandular trichomes are more abundant on immature than mature Leaves and on abaxial rather than adaxial surfaces. This type of trichome has a An SEM micrograph of a mature tanoak leaf cross section is shown in figure 1. The upper multicellular (more than eight cells), globose epidermis is composed of two cell layers. The head on a uniseriate stalk composed of 3 to 4 upper of these is composed of small rectan- cells. The cells comprising the head often gular shaped cells (in cross section) which contain a dense, red-brown material. One or are thick walled (see fig. 11 also). The more viable cells were found about 30 percent lower cell layer is composed of much larger of the time in the glandular trichomes. cells which also have thick walls. Abaxial epidermal cells have rounded outer periclinal The simple, uniseriate trichome (fig. 6, 7a) is composed of 3 to 4 cells, is derived cell walls which give the abaxial leaf surface a more undulating aspect than the adaxial from a single epidermal cell, and frequently surface. is bent horizontally on the leaf surface. The basal or apical cells of the uniseriate Trichomes trichome fluoresced 56 percent of the time but seldom did all the component cells. Immature tanoak leaves are densely pubescent on both surfaces. Mature leaves are Little is known about the uniseriate and tough, leathery and nearly glabrous. Three glandular trichome types. However, stellate distinct trichome types (stellate, glandular, trichomes may have many physiological func- and uniseriate simple) are found on both tions (Uphof, 1962). Initially they may hold Figure 5. SEM of a glandular trichome (gt) Leaf was critical point dried, gold-coated

Figure 7. SEM of the abaxial surface (wax removed) of mature tanoak leaves (Blodgett). a) Oven-dried leaf, gold-coated. Uniseriate trichome (ut) , normal stomata (6). X1260. b) Oven-dried leaf, gold-coated. Large stomata Figure 6. SEM of uniseriate trichomes, (Is), cuticular membrane surface (cs). X1164. platelet wax on the abaxial surface of tanoak leaves (~lod~ett),oven-dried, gold- coated. Uniseriate trichome (ut). X1150. Figure 8, SEM of a cross section of a stomata Figure 10. SEM of the adaxial surface of a on a mature tanoak leaf (Blodgett), critical mature tanoak leaf (Blodgett). Oven dried, point dried, gold-coated. Guard cells (gc), gold-coated. Wax globules (g ), base of cuticular ledge (cl) and baffles (bf). stellate trichome (b). X780. X5O2O.

Figure 9. SEM of the abaxial surface of a Figure 11. Light micrograph of a fresh, mature tanoak leaf (Laytonville) showing free-hand, cross section of the adaxial attachment of the stellate trichome (It) to surface of a mature tanoak leaf (growth its base (b). X1450. chamber), stained with a mixture of Sudan I11 and Sudan IV. Cuticular membrane (cm). Note cuticular pegs or flanges (arrows). X390. the developing leaves together in the bud. The cuticular membrane is significantly After bud-break, they can protect the young thicker on mature than immature tanoak leaves leaves from dessication by increasing the (table 1). A polarized light technique vapor boundary layer thickness. A dense (Norris and Bukovac, 1968) indicated that stellate trichome covering might also reduce embedded waxes are present in both adaxial and the amount of insolation and help keep leaf abaxial cuticular membranes of mature leaves. temperatures from becoming excessive (Uphof, Extensions of the cuticular membrane over the 1962). antic linal adaxial epidermal cell walls were noted on mature leaves (fig. 11). Stomata Tanoak leaves have no stomata on adaxial surfaces. Stomata are more dense on abaxial SUMMARY surfaces of immature than mature leaves (table 1). The stomatal complex has no distinct Tanoak leaves undergo marked changes as subsidiary cell (fig. 7a)which agrees with they mature. The stellate trichome density on earlier descriptions of this species (Camus, mature leaves is 16 percent of that present on 1954). Occasionally stomata which are mor- immature leaves (King, 1978). The frequency phologically different (fig. 7b) from the of the glandular and uniseriate trichome types normal type (fig. 7a) were encountered on also declines with age. Stomata density on lower surfaces of mature and immature leaves. mature leaves is 62 percent of that on imma- The guard cells of the "large" type (fig. 7b) ture leaves. Epicut icular wax quantities have a convoluted surface aspect and the increase with age and the wax ultrastructure cuticular membrane surface of the surrounding changes markedly on both surfaces. Mature epidermal cells is somewhat striated. Guard leaves have a thicker, less permeable cuti- cells of the "normal" type have an unusual cular membrane than immature leaves. pear-shaped appearance in cross section. Baffles on the interior of the pore surface Stellate trichomes on tanoak leaf sur- (fig. 8) and a cuticular ledge over the upper faces may provide mechanical protection to portion of the pore were observed. Both of young, developing leaves. By increasing the these features reduce the effective pore vapor boundary layer (thus increasing diffu- diameter and increase diffusive resistance sive resistance) they may protect the leaf which may aid in water conservation. from excessive water loss. Dense formations of stellate trichomes decrease the amount of Cuticle insolation, aid in maintaining optimal leaf temperatures, and provide physical protec- Tanoak leaves are heavily waxed in tion against damage. Cuticular ledges over comparison to many herbaceous species. Much stomatal pores and baffles lining the pore may greater amounts of wax were found on mature also aid in water conservation. Mature tanoak (200 ug/cm ) than immature (82 ug/cm ) tanoak leaves are heavily waxed and have relatively leaves (King and Radosevich, 1979). The dried thick cuticular membranes which can decrease extracted waxes are a pale yellow-brown and the rate of water loss and provide mechanical are sometimes translucent. Wax ultrastructure protection against disease and physical on tanoak leaves has been previously described abrasion. (King and Radosevich, 1979). Long thin wax ridges are found on the abaxial surfaces of immature tanoak leaves but cover little of LITERATURE CITED the total surface area. Wax globules are scattered randomly over the adaxial surfaces Anderson, J.T. of immature leaves (fig. 3). Dense formations 1951. Technique for the preservation of of wax platelets superimposed on an amorphous 3-dimensional structure in preparing wax sheet are found on the abaxial surfaces of specimens for the SEM. Trans. N.Y. Acad. mature leaves (fig. 6,9). However, wax Sci. 13:130-134. platelets are seldom observed on stellate trichome bases on the abaxial surfaces of Camus, A. mature leaves (fig. 9). No platelets or wax 1954. Les Chenes. In: Encyclopedie econo- ridges were seen on the adaxial surfaces of mique de Sylviculture, Vol. VIII. Ed. tanoak leaves regardless of age. A thick, Paul Lechevalier. Paris. amorphous sheet of wax completely covers the adaxial surfaces of mature leaves (fig. Fowells, H.A. 10). 1965. Silvics of Forest Trees of the United States. Agriculture Handbook No. 271, For. Serv., USDA. 762 pp. Hull, H.M. Radosevich, S.R., P.C. Passof, and O.A. 1970. Leaf structure as related to absorp- Leonard. t ion of pesticides and other compounds. 1976. Douglas fir release from tanoak and Residue Rev. 31:l-155. Pacific madrone competition. Weed Sci. 24:144-145. King, M.G. 1978. Foliar Absorption of Two Herbicides Sass, J.E. in Tanoak (~ithocarpusdensiflora). M.S. 1958. Botanical Microtechnique. The Iowa Thesis, Univ. of California, Davis. State University Press. Ames, Iowa. 228 PP King. M.G. and S.R. Radosevich. 1979. Tanoak (Lithocarpus densiflorus) leaf Uphof, J.C. Th. surface characteristics and absorption of 1962. Plant Hairs. In: Encyclopedia of triclopyr. Weed Sci. 27(6):599-604. Plant Anatomy. Eds. K. Linsbauer, G. Tishler and A. Pasher. GebrUder Born- McDonald, P.M. traeger, Berlin. 1977. Tanoak...a bibliography for a promis- ing species. USDA For. Serv. Gen. Tech. Widholm, J.M. Rep. PSW-22. 1972. The use of fluorescein diacetate and phenosafranine for determining viability Norris, R.F. and M.J. Bukovac. of cultured plant cells. Stain Tech. 1968. Structure of the pear leaf cuticle 47:189-194. with special reference to cuticular penetration. Am. J. Bot. 55:975-983.

Oswald, D.D. 1972. Timber resources of Mendocino and Sonoma counties, California. USDA For. Serv. Resour. Bull. PNW-40. Adaptations of Mediterranean-Climate Oaks to Environmental Stress1

Philip W. ~undel"

Abstract: Plane growth-form and leaf duration are structural traits which provide important adaptations of oaks to individual environments. Shrubby taxa of oaks dominate in areas with relatively severe environmental stresses of drought, short growing season, or nutrient deficiency. Water stress is a primary determinant of leaf duration in oaks.

INTRODUCTION season temperatures as well as length of growing season vary along these gradients, providing a Species adaptations to gradients of broad range of environmental conditions for environmental stress may take many forms in selection to respond to. Since higher mean the oaks. The most significant environmental temperatures in California are generally cor- gradient in California is aridity, brought on related with lower annual precipitation, these by a mediterranean climate. During the winter two factors are interrelated. when precipitation is present, mean temperatures are too low to allow favorable photosynthetic A final major environmental stress activity. When temperatures are favorable influencing the evolution of oaks in California for growth during the summer months, precipita- has been nutrient availability. The complex tion is absent. For oaks, as well as for geological history of many parts of the state other elements of our flora today, the present has produced mosaics of soil types which can assemblage of species representsthe outcome again act as selective factors in the evolution of evolutionary selection of genotypes adapted of a variety of taxa including oaks. Since to these climatic stresses. nutrient cycling in oaks is the subject of a specific review in this volume, it will not In addition to aridity, mediterranean- be considered here. climate conditions also promote a tendency toward frequent fire. Groups of adaptive ADAPTATIONAL STRATEGIES characteristics have clearly evolved in many -California oaks to promote species survival, In looking at broad evolutionary patterns particularly in chaparral and forest environ- in oaks, two groups of structural traits can ments where fires are frequent. be recognized which have a great deal of signif- icance in the adaptation of individual species With the existing degree of topographic to their environments. These traits are the diversity in California, significant temperature plant growth form, whether a shrub or tree, gradients are present. Both mean growing and the leaf duration, whether evergreen or deciduous. The growth form which a plant takes is a function of the relative allocation of carbohydrates synthesized through ^presented by Gail A. Baker at the Symposium to each of four compartments (fig. 1). For on the Ecology, Management, and Utilization trees a very large part of this allocation goes of California Oaks, Claremont, California, to support tissues such as a trunk and branches June 26-28, 1979. to give a plant a large size. Height in plants may be selected for to outcompete plants shorter in stature, to avoid ground dwelling predators, 2'~ssociate Professor, Department of Ecology to reach sunlight at the top of a forest canopy, and Evolutionary Biology, University of or to evade light surface fires. In shrubs California, Irvine, CA 92717. a main trunk is usually absent and much less a more efficient use of these nutrients. In photosynthetic additioqevergreen leaves are able to store tissues nutrients during the winter for later growth, and further drop their old leaves slowly to structural allow a better return of nutrients to the tissues soil through decomposition. Despite these advantages, evergreen leaves have the signif- C02 fixation reproductive icant disadvantage of having a relatively tissues low rate of maximum photosynthesis in comparison to thinner deciduous leaves. L> root tissues In California the 15 species of native Figure 1-The pattern of carbon allocation oaks can be arrayed into community types to plant tissues. where they predominately occur for each of four growth categories (table 1). Montane forests contain all four types, but individual relative allocation to support tissues is habitats commonly contain only a single species. required. Root tissues in most shrub species Foothill woodland communities generally lack are a very significant part of the total biomass shrubby oaks, but both deciduous and evergreen and in some environments may be much greater trees are present. Chaparral and desert in biomass than above-ground tissues. In habitats usually support only a single growth- genera1,shrubby growth and associated high form of evergreen shrubs. This distribution root-to-shoot ratios are associated with pattern of growth-forms of oaks in California conditions of high environmental stress. is very similar to that of the Mediterranean Common forms of stress which may promote region of France where deciduous tree, ever- dominance of shrub species are arid conditions, green tree,and evergreen shrub forms of oak high fire frequency, cold temperatures with are all present. a short growing season, low nutrient avail- ability, and heavy grazing. Finally, herba- The adaptive significance of individual ceous species, not represented in the oaks, growth-forms of oak, as discussed below, can are characterized by allocating high propor- be seen in the differing ecological responses tions of their carbohydrates to photosynthetic of shrubs and trees and of evergreen and and reproductive tissues. Minimal structural deciduous-leaved plants. The diversification support and relatively small root biomasses of California oaks into individual growth-forms are commonly present. In annual plants 15-30 clearly does not follow taxonomic lineages. percent of annual production may go to reproduc- The three species of black oaks in California tion alone. include both deciduous (Q. kelloggii) and ever- green trees (Q. wislizenii and Q. agrifolia). Selective pressures for evergreen or Among the white oaks all four growth-forms deciduous characteristics are a response to are present. The closely related Quercus the seasonality of the environment. When a chrysolepis group includes this evergreen tree predictable drought or cold period is present as well as three evergreen shrubs, 2. dunnii, in an environment so that no photosynthetic Q. vaccinifolia and Q. cedroensis of Baja production can take place during a particular California. Quercus salderiana, an evergreen season, then natural selection should promote shrub in the northern part of the state, is deciduous leaves if the metabolic costs of most closely related to deciduous tree oaks of maintaining leaves during the stress period the eastern United States. Quercus garrayana is greater than the cost of producing new may occur in its typical deciduous tree form leaves the following season. Where stress or in taxonomically distinctive shrub forms. periods are variable in length and intensity A similar pattern of change may occur in so that favorable conditions for photosynthetic Q. wislizenii, normally an evergreen tree. production may occur at any time during the year, evergreen leaves have the advantage of BIOMASS ALLOCATION 'always being present to utilize such favorable conditions during normal stress periods. Patterns of biomass allocation in oaks Since evergreen leaves commonly remain for differ considerably with shrub and tree growth- two years or more, the metabolic expense of forms. Since shrubs typically lack a central producing them maybe much less than for trunk and have much smaller structural require- deciduous leaves. Other advantages of ever- ments for woody tissue than trees, it is not green leaves accrue in nutrient-poor surprising to find that shrubs allocate a environments for several reasons. Long leaf greater proportion of their above-ground biomass duration allows greater net photosynthetic to leaves than do trees. Examples of literature production per unit of leaf nutrient and thus Table 1-Distribution of California oaks by community distribution and growth-form

Growth Form

Community deciduous tree deciduous tree evergreen tree evergreen shrub

montane forest 0. kelloggii Q. sarrayana var. 9. chrysolepis Q. vaccinifolia

Q. salderiana

foothill woodland Q. jgarrayana Q. wislizenii

Q. Q. agrifolii

Q. engelmanii

Q. doufilasli

chaparral Q. prraysna var. brewer1 Q. Q. %

2. dunnii

Q. wislizenii var. f rutescens

desert Q. turbinella

island endemic Q. tomentella

data on those relative allocation patterns are With repeated fires this root crown grad- shown for a series of oaks in table 2, using ually enlarges and the number of resprouted the four major categories of leaf duration stems present increases (Pond and Cable, 1960). and growth-form previously described. For The storage of energy reserves and possibly evergreen and deciduous shrubs the range of nutrients and water in the root crown makes relative leaf biomass ranges from 10-17 percent continued resprouting possible. Even without of above-ground biomass, while values for the root crown biomass, it appears that the evergreen and deciduous trees range from 2-7 root-shoot ratio of shrub oaks is still percent. For most shrubs species the remaining significantly greater than that of tree oaks. biomass is completely allocated to branch Calculations of root-shoot ratio in Quercus tissues, although a significant trunk may form turbinella ignoring root crown biomass still in Q. ilicifolia, an eastern scrub oak. give a value of 1.9 (Davis, 1978).

SHOOT AND ROOT CHARACTERISTICS For obvious reasons detailed studies of root distribution in oaks are relatively few. Comparative data on the ratio of root Early observations noting the correlation of biomass to above-ground biomass (root-shoot --Quercus lobata in California with deep alluvial ratios) in shrubby and tree oaks also show a soils suggested that this species has deep and fundamental difference in patterns of biomass well-developed root system reaching the water allocation (table 2). Root-shoot ratios for table (Jepson, 1910; Cannon, 1914). These four species of trees range from 0.18 to 0.91, same studies suggested that Q. douglasii was indicating a large dry weight of shoot biomass. associated with shallow soils on exposed hill- In shrubby species, however, root biomass far sides and thus root access to the water table exceeds that of shoots with root shoot ratios was unlikely. Cannon (1914) hypothesized that of 3.17 to 6.28. Much of the relatively large Q. agrifolia has no deep roots, but instead proportion of root biomass is concentrated developed an extensive shallow root system. in a massive woody root crown which allows Quercus kelloggii may have a single major tap efficient resprouting following fires (Muller, root or numerous major vertical roots depending 1951; Plumb, 1961, 1963). Most tree oaks sprout on its substrate. principally in an epicormic manner from above- ground tissue following fires, but some deciduous Lewis and Burghy (1964, 1966) used tri- tree oaks such as Q. douglasii and Q. lobata tiated water to obtain the first quantitative may sprout poorly or not at all. data on rooting depths in California tree oaks. Their studies in the foothills of the Sierra of the shrub through the upper 30 cm of soil. Nevada indicate that Q. =, Q. douglasii Major laterals are joined beneath the canopy and Q. wislizenii may all root to depths of to a massive woody root crown similar to those 10-20 m under favorable conditions. On one characteristic of many chaparral shrubs which of their plots they found Q. douglasii tapping resprout following fire. water at 26 m depth. Studies of seasonal water stress patterns of three species of Quercus LEAF CHARACTERISTICS in the Santa Lucia Mountains of Monterey County indicate that both Q. lobata and Q. agrifolia Evergreen and deciduous leaves of oaks, have root systems which reach ground water, , as with other plant groups, have differences while Q. douglasii roots do not (Griffin, 1973). in leaf characteristics which influence their The only eastern deciduous oak for which good physiological behavior. Evergreen leaves in data are available, Q. macrocarpa, has a deep temperate latitudes are characteristically and ramifying root system with a tap root sclerophyllous in texture with a relatively reaching 4 m depth and more than 30 large thick and leathery feel. These leaves typically branch roots extending outward 6-20 m (Weaver remain on oaks for two growing seasons but and Kramer, 1932). occasionally longer. Deciduous leaves which are much thinner and less leathery in texture Shrubby evergreen oaks in Southern are much less resistant to environmental California and Arizona have surprisingly deep extremes and are present on the shrubs only root systems. Hellmers et al. (1955) reported during favorable growing periods. roots of CJ. dumosa in the San Gabriel Mountains at a depth of nearly 9 m, the deepest of any The greater sclerophylly of evergreen oak of the chaparral plants they observed. They leaves can be seen in data on leaf specific noted few feeder roots in the top 15 cm of soil. weight shown in table 3. Evergree shrubs and More detailed excavations of Q. turbinella in trees have values from 12-18 g cm' w-9 ile Arizona chaparral found a tap root penetrating deciduous trees range from 7-10 g cm . One through cracks and fissures to bedrock at a species of deciduous shrub, Q. ilicifolia from depth of nearly 7 m (Davis, 1978; Saunier and arid sandy habitats on the East Coast, has an Wagle, 1967). Even at this depth individual intermediate value which is quite high for a roots still reached 5 mm diameter. A dense deciduous leaf. mat of fine surface roots, most less than 2 mm diameter, extend out radially from the center

Table 2--Above-ground biomass and relative allocation of biomass in the genus Quercus. Data from Mooney et al., 1977; Whittaker and Woodwell, 1963; Lossaint, 1973; Whittaker and Niering, 1975; Whittaker, 1966: Johnson and Risser, 1974; Duvigneaud and Denaeyer-De Smet, 1970; Davis, 1978.

Biomass Distribution

location Above-ground reproductive root-shoot biomass leaves branches trunk tissues ratio

Evergreen shrubs

Q. dumosa California Q. agrifolia California Q. coccifera France Q. turbinella Arizona

Deciduous shrubs

Q. ilicifolia New York

Evergreen trees

Q. France Q. hypoleucoides Arizona

Deciduous trees

Q. coccinea New York Q. New York

Q. stellata Oklahoma Q. marilandica Oklahoma Q. robur Belgium

'current twigs and leaves Included 46 Table 3--Comparative leaf characteristics in the genus Quercus. Sclerophyll index is calculated as (percent lignin and cellulose x 100)/crude protein content. Data from Mooney et al, 1977; Lossaint, 1973; Whittaker and Woodwell, 1968; Whittaker, 1966; Johnson and Risser, 1974; Duvigneaud and DenaeyerDe Smet, 1970; Cromack and Mark, 1977; Loveless, 1962.

specific sclerophyll location 1 weight 1 nitrogen 1 cellulose 1 lignin 1 :z:z 1 index

percent percent percent percent

Evergreen shrub

Q. dumosa California Q. coccifera France Q. chapmanil Florida Q. myrtifolia Florida Q. breviloba Texas Evergreen trees

Q. agrifolia California Q. virginiana Florida Texas 0. wislizenii California Q. chrysolepis California Deciduous shrubs

Q. ilicifolia New York Deciduous trees

Q. douglasii California Q. coccinea New York Q. & New York Tennessee France California Oklahoma Oklahoma Belgium Q. S.E. U.S. g. coccinea S.E. U.S. Q. S.E. U.S. 2.0 14.9 9.1 26.0 132

Another measure of the comparative sclero- PRODUCTIVITY phylly of evergreen and deciduous oak leaves is the sclerophyll index (table 3). This index When productivity of oaks is calculated on is the ratio of crude fiber content (cellulose the basis of some measure of available photo- and lignin) to crude protein content for a leaf synthetic tissue, the significance of evergreen (Loveless 1961, 1962). Evergreen shrubs and and deciduous leaves can be seen. The general trees have sclerophyll indices of 236-450, pattern expected is that sclerophyllous evergreen values typical of evergreen chaparral shrubs. leaves with thick cuticles are slow at taking Values for deciduous trees range from 69-177. up C02 and therefore photosynthesize at much A comparison of the individual components of lower maximum rates than deciduous leaves this sclerophyll index (table 3) indicate that where gas exchange is rapid. Evergreen leaves nitrogen levels (the major limiting component are present all twelve months of the year, of proteins) are not significantly different however, and may therefore be able to photo- in evergreen and deciduous leaves of oaks, synthesize during favorable conditions when with the exception of the high nitrogen levels deciduous plants may be leafless. reported for Q. stellata and Q. marilandica in Oklahoma. Among the evergreen shrubs oak Net annual above-ground productivity leaf nitrogen levels are generally higher calculated per unit of leaf dry weight varies than those of other evergreen shrubs in the from 0.85-1.50 g g1 for everg een shrubs and same habitats, indicating a relatively high trees, and from 2.23-3.66 g g-Y for deciduous nitrogen requirement. The major basis for trees (table 4). Deciduous trees, therefore, the high values of sclerophyll index in ever- are much more efficient at utilizing photo- green species is the high level of both synthetic tissues for production. This pattern cellulose and lignin in the leaves. Together of relative efficiency between evergreen and these structural components comprise 28-47 deciduous leaves is less apparent on a leaf percent of the leaf dry weight of evergreen area basis where evergreen 1 aves have a species. Less than 14 percent of the dry productivity of 160-210 g m 5 , and deciduous weight of deciduous leaves of Q. douglasii trees have a range of 216-345 g m-2. This are cellulose and lignin. more similar pattern of productivity per unit Table 4--Abve-ground net productivity and allocation of new growth in the genus Quercus. Data from Mooney et al.. 1977; Whittaker and Woodwell, 1968; Lossaint, 1973; Whittaker and Nieringf1975; Whittaker, 1966; Johnson and Risaer, 1974; Duvigneaud and Denaeyer-De Smet, 1970.

1 1 relative allocation of growth I productivity

above-ground reproductive Ideation productivity leaves branches trunk tissues

(gn~~~r-l) percent percent percent percent (g g-'leaf) (g *^leaf) Lg leaf N) Evergreen shrubs

Q. California 425 87.4 11.3 Q. agrifolial/ California 338 87.6 7.5 Q. coccifera France 340 Deciduous shrubs

Q. ilicifolia New York 6.2 25.8 11.7 0.3 1.61 254 115 Evergreen trees

France 67 5 Arizona 47.621 27.9 24.5

Deciduous trees

Q. coccinea New York 43.8 29.6 24.5 2.1 2.23 304 28 2 Q. & New York 44.9 31.1 20.2 3.8 2.24 216 284 Tennessee 26.6 35.3 37.8 0.3 3.66 345 26 1 Q. stellata Oklahoma 874 39.7 36.2 24.0 2.51 61 73 Q. narilandica Oklahoma 387 33.3 25.6 41.1 3.00 113 Q. Belgium 282 36.5 40.4 23.0 2.73

/shrub form current twigs and leaves included leaf area is due not to the equal photosynthetic from 26-45 percent Quercus ilicifolia, a rates of the two leaf forms but rather to the deciduous shrub, has a intermediate value. longer period of productivity in evergreen species. Allocation of net productivity to reproduc- tive structures in oaks appears to be relatively Since nitrogen may be limiting to produc- low, although data are limited. Values for six tivity in many environments, productivity can species range from 0.3-4.9 percent (table 4), also be calculated per unit of leaf nitrogen. but careful measurements in years of good acorn On this basis evergreen leave range in production woul likely produce greater alloca- productivity from 49-107 g g-' leaf nitrogen. tions. Griffin has found that production of Deciduous leaves are much more variable on viable acorns by Quercus lobata in the Carmel this basis. Quercus coccinea and Q. which Valley (Monterey County, California) is directly have low concentrations of leaf nitrogen have related to total precipitation of the previous values of 261-284 g g- leaf nitrogen, while growing season (fig. 2). the other four deciduous species for which data are available have values almost identical WATER RELATIONS to those of the evergreen species. In addition to the photosynthetic Differences in productivity patterns are differences between evergreen and deciduous not restricted to evergreen versus deciduous leaves, the greater sclerophylly of evergreen leaves in oaks, but occur in shrubs versus leaves makes them considerably more drought tree growth-forms as well. As with biomass resistant. Leaves of deciduous oaks are highly distribution, the above-ground productivity and sensitive to decreases in leaf water content. relative allocation of new growth in shrub and Both Quercus pubescens and Q. robur, deciduous tree growth-forms of oak differ significantly trees in central Europe, initiate stomata1 (table 4). In the two California evergreen shrubs for which data is available, Q. dumosa and Q. agrifolia (shrubby form), over 87 percent of new growth is allocated to leaves. Leaf "~n~ublisheddata. James R. Griffin, Univ. allocation in the five species of deciduous of Calif., Hastings Nat. History Reservation, oak trees for which data are available range Carmel Valley, Cal. continues,the first symptoms of desiccation injury appear at relative water contents of about 50 percent in Q. pubescens (Larcher, 1960) .

In the evergreen Q. of the mediterra- nean region of Europe,stomatal closure does not begin until the leaves reach a relative water content of 85 percent of their saturated level. Stomata1 closure is fairly rapid, however, and occurs at a similar relative water content to that of the deciduous oak species. The most signficant difference between the two types of leaves is that cuticular transpiration is negligible (less than 3 percent maximum tran- t I I I I spiration rates) in the evergreen leaves 300 400 500 600 700 800 900 PRECIPITATION IN PREVIOUS SEASON (mm) because of their thick cuticle. As a result --Q. ilex is able to limit its transpirational water loss ten times more effectively than the Figure 2--Collection of viable acorns of deciduous species by closing its stomata. Quercus lobata at ground level in relation Furthermore, desiccation injury in Q. to precipitation during the previous growing does not occur until relative water contents season at the Hastings Natural History of 40 percent are reached. Reservation, Carmel Valley. Unpublished data of James R. Griffin. The characteristic pattern of the replace- ment of deciduous oaks by evergreen oaks along a gradient of increasing aridity in both closure when relative leaf water content drops California and Europe results to a large part to 90 percent of its saturated level (Larcher, from the physiological characteristics of 1960; Pisek and Winkler, 1953; Arvidsson, 1951). each leaf type as described above. Both As leaf relative water content drops below 70%, deciduous and evergreen oaks in California stomata1 closure is complete in Q. pubescens may experience midday stomatal closure late and positive net photosynthesis ceases (fig. 3). in the growing season as water stress In Q. robur, a more shade-adapted species, increases. Evergreen leaves limit their water stomatal closure occurs more rapidly (Pisek loss under drought conditions by rapidly and Winkler, 1953). Because of the thin cuticle closing their stomata and restricting cuticular of deciduous leaves, cuticular transpiration transpiration to very low levels. Since the continues at this stage at a level 30-50 percent relative water content of evergreen leaves of the maximum rate of transpirational water can reach much lower levels without desiccation loss with fully open stomata (Pisek and Berger, injury than that of deciduous leaves, they 1938; Larcher, 1960). As leaf water loss are able to endure much longer drought periods. Experimental studies have indicated that the evergreen Q. can endure drought periods 15 times longer than the deciduous Q. pubescens nsiomotoopen ~Graduolclosure Cuticular ME; woter of stoma10 wafer loss . (Larcher, 1960). Quercus ~ubescens-deciduous Few data are available on field measure- ments of the relative drought tolerance of ecological groups of oaks. Griffin (1973) made intensive studies of water relations of Ouercus douglasii, 9. lobata, and Q. agrifolia -in the coast ranges of Monterey County over a three year period. The maximum dawn water stress he recorded in mature trees was 40 bars in Q. douglasii in late summer. Under 1 I I I 1 1 1 I I I I 100 SO 60 40 20 0 stressful conditions, midday water stresses RELATIVE WATER CONTENT (%> in 0. douglasii always exceeded values for Q. agrifolia by 5-10 bars, indicating that the latter species was able to tap ground Figure 3--Comparative water relations of Quercus water supplies unavailable to Q. douglasii. pubescens (deciduous) and Quercus ilex (ever- Bottomland stands of Quercus lobata and Q. green) in the Mediterranean region of Europe. agrifolia showed little difference in maximum See text for discussion. stress between very dry and wet years, again reached in adjacent individuals of but less than those in Heteromeles arbutifolia. Dawn Midday In comparison to California oaks, eastern n deciduous oaks do not develop extreme water stress. Studies of three species of Quercus in New England indicated maximum summer water stresses of only 25 bars (Federer, 1978).

Recent comparative studies of the water relations of four species of oaks in the foot- hill zone of , California, during the very dry winter of 1977 and the subsequent moist winter of 1978 allow an inter- pretation of the response of oaks species to environmental drought. Midday water stresses of over 50 bars were present in Q. douglasii and Q. chrysolepis in the fall of 1977, with stresses close to 50 bars also present in Q. wislizenii (fig. 4 and 5). The severe nature of this drought is indicated by the minimal level of recovery from water stress overnight in the lowered dawn readings. Maximum stesses for the same oaks in 1978 were considerably lower in all species (fig. 4 and 5). Dawn levels of water stress were 10-30 bars lower for the four species, indicating considerable overnight recovery of plant water status. -601

A F B IDAWN 1977 1978 0 MIDDAY Q douglasii A ASH MOUNTAIN B BUCKEYE P POWER STATION Figure 4~Comparativewater potentials of Quercus dou~lasiiat dawn and midday for maximum seasonal stresses of 1977 and 1978 at three sites in the foothill zone of Sequoia National Park, California. indicating their ability to utilize ground water. In these bottomland stands density of trees is unrelated to water stress. On slopes where Q. douglasii occurs on shallower soils, however, density of trees is strongly related to water stress as water is a limiting resource (Griffin, 1973). Under these condi- tions denser stands of vegetation on more "mesic" north-facing slopes may actually undergo drought stress earlier than more open stands of vegetation on the "xeric" south- facing slopes.

Field measurements of water stress of Quercus agrifolia in the Puente Hills of Southern California indicated that drought Figure 5~Comparativewater potentials of stress never exceeded 20 bars in August of ~uercuswislizenii, 9. chr&olepis and 1972, an unusually dry year (Syvertson, 1974). Q. kelloggii at dawn and midday for maximum These stress levels were greater than those seasonal stresses of 1977 and 1978 in the foothill zone of Sequoia National Park, California. Even with the heavy spring of 1978, Two other evergreen oaks from the however, one population of Q. douglasii still Mediterranean region, Q. suber (cork oak) and developed water stress in excess of 50 bars the shrubby Q. coccifera are slightly less at midday. cold resistant than Q. m. Quercus pubescens, a deciduous tree from the same region tolerates COLD RESISTANCE temperatures below -35'~ (Larcher and Mair, 1969). Detailed data on the relative cold tolerance of California oak species have not HERBIVORY been collected, but some indication of the expected response of our mediterranean-climate Herbivory by both insects and vertebrates species can be gained from studies of cold on oaks may be very great. This herbivory is resistance in species of Quercus from the clearly related to the relatively high nutrient Mediterranean region of Europe. These studies content of oak foliage and the abundant resources have shown that cold resistance varies consid- oaks represent in many ecological communities. erably with the age of the plant and the nature feeding on oaks is generally concentrated of the tissue. in the early spring, coinciding with a period of maximum leaf growth. Insect damage studied For stands of Quercus ilex, an evergreen in three species of oaks in New York accounts tree comparable to Q. agrifolia, mature trees for a 7.0-15.6 percent loss in leaf area survive temperatures as low as -20' to -2S° (Whittaker and Woodwell, 1968). so long as cold periods do not last long enough to freeze the thick trunks (Larcher and Mair, The intensity of feeding by lepidopteran 1969). Winter soil surface temperatures of larvae on leaves on Quercus robur has been only -4'~ are sufficient to kill seedlings, shown to be related to chemical and textural however. changes in the composition of leaves (Feeney, 1970). As leaves mature, content The ability to resist cold in shoots of increases from less than 1 percent in the Quercus ilex follows a cyclical pattern of early spring to over 5 percent by the end of increasing frost-hardening over the first five the summer (fig. 7) over the same period leaf years of growth (fig. 6). Seasonal tolerance nitrogen content drops from over 4 percent to of frost is also quite variable. Shoots of about 2 percent. These , concentrated mature plants which survive -25'~ in winter in vacuoles in the palisade parenchyma, have may be killed by -5OC in summer. Mature leaves the ability to form complexes with proteins tolerate -15'~ in winter but only -6'~ in and thereby reduce the availability of nitrogen summer. Roots show a pattern of little seasonal for insect growth. As a result, summer insect change in cold resistance and no change with damage to oak leave is greatly reduced from plant age (Larcher, 1969).

I I I I I I Figure 6--Cold tolerances of Quercus ilex in Apr May Jun Jul Aug Sept the Mediterranean region of Europe. The Figure 7--Seasonal progression of concentra- open area indicates summer responses, tion (% dry weight) of nitrogen and tannins while the shaded areas are winter responses. in the deciduous leaves of Quercus robur. Redrawn from Larcher (1969). Redrawn from Feeney (1970). what it potentially might be. Parallel studies LITERATURE CITED of predation in relation to leaf characteristics have not been carried out with California oaks. Arvidsson, I. It is interesting to note that damage by leaf 1951. Austrocknungs- und Dhreresistenz- miners is proportionally greater in summer vehgltnisse einger reprgsentanten 8lSndisher than in spring for oak leaves. These insects Pflanzenvereihe nebst Bemerkungen uber are able to avoid tannins by feeding in spongy Wasserabsorption durch oberirdische Organe. parenchyma tissue and ignoring palisade cells Oikos l(supp1. ): 1-185. where tannins are concentrated (Feeney, 1970). Axelrod, D.I. Tannins may also be toxic to many grazing 1977. Outline history of California vegeta- vertebrates if large quantities of oak foliage tion. pp. 139-193. 2: Barbour, M.G. and areconsumed. Oak toxicity has been a major J. Major (eds.) Terrestrial vegetation of economic problem in many rangeland areas where California. John Wiley, New York. cattle, sheep or goats may preferentially consume an almost exclusive diet of young oak Cooper, W.S. leaves, buds and acorns (Kingsbury, 1964). 1926. Vegetational development upon alluvial fans in the vicinity of Palo Alto, CONCLUSIONS California. Ecology 7: 1-30.

Plant growth-form and leaf duration are Cromack, K. and C.D. Monk. structural traits which provide important 1977. Litter production, decomposition adaptive value for oak species in individual and nutrient cycling in a mixed hardwood environments. Shrubby growth-forms of oaks watershed and a white pine watershed. are characteristic of habitats where environ- pp. 609-624. In: Mineral Cycling in mental stress is relatively great. These Southeastern Ecosystems. ERDA Tech Inf. include arid regions (chaparral and desert Serv. CONF-740513. areas) regions with short growing season (high mountain areas) and nutrient-deficient sites Davis, E.A. (e.g. as serpentine soils). Tree growth-forms 1978. Root systems of shrub live oak in dominate where drought periods are shorter or relation to water yield by chaparral. absent and neither temperature or nutrients Hydrology and Water Resources in Arizona are strongly limiting to growth. and the Southwest. 7: 241-248.

Where ground water supplies are available Duvigneaud, P. and S. Denaeyer-De Smet. to reduce periods of summer drought stress as 1970. Biological cycling of minerals in in valley or foothill regions, deciduous oaks temperate deciduous forests. pp. 199-225. dominate in California. They are also dominant D.E. Reichle (ed.) Analysis of Temperate on more xeric habitats at higher elevations Forest Ecosystems. Springer-Verlag, where growing seasons are relatively short. New York. Evergreen leaves, characteristic of the shrubby oaks in chaparral and desert areas, have adap- Federer, C.A. tive value over deciduous leave because of 1977. Leaf resistance and xylem potential their greater drought tolerance. Since such differ among broadleaved species. Forest habitats are commonly low in nutrients, an Sci. 23: 411-419. additional value of evergreen leaves is their greater nutrient use efficiency. This greater Feeny, P. nutrient use efficiency also explains ever- 1970. Seasonal changes in oak leaf tannins greeness in serpentine oaks such as Q. durata. and nutrients as a cause of spring feeding The adaptive values present in evergreen trees by winter caterpillers. Ecology 51: are more difficult to explain since evergreen 565-581. and deciduous oaks may occur side by side and water does not appear to be strongly limiting. Griffin, J.R. More detailed physiological studies are needed 1973. Xylem sap tension in three woodland to resolve this question but the basic environ- oaks of central California. Ecology 54: mental stresses of water and nutrient avail- 152-159. ability are clearly still important. Hellmers, H., J.S. Horton, G. Juhren, and J. O'Keefe. 1955. Root systems of some chaparral plants in southern California. Ecology 36: 667- 678. Jepson, W.L. Loveless, A.R. 1910. The silva of California. Univ. Calif. 1961. A nutritional interpretation of sclero- Mem. , 2: 1-480. phylly based on differences in the chemical composition of sclerophyllous and mesophytic Johnson, F.L. and P.G. Risser. leaves. Ann. Bot. 25: 168-184. 1974. Biomass, annual net primary production, and dynamics of six mineral elements in a Loveless, A.R. post oak-blackjack oak forest. Ecology 1962. Further evidence to support a nutri- 55 : 1246-1258. tional interpretation of sclerophylly. Ann. Bot. 26: 551-561. Kingsbury, J.M. 1964. Poisonous plants of the United States Mooney, H.A., J. Kummerow, A.W. Johnson, D.J. and Canada. Prentice-Hall, Englewood Parsons, S. Keeley, A. Hoffman, R.I. Hays, Cliffs, N.J. 626 p. J. Giliberto, and C. Chu. 1977. The producers - their resources and Larcher, W. adaptive responses. pp. 85-143. In: 1960. Transpiration and photosynthesis of Mooney, H.A. (ed.) Convergent Evolution detached leaves and shoots of Quercus in Chile and California. Dowden, Hutchinson pubescens and Q. during desiccation and Ross. Stroudsburg, Penn. under standard conditions. Bull. Res. Counc. Israel. 8D: 213-224. Muller, C.H. 1951. The significance of vegetative Larcher, W. reproductioi in Quercus. ~idrono11: 1961. Jahresgag des Assimilations- und 129-137. ~espirationsvergm8gensvon europea L. ssp. sativa Hoff. et Link, Quercus ilex L. Pisek, A. and E. Berger. und Quercus pubescens Willd. aus dem 1938. Kutikulare Transpiration und Trocken- nMrdlichen Gardaseebebiet. Planta 56: resistenz isolierter Blstter und Sprosse. 575-606. Planta 28: 124-155.

Larcher, W. Pisek, A. and E. Winkler. 1969. Zunahme des FrostabhBrtungsvergmBgen 1953. Die Schiessbewegung der Stomata bei von Quercus ilex in Laufe der Individual- Mkologische verschieden Pflanzentypen in entwicklung. Planta 88: 130-135. Abhgngigkeit von Wassersattingungzustand der Blotter und vom Licht. Planta 42: Larcher, W. and B. Mair. 253-278 1969. Die Temperaturresistenz a1 8ko- physiologisches Konstitutionsmerkmal: Plumb, T.R. 1. Quercus ilex und andere Eichenarten 1961. Sprouting of chaparral by December des Mittelmeergebietes. Oecol. Plant after a wildfire in July. Pacific SW 4: 347-376. Forest & Range Exp. Sta. Tech. Pap. 57, 12 p. Lewis, D.C. and R.H. Burghy. 1964. The relationship between oak tree Plumb, T.R. roots and ground water in fractured rock 1963. Delayed sprouting of scrub oak after as determined by tritium tracing. J. a fire. USDA Forest Serv. Res. Note PSW-1. Geophys. Res. Wash. 69: 2579-2588. Pond, F.W. and D.R. Cable. Lewis, D.C. and R.H. Burghy. 1960. Effect of heat treatment on sprout 1966. Water use by native vegetation and production of some shrubs of the chapparal hydrologic studies. Annual Report 7, in central Arizona. J. Range Manag. 13: 1965-1966. Dept. Water Sci. & Eng., 313-317. Univ. Calif., Davis. 54 p. Saunter, R.E. and R.F. Wagle. Lossaint, P. 1967. Factors affecting the distribution of 1973. Soil-vegetation relationships in shrub live oak (Quercus turbinella Greene). Mediterranean ecosystems of southern Ecology 48: 35-41. France. pp. 199-210. In: di Castro, F. and H.A. Mooney (eds.) Mediterranean Syvertsen, J.P. Type Ecosystems: Origin and Structure. 1974. Relative stem water potentials of Springer Verlag, New York. three woody perennials in a southern oak woodland community. Bull. South. Calif. Acad. Sci. 23: 108-113. Weaver, J.E. and J. Kramer. Whittaker, R.H. and G.M. Woodwell. 1932. Root systems of Quercus macrocarpa in 1968. Dimension and production relations of relation to the invasion of prairie. Bot. trees and shrubs in the Brookhaven forest, Gaz. 94: 51-85. New York. J. Ecol. 56: 1-25. Whittaker, R.H. Whittaker, R.H. and G.W. Woodwell. 1966. Forest dimensions and production in 1969. Structure, production, and diversity the Great Smokey Mountains. Ecology 47: of the oak-pine forest at Brookhaven, 103-121. New York. J. Ecol. 57: 155-174.

Whittaker, R.H. and W.A. Niering. 1975. Vegetation of the Santa Catalina Mountains, Arizona. V. Biomass, production and diversity along the elevation gradient. Ecology 56 : 771-740. Quercus chrysolepis

Wildfire and the Geographic Relationships Between Canyon Live Oak, Coulter Pine, and Bigcone Douglas-fir Forests1

2 Richard A. Minnich- I

Abstract: Analysis of vegetation changes in the eastern between 1938 and 1975 reveal contrasting burning regimes in bigcone Douglas fir (Pseudotsuga macrocarpa) and Coulter pine (Pinus coulteri) Forests. Differences in the flammability of these types result from the variable physiognomic and fuel characteristics of associated canyon live oak (Quercus chrysolepis), and strongly influence geographic and sympatric relationships between these species.

INTRODUCTION Douglas fir (Pseudotsuga macrocarpa) and Coulter pine (Pinus coulteri) which live at Wildland fire does not have a uniform im- intermediate elevations between lowland chap- pact on the landscape geographically because arral and mixed conifer forests above. The the combustibility of vegetation changes spa- distribution of the two conifers broadly overlap tially with the total habitat. It follows that with canyon live oak but not to one another. the geography of some plant species and plant communities may be related to the changing selective role of wildland fire. ECOLOGY OF CANYON LIVE OAK, COULTER PINE AND BIGCONE DOUGLAS FIR A biogeography of conifer forests was evaluated in the eastern Transverse Ranges Canyon live oak is associated with many (east San Gabriel and San Bernardino Mountains), conifer forest communities in southern Califor- an area of impressive topographic, elevational, nia including Coulter pine, bigcone Douglas fir, and habitat differences (Minnich 1978). Recent mixed conifer forest, and pinyon forest (Minnich vegetation changes due to fire were reconstructed 1978; Thorne 1977; Vasek and Thorne 1977). The from aerial photography (color infrared, color, oak's growth form is quite variable, ranging black and white) flown between 1938 and 1975 from shrub to tree, depending on habitat emphasizing the nature of combustion and post- (Sawyer et al., 1977). The shrub form is typ- fire recovery for seven conifer forest types. ically multiple-trunked with crown bases con- tiguous with the ground surface. Under favor- One finding was that many tree species able circumstances it is also a spreading single- with divergent adaptations and fire responses trunked tree. A thin-barked species for its live together as plant communities because they size, it sprouts mostly from a subsurface root are compatible with the fire regime they create. crown even if the upper canopy is only margin- Other species have no range overlap because the ally defoliated by burning or scorching. Horton fire regime of one is inimical to the other. (1960) and Kittredge (1948) suggest that repeated This paper addresses the relationship between burning reduces canyon live oak to a shrub canyon live oak (Quercus chrysolepis), bigcone physiognomy. Horton also observed that it grows more rapidly to tree physiognomy in mesic habitats where there is also greater chance Presented1.1 at the Symposium on the Ecology, individuals will withstand passing conflagra- Management and Utilization of California Oaks, tions. Where stands are destroyed, however, Claremont, CAY June 25-27, 1979. the area becomes infested with dense chaparral until the oak sprouts mature enough to crowd Ñ1~ssistan Professor, Department of Geography, them out (Horton 1960). California State University, Northridge, CA 91330 Coulter pine is a medium-sized tree with a spreading pyramidal crown and relatively thick bark. It self-prunes poorly, the crowns broken when embedded in chamise chaparral and of even mature trees normally extending to the Coulter pine. It is normally contiguous where ground surface or vegetal understory. It sup- associated with bigcone Douglas fir. Coulter ports massive cones with prominent flattened pine stands (c) occur on dry rocky slopes and spurs, mostly at the summit of the tree or the ridgelines. On the Pacific slope it forms a ends of major branches. The cones require two fragmented distribution from west City Creek years to mature. Cone opening occurs in aid- eastward to San Gorgonio Pass. On desert winter (Critchfield personal communication). drainages, more continuous stands occur on Seeds are hard, heavy,and capable of only mesic headwaters of the East Fork Mojave River limited dispersal unless transferred downslope from Lake Arrowhead east to Shay Mountain. Most by rolling cones. Seedlings develop best on stands are immature and even-aged in appearance open mineral soils and are remarkably drought- (Table 1). Canyon live oak is an oversized tolerant, having coarse cotyledons, rapid early shrub admixed with chamise chaparral dominated photosynthesis, and deep root penetration during by Quercus dumosa, Q. wislizenii, Arctostaphylos the first year (Wright 1966, 1968). It matures glandulosa, Ceanothus leucodermis and Adenostoma rapidly to tree size within several decades and fasciculatum. Total cover is usually close to begins bearing cones within 10 to 15 years. 100 percent. Brush and canyon live oak under- Southern California populations are associated story on desert slopes is more open and mature with chamise chaparral as well as canyon live as evi need in data developed from VTM field oak (Wright 1966, 1968; Wilson and Vogl 1965; plots.-97Few fires have occurred in this region Vogl 1976; Hanes 1976; Minnich 1976; Thorne since Forest Service records begin in 1911. 1977). VTM diameter class data show that Coulter pines are apparently short lived with only 16 per cent Bigcone Douglas fir is considered a long- of individuals having a d.b.h. of 24" (0.6 m). lived species found mostly in stable fire- Most Coulter pine forests are vertically con- resistant habitats (Gause 1966; Bolton and tiguous with shrub and woodland understory. Vogl 1969; Vogl 1968; McDonald and Littrell 1976). A southern California endemic, this Bigcone Douglas fir stands (Bs) are sym- tall conifer has thick bark and long, graceful patric with canyon live oak throughout its dis- lenticular branches. Saplings rarely bear tribution. Forests are long lived. Half of cones before 40 years. Pollination occurs in bigcone Douglas fir individuals sampled by VTM late spring and cones open in August or Sep- workers had a d.b.h. greater than 24" (0.6 m). tember. Seed are heavy and only locally dis- One third of canyon live oak individuals had a persed except during strong winds. Canyon d.b.h. of 12" (0.3 m). Most are tall and single- live oak is an important associate throughout trunked rather than multiple-stemmed shrubs. its range and also occurs as large robust trees Brush cover is minimal and consists mostly of with little brush understory (McDonald and Ceanothus integerrimus and Cercocarpus betuloides. Littrell 1976). Although bigcone Douglas fir Bigcone Douglas fir has a highly fragmented dis- seedlings are large and coarse, capable of tribution along the mesic coastal front of the enduring heat stress, reproduction is most eastern Transverse Ranges from the San Dimas successful in the shade of canyon live oak Experimental Forest eastward into San Gorgonio overstory. Growth may be suppressed by shade Pass. Most populations occupy precipitous stress until polesize stage when trees emerge slopes and sheltered canyons. Above 5000 ft. through the canyon live oak layer (Gause 1966). (1500 m) stands broaden out with canyon live Bigcone Douglas fir is the only southern Calif- oak as understory to cover large areas of mostly ornia conifer capable of sprouting after com- steep complex slopes transected with cliffs or plete defoliation by fire or other disturbance. avalanche shoots, especially in the San Gabriel Sprouts develop from epicormic buds within the Mountains and southeastern San Bernardino Moun- bark layer in the larger branches and along tains. the main trunk. Sprouting success is appar- ently dependent on the size of the tree (Bolton and Vogl 1969). FIRE HISTORY

The eastern Transverse Ranges have exper- PRESENT DISTRIBUTION AND STAND PHYSIOGNOMY ienced many fires since the original aerial photography was flown in 1938. Recent vegetation Canyon live oak (W) occurs on steep, shallow soiled terrain over a wide range of elevation from 2000 to 8500 ft. (600-2600 m). It is con- fined to canyons and north-facing slopes at -'vegetation Type Map Survey (VTM). On file, lower elevations. Above 5000 ft. (1500 m) Pacific Southwest Forest and Range Experiment stands broaden out into a continuous belt which Station. Berkeley, CA. In care of Dr. William nearly encircles the mountains above lowland B. Critchfield. chaparral. Canyon live oak cover is open to TABLE 1- VEGETATION SUMMARY

AERIAL PHOTO DATA VTM DATA-31 5 VEGETATION 197537 MEAN COVER^' SHRU& PERcm STEM DuMETERs >24"-" TYPE AREA OAK 1 CONIFER 1 SHRUB 1 TOTAL COVER OAK 1 CONIFER CANYON LIVE OAK (W) 1 423.2 45 * 35 75 98 1 * BIGCONE DOUGLAS FIR- CANYON LIVE OAK (BsW) 111.8 56 40 5 85 13 30 48

COULTER PINE- CANYONLIVEOAK(G) 32.4 35 25 40 80 22 14 16 I 1 4 -Total area of vegetation type -/percent (in hundreds of hectares) Ñ~retally data; see 3/ above. Ñ~ercen 2/~rush plot data of the vegetation type Map Survey. On file, Pacific Southwest Forest and Range Experiment Station, Berkeley, CA

TABLE 2 -WILDLAND FIRE DAMAGE- I1

4/ 3/ - RECENT VEGETATION DAMAGE VEGE- Q' TOTAL- 3/ DEFOR- DEFORESTATION RATE (percent of stand) TATION 1938 FIRE AREA DEFOR-- ESTATION EXPOSURE 1 SLOPE CLASS (degrees) TYPE AREA IN TYPE ESTATION RATE N 1 S 1 T 1 0-9 1 10-19 1 20-29 1 30-39 1 40 w - -- - 73 90 80 - 73 74 83 70 BsW 136.5 91.6 24.7 27 42 40 41 - 63 61 36 10 - CW 48.2 18.6 15.0 81 86 91 90 - 67 92 91 100

11 0 I --L / Minnich 1978 Ñ'~ hundreds of hectares z/~omputed from 1938 vegetation map. i'~eforestationlTota1 fire area in type. history up to the 1975 aerial coverage shows scorch the overstory without burning them. divergent burning regimes in bigcone Douglas fir and Coulter pine forests and the combustion The partial fire-retardant character of of associated canyon live oak understory tree-size oak woodlands appearsto stem from (Table 2). several factors, including the large living biomass of individual trees, low dead fuel Canyon live oak stands were very sensitive content of crowns owing to leaf fall in early to fire, even low-intensity ground fires. Its summer and most importantly, the distance be- defoliation rate either by char or scorch was tween the crown undercanopy and the ground sur- a high 78% of stands (by area) in recent fires face fuels, which may be as much as 15 to 30 ft. covered by color infrared aerial photography. (5 to 10 m). The most resistant stands were those which assume tree size proportions in canyon bottoms, Nearly 60 percent of bigcone Douglas fir north facing slopes, and as open cover at higher forests escaped defoliation in recent fires. elevations (Fig. 1). Shrub-like stands were Fifteen percent resprouted later, giving a destroyed in the same manner as chaparral because total survival rate of about 75 percent, approx- of the horizontal and vertical contiguity of imating the long-term survival rate for all fuels. There were also numerous islands of fires since 1938. Although this species has yellow-foliaged oak canopies on color infrared the advantage of height over other chaparral photography (CIR) surrounded by burned chap- trees, its success in avoiding combustion may arral indicating that ground fires were able to be better related to its general sympatry with ably impeded the momentum and intensity of the spreading conflagration. Survival of bigcone Douglas fir increases dramatically with increas- ing slope class- from 37 percent on slopes less than 20 to more than 90 percent survival on slopes greater than 40'.

In contrast, most Coulter pine-canyon live oak stands involved in fire since 1938 were killed (81 percent, Fig. 2). The deforestation rate is also high for all slope classes. The physiognomy of this vegetation type virtually guarantees its destruction. The chaparral and oak understory normally burned completely and intensely, leaving little above-ground biomass except for largest fuels. Lacking shade stress, Coulter pine crowns extend downward to the

Figure 1. Fire map and profile of Lytle Creek Canyon burned in 1970. Surviving bigcone Douglas fir and tree-sized canyon live oak (BsW) in canyon bottoms (solid line work on profile, stipple on map) are surrounded by destroyed chamise chaparral and canyon live oak scrub on exposed slopes and ridges. Some bigcone Douglas fir resprouted later (slash on map). Elevation (y axis) in thousands of feet. Scale, 1:12,000. tree-sized canyon live oak woodlands (Fig. 1). These oaks seem to act as a buffer against severe combustion characteristic of nearby chaparral. Analysis of CIR photography shows Figure 2. Fire map and profile of Bear Canyon that the degree of fire injury sustained by burnedin 1970. Sequence of burned Coulter bigcone Douglas fir is spatially congruent with Pine (C) and unburned mixed conifer forests the extent of fire damage to the canyon live (Yellow pine, JY; Sugar Pine-White Fir, SF) oak; i.e., areas of surviving bigcone Douglas on south and north facing slopes, respectively. fir are underlain by either unburned or scorched Coulter pine was destroyed more completely oak. In all defoliated stands of bigcone because of the greater abundance of canyon live Douglas fir, the oak was also burned. oak scrub and chamise chaparral understory (CW, CC). Bigcone Douglas fir groves on cliffs The survival of bigcone Douglas fir was at the bottom of Bear Canyon escaped the burn also enhanced by terrain roughness, especially or resprouted. For explanation of linework, where stands occupy vegetation-free cliffs, toning, and scale, see Figure 1. talus gullies and rugged canyons. These invari- TABLE 3--POST-FIRE VEGETATION RECOVE IY-1/

VEGE- CONIFER REPRO. PERCENT CONIFER TATION CANYON LIVE FREQUENCY / SAPLINGS TYPE CLASS SECTS COVER OAK COVER 100 m >15 ft (5 m) TALL :I.) :I.) I z ercent) - cw

BsW

-"^compiled from field transects (Minnich 1978). burning vegetal understory and easily ignite. seedlings in nearly every transect covering Many stands also occur on smooth undissected recent burns including the large Bear fire slopes where conflagrations may sustain great 50,000 acres (20,000 hectares) which occurred intensities without topographic interruptions. 4 years before field work. Most individuals in this burn were 6-18 inches (10-30 cm) tall and contained 2 or 3 branch whorls suggesting POST-FIRE VEGETATION SUCCESSION they germinated either 1 or 2 years after the fire. The offspring germinated from seed The distribution of canyon live oak stored in cones persistent on nearby adults changed little between 1938-75 because it killed by the fire. Abundant slightly scorched sprouts vigorously and stand turnover is mini- open cones were observed on the ground at the mal. After fire, most individuals sent up num- top of killed trees. Coulter pine is not a erous stems from a basal woody mass which later closed cone pine, yet its reproductive strategy developed into a large spherically shaped shrub. appears similar to Knobcone pine (Pinus Root sprouting was characteristic not only for attenuata) which is truly serotinous (Vogl 1968). incinerated individuals, but also for those Because cones appear to open in mid-winter, they merely scorched. A few individuals crown- were apparently closed at the time of the fire sprouted but only if they were quite large, (November). Because cones and seed are heavy, having adequate bark thickness to prevent cam- long-range seed dispersal from nearest living bium damage, and only marginally singed. 1938 populations several miles distant is unlikely. and 1975 aerial photographs indicate that the Reproduction was most abundant along roads and stature of most canyon live oak stands exper- trails where soil compaction and surface erosion iencing fire disturbance since 1938 was mar- from subsequent winter rains may have improved kedly reduced and in some cases, tree-size seed bed preparation. assemblages were reduced to shrubs. Cross com- parison of stands of different age class show Comparison of stands by age class indicates a pattern of rapid early growth, then contin- that the pine develops height advantage over uous height extension thereafter, reaching 10 associated shrub and woodland species. Indi- to 20 ft. (3-6 m) after ca. 50 years. viduals averaged 5 to 15 ft. (2-5 m) height after 20 years and 25 to 50 ft. (8-15 m) after Early post-fire recovery of destroyed 45 years. Cones were produced within 10 years. Coulter pine forests is visually dominated by Second generation saplings beneath mature trees rapid redevelopment of sclerophyllous shrub and brush, however, were consistently in poor vegetation (table 3). Dominant species were condition in heavy shade. It appears that, chiefly sprouters including Adenostoma &- like most yellow pines, this species' regenera- ciculatum, Arctostaphylos glandulosa, Quercus tion is enhanced by disturbance. wislizenii and canyon live oak. There were lesser quantities of shrub seedlings, mostly Post-fire crown sprouting of bigcone Doug- Ceanothus integerrimus, c. leucodermis, 5. las fir after the 1970 Meyer and Bear fires greggii vestitus, and Adenostoma fasciculatum. became detectable in subsequent aerial photog- Sprouting canyon live oak were 3 to 6 ft. (1-2 raphy flown 2 to 3 years afterwards. Sprouting m) tall in 4-year-old burns and 5 to 15 ft. success appears dependent primarily on site (2-5 m) tall in 10 to 20-year-old burns. severity of combustion rather than tree-size class. As a rule, scorched stands with per- There was an abundance of Coulter pine sistent dead foliage resprouted, but severely burned stands were killed. Moreover, field shrub canyon live oak admixed with chamise reconnaissance of stands burned recently by the chaparral and effectively adapts to frequent 1975 "Village" fire near Mt. Baldy, revealed a severe fire through its closed cone tendency striking sprouting success among polesize trees during the fire season, drought tolerance, and and saplings as small as 10 ft. (3 m) in height. vigorous regeneration to reproductive stage In a number of individuals, sprouting proved to within two or three decades. The life span of be abortive after one season, but others re- shrub species is greater than the interval be- covered rapidly to full crown within 2 to 3 tween fires; shrubs and therefore a permanent years. part of the vegetation which actually contribute to the deforestation of Coulter pine overstory. Areas of bigcone Douglas fir deforested Frequent intense disturbance, therefore, appears since 1938 were converted into canyon live oak to be compatible with this species. ranging from an open stand of root sprout rosettes mixed with chaparral in recent burns Bigcone Douglas fir occupies steep slopes to contiguous woodlands in stands older than with relatively non-flammable tree-sized canyon 30 years (table 3). Four years after the 1970 live oak woodlands. It frequently escapes fire Bear and Meyer fires, destroyed stands were or sprouts after moderately intense fires. The dominated by the carcasses of bigcone Douglas interval between defoliating fires is long fir and canyon live oak. Living biomass con- enough for the maturation of slow growing sap- sisted of canyon live oak sprouts 3 to 6 ft. lings and concomitant development of tree-sized (1-2 m) in height and seedlings of Ceanothus canyon live oak which root sprout. Shrub seed- integerrimus and s. leucodermis. In older stands lings which germinate after fire disturbance, 15 to 30 years of age, shrubs and canyon live mostly Ceanothus, are short-lived and do not oak formed a relatively impenetrable chaparral contribute as fuels to the next fire. Bigcone 3 to 10 ft. (1-3 m) in height with emergent oaks Douglas fir reproduces best in the shade of the as tall as 15 ft. (5 m). In stands older than oak canopy. Because of its poor reproductive 30 years, robust canyon live oak trees, still capacity, it cannot compete with highly flam- multi-stemmed and shrub-like, formed a closed mable chamise chaparral where the frequency of canopy 15 to 30 ft. (5-10 m) tall. Chaparral lethal fire events exceeds its regeneration understory was not present except for carcasses time. Instead, bigcone Douglas fir refuges in of Ceanothus spp. which died en masse at about canyons with canyon live oak, especially at 30 years of age. lower elevations.

In contrast with disturbed Coulter pine In spite of their common distribution by forests, bigcone Douglas fir reproduction in elevation and association with canyon live oak, deforested stands was practically non-existent. bigcone Douglas fir and Coulter pine are seldom No offspring was found in stands less than 19 found together. The stability of bigcone Douglas years old (24 transects covering 2995 m). A few fir canyon live oak forests would appear to be seedlings and saplings were found in stands at adverse to Coulter pine. Clearly, if stands least 55 years old. The reasons for this are normally escape fire, then shady undisturbed unclear. Cones and seed are killed by fire. conditions would not be conducive for the regen- Long-distance seed dispersal from living popula- eration of Coulter pine which reproduces and tions by wind may be inefficient because the grows best under disturbed mineral soil condi- seed is heavy. Reproduction may also be inhib- tions in full sun. Moreover, the occasional ited by the lack of shade due to the combustion circumstances of stand defoliation would select of canyon live oak, a time-consuming condition in favor of bigcone Douglas fir because of its for shade-tolerant bigcone Douglas fir which sprouting habit when Coulter pine would be must await the redevelopment of oak overstory. killed. Conversely, the intense disturbance Field reconnaissance elsewhere in the study area pattern associated with chaparral or canyon suggest that reproduction was most conspicuous live oak scrub would select for Coulter pine in the least disturbed habitats free of fire for because it is a good pioneer compared to bigcone 50 years. Douglas fir.

This is seen where their distributions over- DISCUSSION lap and their sympatry with canyon live oak. Bigcone Douglas fir tends to occupy the most Analysis of the vegetation history of the sheltered, interrupted slope surfaces where can- eastern Transverse Ranges for the period 1938-75 yon live oak is relatively non-flammable owing suggests that the rate of deforestation and re- to its size. On exposed smooth brush-covered covery of bigcone Douglas fir and Coulter pine slopes where Coulter pine is found, canyon live forest is different. This is explained by the oak is a fuel contributing to the disturbance variable physiognomic and fuel characteristics necessary for the pine. of canyon live oak in promoting contrasting fire regimes. Coulter pine is usually sympatric with LITERATURE CITED Sawyer, J. O., D. A. Thornburge and J. R. Griffin 1977. Mixed evergreen forest. Pp. 359-382 Bolton, R. B., and R. J. Vogl -in M. G. Barbour and J. Major, eds. Terres- 1969. Ecological requirements of Pseudotsuga trial Vegetation of California. John Wiley macrocarpa (Vasey) Mayr in the Santa Ana Moun- and Sons. New York tains, California, J. For. 67:112-116. Thorne, R. F. Cause, G. W. 1977. Montane and subalpine forests of the 1966. Silvical characteristics of bigcone Transverse and Peninsular Ranges. Pp. 537- Douglas fir (Pseudotsuga macrocarpa). Forest 558 &M. G. Barbour and J. Major. Terres- Service. Pacific Southwest Forest and Range trial Vegetation of California. John Wiley Experiment Station Res. Pap. PSW-39. and Sons. New York. Berkeley, CA. Vasek, F. C. and R. F. Thorne Hanes, T. L. 1977. Transmontane coniferous vegetation. 1976. Vegetation types of the San Gabriel Mountains. Pp. 65-76 ±a J. Latting, ed., Pp. 797-832 &M. G. Barbour and J. Major, eds. Terrestrial Vegetation of California. Plant Communities of Southern California. John Wiley and Sons. New York. Spec. Pub. No. 2. California Native Plant Society. Vogl, R. J. 1968. Fire adaptations of some southern Horton, J. S. California plants. Proc. Annl. Tall Timbers 1960. Vegetation types of the San Bernardino Fire Ecol. Conf. 7:79-110. Mountains. Forest Service. Pacific Southwest Forest and Range Experiment Station Tech. Paper No. 44. Berkeley, CA. Vogl, R. J. 1976. An introduction to the plant comuni- ties of the Santa Ana and San Jacinto Moun- Kittredge, J. tains. Pp. 77-98 & J. Latting, ed. Plant 1948. Forest Influences. McGraw-Hill. Communities of Southern California. Spec. New York. Pub. No.2. California Native Plant Society. McDonald, P. M., and E. E. Littrell Wilson, R. and R. J. Vogl 1976. The bigcone Douglas fir-canyon live 1965. Manzanita chaparral in the Santa Ana oak community in southern California. Mountains, California. Madrono 18: 18:47-62. Madrono 23:310-320. Wright, R. D. Minnich, R. A. 1966. Lower elevational limits of montane Vegetation of the San Bernardino 1976. trees: I Vegetation and environmental sur- Mountains. Pp. 99-126 J. Latting, ed. in vey in the San Bernardino Mountains of Cal- Plant Communities of Southern California. ifornia. Bot. 127:184-193. Spec. Pub. No. 2. California Native Plant &. Society. Wright, R. D. 1968. Lower elevational limits of montane Minnich, R. A. trees: I1 Environmental Keyed responses of 1978. The geography of fire and conifer for- three conifer specieso 129:219-2260 est in the eastern Transverse Ranges, Calif- E.K. ornia. Ph.D. Dissertation. Department of Geography. University of California, Los Angeles. The Fire Resistance of Engelrnann and Coast Live Oak Seedlings1

Gerald E. ~now2/

Abstract: Southern oak woodlands have probably experienced more frequent fires in the past than during the last 30-50 years, Mature Engelmann (Quercus engelmanni) and coast live oaks (Q. agrifolia) appear to survive most fires except the hottest brush fires. However, differential seedling and sapling resistance to fire may have an influence on where these species grow. Seedlings of both species were burned under controlled conditions. Buds of Engelmann oak are better protected and/or more resistant to fire and heat than those of coast live oak. An analysis of 15 Vegetation Type Map survey profiles in southern California of stands contain- ing either or both of these species would tend to indicate Engelmann oak grows more frequently in or next to more fire prone habitats. Woodlands with Engelmann oak are quite rare and many have already been and are continuing to be lost to agricultural and urban development.

INTRODUCTION The 2 major oak species in southern oak woodlands are Engelmann oak (Quercus engelmanni Southern oak woodland (Griffin 1977) occurs Greene) and coast live oak (g. agrifolia Nee) in patches surrounded by an almost continuous the former often growing in open savannas sea of brush (chaparral) while to the north the called the "Engelmann oak phase" and the later chaparral occurs primarily as islands surrounded growing in denser more widespread woodlands by oak woodland (Benson 1957). Since chaparral termed the "coast live oak phase" (Griffin has had such a long history with fire (Aschmann 1977). Some of the factors influencing the 1976 and Hanes 1977) one might expect oak reproduction and distribution of these 2 woodlands to be influenced in composition and species on the Santa Rosa plateau in the Santa between-species distribution by fires also. Up Ana Mts. were inhibition of seedling establish- until the last 30-50 years fires were more ment by cattle in open areas (especially frequent,resulting in less fuel to carry hot Engelmann) and the consentration of coast live destructive fires into woodlands (Aschmann 1976 oak around rock outcrops (especially in cracks and Dodge 1975). Due to fire supression with and the north side) due to ground squirrel resulting fuel buildup, we have recently transport and high moisture requirements for experienced fires in southern California which germination (Snow 1973) . have destroyed half of the oaks in some wood- lands (Dodge 1975). This paper presents some evidence that the differential response of these 2 species to fire during establishment may be an addition- al factor influencing their distribution on the -I/ Presented at the symposium on the Ecology, Santa Rosa plateau and in woodland communities Management and Utilization of California in southern California. Oaks, Claremont, California, June 26-28, 1979. MATERIALS AND METHODS -2/ Associate Professor of Biology, Andrews University, Berrien Springs, Michigan, As an index to the resistance of the 2 oak 49104. species to fire, greenhouse grown seedlings were observed for resprouting following 2 seedlings were maintained for 2 months under the intensities of burning. Three wooden boxes greenhouse conditions described above. At were filled with vermiculite and 10 acorns of weekly intervals any new shoots were noted at or each species per box were planted alternately above the soil surface and the distance in milli- 1.5 cm below the surface in January 1971. After meters from the soil surface to the new shoot germination was completed in the laboratory at base above or below the soil surface was recorded. 20OC the seedlings were transferred to the greenhouse under controlled day temperatures of Theoccurrenceof the 2 oak species in 21 to 24OC and a night temperature of l6OC. different woodland types in southern California The seedlings were watered to field capacity and the immediately adjacent habitats was tabu- twice each week with 1 of the waterings made lated from 15 profiles of California vegetation with a nutrient solution. based on "Vegetative Type Maps" (VTM) surveyed between 1928 and 1934 (Critchfield 1971 and U.S. After the seedlings were 4 months old, the Forest Service 1934). vermiculite in the boxes had settled about 1.5 cm. About 1.5 cm of field-collected soil was added to the top of the boxes, watered and RESULTS AND DISCUSSION smoothed out and allowed to dry in order to provide a more realistic soil surface for the The resprouting curves for the clipping burn treatment. In order not to disturb the and burn treatments are presented in figure 1. dry soil surface, the boxes were subirrigated Engelmann oak resprouted more rapidly after once a week. clipping (100 percent after 1 week) than did coast live oak (50 percent after 1 week; 100 After the seedlings were 5 months old (up percent after 2 weeks). Engelmann resprouted to 15 cm tall) they were prepared for the burn more quickly and completely after the burn treatment. All of the seedlings stems were treatments (100 percent after 3 weeks) than clipped from between 1.5 and 2.5 cm above the did coast live oak (80 percent after 6 weeks). soil surface thereby removing all the leaves. The largest difference between species and This was done to provide an even exposure of treatment occurred 2 weeks following the burn the stems and soil surface to the burner heat treatments. Then Engelmann and coast live oak and flame. One of the 3 seedling boxes was not had 90 percent and 10 percent resprouting burned in order to provide a control for the respectively following the light burn while clipping treatment. Of the 2 remaining burn after the more intense bum they had 60 percent treatment seedling boxes, 1 was treated to and 10 percent resprouting respectively. simulate a light grass fire and the other a more intense grass fire. In the control seedlings all the resprouts were well above the soil surface from the high- The intensity of the burn treatments was est buds remaining on the clipped stems. In the monitored using 3 thermocouples 20 cm apart at light bum treatment the mean distance from the the soil surface in each box. The thermocouples soil surface to the new shoot base was 2.2 nun were positioned so that 1 side was exposed to below the surface for Engelmann oak (ranging the air and the other in contact with the soil. from 4 mm above to 8 nun below) and 5.4 mm below The temperatures were continuously recorded the surface for coast live oak (ranging from using a Sanborn 350 multiple channel recorder. 3 mm above to 14 mm below). In the more intense burn treatment this mean distance was 5.2 mm To effect the burn treatments a seedling below the surface for Engelmann oak (ranging box was placed in a gravel bed over which a from the soil surface to 10 mm below) and 7.8 propane burner was pulled on a track at an below the surface for coast live oak (ranging adjustable constant rate of speed. The burner from 4 mm below to 11 mm below). Although was a one-twelfth scale model of the burner box Engelmann oak tended to have buds resprouting described by Bonlie and Kirk (1971). For the closer to the surface than coast live oak,in light burn treatment the burner was passed over the burn treatments the means were not signifi- the seedlings 10 cm above the soil surface at a cantly different at the 0.05 level. rate of 10 cm per second resulting in an average peak soil surface temperature of 85O~and 4 Tothill and Shaw (1968) recorded soil sur- seconds above 65O~. For the more intense burn face temperatures under fire in grass pastures treatment the burner was passed over the seed- in Australia. They found that these temperatures lings at the same height but with more flame varied considerably according to the fuel supply and half the speed of the light burn treatment. and environmental conditions. The temperatures This resulted in an average peak soil surface they recorded ran from 7S° to well over 220° temperature of 175'~ and 20 seconds above 6S°C but peak temperatures above 100~~had a duration of a minute or less. Temperatures they recorded After the clipping and burn treatments the 12 mm below the surface seldom exceeded 65 to In this study the two intensities of burn- agrifolia ing had little effect on the completeness of recovery; mainly an effect on the speed of engelmannii recovery which would be related to the depth from which a shoot might come from below the surface until it was noted at the surface. Even though the distances measured from the soil surface to the base of the new shoots were not CONTROL significantly different between the 2 species due to the wide range of values, only half of the Engelmann oak buds above the soil surface were killed with the light burn treatment while 80 percent of the above surface buds on coast live oak were killed with this treatment. In the more intense burn treatment the coast live oak buds 4 mm below the surface were the highest buds on the stem to resprout while 40 percent of the Engelmann oak buds resprouting were between this level and the soil surface. Appar- ently the buds of Engelmann oak are better pro- tected and/or more resistant to fire and heat than those of coast live oak. Also the buds of the cotyledonary node (the lowest point on the stem from which new shoots normally arise) of Engelmann oak are about 14 mm below those of coast live oak due to the self-planting mechan- ism of Engelmann oak (Snow 1973). With a dry soil surface for insulation I would expect Engelmann oak seedlings to survive rather intense grass fires.

While mature trees of both species probably 20 - HEAVY BURN survive most fires (Lawrence, 1966; Wells, 1962), - saplings may be more vulnerable. On some sap- o4.^.J I I I lings of both species that I cut off near the I 2 3 4 5 6 7 ground (4.0-7.5 cm diameter and 15 to 23 years old), the bark (live and dead) of Engelmann oak WEEKS AFTER TREATMENT was more than twice as thick (5.7 mm) as the bark of coast live oak (2-3 mm). I would expect that the thicker bark of Engelmann oak saplings Figure I--The resprouting curves of coast live would afford them more protection from fire than oak (Quercus agrifolia) and Engelmann oak coast live oak saplings. Lawrence (1966), (Q. engelmannii) after being treated by studying the effect of chaparral fires in the clipping (control), light burning,. and foothills of the Sierra Nevada in California, heavy burning. found that the insulating effect of cracked and fractured granite boulder outcrops was sufficient 70OC. Heyward (1938) recorded surface and below- to protect several woody species that would surface temperatures in an open pine forest burn otherwise have been destroyed. The protection with grass understory. At 12 mm depth there was from fire afforded to coast live oak by being very little rise in temperature. With drier associated with granite rock outcrops especially soils there were higher surface temperatures in cracks or fractures within outcrops may be recorded but less heat conducted downward. another explanation for their occurrence in Bentley and Fenner (1958) recorded a maximum these locations on the Santa Rosa plateau. of 121 C at the soil surface in a woodland range fire. Lawrence (1966) recorded 280'~ From the southern California VTM survey 'on a grassy surface" in a California chaparral profiles (478 km total length) only 13 stands fire. Based on these previous studies the peak of woodland containing Engelmann oak occurred surface temperature of 85'~ used in the light while 111 stands of coast live oak below 1,000 burn in this study would be considered quite meters elevation were noted. The percent cool for a grass fire. The 175'~ peak used in occurrence of each species in 4 woodland types the more intense burn might be considered a ranked from the highest fire frequency (histor- moderate or hot surface temperature for a grass ically) to the least were: fire. Engelmann Coast Live LITERATURE CITED Oak Oak Aschermann, Homer Mixture or mosaic of 1976. Man's impact on the Southern California grass or coastal sage 23 23 Flora. In Symp. Proc., Plant Communities of southernCalifornia, Special Publication No. Mixture or mosaic of 2, California Native Plant Society (June chaparral 8 2 Latting, ed.) p. 40-47.

Largely closed canopy 62 37 Benson, Lyman 1957. Plant classification. 688 p. D. C. Riparian 8 39 Heath & Co., Boston.

Both species may be excluded from chaparral Bentley, J. R. and R. L. Fenner due to the more intense heat generated in 1958. 'Soil temperatures during burning rela- chaparral fires. Debano and Conrad (1978) ted to post-fire seedbeds on woodland range. recorded soil surface temperatures in chaparral J. For. 56:737-774. fires more than twice that used in this study simulating a moderately hot grass fire. Fires Bonlie, R. W. and D. E. Kirk. in closed canopy woodlands would usually be 1971. Use of mobile field burner and sanitizer ground fires similar to grass fires. to reduce air pollution and provide sanita- tion. Paper no. 71-416 presented at the I created the riparian woodland type out annual meeting of the American Society of of the closed canopy woodland of the VTM survey Agricultural Engineers, Pullman, Washington when either species of oak was in a canyon State University, June 27-30, 1971. bottom and associated with a typical riparian species such as cottonwood, sycamore, alder or Critchfield, William B. willow. It is in this woodland type where the 1971. Profiles of California vegetation. USDA greatest difference between these oaks is seen. Forest Serv. Res. Paper PSW-76, 54 p. Paci- This occurrence of coast live oak in wetter fic Southwest Forest and Range Exp. Stn., sites and Engelmann oak in drier has also been Berkeley, Calif. noted for all of the Santa Ana Mountains (Lath- rop and Thorne 1978). Because of Engelmann oak Debano, L. F., and C. E. Conrad occurrence in more dry habitats it would more 1978. The effect of fire on nutrients in a likely be exposed to fire. Plumb (1979) has chaparral ecosystem. Ecology 59:489-497. noted however that mature coast live oaks are the most fire resistant of all other southern Dodge, John M. California oak species (mature Engelmann have 1975. Vegetational changes associated with not been evaluated). land use and fire history in San Diego County. Ph.D. dissertation, Univ. Calif., A tabulation of the vegetation types Riverside. 216 p. (from the VTM survey profiles) next to oak woodlands indicated 65 percent were chamise Griffin, James R. chaparral for woodlands with Engelmann oak 1977. Oak woodland. In Terrestrial vegetation present but only 37 percent when coast live of California. ~ichzlG. Barbour and Jack oak was present. Coast live oaks were associa- Major, eds. p. 383-415. John Wiley & Sons, ted with 6 other vegetation types while Engel- Inc ., New York. mann was associated with only 3. The other vegetation types adjacent to Engelmann contain- Hanes, Ted L. ing woodlands were grassland, coastal sage and 1977. Chaparral. In Terrestrial vegetation agricultural or residential. Most of these of California. ~ShaelG. Barbour and Jack woodlands have been or are being lost to agri- Major, eds. p. 417-469. John Wiley & Sons, cultural and urban development. Protection of Inc., New York. the few remaining "Engelmann oak phase" wood- lands should be a high priority item for oak Heyward, F. management in southern California. 1938. Soil temperatures during forest fires in the longleaf pine region. J. For. 36:478- 491.

Lathrop, Earl W., and Robert F. Thorne 1978. A flora of the Santa Ana Mountains, California. Aliso 9:197-278. Lawrence, G. E. Tothill, J. C. and N. H. Shaw. 1966. Ecology of vertebrate animals in rela- 1968. Temperature under fires in bunch spear tion to chaparral fire in the Sierra Nevada grass pastures of southeast Queensland. foothills. Ecology 47:278-291. The J. Austral. Inst. Agric. Sci. 34:94-97.

Plumb, Tim R. U.S. Forest Service 1979. Response of oaks to fire. Proceedings 1934. Vegetation types of California, Pomona of the Symposium on the Ecology, Management quadrangle (163~). U.S. Forest Serv . (map) and Utilization of California Oaks, Claremont, California. Wells, P. V. 1962. Vegetation in relation to geological Snow, Gerald E. substratum and fire in the San Luis Obispo 1973. Some factors controlling the establish- quadrangle, California. Ecol. Monogr. ment and distribution of ~uercusagrifolia 32:79-103. Nee and engelmanii Greene in certain southern California oak woodlands. Ph.D. dissertation, Oregon State Univ., Corvallis. 105 p. Inventory and Distribution Records of Oaks in California1 Quercus Timothy E. Paysen-2 1 wislizenii

Abstract: Inventory and distribution records for California's oaks are poor. Our requirements for information about California oaks have been evolving, but classification systems and related inventory systems have not kept pace. Unless we understand and promote the interactive data communication process, the inventory and distribution records on California's oaks will not improve. Once we have clearly established our information requirements, as by developing inventory models, we can use existing technology to fill the gaps in our knowledge.

INTRODUCTION INVENTORIES AND INFORMATION NEEDS

Our knowledge about the distribution of California's oaks is clear1y inadequate. We Current Information have a general idea of where we may find the various species of oaks that grow in the State An understanding of oak distribution of California; we don't know how many of each begins with species range. The ranges of species we will find, nor do we know very much California's oaks are we1 l documented. We can about their condition and physical follow historical references from the characteristics. expedition records of early California travelers,? through the time of Kel logg and Why is this true? I believe it is because Greene (1889) and Cooper (1922). to current our knowledge of oaks, like that of any "discoveries" of investigators who encounter resource, results from the interaction between oaks in the field. Together, these form a our information requirements and the response pattern of oak distribution in the State of that is made to them. We do not know enough California that is controversial on1 y in minor because we have not properly determined what we points. The information has been well need to know. summarized for the tree species of oaks by Griffin and Critchfield (1972). In this paper, I will show how our failure to define our needs has affected the inventory Information on the specific areal and distribution records of oaks in California. distribution of individual oak species within The relations between information needs and the their ranges is less easily available and our activities that lead to development of a data needs are less clearly defined. Are we base are diagrammed in figure 1. All these interested only in extensive, dense stands of activities reflect a set of requirements. oak trees, or also in sparsely scattered Exploring the relationships shown, in terms of stands, or wen in scattered individuals within oak distribution, will help us to see how a matrix of other species? Until we can answer future efforts to improve our knowledge should this question, our knowledge of oak be directed. distribution will be rather shallow. Isolated inventories provide us with some answers (see, for example, Bolsinger 1980 and McBride 1973), Ñ1~resente at the Symposium on the Ecology, but a comprehensive account of oak distribution Management, and Utilization of California Oaks, does not exist. Claremont , California, June 26-28, 1979.

2'~esearch Forester, Pacific Southwest Forest ;'~xtracts of these records are in the files of and Range Experiment Station, Forest Service, A. E. Wieslander, available at the Pacific U. S. Department of Agriculture, Berkeley, Southwest Forest and Range Experiment Station, Calif. , stationed at Riverside, Calif. Berkeley, Calif. . >- Inventory Data base

Distribution record

Figure I--Our knowledge about any given resource is the result of an interactive process. The definition of information requirements is a key element, linking the abstract (classification) to the tangible (data acquisition, storage, and retrieval). This paper is primarily concerned with the elements emphasized.

When anyone asks how many oaks we have in defined, and we can test its adequacy. If we California, or wants more technical details work with a loosely defined system, our concept about their numbers, we have little choice than is loosely defined, and we really don't know to turn to a 1946 Forest Survey release where we are. (Wieslander and Jensen 1946) and quote the number of acres covered by the Woodland To see how our dearth of knowledge is (hardwoods) vegetation type. We may then add related to classification, consider the major some qualifying statement that reflects our categories used in a number of prominent guess as to the questioner's reason for asking. classification systems to directly or We can only assume that some proportion of this indirect1y address California's oaks (table 1). Woodland type is oak. Furthermore, we must Each system represents the perspective of a assume that an unknown proportion of other particular resource management function, vegetation types mentioned in the publication, organization, or discipline. Consider also the such as Woodland-grass, Pine, and Chaparral, selected lists (table 2) of formally recognized contain oak. And, of course, we don't know the oak species; these lists are associated with density of oaks in any of these types, nor do the classification systems in Table 1, or, more we know anything about the type structure in generally, with the functions, organizations, general. and disciplines represented by those systems.

An interesting picture emerges. Table 1 Classification and Inventory reveals that the concept of oak "types" or oak "communities" is viewed from a number of If we reconsider the information diagram different perspectives by resource management (fig. 1). we see that classification is the professionals. Of the classification systems first step in the process. General information in Table 1, four come from a single organiza- requirements usually stem from an ill-def ined tion, the Forest Service, but each represents a classification system, based on recognition of different viewpoint. Each breaks down the primitive traits. Once these requirements have broad vegetation categories with a different been specified, a formal classification degree of precision. The names of the classes emerges. More definite information that could include oak as a component represent requirements then generate inventories, with unique functional perspectives: (1) commercial the target of each inventory direct 1y defined timber value, (2) range habitat, (3) a global by a specific information requirement. The synthesis of each, and (4) a structural break- framework of these inventories is defined by down of vegetation using physiognomic criteria. the classification system. The arrows in the Formal recognition of specific oak communities diagram point up the two-way process. or vegetation types (those identified by a given species of oak) is limited to a small A classification system is simply the number of geographic "types" within the Forest embodiment of our concept of a particular set Survey system. These are categories Included of things, and it provides a language for for completeness; however, no commercial timber communicating this concept. The very basic value is implied for these oak species. unit that we call an oak community, a stand of oaks, or an element of an oak vegetation type, The Society of American Foresters (S.A.F.) is defined and limited by the classification system is not directly represented by a species system we use. If we work with a formally list in Table 2, but it represents the defined system, our concept is formally perspective of a national forestry society, and Table 1--Categories in vegetation classification systems that specify or include California's oaks. -- Range Analysis California Forest Survey Hand book Hand book RPA Assessment VTM Survey Society of American Plant Communities (U.S. Dep. Agric., For. Serv. 1975) (Forest Serv. 1969) (Forest Serv. 1975) (Critchfield 1971) Foresters (1954) Munz (1963)

Oak Geographic Forest Classif i- Vegetation Plant Type (GFT) Vegetation type Category cation Vegetation types Cover types type community -- Redwood Tanoak -- Broadleaf trees Forest Commercial Chaparral Oak-madrone Coniferous Redwood types timber forest forest Hardwoods Other California Woodland- Timterland- California western black oak chaparral Nonforest Western chaparral black oak Douglas- hardwoods tY pe hardwoods fir Canyon Woodland- Canyon forest live oak chaparral live oak Yellow Oak-madrone Woodland- Digger pine sagebrush pi ne-oak forest Chaparral Woodland- Mixed Mixed Noncommercial Chaparral Chaparral grass evergreen evergreen types (with forest forest Quercus Woodland ~PP.) Woodland Northern Pine and savannah oak wood- pine/Douglas-fir land

Southern oak wood- 1and

Foothill woodl and

Chaparral Chaparral

Desert Pinyon- woodland juniper wood 1and Table 2~Speciesof California's oaks recognized in major source documents relating to the distribution or inventory of oaks and other flora. These lists can be associated directly or indirectly with the classification systems in table 1.

Physical characterisics Forest Range Griffin Survey Analysis Wieslander and Quercus species Ever- Decid- Hand book Handbook and Jensen Munz Critchfield , Little green uous . Tree Shrub (1975) (1969) (1946) (1963) (1972) (1971, 1976)

agri-folia x x x x x x x x alvordiana x -21 -21 x x x chrysolepis x x x x x x x x douglasii x x x x x x x x dumosa x x x x x dunniil-1 x x x x durata x x x x x engelmanii -21 -21 x x x x x x 8 garryana x x x x x x x x kel loggii x x x x x x x x lobata x x x x x x x macdonal dii x x x x x morehus x x x x sadleriana x x x toment ella x x x x x turbine1la x x x x vaccinifolia x x x x x wisllzenii x x x x x x x x

l-l~eco~nizedas Q. palmeri in Munz (1963).

21~isted in either category* depending on source. serves as a point of reference. In its collection, and the categories used for data treatment of oak vegetation classes, the S.A.F. storage, are directly linked to classification. system offers little more than the Forest Survey system does. The reasons for this are not obvious since the S.A.F. perspective is not Masking in Inventories limited to timber production. The system was designed, however, to characterize major forest Some of us may not like to admit that we types that occupy "large areas in the inventory what we think is there-it,sounds aggregate" (Soc. Amer. For. 1954), which unscientific; but there is no other way.- The explains why its treatment of western oak types focus of an inventory, the way sampling is or oak communities differs little from that of designed, and often what we do and do not the economics-oriented timber survey system. measure, are a11 related to concepts embodied Both systems must take on a somewhat global in the classification system that we use. If perspective, and individual western oak species we do not recognize an oak community, we are do not dominate extensive land masses. not going to inventory it. We may measure oak trees, but the information that defines a The one "neutral" plant community community will of ten be masked. This brings us system-that of Munz (1963)Ñhint at the to another relation between inventories and importance of oaks, but does not address them information needs: we must be able to single by species. Munz did not intend to be more out communities that, while dominated by precise than this; he wanted to provide a plant species other than oaks, have oaks as integral community classification system at a very components. general level. An interesting example is found in a It is interesting that none of the recent sampling study (Paysen 1978). The study classification systems identifies communities area was in a portion of the San Bernardino or types specific to the oak species recognized Mountains, and covered a variety of vegetation in the species list associated with it (except types (fig. 2). The area is commonly described for Quercus kelloggii and 2. chrysolepis, both as one containing distinct zones of soft represented in the Forest Survey system and the chaparral or coastal sage, chaparral, and S.A.F. system). For some species, this is conifer forest or mixed conifer-hardwood probably reasonable, since not a11 oaks forest. It is not an area that we would dominate the stands in which they grow. normally describe as an "oak area8'--a place that is dominated by the genus Quercus. Yet, A functional and organizational disagree- the data reveal an overwhelming occurrence of ment on the significance of the various species oaks--not only in numbers, but in the biomass is evident from Table 2, but there is that may be assumed to be present, that is, inconsistency between the lists that can't be potential biomass. entirely explained by such perspectives. For example, the Range Analysis Handbook does not If we consider all of the major species recognize Quercus lobata nor 9. agrifolia even found in the area (excluding annuals that were though they are important components of unavailable during the time of sampling), and oak-grass communities in many parts of the look at the live oaks as a group, we see that State. These two species . are more the presence of the live oaks is greater than characteristic of rangelands than are many of that of any other species (fig. 3). Grouping the other species listed in the Handbook. the different species of live oaks in this manner may seem a bit unfair, but as I am Together. Tables 1 and 2 show that in addressing the presence of oaks in general, the broad-scaled inventories, California's oaks are grouping is valid. Black oak (Q. kelloga) relegated to a nebulous "other" category. They has been charted as a distinct species. do not fit into the classical commercial Furthermore, the presence of black oak compares timber pattern, and therefore do not appear in admirably with that of each of the other timber-oriented classification systems. Oaks species; as a matter of fact, the data imply often appear as elements of range ecosystems, that it is the most ubiquitous tree species in but their treatment in range-oriented the area. If the volume of space occupied by classification systems is little better than the plants is used as a relative indication, that in the timber systems.

Although these conclusions are not surprising, their implications may not be fully i'~xceptions are exploratory activities such as appreciated. What we as individuals and as "botanizing," which differ from the formally professionals see when we survey vegetation defined inventory process, but are probably the depends strictly on the classification system best source of our information on species that we use. The framework used for data ranges. the live oaks have more potential biomass than information without the appropriate inventory any other species in the study area (fig. 4), models and the appropriate identification and black oak again holds its own quite well criteria. when compared to the other species. Inventory models allow us to determine the amounts of a particular resource, or more commonly of a particular resource value, from a functional perspective , by measuring easily obtained parameters in the field. The required information might be board feet of timber, pounds of forage, or acres of multiple-stemmed trees suitable for a particular recreation activity. Until our information requirements clearly state the kind of productivity that is needed, and the viewpoint for assessing suitability (say, recreation use or fuelwood use), we will not be able to develop identifi- cation criteria and inventory models. And we will not have our inventories.

After living so long with timber-oriented inventory models, we are shocked when we realize that we have to start from first principles in developing site index curves, and productivity tables for trees that we have been looking at all of our lives. Work in these areas is just beginning (Pillsbury and Stephens 1978, Powers 1972). One thing is clear: we will have to define such concepts as growing site and productivity for oaks in other than timber production terms. The relation between board feet of merchantable timber and cubic feet of fuelwood, for example, is not direct. Sari Bernardino t Neither are the number of trees per acre on Figure 2--Vegetation zones in the San good timber site and the number of trees per Bernardino Mountains study area were found acre on good recreation site equivalent to contain large numbers of oaks. measures. Our current interest in oaks, in itself, is not enough to generate inventory Looking at these results, we realize that data and complete distribution records as I a review of maps, classification systems have defined them here. We must develop applied to the area, and distribution records appropriate systems by which to recognize oak would not give a clue to the importance of oaks communities, and communities with strong oak in this area. The oaks are masked in the associations. We must then proceed to develop record by such terms as "ch-aparral" and inventory models that will address our specific "conifer forest." There is nothing that would requirements. We then have to adjust our provoke a request for inventory data on oaks in management focus in a way that will allow oak that portion of the San Bernardino Mountains. inventory requirements to receive an Such a request could on1 y come from someone who appropriate priority. Only then can an has firsthand knowledge of their importance as adequate inventory of California's oaks components of the vegetation cover. proceed.

The Inventory Model Available Tools

The relation between inventories and Once we have developed Inventory information needs raises another question: techniques and inventory rationale, the job of How are we going to get the information we need collecting data should be straightforward. about oaks? Assuming that we can recognize oak California's oaks have a distinct inventory communities and communities wherein oak is an advantage over many other species~theyare important associate, we can go out and count easy to find. Remote sensing products that are oaks. But, what if we want productivity readily available provide an easy means of information? What if we want Information on identifying stands of oaks. Infrared suitability for a particular management photography, in particular. is a useful tool. objective? We cannot get these kinds of By virtue of their structure and leaf Species presence Volume Q = Oaks B = Shrubs G = Grasses C = Conifers S = Semiwoody shrubs H = Broadleaf trees F = Forbs D = Succulent shrubs

Species Figure 3--The importance of oak species in the San Bemardino Mountains study area is evident from their presence in relation to other plants, and from their mean volume, which can be viewed as a relative indicator of biomass. Each set of bars represents a different species, except that live- oaks include Ouercus agrifolia, &.- chrysolepis. Q.- cl!mz, and 2. wislizenii.. configuration, oak trees stand out clearly Organizations that deal with large-scale within stands of conifers, within chaparral, resource inventory are just beginning to adopt and in grasslands. We can take advantage of classification systems that allow recognition small-scale imagery for sample layout work and of oak communities to some degree of depth- rough estimation, and use large-scale imagery (Paysen and others 1980, Browne and Lowe 1974). for detailed inventory work. These systems will provide the appropriate framework for collecting data, and "pigeon holes" for storing data; they will encourage EVOLVING INFORMATION NEEDS others to begin to ask questions about the oak communities that are being recognized; resource The relation of information requirements inventories will be able to take on a new to classification systems is a, continuing one. dimension. Slowly, as inventories proceed, and as we begin to look at resource systems in greater depth, In summary, although the present state of our information requirements change, eventually our knowledge regarding the inventory and reaching a point at which they no longer call distribution of California's oaks is perceived for additional inventories driven by- the as being poor, this cannot be established as original formal classification systems. Then fact until our information requirements are these systems are modified, or even replaced, clearly stated. Only then will we be able to to accommodate the new set of information evaluate the state of our knowledge, and requirements. establish the links in the information process. Adequate classification systems, and responsive This does not always proceed at a steady inventory systems and techniques will provide rate. We sometimes let existing classification systems~andtheir secondary products, such as maps and inventoried data-def ine our information requirements. The result is a kind of holding pattern, which inhibits recognition ?'~riscoll, Richard S., .I. W. Russel, and M. C. of new or emerging lines of investigation of Meier . Recommended national 1and the resource. classification system for renewable resource assessments. Unpublished report on file, Rocky We can identify the evolutionary process Mountain Forest and Range Exp. Stn., Forest in the development of oak inventory. Serv., U.S. Dep. Agric., Ft. Collins, Colo. the inventory and distribution records that are Air Pollutant Effects on a Western needed. Coniferous Forest Ecosystem, Task C. Report. 0. C. Taylor, principal We have the tools and technology needed to investigator. University of California fill the gaps in our knowledge; all we have to Statewide Air Pollution Research Center, do then is identify the gaps. Riverside, Calif. 220 p.

Munz, Phillip A. LITERATURE CITED 1963. A California flora. University of California Press, Berkeley, Calif. 1681 p. Bolsinger , Charles 1980. Oak in California's commercial Paysen, Timothy E. forests-volume, stand structure, and 1978. Sampling wildland vegetation. Ph .D. defect characteristics. Proceedings of the dissertation. University of California, Symposium on the Ecology, Management, and Riverside, Calif. 185 p. Utilization of California Oaks, June 26-28, 1979, Claremont, Calif. Paysen, Timothy E., Jeanine A. Derby, Hugh Black, Jr., Vernon C. Bleich, and John W. Browne, David, and Charles H. Lowe Mincks . . 1974. A digitized computer-compatible 1980. A vegetation classification system classification for natural and potential applied to southern California. Gen. Tech. vegetation in the southwest with particular Rep. PSW-41. Pacific Southwest Forest and reference to Arizona. J. Ariz. Acad. Sci., Range Exp. Stn., Forest Serv., U.S. Dep. Vol. 9, No. 3, 11 p. Agric. , Berkeley, Calif. [In press. 1

Cooper, William S. Pillsbury, Norman H., and Jeffrey A. Stephens 1922. The broad-sclerophyll vegetation of 1978. Hardwood volume and weight tables for California. Carnegie Institute of California's central coast. Calif. Dep. Washington, Washington, D.C., 145 p. For., 54 p.

Critchfield, William B. Powers, Robert F. 1971. Profiles of California's vegetation. 1972. Site index curves for unmanaged stands USDA Forest Serv. Res. Pap. PSW-76, 54 p. of California black oak. USDA Forest Serv. Pacific Southwest Forest and Range Exp. Res. Note PSW-262, 5 p. Pacific Southwest Stn., Berkeley, Calif. Forest and Range Exp. Stn., Berkeley, Calif. Griffin, J. R., and W. B. Critchfield 1972. The distribution of forest trees in Society of American Foresters. California. USDA Forest Sew. Res. Pap. 1954. Forest cover types of North America PSW-82, 114 p., illus. Pacific Southwest (exclusive of Mexico). Soc. Amer. For., Forest and Range Exp. Stn., Berkeley, Washington, D.C., 67 p. Calif. U.S. Department of Agriculture, Forest Service Kellogg, Albert, and Edward L. Greene 1975. Forest Survey Handbook, FSH 4809.11. 1889. Illustrations of West American oaks. Published from funds provided by James M. U.S. Department of Agriculture, Forest Service McDonald, Esq., San Francisco, California, 1975. The nation's renewable resourcesÑa 84 p. assessment, 1975 (draft), as required by the Forest and Range Renewable Resources Little, Elbert L., Jr. Planning Act of 1974. 1971. Atlas of United States trees,. conifers and important hardwoods. Misc. Publ. 1146. U.S. Department of Agriculture, Forest Service USDA Forest Serv., Washington, D.C. 1969. Range Analysis Handbook, FSH 2209.21, California Region. Little, Elbert L., Jr. 1976. Atlas of United States trees, minor Wieslander, A. E., and Herbert A. Jensen western hardwoods. Misc. Publ 1314. USDA . 1946. Forest areas, timber volumes, and Forest Serv., Washington, D.C. vegetation types in California. USDA Forest Serv. Forest Survey Release No. 4, McBride, Joe R. 66 p. California Forest and Range Exp. 1973. Vegetation of principal study sites in Stn., Berkeley, Calif. the San Bernardino Mountains. In Oxidant Quercus sadleriana R. Br. Campst., Its Quercus Distribution, Ecology, and Relationships to Other sad1eriana

Gilbert Jerome MU&/

Abstract: Quercus sadleriana R. Br. Campst. is a relict endemic of the Klamath Ranges of northern California and southern Oregon that is a dominant member of the shrub layer of the more mesic forests as well as the more xeric Montane Scrub Community of the middle to upper elevations. Its closest relatives are in the temperate deciduous forests of eastern North America and East Asia,giving it an anomalous distribution. Quercus sadleriana grows in soils with a wide range of pH and soil nutrients including low to high levels of magnesium,suggesting the possibility of serpentine races. The major form of reproduction appears to be vegetative by layering.

CHESTNUT OAKS oaks, Quercus sadleriana R. Br. Campst., in a considerably different forest type and climatic Chestnut oaks have been generally recog- regime. What makes the western North American nized but have not previously been formally distribution more interesting is that Q. sadler- defined in the taxonomic literature. The a occurs as a relict endemic in an area which leaves very strongly resemble chestnut (Castan- Whittaker (1961) and others (Stebbins & Major, -eatleaves having elliptic shape and dentate 1965; Wood, 1970; Wolfe, 1969) define as a to shallowly lobed margins with regularly major center of floristic diversity and endemism. spaced secondary veins running through each The southern Appalachian region of eastern North tooth to the margin. These oaks comprise the America, from where most of the eastern North North American series Krinoideae and Sadler- American seem to emanate, is also known ianae (Trelease, 1924; treated as subsection for these attributes. Sadlerianae by Camus, 1934-1954)-, and the Asiatic subsection Diversipilosae (Camus, 1934- The purpose of this paper is to (1) define 1954). Included under the subheading chestnut the chestnut oaks, (2) give their salient char- oaks are five species in eastern North America acters, (3) discuss their distribution in gen- and eight species in East Asia. It is not sur- eral and give the distribution of Q. sadleriana prising that chestnut oaks are found both in in particular, and (4) discuss the ecology of East Asia and eastern North America considering the chestnut oaks and Q. sadleriana. the floristic similarities between these two regions. However, a paradox arises when we examine the forests of western North America, Definition of the Chestnut Oaks for there we find a shrub form of the chestnut The chestnut oaks have been defined as be- longing to the secteon Quercus (white oaks) of Ñj~resenteat the Symposium on the Ecology, the genus Quercus.27 Three subsections in Management, and Utilization of California Oaks, Claremont, California, June 26-28, 1979. ?/unpublished Doctoral Dissertation, G. J. Muth, ^./~ssociate Professor of Biology, Pacific 1976, The taxonomic and floristic relationships Union College, Angwin, California of Quercus sadleriana R. Br. Campst. to other chestnut oaks, University of California, Davis, California. Figure 1-- Comparison of Quercus sadleriana with its two closest relatives.

section Quercus contain all of the chestnut oaks 5. Q. prinoides Willd., eastern as follows (fig. 1) : North America.

A. Subsection Diversipilosae Schneider 1. Q. crispula Blume, NE Asia, Japan, Characters Distinguishing Chestnut Oaks Korea 2. Q. serrata Thunb. , China, Japan, The following is a list of the more salient Korea external morphological features distinguishing 3. Q. griffithii Hook. f. and Th., the chestnut oaks: Bhutan, Burma, China, India, Laos, Sikkim Evergreen to deciduous leaves 4. Q. malacothricha A. Camus, China Generally large leaves with mean 5. Q. aliena Bl. , China, Japan, Korea widths of 3.2 inches and mean lengths 6. Q. mongolica ~ischer,China, of 6.4 inches Japan, Korea, S. Kuriles, Manchur- Cupule, generally rather large, ap- ia, Mongolia, Sakhalin, E. Si- proximately 0.2-0.8 inches in diameter beria Leaves chestnut-shaped; more or less 7. Q. fabri Hance, China, Korea oval with a serrate to dentate margin 8. Q. liaotungensis Koidz., China, Teeth small to more or less deep, Korea, Manchuria, Mongolia. acuminate to obtuse, with or without small mucros at the tip of the teeth B. Subsection Sadlerianae Trelease Leaves with numerous, straight, un- 1. Q. sadleriana R. Br. Campst., branched secondary veins somewhat western North America. regularly spaced, at an angle of 45'- 60Â to the midvein, and extending to C. Subsection Prinoideae Trelease the apex of each tooth 1. Q. bicolor Willd. , eastern North Trichomes may or may not be present on America the upper leaf surface, however, if 2, Q. prinus L. , eastern North they are present, they are generally America quite sparse and simple or stellate or 3. Q. muehlenber~iiEngelm., eastern both North America, When mature, most species are trees. 4. Q. montana Wlld., eastern North However, Q. sadleriana and Q. prinoides America are both shrubs. All species of chestnut oaks in North The chestnut oaks are generally found in America occupy relatively mesic habitats. As the temperate deciduous forests of Asia and far as I can determine, this is also the case North America that receive summer rainfall. for the eight East Asian species. The individual taxa of Diversipilosae and Prinoideae occupy a spectrum of habitats from relatively dry rocky conditions on limestone DISTRIBUTION OF QUERCUS SADLERIANA outcrops (Q. aliena and Q. muehlenbergit) to relatively mesic conditions (Q. montana and As was previously indicated, Diversipilosae Q. serrata) to relatively wet lowland condi- is generally distributed throughout eastern tions (Q.prinus). No one species is found at Asia, Prinoideae ranges through eastern North all elevational levels but the group as a whole America, and Sadlerianae is located through may be found at all elevational levels from northern California and southern Oregon. Maps timberline to wet lowlands at or near sea showing the distribution of each of the chestnut level. Quercus sadleriana, on the other hand, oak species are in my doctoral dissertation.?/ is distributed through an evergreen conifer forest under essentially summer-dry conditions. Quercus sadleriana occurs in Josephine, Comparing it with the range of habitats de- Curry, Douglas, and Coos counties of Oregon, scribed for Prinoideae and Diversipilosae, Q. and Humboldt , Trinity, Siskiyou, Shasta and sadleriana inhabits the dry to mesic habita Del Norte counties of California. The type in the middle o upper elevations. Siemens-^ locality is on the Crescent City Trail between and KimbroughÃ55 both did ecological studies of Sailor's Diggings, Oregon, and Smith Creek, the general area inhabited by Q. sadleriana. California. The elevational extremes are from Siemens' work was an ecological analysis of the 2000 to 7260 feet. The following information, Preston Peak Area while Kimbrough compared the from the accumulated data of 187 collections, Montane Scrub Communities of the Trinity Alps, shows these extremes: Marble Mountains and Preston Peak. Quercus sadleriana is a dominant member of the Montane A. Distribution extremes Scrub Community on the more xeric south- and 1. North---Wooden Rock Creek, near west-facing slopes and is dominant in the shrub Agness, Coos County, layer of the more mesic Red Fir and Mixed Ever- Oregon, on the Bone Mount- green Forests. On the top of Preston Peak, it ain Quadrangle, 42' 48' is a low shrub occupying somewhat protected north latitude, 123O 55' areas. west longitude 2. South---Kerlin Creek, near Hyam- On Preston Peak, where Q. pom, Trinity County, Cal- tends to its highest elevation, ifornia, in the Pilot recognized three major associations: Mixed Creek Quadrangle, 40Â 36' Evergreen Association, Montane Forest Associa- north latitude, 123O 55' tion and Subalpine Forest Association. He west longitude further subdivides them as follows: 3. East----Sweetbrier Ridge, near Castella, Shasta County, A. Mixed Evergreen Forest Association California, Dunsmuir Quad- 1. 2085 to 3230 feet elevation rangle, 41Â 4' north lat- 2. Includes the following forest itude, 122O 21' west subtypes longitude a. Black Oak Woodland 4. West----Snow Camp Mountain, near b . Madrone-Tan Oak Woodland Gold Beach, Curry County, c. Douglas Fir Forest. Oregon, Collier Butte Quadrangle, 42O 20' north B. Montane Forest Association latitude, 124" 9' west 1. 3230-5375 feet elevation longitude.

B. Elevational extremes 1. Highest---7260 feet, Preston Peak, ^unpublished Masters Thesis, L.A. Siemens, near Happy Camp, Siski- 1972, A survey of the montane forest of the you County, Oregon, Preston Peak Study Area, Siskiyou County, Cal- Preston Peak Quadrangle, ifornia, Pacific Union College, Angwin, Calif. 41' 50' north latitude, 123O 37' west longitude. "-unpublished Masters Thesis, D. J. Kimbrough, 1975, An ecological analysis of montane scrub in the Siskiyou Mountains, Trinity Alps, and ECOLOGY OF QUERCUS SADLERIANA Marble Mountains, Pacific Union College, Angwin, California. 2. Includes the following forest 5 moist sub types 2 wet a. Douglas Fir With soil texture data ...... 23 rocky b. Sugar Pine 4 gravel c. Ponderosa Pine 1 deep humus d. Knobcone Pine With soil color data ...... 14 black e. Lodgepole Pine 12 yellow f. Port Orford Cedar. 8 gray 7 red C. Subalpine Forest Association 1. 5735 feet and higher elevation in isolated stands on peaks and Soil Nutrients ridges 2. Includes the following forest pH ...... 4.7 low subtypes 5.2 mean a. Noble Fir 5.7 high b. Weeping Spruce Nitrates in ppm...... 0.0 low c. Mountain Hemlock 1.0 mean d. Alaskan Yellow Cedar 8.0 high e. Jeffrey Pine-White Pine Calcium in ppm ...... 0.0 low Woodland. 527.0 mean 2800.0 high Siemens further indicates that the winters Phosphorus in ppm...... 5.0 low are long in this region with the first snows 36.0 mean coining as early as September and lasting till 100.0 high as late as June or the first of July. All the Magnesium in number significant precipitation comes during the of transects .....1 very high winter with little or none during the summer. 2 high 2 medium He describes the topography as being 6 low rugged and steep. The direction of the slope 18 very low generally determines the forest type. On the 2 not present steepest upper slopes where soil does not col- lect, Alaskan yellow cedar (Chamaecyparis e- katensis (D. Don) Spach. ) is the only woody plant clinging to the rocks wherever it can Although Siemens doesn't recognize Montane find sufficient moisture. Scrub in his study of the Preston Peak area, ~imbrou~hJl/sees this as a valid vegetation Edaphically, this area contains many spec- type along with the three types listed by ial areas such as acid bogs, seepages, etc. Siemens. Thus, four vegetation types can be with small "islands" of relict and uncommon said to occur on Preston Peak: (1) Mixed Ever- plants. Siemens includes Port Orford cedar green Forest, (2) Montane Forest, (3) Subalpine (Chamaecyparis lawsoniana (A. Murr.) Parl.) Forest and (4) Montane Scrub. and Alaskan yellow cedar among a number of species occurring in these relict populations. Kimbrough divides the Montane Scrub into three subtypes for the Preston Peak Area: According to Siemens, Q. sadleriana is a ''Typical" Montane Scrub, Woodland Scrub and prominent member of the Sugar Pine Forest of Lowland Scrub. "Typical" Montane Scrub and the Montane Forest Association and of the Noble Woodland both occur above 5200 feet as part of Fir and Weeping Spruce Forests of the Subalpine the Canadian Life Zone. Lowland Scrub occurs Forest Association. Quercus sadleriana appears below 4300 feet in the Humid Transition Life in nearly all his transects except the Black Zone. Oak Woodland and Madrone-Tan Oak Forest of the Mixed Evergreen Forest Association. In addition "Typical" Montane Scrub has four dominants to transect data, he did some soil analyses in this area: greenleaf manzanita (Arctostaph- that included such factors as moisture, texture, ylos patula Greene), huckleberry oak (Quercus color, pH, nitrates, calcium, phosphorus and vaccinifolia Kell.), deer oak (Quercus sadler- magnesium on a total of 41 transects. -iana R. Br. Campst.), and silk tassel bush (Garrya fremontii Torr.). Kimbrough indicates that it appears to be a successional stage to forest associations because of the broad eco- Number of Transects tones between it and the forest associations maintained as a subclimax. This is due to lack With Q. sadleriana ...... 32 of soil, soil moisture and soil build-up result- With soil moisture data...... 17 dry ing from steepness of slopes and frequent fires. Woodland Scrub is typified by Jeffrey pine to germinate acorns. Therefore, from the scan- (Pinus jeffreyi Grev. and Balf. in A. Murr.) ty evidence available, it appears that the major and western white pine (Pinus monticola Dougl.) form of reproduction is by and/or root- as major dominants with smaller amounts of ing at the nodes. .I have personally observed incense cedar (Calocedrus decurrens (Torr.) node rooting in Q. sadleriana. Florin) and Douglas fir (Pseudotsuga menziesii (Mirb .) Franco.) in a very open woodland as the Summarizing the ecology of Q. sadleriana, canopy layer. The greatest cover in this asso- it is possible to say that it occupies a spec- ciation is composed of a shrub layer of scrub trum of habitats from the cool, damp, moderately species from the "Typical" Montane Scrub except lighted forest shrub layer to the hot, dry, for the subdominant pinemat manzanita (Arcto- brilliantly lighted south slopes of the higher staphylos nevadensis Gray). This association mountains. The soil in which it grows is usual- is normally at elevations above 4850 feet and ly rocky and generally black or yellow. The appears to be closely related to serpentine soil pH is always acid and occasionally very soils. Kimbrough feels that this community is acidic while the nitrates are usually quite low climax on serpentine soils. with a substantial range of calcium (from 0- 2800 ppm). The range of phosphorus as well as Lowland Scrub, occurring on the hillsides magnesium is also quite wide. It appears that of the lower elevations, is associated with Q. sadleriana is adapted to serpentine soils, Mixed Evergreen Forest. Except for the dom- with possibly even some serpentine races. By inant white-leaf manzanita (Arctostaphylos observation only, the major fonn of reproduction viscida Parry) and two incidental shrubs, buck- seems to be vegetative. -~eanothus cuneatus (Hook. ) Nutt. ) and red huckleberry (Vaccinium parvifolium Sm. in Rees.), the associates of this community are SUMMARY AND CONCLUSIONS essentially the same as those of the "Typical" Montane Scrub. The chestnut oaks were defined as belong- ing to subsections Prinoideae, the five eastern The Preston Peak Montane Scrub patterns North American chestnut oaks; Sadlerianae, the and those in the Trinity Alps are floristically western North American chestnut oak, Quercus similar except that greenleaf manzanita, huckle- sadleriana R. Br. Campst.; and Diversipilosae berry oak and sticky laurel (Ceanothus velutinus the eight East Asian chestnut oaks. The three Dougl. ex Hook.) are the major dominants. West- subsections are within the subgenus Leuco- em service berry (Amelanchier pallida Greene) balanus, the white oaks. They typically have and pinemat manzanita,which occur as subdomin- elliptic leaves with dentate to shallowly-lobed ants in the Preston Peak area, are dominants in margins showing regularly spaced secondary veins the Trinity Alps. Quercus sadleriana, not being running out through each tooth to the margin, a member of the flora in the Trinity Alps, is very strongly resembling Castanea leaves. not found in the Montane Scrub Association. Quercus sadleriana is distributed through The Marble Mountain Montane Scrub domin- the Klamath Ranges of northern California and ants are greenleaf manzanita, huckleberry oak, southern Oregon in Josephine, Curry, Douglas, sticky laurel, silk tassel bush (Garrya fre- Coos, Del Norte, Siskiyou, Humboldt, Trinity montii Torr.) and bitter cherry, (Prunus emargin- and Shasta counties. It occurs as a dominant -ata (Dougl.) Walp.). These last two species are member of the shrub layer in the more mesic subdominants around Preston Peak and the Trinity forests under shaded conditions, as well as a Alps. Brewer's oak (Quercus garryana Dougl. var. dominant member of the Montane Scrub Community brewer! (Engelm. in Wats.) Jeps.) is dominant under dry and hot conditions. It is exposed to in the Marble Mountains, and subdominant on full sunlight on the southern slopes, and oc- Preston Peak and the Trinity Alps, while Quercus casionally extends up into subalpine areas. It sadleriana is dominant in the Marble Mountains grows in a wide range of pH and soil nutrients and Preston Peak, and totally absent in the including high to low levels of magnesium. The Trinity Alps. data reported by siemens^./ shows Q. sadleriana growing on serpentine soils suggesting that In areas of relatively high abundance, it there may be some serpentine races of this is difficult to distinguish between individual species. The majority of reproduction seems clones of 0. sadleriana, because the variation to be vegetative. in many of the vegetative characters is very narrow from one clone to another. Although LITERATURE CITED seems to be good, with many acorns being produced, I am not aware of any Camus , A. significant studies documenting germination per- 1934-1954. Les Chenes, monographic du genre centages and conditions for germination. I and Quercus. Paul Lechevalier & Fils, Editeurs, my colleagues have, with great difficulty, tried 12, Rue de Tournon, 12, Paris (lve). Stebbins, G.L., and J. Major Wolfe, J.A. 1965. Endemism and speciation in California 1969. Neogene floristic and vegetational flora. Ecological Monographs 35:l-35. history of the Pacific Northwest. Madrono 20:83-110. Trelease, W. 1924. The American oaks. Memoirs of the Wood, C.E., Jr. National Academy of Sciences, Volume XX. 1970. Some floristic relationships between Government Printing Office, Washington. the southern Appalachians and western North America. In, The distributional history of Whittaker, R.H. the biota of the southern Appalachians, 1961. Vegetation history of the Pacific Part 11, P.C. Holt and R.A. Patterson Ed- Coast and the "central" significance of the itors. Research Division Monograph 2, Klamath Region. Madrono 16:5-23. Virginia Polytechnic Institute and State University, Blacksburg, Virginia. Change in Vegetative Cover of Oak Stands in Southern San Diego County: 1928-1970'

Carla R. Scheidlinger and Paul H. Zedler-21

Abstract: The changein vegetative cover of thirty oak standsin southern San Diego County was estimated by comparing aerial photographs from 1928 and 1970. Point cover data showed a 13-percent decline in oak cover during the interval, with oak woodland declining at the expense of grassland and chaparral. Extrapolation of the 42-year transitions by use of Markov chain methods indicated a hypothetical equilibrium not far from present conditions. It is concluded that if the effects of land development are ignored,the cover of oak trees has not changed much in the last 50 years, but that this is not inconsistent with the view that many oak stands are senescent.

INTRODUCTION estimate change in the tree cover of thirty oak stands in southern San Diego County between There is good reason to suspect that the 1928 and 1970. oak forests of Southern California are declin- ing under the combined pressures of livestock In this paper we consider only changes grazing, recreational use, and urban and rural in total tree cover, and not changes in stand development (Hanes 1974, White 1966). But perimeter. We also exclude those stands that because oaks are long-lived trees, it is dif- were obviously disturbed by urban development ficult to know just how rapid these changes or clearing in either 1928 or 1970. The are, and if the decline is general or confined changes we determine, then,do not include to only a few stands. Aerial photographs are losses due to urban expansion; and represent a potentially valuable source of information what occurred in stands that remained in a on rates of change in oak forests, and tn this more or less natural state for the 42-year paper we report the results of a preliminary period. study using two sets of aerial photos to

MATERIALS AND METHODS Ñ1~resente at the Symposium on the Ecology, Management and Utilization of California Oaks, Two sets of photographs from the Map Claremont, California, June 26-28, 1979., Records Section in the Office of the San Diego County Engineer were used. The 1928 photographs were black and white vertical 21~arlaR. Scheidlinger and Paul H. Zedler, - photographs of excellent quality at a scale Department of Biology, San Diego State of about 1:12500. The 1970 photographs, the University, San Diego, CA 92182 only recent complete set available, are verti- cal aerial color photographs taken after the Kitchen Creek fire in 1970. These had a scale oak stands were sampled giving a total of of about 1:33,333. 2579 individual points.

It was decided to restrict the area to The sampling amounted to a point method be examined to the south central portion of applied to photographs. The number of points San Diego County, a rough quadrangle bounded which fell on each of eight cover types was by El Cajon to the northwest, Pine Valley and recorded and a few of the smaller groups com- Laguna Junction to the northeast, the Otay bined into the categories which are given in Reservoir to the southwest, and Cameron Corners Tables 1 and 2 to give estimates of percent on the southeast. The 1928 photographs cov- cover. We feel that the method is relatively ering this region were scanned for oak forests. accurate, and few ambiguities were encountered. Stands large enough to provide some sample However, it is clearly possible that small hits were subjectively selected and located oak trees might be missed, especially when on USGS topographic maps. The same forests these occur in or near chaparral cover. It were then located on the 1970 photographs. is also possible that some sycamores, willows, Stands that had disappeared or been exten- and cottonwoods might have been included in sively altered by development between 1928 the oak category, especially in cases where and 1970 were not considered. these might have crowns contiguous with oaks. It was not possible to separate Quercus Determination of the exact scale of each agrifolia (coast 12 e oak) from Quercus oak stand was made by use of permanent topo- engelmannii (Engelmann oak) and since both graphic or manmade features that could be occur in the area surveyed, the oak category located on both sets of photographs and on is a composite of these two species. However, the USGS maps. Distance between two such -Q. agrifolia is by far the more abundant points was measured on the USGS map, and cal- species. culations made to determine the actual ground distance spanned, and hence the scale of the two photos. RESULTS

A proportional divider was used to mark The overall results of the study are off a straight row of eleven points or dots summarized in tabular form (table 1) where in a sheet of acetate, spaced to represent for each interval exactly 100 meters on the scale TABLE 1 COMBINED COVER DATA FOR ALL STANDS AND ALL CATEGORIES GIVING TOTALS IN THE LAST ROW AND LAST COLUMN AND THE NUMBERS OF POINTS THAT CHANGED of the 1928 photograph. The first dot served CATEGORY OR REMAINED IN A CATEGORY IN THE REMAINDER OF THE TABLE THE UPPER VALUES IN EACH CELL ARE THE ABSOLUTE NUMBER OF POINTS AND THE as an intercept for a pencil line drawn on LOWER NUMBER THE PROPORTIONS FOR FURTHER EXPLANATION SEE THE TEXT the acetate perpendicular to the line of the CLASSIFICATION IN 1970 dots. When a ruler marked in increments of 1928 0.5 mm was laid across the photograph, con- OAK GRASS CHAPARRAL ROCK DEVELOPED TOTAL I152 I92 I156 I 1 1 13 I17 I430 I necting two permanent topographic or man-made OAK features, the dot line could be oriented over 3535 2140 3628 0256 0047 03961667 CO 75 173 109 9 33 400 the photograph perpendicular to the ruler 7875 4325 2725 0225 0025 0825 755, along the pencil line. Land cover type was recorded on data sheets for each dot along - -...... - 0926 If29 7377 0302 0021 0245 5529 the line a distance of 1 km In the photo- z - 4 7 37 221 t 4 274 graph. The line was then moved along the ROCK < Old6 0255 I351 8067 0036 Of46 ,062 ruler for the same distance that separated 0 4 2 2 1 2 0 1, & STREAM the dots on the acetate, and another ten points 3636 1818 7878 0000 I8fB 0000 0043 (D - of land cover were recorded. This procedure en 14 4 0 0 14 38 < DEVELOPED 1579 3684 1053 0000 0000 3684 0747 continued for ten increments, or until well 0 , ,h7; ,""" beyond the limits of the oak stand, whichever , 373 449 1360 285 9 103 came first. This meant that most stands were TOTAL 1446 1741 5273 11050035 0399 sampled with 100 points, and all with at least 50 points. the combined data for all 30 stands and 2579 points are given. The identical procedure,modified for The total number of points recorded in each of the categories in 1928 and differences in scale, was used to assess land 1970 are in the final column and row of the cover of the same areas on 1970 photographs, table respectively. The remainder of the which could be located by reference to perma- table is a transition matrix which gives the nent features. In this fashion, the same number of points which changed category or ground points could be evaluated for land remained the same between the two periods. cover in both 1928 and in 1970, and the same The integer values along the diagonal, such density of points, measured in actual ground as 152 for oak, represent the number of points distance, was used for both photos. Thirty which did not change classification, while been, overall, a statistically significant the off-diagonal elements, such as the 75 for but not drastic decline in the abundance of grass to oak and 92 for oak to grass, repre- oaks, from 4.30 K.m2 to 3.73 ~ r overn ~ the en- sent the number of points which changed cate- tire area surveyed. At the same time, grass gories. These values are interpreted by and developed areas increased slightly, while remembering that the row categories represent chaparral also showed a slight decrease. the 1928 state, and the column categories the These data, as well as the subjective impres- 1970 state. Thus 75 grass points in the 1928 sions gained from the photos seem to indicate photos became oak points in the 1970 photos, that oak forests are becoming more open and while 92 oak points In the 1928 photos became losing out to grass, which would be expected grass points in the 1970 photos. if decline was a result of failure of repro- duction within stands rather than encroach- The fractional values in italics beneath ment by chaparral. An additional factor that the numbers in the last column and last row probably contributed to the observed decline represent the proportion of each category pre- of oaks is fire. The 1970 set of photographs, sent in 1928 and 1970 respectively, while the only complete set available for the area, the italicized fractional values in the had been made shortly following a fire, the remainder of the table are the proportions of range of which had encompassed many of the the 1928 stands that changed, or did not stands surveyed. This fact did not affect change, to another category. These proportions, the accuracy of the ground cover estimates, which sum to one across the row, may be taken but a cursory review of photographs taken as estimates of the probability of a transi- from 1 to 6 years previous to the burn tion from one state to another. Thus 21 suggested that there had been some loss of percent of the 430 1928 oak points became cover attributable to the fire. grass points. The same data can be expressed on an The rock category gives an estimate of area basis, to give a better feeling for the reproducibility of the sample points. the sample sizes and the areas involved. In Since the rocks which were recorded were table 2 the decline in oak cover is estimated mostly relatively large, a perfectly accurate to be 13.13 percent while grass increased by placement of points would lead to little change 12.3 percent, these changes all expressed in the proportion of rock cover, and most relative to the cover in 1928. Not surpris- points recorded in this category in 1928 would ingly, the largest percentage change was in remain in that category, excluding those cases the developed area, which increased by over where the crowns of trees or large shrubs 17 percent. might overgrow them. Thus the majority of the 274 points recorded as rock in 1928 should While the evidence is against any catas- remain as rock, which is verified by noting trophic decline, it is sufficiently large to that there are 221 points in the rock - rock justify concern over the future of the oak category, indicating that 81 percent of the forests. In interpreting our data, it must points did not change, and that therefore be remembered that individual tree size was there is an acceptable margin of error in the not measured, and it is an important piece of relocation of points. While the ideal would information in interpreting rates of decline. be exact relocation of points, there is no On the one hand, a woodland with a lower reason to suppose that minor displacements cover in 1970 than in 1928 might nevertheless would lead to significant biases in estimating be on the increase if in the interim fewer change in cover of the various cover types. large trees were replaced with a larger number of small vigorous trees. On the other hand, From table 2 we can see that there has a forest which in 1970 showed an increase in coverage might nonetheless still be on a downward trend if the increase in cover was TABLE 2. AREA IN SQUARE KILOMETERS OF LAND COVER due solely to the increase in crown cover of TYPE. AND PERCENT CHANGE OF EACH TYPE old trees with no new trees having become FROM 1928 TO 1970. CHANGES WITH AN ASTERISK ARE SIGNIFICANT WITH P<0.05 USING established. A more detailed examination of THE NORMAL APPROXIMATION TO TEST FOR the photos could provide some quantitative DIFFERENCES IN PROPORTIONS. information to characterize better the nature of the change, but it is our subjective opinion that the declines are a combination of a loss both of cover and of individuals, and may indicate a long term but gradual downward AREA IN trend which may accelerate as the large old +4.0 +171.1* trees which seem to be the most abundant in- dividuals in many oak forests begin to die off. To this point, we have considered only and column, could be taken as estimates of the overall summary which combined all data the probability that a point in one of the points for all 30 oak stands. A somewhat categories will transform to any of the other different perspective is given by looking at categories in the 42 year period. Thus the the degree of decline on an individual stand probability that an oak point on the 1928 basis. In figure 1 the percent of cover of photos will be recorded as a grass in the 1970 photos is estimated at .21while the probability that a grass point will be re- 0.4- corded as an oak point is .19. o SAVANNAH WOODLAND If the assumption is made that the proba- 0.3- ARIPARIAN STRIP bilities of transition will be the same for  all 42-year periods in the future; that is, E v if they are held constant, the matrix may be 0.2r A used to project the future proportions of cover types. This is a simple application of Markov chains which was suggested by Anderson (1966) and which has been used by Stephens and Waggoner (1970). The particular matrix of probabilities obtained here predicts that an equilibrium will eventually be reached, 90 80 70 60 50 40 30 20 10 !I 10 30 30 and in accordance with the properties of PERCENT CHANGE Markov chains, this equilibrium is independent of the initial conditions. The predicted Figure 1--Percent change in oak cover between equilibrium proportions are: 1928 and 1970, plotted against the area of the stands in 1928. See text for a defini- Oak Grass Chaparral Rock Stream Developed tion of terms used. .14 .19 .49 .12 c.01 .05

At the hypothetical stable point oak is close oaks lost or gained between 1928 and 1970 is to the observed 1970 value, grassland is plotted against the area of the oak stands somewhat higher, chaparral lower, and developed in square kilometers. In addition, the stands land considerably increased. This would seem are classified into three types - savannah, to indicate that a continuation of the present where the oaks were dotted fairly sparsely trends will lead to relatively little change across chaparral or grassland; woodland, where from the present state of the oak forests. the oaks presented a dense, more or less un- But it is of course debatable if present trends broken, canopy to the aerial view; and riparian will hold, and the projection must be taken strips, in which dense narrow bands of oaks only as an indication that there is nothing lined the sides of a streambed. in our numerical results that would predict a drastic decline. It is clear from figure 1 that the de- cline in oak forests is not general, since four out of thirty forests showed increases. DISCUSSION As mentioned above, this does not necessarily mean that these stands are "recovering" since Since very few field studies have been the increase in cover could be merely due to conducted on the oak communities in southern established trees become larger. Most of the California, our interpretations can only be stands, though, are on the negative side, with compared to work done in the northern or cen- one third of the stands showing a loss of one tral parts of the state (Sampson 144, and third or more of their 1928 cover value. For White 1966). The general overall losses of the graph as a whole, there is a hint of a both chaparral and oak to grass are not too correlation between the total cover of the surprising, especially in areas where live- woodlands in 1928 and their degree of decline, stock grazing or browsing by deer is heavy. with the smaller stands tending to show greater Sampson 0.944) reported that grassland is decline. While plausible explanations for favored in areas where chaparral is experi- this pattern might be suggested, we feel that encing a general decadence following a long more data are necessary before firm conclu- fire-free period. The conclusion that oak sions can be drawn. This is especially true declines are a combination of loss both of because the 1970 photos include the effects cover and of individuals is consistent with of the Laguna fire. White's (1966) observation that grazing can severelyrestrict recruitment of new individ- We pointed out earlier that the data in uals due to failure of seedlings to success- the body of table 1, excluding the last row fully establish. The generally favorable showing of denser woodlands in Figure 1 echoes LITERATURE CITED Griffin's (1977) reports that oaks may be increasing in density but not in range. Anderson, Margaret C. 1966. Ecological grouping of plants. There are good reasons to suppose that Nature 212:54-56. oak woodlands are declining, and yet we did not find a very large decrease between 1928 and Griffin, James R. 1970. Moreover a large part of the change 1977. Oak Woodland. In: Barbour, Michael observed may be the result of the 1970 fire, J. and Jack Major (editors) Terrestrial and it seems likely that the same analysis, Vegetation of California. John Wiley and using photos taken either just before the 1970 Sons: New York. pp 383-415. fire or long enough after it to include the recovery of crowns,would indicate an even Hanes, Ted L. smaller negative change. While our study 1974. The vegetation called chaparral. seems to show that the decline in oaks is not In: Symposium on Living with the critical, it does not allow us to conclude that Chaparral. Sierra Club special publication. there is no problem. More detailed studies are needed to determine if the gross trends we Sampson, A. W. observed indicate a stable population of oaks 1944. Plant succession on burned chaparral or an accumulation of large but senescent lands in northern California. Univ . of individuals. Calif. Coll. of Agric., Agric. Exp~ Sta. Bull. 685.

ACKNOWLEDGEMENTS Stephens, George R. and Paul E. Waggoner. 1970. The forests anticipated from 40 years We wish to thank the San Diego County of natural transitions in mixed hardwoods. Engineer's office for permission to use the Bull. Conn. Agr. Exp. Sta. 707. aerial photographs, and C. Cooper, T. Plumb, and J. Griffin for reading the manuscript and White, Keith L. making helpful suggestions. This work was 1966. Structure and composition of foothill partially supported by NSF grant DEB 76-19742. woodland in central coastal California. Ecology 47~229-237. Quercus chrysol epis

Canyon Live Oak Vegetation in the Sierra Nevada1

Rodney G. Myatt -21

Abstract: In the northern Sierra Nevada, data from stand surveys were used to categorize the phases in the canyon live oak (Quercus chrysolepis) dominated oak-hardwood forest and relate them to the environmental gradients of soil moisture and elevation. The soil moisture gradient was determined primarily from indicator species. Canyon live oak is the major species bridging the Foothill Woodland, Mixed Conifer and Mixed Evergreen associations. The overlapping nature of canyon live oak vegetation is an important factor in the species' morphological variation.

INTRODUCTION transitional relationships between elements of the Arcto-Tertiary and Madro-Tertiary Geofloras Canyon live oak (Quercus -) is and their derivatives (Axelrod 1958, 1959, 1977, considered one of the most variable, ecologi- Raven and Axelrod 1978, Whittaker 1961). cally and morphologically, of the California oaks (Jepson 1925, Munz and Keck 1959, Myatt Because of its widespread geographic dis- 1975). It is certainly the most widespread tribution and elevational range, canyon live oak (Griffin and Critchfield 1972). Its many common overlaps into a number of climatic zones, vege- names reflect also the diversity of outlooks tation types, and floristic regions. It occurs botanists and laymen have had with the species: in twelve of the seventeen forest communities canyon live oak, maul oak, gold-cup oak, laurel described by Munz and Keck (1949, 1959). Within oak, pin oak, mountain live oak, white live oak, a given region, the terrain associated with hickory oak, and drooping live oak. mountains and canyons results in a close juxta- position of varying slopes, aspects, soils, and Canyon live oak occurs in the general as- microclimates. The passage of rivers through semblage of vegetation types occupying the zone several zones and the climatic vagaries of can- between the oak woodlands and themontane for- yons contribute to the opportunity for such ests. This makes it a central member of the species as canyon live oak to occur in many Mixed Evergreen forests of the north coastal habitats. region and the related oak-hardwood forests of the Sierra Nevada and southern California The purpose of this study was to categorize (Sawyer, Thornburgh, and Griffin 1977, Griffin the community types and phases in which canyon 1977, Whittaker 1960). These associations, esp- live oak occurs within one region, the northern ecially the Mixed Evergreen, represent a highly Sierra Nevada, and to relate these to the major variable vegetation with a long history of environmental gradients, namely soil moisture and elevation (temperature). Alpresented at the Symposium on the Ecology, Management, and Utilization of California Oaks, Claremont, California, June 26-28, 1979. STAND SURVEYS The northern portion traversed by the Yuba ?I~ssistant Professor of Biology, Department River has a relatively high annual precipitation of Biological Sciences, San Jose State Univer- of about 60 inches (1500+ mm) and a well devel- sity, San Jose, California. oped oak-hardwood association equivalent to the Mixed Evergreen. The region to south has less precipitation, 40+ inches (1100 mm) and lacks many of the Mixed Evergreen con- stituents. Douglas-Fir (Pseudotsuga menziesii) Table I--Stands and data from the Yuba River and madrone (Arbutus menziesii) are only occa- and Stanislaus River regions, Sierra Nevada sionally found together here.

Forty-one stands were sampled and data ob- Stand Asp. Vegetation Type tained on species composition, abundance, cover and habitat characteristics (table 1, figure 1). (Yub The stands were subsequently grouped into eight 40 s Oak Wood1 . I 7.0 vegetation classes, based primarily on the woody 41 N Mix Oak F. I11 5.9 perennials. The stands' placement along a soil 4 2A s Oak Wood1 . I 6.4 moisture gradient was determined by calculating 42B N Mix Oak F. I11 5.5 the Vegetation Moisture Index (VMI) for each 43 N- s Oak-Evrgn. IV 4.8 stand. This is done by compiling a list of 44 wsw Oak-Evrgn. IV 5.0 indicator species of known soil moisture pref- 45 N Mix Evrgn . v 4.3 erences. Each indicator species is assigned to 17 SE Oak-Evrgn. IV 5.2 a soil moisture class, with its respective 18 SE Oak-Evrgn. IV 5.5 Drought Index number. The VMI for a stand is the 19 ESE Oak-Evrgn. IV 5.1 mean of the Drought Index numbers of the indi- 20 SE Mix Oak W. I1 5.1 cator species present. The list of indicator 21 N-S Mix Conif. VIII 5.0 species was taken primarily from work by Griffin 22 s Oak Wood1 . I 6.1 (1967) and Waring (1969, Waring and Major 1964), 23 N Mix Evrgn. v 4.4 with some species from my own data. Soil moist- 46 s Canyon Oak VI 4.7 ure conditions were also determined for a few 4 7 s Oak-Conif. VII 5.3 sites by measuring the pre-dawn xylem sap ten- 24A s Canyon Oak VI 4.7 sions of canyon live oak specimens during late 24B s Mix Conif. VIII 4.9 summer. A pressure chamber (Schollander bomb) 48 S-E Mix Conif. VIII --- was used for this. 49A s Canyon Oak VI 4.8 49B w Mix Conif. VIII 4.1 51 ENE Mix Conif. VIII 4.4 VEGETATION TYPES (Sta ENE Mix Oak W. I1 6.5 I have recognized eight phases, or dominance SE Oak Wood1 . I 7.4 types, of canyon live oak vegetation, based on NE Mix Oak W. I1 7.0 the relative abundance of the major woody NW Mix Oak F. I11 6.35 species. These represent recognizable units in N Mix Oak F. I11 5.7 the transitions between the three basic vegeta- WNW Canyon Oak VI 6.4 tion types. They are described as follows: w Mix Oak F. I11 5.25 SE Mix Oak W. I1 5.8 N Oak-Conif. VII 5.5 Oak Woodland N Oak-Conif. VII 5.4 NE Oak-Conif. VII 5.9 I. Oak - Digger Pine (Q. wislizenii - Q. m Canyon Oak VI 7.7 douglasii - P. sabiniana). E Oak-Conif. VII 5.9 This is the Foothill Woodland-ofmost clas- E Oak-Evrgn. IV 6.3 sifications, especially the interior live oak SE Mix Conif. VIII 5.0 phase (Griffin 1977). Canyon live oak is only SE Oak-Conif. VII 4.6 an occasional associate on north-facing slopes SE Canyon Oak VI 5.25 of ravines. ESE Canyon Oak VI 5.25 N- S Oak-Evrgn. IV 5.2 11. Mixed Live Oak Woodland (Q. wislizenii - -Q. chrysolepis). This is a slightly more closed woodland This occurs on north-facing slopes and than "I", tending towards forest. Both live extends into riparian forests along summer-wet oaks occur on steeper slopes within the Foot- creeks through the upper Mixed Oak Woodland. hill Woodland where blue oak is absent. There It is more mesic than "II", with Acer, Vitis, is a prominent understory of shrubs: and Umbellularia. It grades into Foothill Wood- (Toxicodendron), Arctostaphylos, Heteromeles. land on south-facing slopes and Oak-Pine on the north-facing and upper slopes. Mixed Evergreen IV. Mixed Oak - Evergreen Forest (Q. chrysolepis - Q. kelloggii - p. ponderosa - Pseudotsuga 111. Mixed Oak Forest (2. wislizenii - Q. menziesii). chrysolepis - Q. kelloggii). Figure I-- Locations of stands in the Yuba River (A) and Stanislaus River (B) regions.

B. STANISLAUS R.

This type occurs on all slopes at mid-to- Mixed Conifer lower elevations in more mesic climates, above the Oak Woodland. It includes Arbutus, Aesculus, VII. Mixed Oak - Conifer Forest (Q. chrysolepis - Calocedrus, and diversiloba. It is the more Q. kelloggii) xeric phase of the Mixed Evergreen Association . and consists of two subphases itself: 1) Quercus This occurs as groves of mixed oak forest chrysolepis - 'Dmbellularia on steep slopes with- within the Mixed Conifer zone. It usually occurs in the Mixed Evergreen and 2) Q. kelloggii - on southerly exposures or less favorable sites Arbutus on the flatter, south-facing slopes in than the conifer forest, and represents a phase the Yuba River region and on north-facing slopes between the canyon live oak and the conifer in parts of the Stanislaus River region. forests. V. Mixed Conifer - Evergreen Forest (Pseudotsuga VIII. Mixed Conifer - Oak Forest (P. ponderosa - menziesii - Q. kelloggii - 2. ponderosa - Q. -Ps. menziesii - Q. kelloggii - Q. chrysolepis) . chrysolepis). This occurs along north-facing slopes op- posite and along creeks and draws through "IV". Canyon live oak overlaps into the Mixed There usually are more shrubs and less herbs, Conifer Forest as an understory element. Also and includes Acer, Cornus, Corylus, and included are Abies, Calocedrus, E. lambertiana, Calycanthus. Ceanothus, Arctostaphylos, and Chamabatia. Pseudotsuga is less common in the Stanislaus River region. In the Yuba River region it is Types IV and V make up the typical Mixed Evergreen Forest and represent the two ends of more prominent on north-facing slopes and ridges the hardwood to conifer phases. Neither type is above the canyon live oak. represented well in the Stanislaus River region. In the Yuba River .region a Lithocarpus Arbutus- In the above vegetation types, canyon live - oak occurs in its typical tree form. In addition Pseudotsuga phase occurs, lacking canyon live -. - oak. it may occur in chaparral vegetation as a result of being able to stump-sprout and exist as a VI. Canyon Live Oak Forest (Q. chrysolepis shrub and also to hybridize with the shrubby huckleberry oak (Q. vaccinifolia). Canyon live oak groves and small forests occur within the Mixed Conifer zone especially. There are few associates, but usually some R. MOISTURE GRADIENT diversiloba and Polystichum munitum. This type occurs also as depauperate patches of oak-hard- The above placement of stands into domin- wood forest on rocky points and steep slopes ance types roughly relates to their placement within the Yuba River region. along a moisture gradient. A temperature gradient and varying soil conditions also enter in,owing VEGETATIONAL RELATIONSHIPS to the elevational, topographic, and edaphic changes within the regions. Certain species are The general slope of the stand arrangement well known as indicators of given moisture or is positive (fig. 2) since the elevation gradi- other habitat conditions. Using the Drought Index ent corresponds to a moisture gradient. The groups and indicator species as compiled by arrangement of the stands, particularly those Griffin and Waring, I listed those which are in the Yuba River region, appear as a somewhat associated with canyon live oak in one place or elongated triangle, with the Foothill Woodland another (table 2). Not all of these, however, in the lower left corner, the Mixed Evergreen were present in the stands that I surveyed here, in the lower right, and the Mixed Conifer in at least at the time. The starred (*,**) species the upper right. Stands of predominantly canyon are those that were used in computing the Vege- live oak (VI) seem out of place in a simple tation Moisture Index for the stands I surveyed. moisture gradient and instead represent phases The double starred (**) are those not on the of the major types in which other factors are lists of Griffin and Waring, but added here important, such as steepness of slope, soil based on their close associations with the other depth, and rockiness. Such stands occur mainly species. In table 1 can be found the Vegetation at the higher elevations within the Mixed Moisture Index (VMI) for each stand. Conifer zone where slope, aspect, and soil depth differences can result in marked contrasts in The stands were then graphed with the VMI habitats. Thus separation of the more tolerant plotted against the elevation (fig. 2). Stand canyon oak from the conifers and black oak is 58, taken at Pine Grove, Amador County, is possible. Within the Mixed Evergreen zone, slightly to the north of the Stanislaus River particularly near the Yuba River, there is region stands and is included here as a point apparently enough moisture to support a number of reference. It is the only stand sampled near of associates on most sites where canyon oak the Stanislaus River with some semblance of a can occur. Mixed Evergreen Forest.

Table 2-- Soil moisture indicator species found occurring with canyon live oak and their respective Vegetation Drought Index groups (DI)

DI Species Species DI Species * I Taxus brevifolia Ceanothus prostratus VII Agoseris retrosa I1 Acer macrophyllum** Chamabatia foliolosa** Arabis holboelii Chrysolepis sempervirens Hieracium albiflorum Brodiaea multiflora Calycanthus occidentalis** aristata Ceanothus cuneatus* Smilacina racemosa P. ponderosa* C. lemmonii Polygala cornuta* Cercis occidentalis* I11 Abies concolor* Pteridium aquilinum* Cercocarpus betuloides* Cornus nuttallii* Rhamnus rubra** Collinsia parviflora Galium triflorum Sitanium hystrix Dodecatheon hendersonii Corylus cornuta californica** Viola lobata Eriophyllum lanatum* Lithocarpus densiflorus** VI Amelanchier pallida* Lonicera interrupta* IV Arbutus menziesii** Arctostaphylos manzanita Purshia tridentata Ceanothus integerrimus* A. viscida* Q. wislizenii** Berberis piperiana Castileja applegatei Ranunculus occidentalis Carex rossii Clarkia rhomboidea Rhamnus californica* Festuca occidentalis Collomia erandiflora- Rhus diversiloba* Pinus lambertiana* Comandra pallida VIII Bromus tectorum Pseudotsuga menziesii* Galium bolanderi Penstemon deustus Ribes roezlii Lathryus sulphureus Rosa gymnocarpa* pedicularis densiflora IX Adenostema fasciculatum** Symphoricarpos acutus* Prunus subcordata Pinus sabiniana** Trientalis latifolia* Quercus earryana Q. douglasii** V Arctostaphylos patula Q. kelloggii* Bromus orcuttianus bipinnata Calocedrus decurrens* lemmonii Wyethia mollis Figure 2-- Relationships of stands to elevation Figure 3-- Vegetation relationships in the Yuba and Vegetation Moisture Index. River and Stanislaus River regions.

i c e class 1- 0 II- [TI HI-E~S IV-0V-0VI-@VII- A vin- A

A. YUBA

MIXED EVERGREEN

and draws

At. B. STANISLAUS

7.0 6.5 6.0 5.5 5.0 4.5 4.0 7.0 6.5 6.0 5.5 5.0 4.5 4.0 Keric Mesic Mesic VEGETATION MOISTURE INDEX Xeric VEGETATION- MOISTURE INDEX

From the plotting of stands in figure 2, and The Live Oak Woodland and Live Oak Forest are from other observations, I have come up with a combined in the Stanislaus graph. The oak forests graphical representation of the relationships have become mostly canyon oak forests. of canyon live oak vegetation in the northern Sierra Nevada (fig. 3). The dashed line in the Even with its broad distribution throughout middle of each graphically represents the can- several communities, the compensation of moist- yon slopes near the river, excluding the strict- ure related factors results in a relative site ly riparian vegetation. To the right are the constancy for canyon live oak with regard to north-facing slopes and relatively more mesic the moisture gradient. Most of the measures of habitats. To the left are the exposed ridges minimum xylem sap tensions were similar (-5 to and south-facing slopes. The limits of the -10 atm) and indicative of root systems probab- vegetation groups are of course arbitrary, re- ly reaching ground water. Some higher stresses flecting the gradual transitions. (to -22 atm) from some exposed xeric sites also indicate some amount of variability here and The three basic vegetation types are shown, may account for the species' abilities to in- with the Mixed Evergreen considerably shrunk trude into chaparral habitats within the forest. or eliminated in the Stanislaus River region. Likewise, its noted tolerance for poor soils Canyon live oak generally occupies intermediate (e.g. serpentine) and infrequent burning has associations between the three basic types and apparently resulted in its prominence in such is the primary species bridging all three. azonal habitats where there is less competition from the faster growing conifers and other Munz, P. A. and D. Keck hardwoods. There seems to be a relationship 1959. A California flora. Univ. Calif. Press, between widespread adaptability and lack of Berkeley. 1681 p. competitiveness, where a species is either able to utilize many habitats to some extent or to Myatt, Rodney G. utilize one or a few effectively (Solbrig 1970) 1975. Geographical and ecological variation in Quercus chrysolepis Liebm. Ph.D. dissertation, Univ. Calif., Davis. 220 p. LITERATURE CITED Raven, Peter and D. I. Axelrod Axelrod, D. I. 1978. Origin and relationships of the 1958. Evolution of the Madro-Tertiary Geoflora. California flora. Univ. Calif. Publ. Bot. Bot. Rev. 24:433-509. 72:1-134.

Axelrod, D. I. Sawyer, John, D. Thornburgh, and J. Griffin 1959. Geological history. 3P. Munz and D. 1977. Mixed evergreen forest. 3M.G. Barbour Keck, A California flora, p. 5-9. Univ. and J. Major (eds.), Terrestrial vegetation Calif. Press, Berkeley. 1681 p. of California, p. 359-381. J. Wiley and Sons, New York. 1002 p. Axelrod, D. I. 1977. Outline history of California vegetation. Solbrig, 0. -In M.G. Barbour and J. Major (eds.), 1970. Principles and methods of plant bio- Terrestrial vegetation of California, p. systematics. The Macmillan Co., London. 140-193. J. Wiley and Sons, New York. 1002 p. 226 p. Griffin, James Waring, R. H. 1967. Soil moisture and vegetation patterns 1969. Forest plants of the eastern Siskiyous: in northern California forests. U.S.D.A. their environment and vegetational distri- Forest Service Res. Paper PSW-46. 22 p. bution. Northwest Sci. 43:l-17. Griffin, James Waring, R. H., and J. Major 1977. Oak woodland. &I M.G. Harbour and J. 1964. Some vegetation of the California Major (eds.), Terrestrial vegetation of coastal redwood region in relation to California. p. 383-415. J. Wiley and Sons, gradients of moisture, nutrients, light, New York. 1002 p. and temperature. Ecol. Mon. 34:167-215.

Griffin, James and W. Critchfield Whittaker, R. H. 1972. The distribution of forest trees in 1960. Vegetation of the Siskiyou Mountains, California. U.S.D.A. Forest Service Res. Oregon and California. Ecol. Mon. 30:279-338. Paper PSW-82. 114 p. Whittaker, R. H. Jepson, W. L. 1961. Vegetation history of the Pacific Coast 1925. A manual of the flowering plants of states and the "central" significance of California. Univ. Calif. Press, Berkeley. the Klamath Region. Madrono 16:5-23. 1238 p.

Munz, P. A. and D. Keck 1949. California plant communities. El Aliso 1:87-lOS. Inventory and Quantification of Central Coast Hardwood Resources in California1

Norman H. Pi1 1sburycl

Abstract: A method for determining the volume and weight of standing hardwood trees has been developed and tested. Cubic volume and weight tableshave been developed for coast live oak (berms agrifolia Nee), blue oak (qercus dougtasii Hook. and Arn.), valley oak (~uercuslobata Nee) and tanoak [~ithocarpsdensiflorus (Hook. and Arn. ) Rehd.]. Diameter at breast height and total tree height provided the best relationship for determining tree volume and weight. Hardwood stand characteristics are presented for volume, weight, basal area, and number of trees. Three stand density classes are defined by class average and range of values for volume, weight, and basal area. Current and future studies include the development of hardwood photo volume and weight tables, preparation of maps showing volume and weight distri- butions, and evaluation of growth, regeneration,and thinning data.

INTRODUCTION As a commodity, hardwoods in central Cali- fornia are used mostly for fireplace fuel and Until recent1 y a cubic foot volume or total seldom for other wood products. As other forms fibre inventory of the central California hard- of energy decrease in availability and increase wood species was not available to property in cost, the use of these renewable hardwoods owners or resource agencies responsible for for fuel in power plants and fireplaces becomes their management. Consequent1 y the Forestry more attractive and practical. As an amenity, Committee, Central C st Resource Conservation hardwoods are recognized for recreation, esthet- and Development Area-37 (CCRC&D), assisted by the ics, and watershed protection in the woodland California Department of Forestry, Soil Conser- environment, while shade and visual enhancement vation Service, and U.S. Forest Service has are important in the urban setting. Native hard- sponsored this study to inventory and evaluate woods are often ignored or viewed as a nuisance. the hardwood resources in the Central Coast This opinion, although rapidly changing in many counties, California (fig. 1). Also, the Renew- areas, is still shared by some landowners who able Resources Eval uation Research Unit, Pacific prefer converting woodland to rangeland or agri- Northwest Forest and Range Experiment Station, cultural fields. Portland, Oregon is planning to include a hard- wood inventory as part of the next forest re- The objectives of the study (fig. 2) are to source assessment for the State of California.-4/ provide property owners and resource managers with a method for estimating volume and weight for individual trees, small stands of trees, and lipresented at the Symposium on the Ecology, large tracts of woodlands. Eventually, guide- Management, and Utilization of California Oaks, 1ines will be developed for regeneration and Claremont, California, June 26-28, 1979. planting of hardwoods and for stand improvement and protection. The opportunity for local citi- ^/~ssociate Professor, Natural Resources zens to manage and market hardwood products Management Department, Cal ifornia Polytechnic through an oak-woodland cooperative will be ex- State University, San Luis Obispo. plored. Species under study are coast live oak he Central Coast Resource Conservation and Development Area is composed of Resource Conser- ^/personal Communication, 1979, Charles vation Districts from the foll owing Central Bol singer, Renewable Resources Eval uation Re- Coast Counties : Santa Cruz, Monterey, San search Unit, Pacific Northwest Forest and Range Benito, and San Luis Obispo, California. Experiment Station, Portland, Oregon. Figure I--Sampl e plot locations in central coast counties, California. Squares are field plots, circles are photo plots. PHASE I PHASE I1 PHASE I11 PHASE IV PHASE V

A. Feasibility study. A. Construct hardwood A. Develop photo- A. Determine hardwood A. To conduct a pulpwood Development of volume and weight volume tables for site index and and firewood market technique for tables for the Central Coast yield data for study for existing a) Volume and Central Coast counties. plots in the hardwoods in the density measure- counties. Central Coast Central Coast. ment methodology counties.

Status: Status: Status: Status: Status:

Completed Completed In progress Proposed Conceptual

Report submitted: Report published: Completion date: Duration: Duration :

February 1978 April 1978 Summer 1979 1-2 years

B. Determine hardwood B. Construct fuel B. Develop guidelines B. Development of stand density inventory maps for regeneration an oak-woodland characteristics for Central Coast stand improvements, cooperative. for the Central counties. protection, and Coast counties. rotation.

Status: Status: Status: Status:

Completed In progress Conceptual Conceptual

Report pub1 ished: Completion date: Duration: Duration:

July 1978 Summer 1980

Figure 2. Schedule for the inventory and quantification of Central Coast woodland resources in California.

(~uepcusaqrifolia ~ee),bl ue oak (Quercus ments of the volumes of standing trees. This, dougtasi{ Hook. and Arn. ), valley oak (Quercus of course, needs checking by direct measurement Zobata Nee), tanoak [~ithoearpusdensi.flo~us of fa1 1en trees. (Hook. and Arn.) Rehd.], interior live oak (~uereusuisZizenii A. DC. ) , and Pacific madrone The problem of accurately measuring the (~rbutusmenziesii Pursh) . volume of standing trees was solved as foll ows. Indirect measurements were obtained on standing The results from this study should aid trees with a Spiegel relascope (fig. 3); any woodland owners to objectively manage their land equivalent upper stem dendrometer can be used. for hardwood products or for esthetics and Each tree was divided into "stem and branch" other uses. The manager will now have a better segments (minimum diameter to 4 inches) and "ter- information base from which to make his deci- minal" segments. End diameters and the length sions. of each stem and branch segment were measured and the volume was calculated from Smal ian's for- mula (Husch et at 1972) as follows: METHODS AND RESULTS OF COMPLETED STUDIES Segment volume = [(h/2)(Ab + An)] where Hardwood Volume Tables Ab is the cross-sectional area at the The hardwood species of the Central Coast large end of the segment tend to be characterized by rather short boles Au is the cross-sectional area at the and branchy crowns. The number of segments and small end of each segment, and the complexity of the branching network makes h is the segment length. volume measurement of hardwoods both difficult and time consuming. Measuring tree volume after The lengths of terminal segments 4 inches (10 a tree has been cut gives reliable data but is cm) in diameter (at the large end) were averaged very time consuming. Consequently, an indirect for each tree, and the segment volume was com- procedure is needed that allows accurate measure- puted as a cone (fig. 3). Also, direct volume Each tree was cut into firewood-size pieces 18 inches (45 cm) long and loaded on to a flatbed truck where each tree was weighed by a set of portable truck scales on loan from the Califor- nia Highway Patrol. Merchantable tree weight is green weight, excl uding fol iage and branches less than 2 inches (5 cm) in diameter. A total of 250,000 pounds (113,000 kg) of wood was cut and weighed.

A strong correlation was found between volume and weight values (mu1 tiple correlation coefficient, R2 = 0.904 or higher for individual species), and this relationship was used to estimate weight values for uncut trees. Tree weight equations shown in table 1 were developed using diameter at breast height and total tree height as independent variables. Volume and weight tables for coast live oak, blue oak, tanoak, valley oak, and a general a11- species tab1 e resulted (Pi11 sbury and Stephens ~igure3--Volume determination of standing 1978). trees as determined by measuring segment diameters and lengths with a relascope. Segment volumes (numbered on sketch) are Stand Characteristics for Central Coast summed to obtain tree volume. Hardwood Species

data was obtained by a tree caliper and cloth While individual tree measurements were tape after each tree was cut. Cut segment vol- required for volume and weight table develop- ume was computed in the same manner as for ment, total data from each plot were used to standing trees (Pillsbury and Stephens 1978). gather information about the stand itself. The computed stand characteristics are shown in For both standing and cut trees, the sum Appendix A, Stand Variables. Data are expressed of all segment volumes provides both an indirect on a per acre basis, e.g., individual tree vol- and direct measurement of the total tree volume. umes are summed to obtain plot volumes, and Cut and standing measurements were obtained for a sample of 61 trees of different species located throughout the study area. The relationship between standing and cut tree volumes is shown in figure 4. This equation was used to adjust indirect volume measurements for the remaining 109 trees in the study.

Twenty-six sample plots (fig. 1) were random1y selected in hardwood stands at sites which appeared to be similar in size distribu- tion and volume to the surrounding stand. A total of 170 trees, totalling 7,880 cubic feet (223 cubic meters) of wood, were measured by the technique shown in figure 3. Tree volume equa-

tions listed in table l were developed by multi- R~ = 0.990 ple regression. Two independent variables, N -61 VCi- S = VOLUTE STANDING OUTSIDE BARK diameter at breast height and total tree height, VCi- C = VOLUTE CUT OUTSIDE BACK provided the best correlation to tree volume. The addition of tree form, soil and site vari- ables did not improve the correlation at the 5 percent 1eve1 of significance and were el iminated from further consideration in the analysis.

Hardwood Weight Tables Figure 4--Re1 ationship between tree volume standing and tree volume cut for 61trees Tree weights were obtained from 84 trees. in the Central Coast counties, California. Table 1. Tree volume and weight equations for Central Coast hardwoods.

Species Equation l R 2 1 n

All species VOL (ob) = 0.00469458 (DBH~-~~~~)(HT~~~~~~)

VOL (ib) = 0.00371214 (DBH~-~~~~)(HTO-~~~~)

Coast Live VOL (ob) = 0.01632627 (DBH1-6725)(HT0-8259)

Oak VOL (ib) = 0.01045289 (DBH~-~~~~)(HT~.~~~~)

Blue Oak VOL (ob) = 0.00105029 (DBH2-3660)(HT1-0966)

VOL (ib) = 0.00072834 (DBH~^~~~)

Tanoak VOL (ob) = 0.00347878 (DBH2-0397)(HT0s8^02)

VOL (ib) = 0.00475941 (DBH1-9333)(HT0-8190)

Val 1ey Oak VOL (ob) = 0.00077572 (DBH~-~~~~)(HT~.~~~~)

All species MWT = 0.81259 (DBH~-~~~~)(HT~~~~~~)0.931 150

Coast Live MWT = 0.6464167 (DBH~-~~'+~)(HTOO'~~~~) 0.905 5/6 Oak

Blue Oak MWT = 1.2193549 (DBH~-~~~'+)(HTOO-~~~~) 0.901 55

Tanoak MWT = 0.1 199063 (DBH~-O~~~)(HT0-9821) 0.982 20

VOL (ob) is total tree volume outside bark in cubic feet VOL (ib) is total tree volume inside bark in cubic feet MWT is merchantable green weight in pounds to a 2" stem DBH is diameter at breast height in inches HT is total height in feet R2 is mu1 tiple correlation coefficient n is the number of observations Table 2. Stand and yield characteristics for Central Coast hardwoods.

Variable Name Units Average Range Standard Deviation Volume outside bark per acre

Number of cords'-/ per acre

Volume inside bark per acre

Green wei ght per acre

Number of trees per acre

Basal area per acre

I/~mountof wood stacked in a 4' x 4' x 8' space. Computation is based on a volume outside bark of 80 cubic feet (62.5%) of actual wood per cord. extrapolated to obtain volumes per acre. Other density class limits. The frequency of plots stand variables are calculated in a similar sampled and the range of stand volume and weight manner. Results for species in the Central values were divided into stand density classes Coast counties are shown in table 2. Total (I, 11, I11 in table 3). The limits and aver- stand volume (outside bark) and weight averaged ages used to define each class are shown in 3010 cubic feet per acre (211 cubic meters per table 3. hectare) and 96 tons per acre (215 metric tons per hectare). Assuming that a standard cord Stand density classes may be used on maps (wood stacked in a 4' x 4' x 8' space) contains to show relative distributions of hardwood vol- an actual volume of 80 cubic feet of wood. the ume and weight. A stand density class can be average hardwood stand in the Central Coast obtained by determining the volume per acre from counties contains about 37.5 cords per acre, a sample plot and referring to table 3. An and a cord weighs about 5100 pounds. A large easier method has been found based on the high variation exists for these and other variables correlation between basal area per acre and measured because of the wide range of densities weight per acre (R2 = 0.90). This method uses included in the sample design. the variable plot sampling technique described by Dilworth and Bell (1971). The basal area is obtained by counting the number of trees ob- Stand Density Classes served from the center of each sample plot multiplied by the basal area factor stamped on an Because hardwood stands were found to occur angle gage. wedge prism or relascope. This value in a wide range of volume weight, number of is the basal area per acre. The density class treeslacre, and basal area densities, it is de- and average volume and weight per acre can be sirable to categorize hardwood stands by specific obtained from table 3. density classes. A correlation matrix was calculated to evaluate the degree of correlation among stand density variables. Variables with Summary the highest correlation, measured by the cor- relation coefficient (R2), that are easily Based on this research, land and resource measured or estimated were used to establish managers now are able to quantify hardwood Table 3. Stand density class limits and averages!/

Green weight in Basal area in Density Volume (ob) in cubic feetiacre tonslacre square feetlacre * Class Average Range Average Range Average Range

I 9 74 1 - 1430 32 1 - 55 37.3 1 - 70

I/~vera~esare based on the average value measured per density class from plot data. species and stands by: photos and from volume and weight calculated from field measurements will be used to develop 1. Determining individual tree volume photo volume and weight tables as outlined by and weight. Paine (1978). 2. Obtaining a general estimate of stand volume and weight per acre. These tables will be used to determine 3. Compiling a detailed estimate of stand volume and weight of individual trees from volume and weight per acre. aerial photos. Volume and weights for small stands of hardwoods can be estimated by taking Specific examples and recommended techniques measurements from a series of photo sample are discussed in Hardwood Stand Density Charac- plots. Photo volume and weight tables will be teristics for Central Coast Counties in Califor- used for classifying homogeneous hardwood nia (Pillsbury 1978). stands into volume and weight density classes for the fuel inventory mapping project.

CURRENT HARDWOOD STUDIES AND ANTICIPATED RESULTS Hardwood Fuel Inventory Maps Aerial Photo Volume and Weight Tables Determining hardwood volume and weight dis- Other studies in progress include the tributions for the Central Coast counties is development of hardwood photo vol ume and weight the primary objective of this study. This will tables. Low altitude (scale of 1 :5,000) color be accomplished by generating a set of hardwood photographs have been taken and processed by fuel inventory maps. The U.S. Geological Sur- the U.S. Forest ~ervice.5/ Tree height, crown vey, Land Use and Data Analysis (LUDA) Program diameter, and crown area measurements are being has prepared vegetation cover maps (scale of 1: determined for 168 sample trees located on 21 24,000) for the Central Coast counties. These plots in the Central Coast counties (fig. 1). maps will be used as "base maps" for the fuel Values are being obtained from two types of inventory project. Forest lands are divided photo measuring equipment. The first type is a into deciduous, evergreen, and mi xed forest 1and digitized Wi1 d STK-1 stereocomparator and card- (Anderson et a2 1976). Volume and weight punch combination. This equipment provides high estimates from aerial photos will be used to precision measurements; however, it is very obtain stand density classes (table 3) for the expensive to purchase or lease. Secondly, the deciduous forest 1ands. Deciduous forest lands relative1y common, less expensive para11 ax bar will be subdivided into stand density classes I, is used a1 though it has lower precision. A com- I1 or I11 and mapped on USGS topographic maps. parison of measurements taken by these two types Photo estimates will be checked in the field to of equipment will allow us to determine the assure correctness of classification. degree of variability that can be expected from low precision equipment. The relationship be- Fuel inventory maps will provide regional tween tree measurements obtained from aerial estimates and distribution of hardwoods. Also, woodland owners, with assistance' from resource agency personnel, will be able to identify their ^-~U.S. Forest Service, State and Private For- property on these maps and obtain volume and estry, Region 5, San Francisco, California. weight estimates for the hardwood portions. Thus, a hardwood volume and weight estimate LITERATURE CITED will be obtained for the Central Coast counties for the first time. Anderson, J.R., E.E. Hardy, J.T. Roach, and R.E. Witmer. 1976. A land use and land cover classification OUTLINE OF FUTURE STUDIES FOR system for use with remote sensor data. CENTRAL COAST HARDWOODS Geol . Surv. Prof. Paper 964. 28 p. US Gov. Print. Off., Washington, DC. Future studies planned for the Central Coast hardwoods include growth and yield evalua- Dilworth, J.R. and J.F. Bell. tion and analysis of regeneration, thinning, and 1971. Variable plot sampling. 130 p. Oregon stand improvement techniques. This information State University Book Stores, Inc. is essential before management recommendations can be made. Further studies will analyze the Husch, B. , C. I. Miller, and T. W. Beers. percentage of harvest that will allow for proper 1972. Forest mensuration. 410 p. Ronald Press soil and watershed protection. Co . Most woodland owners do not have retail Paine, David. outlets nearby and do not have the time to 1978. Aerial photography for natural resource transport firewood to high demand metropolitan management. 324 p. Oregon State University areas where prices are favorable. Studies are Book Stores, Inc. neededto evaluate how a local economy might benefit from an oak-woodland cooperative. Pillsbury, N.H. and J.A. Stephens. 1978. Hardwood volume and weight tables for California's central coast. 54 p. California Department of For. , Sacramento. Pillsbury, N.H. 1978. Hardwood stand density characteristics for central coast counties in California. 32 p. Central Coast Resource Conservation and Development Area, Salinas, Calif. APPENDIX A. Summary of tree and stand variables for Central Coast Counties in California.

Variable Units Measurement description

A. Tree Variables Species code 1. coast live oak; 2. blue oak; 3. valley oak; 4. madrone; 5. tanoak; 6. interior live oak.

Diameter at breast in Diameter of main stem at 4.5' (1.35 m) height outside bark measured with a D-tape.

Total tree height ft Determined by re1 askop.

Crown area ft2 Computed from average of maximum and minimum crown diameter (based on circle).

Volume outside bark ft3 Computed from segment end diameters and seg- (standing) ment lengths by relaskop (fig. 3).

Volume outside bark ft3 Computed by tree calipers and cloth tape or (cut) , figure 4.

Volume inside bark ft3 Volume outside bark (cut) minus volume lost (cut1 due to bark.

Merchantable tree lbs Green weight excluding foliage and growths weight (green) less than 2 in (5 cm) in diameter, by truck scales.

B. Stand Variables Volume outside bark ft3/ac Volume inside bark ft3/ac Technique described by Dilworth and Be1 1 Merchantable tree tonslac (1971); data obtained from tree weight (green) variable measurements (part A). Basal area ft2/ac Number of trees #/ac Oaks in California's Commercial Forests-Volume, Stand Structure, and Defect Quercus Characteristics1 kelloqgii

Charles L. Bolsinger-2'

Abstract: Information on area of hardwood types on commercial forest land in California, and volume and defects of oaks is summarized. Studies done in Trinity County and the southern Sierra Nevada show similar species, size, and defect characteristics. Black oak made up 60 percent of the volume. Most stands had less than 1,000 cubic feet per acre. Larger older trees were more defective than smaller, younger trees. About one-fourth of the trees under 11.0 inches in diameter had visible decay indicators, compared with 100 percent of the trees over 29 inches. About half of the black oaks over 29 inches in diameter were cull.

INTRODUCTION In addition to the hardwood types, hardwood trees make up 10 percent or more of the stocking on California has 16.3 million acres of forest 2.7 million acres of commercial conifer types. land, excluding Parks and Wilderness Areas, capable of growing 20 or more cubic feet of About 80 percent of the total cubic-foot industrial wood per acre annually. All but volume in hardwoods in California is oaks- about 50,000 acres of this "commercial forest (including Quereus spp and Lithoearpus densi- land" is capable of growing conifers, though fZoms) as shown below (see also species list currently hardwood forest types cover 2.8 million at end of this article). acres. About 77 percent is on private lands, 15 percent is in National Forests, and 8 percent is on other public lands. By site class, Million cubic Million board feet ^e Species or feet in trees (Int. 1/4" rule) in hardwood types are distributed as follows:- species .group 5.0 inches* trees 11.0 inchest Site class Thousand acres Percent California black oak 1,078 2,659 (cubic feet per White and live oaks 718 1,771 Tanoak 1,087 2,048 acre per year) Madrone 544 1,024 Red alder 64 179 20-49 267 9 All other hardwoods -202 394 50-84 968 34 Total 3.693 -8,075 85+ 1,606 -57 Total 2,841 100

-'see Griffin and Critchfield 1972 for details on the distribution of hardwoods in California. Ñ'presente at the Symposium on Ecology, Management, and Utilization of California Oaks. f'~ot included is the volume of oaks on over Claremont, California, June 26-28, 1979. 7 million acres of unproductive oak woodland, consisting primarily of California blue and Ñl~esearcForester, Pacific Northwest Forest valley oaks and California live, interior live, and Range Experiment Station, Portland, Oregon. and canyon live oaks. No volume inventory has been made of these species except where they occur on "commercial forest land." These estimates of forest area and timber A canvass of 100 percent of California's volume,were made by the Renewable Resources forest products industries in 1976 showed that Evaluation Research Unit at the Pacific North- hardwoods amounted to less than one-fourth of west Forest and Range Experiment Station, 1 percent of wood consumed (Hiserote and Howard Portland, Oregon. Volume was calculated for 1978). Conifer consumption was 135 percent of trees having at least one 8-foot log above a annual growth and 2.1 percent of inventory, 1-foot stump to a top diameter of 4 inches while industrial hardwood consumption was outside bark for cubic-foot estimates, and 6 percent of growth and 0.1 percent of inventory. 9 inches for board-foot estimates. Some hardwoods were used as fuel. About 1.5 million cubic feet of fuelwood was harvested To approximate the total volume in hardwoods by timber operators (California Department of on California's commercial forest land, factors Forestry 1977), and 47,707 fuelwood cutting were developed as follows: A sample of trees permits were issued by the USDA Forest Service. measured by the Resources Evaluation Unit were An unknown but substantial portion was oak. selected and main bole net volumes were calcu- Still, the total consumption of oak in California lated. Values developed by Pillsbury and is a small fraction of the resource. Stephens (1978) in California's central coast area were used to estimate total tree volume The effect of removing conifers from mixed including stumps, limbs, branches, and tops stands and leaving hardwoods is seen in a stand in the same trees. Conversion factors were sampled in Trinity County. This stand was logged calculated by broad diameter class and applied about 20 years ago and again within the past to the State totals. Because the species mix 10 years. The older logging removed large in Pillsbury's study differs from the total pines. Recent logging removed large Douglas-firs. mix of hardwoods in California, these results No hardwood trees were cut or killed by logging, can be viewed only as rough approximations: but many hardwoods--mostly California black oak and canyon live oak--were damaged. Trees Net cubic-foot volume of mln bole from a Conversion factor" and stumps were tallied so stand data could be Diameter at I-foot stump to total tree volume/ Approximate total displayed before and after the recent logging. breast height &-inch top main bole volume tree volume (A) (B) (A) x (B) The results are: Inches Million cubic feet Million cubic feet 5.0-10.9 1.047 1.56 1,633 11.0-14.9 725 1.90 I ,378 15.0-20.9 857 I .98 1,697 Square feet of basal area saplings seedlings 21 .O-28.9 69 1 I .98 1,368 per acre in trees 5.0 inches+ per acre at time of 29.0+ Ñ27 -1.98 -738 Before logging After logging sampling Total 3,693 1.84 6,814 Stand Total Total component BA Percent BA Percent Number Percent Conifers 56 52 24 32 342 26 A similar relationship between main bole Hardwoods 52 48 52 68 960 74 volume and total tree volume was reported by Total 108 100 76 100 1,302 100 Noel Cost (1978) in mountain hardwoods in North Carolina. Cost's study consisted mostly of smaller trees. His factor--1.46--is similar In this stand the proportion of hardwood to the 1.56 shown above for trees in the 5.0- stocking increased 20 percent after reftioval of to 10.9-inch class. dominant Douglas-fir trees. A closer examination revealed that many of the hardwoods were crooked Although oaks occur naturally on 5.5 million and/or rotten. Of more importance is the acres of commercial forest land, logging long-term effect. The future forest, represented practices have promoted their growth and estab- by the saplings and seedlings, is three-fourths lishment. California black oak and canyon live oak.

Since 1953 (USDA Forest Service 1954), To get a bett.er idea of oak characteristics cubic-foot volume of oaks has increased on commercial conifer site lands, two areas 34 percent while conifer volume has decreased (see fig. 1) were selected for study: Trinity 29 percent. Selective cutting has removed County in the and northern conifers from mixed stands, often leaving oaks Coast Ranges, and a five-county area in the to control the site. McDonald (1973) reported southern Sierra Nevada and the Tehachapi Moun- that oak stocking on the Challenge Experimental tains (Mariposa, Madera, Fresno, Tulare, and Forest increased following logging to meet the Kern Counties). Forest Survey plot records for former California Forest Practice Act Standards. lands outside National Forests were examined. Although current standards allow oaks to count as stocking only if designated for management (California, State of, 1975) their presence 2'~ield plots were randomly selected from a influences stand development even when not larger sample of aerial photo plots and counted. Logging promotes oak in many areas established on the ground. For details on the of California. sampling procedures see Bolsinger 1976 and 1978. Interior

TRINITY COUNTY

~FNTO SOUTHERN SIERRA- Nevada and Tehochapi

Trinity Southern RA County Sierra ...... ¥LO ANGELES Figure 2--Percent of total net volume of oaks by species, Trinity County and southern SAN DIEGO \^ Sierra Nevada. Figure 1--Map of California showing location of oak study areas. the white oak was Onerous garrycma, including the large tree form and the smaller var. The following summary shows area and number brewerii. In the southern Sierra Nevada, field Of plots: crews identified both Onerous garmjana and Quercus Zobata. Tanoak accounted for about Acres of Percent of plots 2 percent of the oak volume in Trinity County. commercial Number of with oak trees Study area forest land field plots 5.0 inches+ In the southern Sierra Nevada, interior live oak accounted for 2 percent of the oak volume. Trinity County 460,000 Southern Sierra 174,000 Figure 3 shows that the distribution of oaks by diameter class was somewhat similar in both areas, though the southern Sierra Nevada has a higher proportion of larger trees than Plots consisted of 10 points scattered Trinity County. over an acre. At each point trees were tallied and measured. Deductions were made for visible Oaks in California often are crooked, indicators of decay, missing and broken parts, forked, and sprawling, making them difficult and crook. Net volumes were calculated and to handle in conventional industrial processes. summarized by plot and area: Oaks in California's conifer stands often are rotten and broken, especially large old trees. Hardwood plots by cubic-foot-per-acre A number of wood-rotting fungi attack oak trees, Average conifer Average hardwood volume class including Arm¥i,ZZarimelted, PoZypoms dryophi'lus, volume in all volume in plots P. suzphweus, and Fomes upplanatus, and several Study area plots with hardwoods 1-449 500-99 1,000-t wound rot species of Pohjporns (Hepting 1971 - -- Cubic feet per acre -- Percent ------and McDonald 1969). Deductions in volume were Trinity 2,696 376 70 20 10 made only for visible indicators. Figure 4 Southern Sierra 2,442 497 62 33 5 shows the proportion of the 1,183 oak trees tallied in the two study areas by soundness categories. Defect was much greater than the 3 percent found by Pillsbury and Stephens In both study areas, nearly 60 percent of (1978) in oaks in California's central coast. the total oak volume was California black oak Their study included total wood volume, not (fig. 2). Canyon live oak and white oak made just bole volume, and contained no California up most of the balance. In Trinity County black oak. E CULL DUE TO DECAY gz AND BREAKAGE - ¤. TRINITY COUNTY -1 Cnm SOUTHERN SIERRA >0 .,...... s m .-en c .c 0

13-Calif. in- Interior White ok LiveOak Oak Figure 5--Percent of oak trees on commercial forest land in Trinity County and southern Sierra Nevada that were cull due to form 5.0- 10.9 11.0-20.9 21.0-28.9 29.0 + and cull and breakage. DIAMETER CLASS- INCHES

Figure 3--Percent of total net volume of oaks by diameter class, Trinity County, and Larger, older trees are more defective southern Sierra Nevada. than the younger, smaller trees. About 6 percent of the black oak trees in the 5.0- to 10.9-inch diameter class were cull because of decay, compared with 22 percent of 11.0- to 20.9-inch Won't make one 8-foot 100% Sound (no defect) log due to form trees and 50 percent of trees 29.0 inches and larger (fig. 6). Similar patterns held for

Less than 25% . . 25 PO-90%Sound sound due to -M, -18 decay and breakage CALIFORNIA BLACK OAK (Southern Sierra) &--A CALIFORNIA BLACK OAK (Trinity County)

69 O/O W CANYON LIVE OAK 2550 - Sound (Trinity County) Figure 4--Proportion of oak trees tallied in M CANYON LIVE OAK Trinity County and southern Sierra Nevada (Southern Colifornio) by soundness categories (basis: 1,183 trees). 0 - OREGON WHITE OAK (Trinity County)

In both Trinity County and the southern Sierra Nevada, California black oak was found to have a higher incidence of decay than other oak species. Figure 5, for example, shows that 23 percent of the black oak trees in the southern Sierra were cull- due to decay compared with 9 percent of the canyon live oak and 13 percent of the interior live oak. Because much of the decay was confined to butt sections of trees, inclusion of top and limb wood volume I I I as done by Pillsbury and Stephens would decrease 5.0-10.9 11.0-20.9 21.0-28.9 29.0+ the average proportion of defect. DIAMETER CLASS - INCHES

Figure 6--Percent of trees tallied in Trinity Cull trees are less than 25 percent sound, County and the southern Sierra Nevada that or won't make one 8-foot log. are cull due to decay and breakage. other oaks. Much of the defect seemed related California Department of Forestry. to logging wounds and fire scars. Because 1977. Production of California timber deductions were made only for visible indicators operators in 1976. State Forest Notes, of defect, these cull estimates are considered 6 p., illus. The Resources Agency, to be conservative. Decay indicators were: Sacramento, Calif. visible rot, hollows, breaks, and fungus sporophores. The following tabulation shows California, State of. percent of trees by diameter class with visible 1975. Administrative Code, Title 14--Forest decay indicators: Practice Rules, Sacramento, Calif. Diameter class Percent of trees with indicators Cost, Noel D. inches 1978. Aboveground volume of hardwoods in the mountain region of North Carolina. USDA For. Serv. Res. Note SE-266, 4 p. Southeast For. Exp. Stn., Asheville, N.C. Griffin, James R., and William B. Critchfield 1972. The distribution of forest trees in Discussion California. USDA For. Serv. Res. Pap. PSW-82, 114 p., maps. Pac. Southwest Oaks in California's commercial forests For. and Range Exp. Stn., Berkeley, Calif. are currently an underutilized resource, and they have been increasing. The oaks are Hepting, George H. valuable as wildlife habitat and important in 1971. Diseases of forest and shade trees of watershed protection. Their presence adds to the United States. USDA For. Serv. Ag. the unique character of California's forests. Hdbk. No. 386, 658 p. Washington, D.C. They are an essentially untapped resource for energy and other uses. Development of a use Hiserote, Bruce A., and James 0. Howard. for these species would have many positive 1978. California's forest industry, 1976. results, including an economical way to release USDA For. Serv. Resour. Bull. PNW-80, conifers from competition on extensive areas. 95 p., illus. Pac. Northwest For. and Any technology that is developed has to take Range Exp. Stn., Portland, Oreg. into account the defective nature of these trees. For example, oaks suitablefor lumber products McDonald, Philip M. usually must be fairly large, yet most large 1973. Cutting a young-growth, mixed conifer oak trees contain substantial amounts of cull. stand to California forest practice act Smaller oak trees could be suitable for fire- standards. USDA For. Serv. Res. Pap. wood and other uses for which the presence PSW-89, 16 p., illus. Pac. Southwest For. of decay or other defect would not be critical. and Range Exp. Stn., Berkeley, Calif. In some areas, oaks may promote the establish- ment and early survival and growth of conifers McDonald, Philip M. by creating a more favorable soil pH and 1969. Silvical characteristics of California sheltering them from the harsh summer sun. black oak. USDA For. Serv. Res. Pap. It may be possible to grow both oaks and PSW-53, 20 p., illus. Pac. Southwest For. conifers on the same piece of ground. Oaks and Range Exp. Stn., Berkeley, Calif. would be the nurse crop; they could be harvested when the conifers are large enough Pillsbury, Norman H., and Jeffrey A. Stephens. to make it on their own in the sun. Under 1978. Hardwood volume and weight tables for intensive management, undesirable features of California's central coast. Natural oak such as decay and crook could be minimized. Resources Management Dept., California Polytechnic State Univ., San Luis Obispo, Calif. 54 p., illus. LITERATURE CITED Pillsbury, Norman H. Bolsinger, Charles L. 1978. Hardwood stand density characteristics 1976. Timber resources of northern interior for central coast counties in California. California. USDA For. Serv. Resour. Bull. Natural Resources Management Dept., PNW-65, 75 p., illus. Pac. Northwest California Polytechnic State Univ., San For. and Range Exp. Stn., Portland, Oreg. Luis Obispo, Calif. 32 p., illus. Bolsinger, Charles L. USDA Forest Service. 1978. Forest area and timber resources of 1954. Forest statistics for California. USDA For. Serv. Resour. Bull. PNW-75, For. Serv. For. Survey Release No. 25, 71 p., illus. Pac. Northwest For. and 66 p., Calif. For. and Range Exp. Stn., Range Exp. Stn., Portland, Oreg. Berkeley, Calif. SCIENTIFIC AND COMMON NAMES OF TREES

Scientific name Common name

AZnus rubra Bong. red alder Arbutus menziesii Pursh madrone Lithocarpus densiflows (Hook. & Am.) Rehd. tanoak Quercus agrifolia Nee California live oak, coast live oak Q. chrysotepis Liebm. canyon live oak Q. douglasii Hook. & Arn. blue oak Q. garryana Doug1 Oregon white oak . 7/ Q. garryana var. brewerii (E~gelm.)Jeps- Brewer oak Q. garryana var. semota Jeps- Kaweah oak, shin oak Q. keZZoggii Newb . California black oak Q. Zobata Nee California white oak, valley oak Q. uislizenii A. DC. Interior live oak Pseudotsuga menziesii. (Mirb.) Franco Douglas-fir

'1-! From Griffin and Critchfield (1972) Silviculture and Management

California Black Oak in the Sierra Nevada1 TW

2/ John Tappeiner and Philip ~c~onald-

Abstract: Ecologically, California black oak is an import- ant species in mixed-conifer and ponderosa pine forests. The occurrence of this oak in these forests is reviewed in terms of site considerations, species composition and stand structure. Its response to fire and role as a nurse crop for conifers are discussed. This discussion, along with a brief summary of current research findings, leads to recommendations for manag- ing this oak for wildlife, wood and aesthetics in the Sierra Nevada. We envision growing pure black oak in groups which range from about 0.5 to 10 acres. On poorer sites this oak appears to be able to maintain itself, while on better sites treatment will be necessary to counteract the natural succession toward conifers.

INTRODUCTION

Recent interest in more intensive manage- a stand is managed. Stand management objec- ment of California black oak (Quercus kelloggii tives depend, in part, upon site productivity, Newb.) in the Sierra Nevada, especially for species composition, stand structure, and wildlife habitat, has stimulated development economic alternatives. In addition, prescrip- of preliminary management recommendations for tions must be developed on a stand-by-stand this species. These are based on McDonald's basis with careful regard to the ecological (1969, 1978) work, discussion with silvicultur- forces interacting on the stand. The recommen- ists throughout California, and field observa- dations that follow are intended to match the tions of both authors. It is our hope that ecology of this oak to management considerations. presenting these recommendations will lead to their discussion and improvement. They should California black oak is found in essential- be considered only as preliminary. ly three broad vegetative categories, and we feel that stand management will differ somewhat Any silvicultural prescription depends in each. Furthermore, these guidelines are upon the objectives and the products for which aimed not only at stands managed for wood pro- ducts, but also at those where wildlife and aesthetics are emphasized. - Presented at the Symposium on the Ecology, Before we present these recommendations, Management, and Utilization of California Oaks, background must be given to show their basis Claremont, California, June 26-28, 1979. and logic. This background will consist of a brief presentation on site productivity, species -2/ composition, and structure of California black Regional Silviculturist, Pacific Southwest oak stands, as well as this oak's role as a Region, Forest Service, U.S. Department of nurse crop for conifers, its response to fire, Agriculture, San Francisco, California 94111; and its reproduction from seed and sprouts. and Research Forester, Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Redding, Calif. 96001 California black oak is found in three part of the species' range. Where disturbance broad vegetation types: (1) conifer forest has been frequent, the black oak forest can be (Pacific ponderosa pine, Pacific ponderosa extensive, made up of a mosaic of even-aged piae--Douglas-fir, and Sierra Nevada mixed stands, or sometimes of two-aged stands with conifer), (2) California black oak, and (3) large scattered old-growth trees above and oak woodland-chaparral. more numerous young-growth trees below.

Recommendations for management of black oak in the conifer forest are presented in Black Oak as a Nurse Crop detail. We will only briefly mention manage- ment possibilities for this oak in the other On drier sites on south and west slopes types. with good soils, and at lower elevations, Cali- fornia black oak can be a nurse crop for conifer reproduction (Baker 1942, Tappeiner 1966). BACKGROUND Often there appears to be a positive relation- ship between oak shade and the occurrence of Site Productivity conifer seedlings, saplings, and poles on slopes otherwise occupied by bear-clover (Chamaeba^MX California black oak is found on a wide dofio&&a.} or other woody shrubs. Apparently range of sites. It grows vigorously on deep the conifers are not affected as much by the well-drained soils of loam or clay-loam texture oaks as they are by the less shade-tolerant and does well on sandy, gravelly, or stoney shrubs. Generally, regeneration under oaks is soils. Poorly drained soils, however, restrict a slow process, and 20 years or more are often downward root penetration and lead to its early necessary for the area to become stocked with demise. This oak is often found occupying the conifer seedlings. Even then, the presence poorer, harsher sites. However, its best de- of oak does not ensure adequate conifer velopment is on high sites~siteswhere the regeneration. conifers are more competitive and hence respon- sible for eventually reducing oak density. While oak shade favors natural regener- ation of conifers, it retards their later development. Ponderosa pine (P&t^A ponduo-ia.1 Stand Structure is relatively intolerant and the lower light levels under oak, along with competition from Vegetative associates are several species established oak roots, slows its growth. of conifers, other hardwoods, and woody shrubs. Seedlings often appear weak and spindly and Host conifers inherently grow taller than this are frequently damaged by the reproduction oak, and given enough time, will overtop it. weevil (C~~a!hocop~t^Ae-&oflk] . Douglas- liecause the oak cannot tolerate shade when fir ( Pbe-udotkuga rnw.~.iUi^-ii} , white fir (Abie.4 mature, it loses vigor and usually dies once COKCO~O'~.},and sugar pine (P&LL&-tonbeA.fccfl.naI overtopped. California black oak is favored grow much better in oak shade as seedlings by disturbance such as fire, which often kills and saplings. Their leaders and crowns, how- competitive vegetation, but only kills the oak ever, usually are damaged as they grow through back to ground line. It quickly sprouts, and the oak branches. Also, their tolerance if present in sufficient numbers, forms a closed decreases with age, and light levels under canopy. Thus, the purest stands of oak often oak may be somewhat low for their best develop- are found on poorer sites and in areas of heavy men t . past disturbance.

In natural young-growth ponderosa pine and Fire mixed-conifer stands, black oak is found as scattered individual trees and in small groups. California black oak is severely damaged Scattered trees are most common on better sites, by crown fires and unless mature, even by while groups generally occur on moderate sites relatively cool ground fires (McDonald 1969). on south slopes or in small draws and areas of Fire can kill the stem outright or cause rocky soil. Within the groups there usually feathering" along the stem from epicormic is not a wide range of age classes. In fact, branching. These branches are a serious because of sprout origin, most trees in a group lumber degrade, and in general are short-lived are of one age. New saplings or poles estab- on all but open-grown trees. Fire-damaged lished between disturbances generally are lacking. stems are especially susceptible to pathogens, which weaken the tree and result in windthrow On harsher sites, black oak stands tend and breakage. Therefore, fire must be used toward being pure, especially in the northern with caution, if at all, in managing saplings or older black oak trees. Mixed-oak and Reproduction by sprouting conifer stands in general may not be compatible with burning if good quality oak wood is an After cutting, black oak sprouts objective of stand management. vigorously from the root crown or the stump. It is possible that fire could be used to stimulate suppressed advance oak repro- Stumps should not be higher than duction and this possibility needs careful 8 inches (20 cm) in order to obtain study on several sites. Often, older oak sound, windf inn and reasonably seedlings, which are 0.5 to 2.0 feet (0.1 to straight sprouts. 0.6 m) tall and about 20 years old, grow under large oak trees in competition with tolerant Stool sprouts originate from tall conifer seedlings and saplings and various stumps caused by cutting or breakage shrubs. These oak seedlings are often repeat- of the tree. They are weakly attached edly browsed. Fire might reduce the vegetative to the stump and are peeled off easily competition and result in seedling-sprouts more by wind and snow. They also are prone vigorous and of better form than the seedlings. to heart rot introduced from the stump. Fire would kill the advance oak reproduction For these reasons they are undesirable back to ground line. The oak probably would and to be avoided. sprout from the root crown, often with only one stem, and quickly grow beyond browse height. Sprouts from the root crown grow about 2 feet (0.6 m) per year in clearcuttings and about 0.7 feet (0.2 m) per year Reproduction in shelterwood cuttings.

At present, foresters have had little In clearcuttings and burnsblack oak experience in outplanting black oak; therefore, stump sprouts will outgrow planted they must rely for the most part on natural or natural conifer seedlings for at regeneration, which is composed of advance least 15-20 years. Thus, planting reproduction and stump sprouts. McDonald these areas with conifers does not (1978) noted the following points with regard eliminate oak from the new stand. to regeneration:

Artificial regeneration Natural oak seedlings and advance reproduction Black oak can be established by artificial a. In young-growth stands, large seed regeneration if a good seedbed free of compet- crops occur every 5 to 6 years, and ing shrubs and trees is provided. Newly fallen seem to either be excellent or non- acorns should be gathered in the fall or spring, existent. Inclement weather and and outplanted when just beginning to germin- insect infestation often reduce seed ate. Pinned-down cone screens must be used crops greatly. for protection from rodents, especially squir- rels. With use of these techniques, on a high b. Height growth of new seedlings aver- site in north central California, survival ages only about 0.1 foot (3 cm) per after 10 years was 40 to 45 percent. Annual year, advance growth about 0.3 foot fertilization with 0.25 pound (0.1 kg) per (9 cm) per year for the first 5 seedling of 16-20-0 enhanced survival and growing seasons. height growth. Fertilized seedlings were 2.5 feet (0.8 m) tall after 5 years and over c. High mortality of acorns and newly three times taller than unfertilized seedlinfs. germinated seedlings is common. Protection from pocket gophers, and at specific locales in California protection from deer and d. Advance reproduction of black oak cattle, would aid in seedling establishment. often is quite plentiful, averaging 500 to 800 seedlings per acre (1200 Thus it appears that regeneration of to 2000lha) in mixed conifer and California black oak is most likely to be hardwood stands. successful with sprouts in clearcuttings. Seedling-sprouts, if plentiful, could enhance e. Tree form often is better if the tree stocking if burned or slashed and stimulated is from seed, rather than from sprouts. to a higher growth rate by so doing. Arti- ficial seeding has promise and this technique should improve with experience. Stand Density - Thinning Conifer Forest Type

To obtain the proper density and quality Black oak on poor sites on west and of black oak trees to increase stand produc- south slopes should be maintained in tivity, thinning often will be necessary. pure stands. It should be relatively Such treatment should promote good stem and easy to do so. On better sites, the crown development and even enhance the value species is subject to overtopping by of wildlife and aesthetics. Stump sprouts conifers and considerable stand man- can be thinned, beginning about 4 years after ipulation will be needed to maintain sprouting, but earlier thinning generally a constant proportion of groups of results in additional sprouting (McDonald well-developed oak trees. 1978). Thinning at an early age (4 to 8 years), has the advantage of smaller material to cut For practical management of mixed and less slash to dispose of, but this black oak-conifer stands, black oak practice should be used with caution because should be grown in pure groups with there is an indication that early thinning a range in size of about 0.5 to 10 may result in forked trees. And thinned acres (0.2 to 4 ha). In this manner, sprouts grow no faster than unthinned sprouts, treatments favoring oak can be applied at least for the first 10 years after to discrete parts of the stand. Be- thinning. cause the smaller groups generally are more common where the site is To produce well-formed trees with no loss higher and the larger groups are of stand increment, thinning of natural stands located where the site is lower, should be done when sprouts and seedlings are management will follow accordingly. 30 to 50 feet (9 to 15 m) tall or when the Large stands on poor sites probably stand exceeds 125 square feet of basal area should remain natural unless uses per acre (29 m /ha). On a high site in north are well defined. Groups of oak are central California, 60-year-old hardwood common in mixed-conifer stands, and stands thinned at 100 to 125 square feet of it should be necessary only to recog- basal area per acre (23 to 29 m /ha) tenta- nize and recommend for them in silvi- tively produced the most cubic volume for the cultural prescriptions; only occasion- first 8 years after thinning. On lower sites ally will special treatment be this residual level of growing stock could be necessary to establish new groups. too high and 80 to 100 square feet per acre Furthermore, managing oaks in groups (18 to 23 m /ha) might be more appropriate. will aid the orderly management (regeneration, release, logging, Where accessible, thinning can be done slash disposal) not only of the oak, for fuelwood, usually at no cost to the owner. but also of the surrounding conifers. In thinning and other stand tending, trees of seed origin should be favored as they usually The number of various-sized oak groups have good form. recommended for retention or creation in each compartment cannot be answered In the future, plantations from seed will here. It will depend on the use or be established at different spacings, and from mix of uses and their intensity, which them will come thinning schedules that will in turn is geared to management goals. maximize growth and value. Such schedules may differ from those for stands of sprout origin. If oak is to be used as a nurse crop It is likely that the thrifty, more fully- for conifers, its canopy density crowned plantation-grown trees so produced, must be regulated for best conifer will yield abundant acorns at a much earlier development. Need for periodic age than the narrow-crowned trees in the opening-up of the stand depends pri- dense sprout stands of today. marily on the tolerance and size of the conifers and the density of the oak canopy. RECOMMENDATIONS If used in stands with oaks in them, Following are preliminary recommendations fire should be very light and confined for management of California black oak in the to the ground surface. It must not three broad vegetative types defined earlier. be hot enough to damage oak stems They serve as a starting point; use them with and hence allow formation of heart caution. rot. Fire can possibly be used to stimulate height growth of oak advance reproduction. 6. Because of the slow growth rate of life species. Thus the forest manager is natural reproduction, oak regeneration faced with a number of manipulative possibil- should be accomplished mostly from ties for managing the different uses. root crown sprouts or from advance reproduction. Stumps should be lower The preliminary stocking and regeneration than 8 inches to avoid stool sprouting. recommendations listed above will probably apply to this type. To begin stand management 7. Thinning of oak should begin when stems both for mast and wood production, initial are 30 to 50 feet tall and obviously prescriptions could call for the removal of overcrowded. After thinning, basal poorly formed or damaged trees. Growth then areas of 100 to 125 square feet per would accrue on the better stems. The poor acre should be satisfactory for cubic quality trees could be sold for fuelwood. volume growth on good sites, with somewhat lower density on sites of lesser quality. The reduced stand Oak Woodland-Chaparral Type density brought about by thinning should create a more open stand with In this type California black oak is an a longer view and hence be more occasional associate on deep, well-drained pleasing aesthetically. soils. Here it generally is the dominant vegetation. It is often favored for shade, 8. Because the incidence of heart rot aesthetics, mast, and fuelwood in both sub- increases in stands over age 80, urban and rural settings. California black these stands are increasingly poor oak will reproduce by sprouts in this type risks. Yet acorn production increases and the material on vegetative reproduction after age 80. Thus, a compromise be- should apply. Beyond this, however, the tween wood and acorns may often be foregoing recommendations become increasingly necessary for multiple-use manage- questionable. Simply not enough information ment. At least two broad age classes is available to recommend them with any (0 to 80 and 81 to 120+ years) should certainty. be maintained for continuous mast production. LITERATURE CITED 9. In areas where oaks already are ag- gregated, artificial regeneration Baker, F. S. of conifers after fire or clearcutting 1942. Reproduction of ponderosa pine at does not preclude oak management. low elevations in the Sierra Nevada. Of course, the oak group and about J. Forestry 40:401-404. 20 feet (6.1 m) of buffer need not be planted. The oaks will sprout McDonald, P. M. and the sprouts will grow faster in 1969. Silvical characteristics of Cali- height than the conifers and thus be fornia black oak. USDA Forest Serv., competitive with them at least for Res. Paper PSW-53, 20 p. Pacific South- several decades. Trees from these west Forest and Range Exp. Stn., Berkeley, sprouts can be precomercially Calif. thinned along with the surrounding conifers and thus groups of oaks McDonald, P. M. will again be present in the mature 1978. Silviculture--ecology of three stand. native California hardwoods on high sites in north central California. Ph.D. Dis- sertation, Oregon State Univ., Corvallis, California Black Oak Type 309 p.

This type consists of nearly pure black Tappeiner, John C. 11. oak stands, some of which are quite extensive. 1966. Natural regeneration of Douglas-fir Without fire the stands will remain pure on on Blodgett Forest in the mixed conifer poor sites and probably slowly change to type in the Sierra Nevada of California. mixed oak-conifer stands on better sites. Ph.D. Dissertation, Univ. of California, The large number of trees and hence concen- Berkeley, 237 p. trated volume of wood could lead to develop- ment of an intensive program of stand manage- ment and utilization. Because many of these stands are found at low elevations, they form part of the important winter range for wild- An Approach to Managing California Black Oak and Hardwoods on a Deer Winter Range in Central California1

Donald Potter and Barbara Johnston 2/

Abstract: On the Stanislaus deer winter range, a method for determining stocking levels of California Black Oak (Quercus kelloggii) was developed. Mast needs for the deer herd and mast production per tree were first determined. The required number of oak trees per acre and percent of land to be occupied by oaks was calculated. A stand structure describing the distribution of the oak component in space and time was developed to achieve a desired balance between timber and deer production.

INTRODUCTION

The effects of timber management activities 1. Population objectives for the Stanislaus on the winter range of the Stanislaus deer herd herd. have long been a management concern. Past timber management activities stressed optimizing 2. A quantitative estimate of mast requirements growth and yield of commercial conifers. The for wintering deer. wildlife biologists' primary concern was the decrease in oaks with accompanying decreases in 3. A determination of oak basal area and stand acorns available to wintering deer. Guidelines structure needed over time to support the mast for California black oak (Quercus kelloggii) requirements. retention often were developed on a small pro- ject basis, without data to quantify the effects 4. A vegetative analysis of the winter range of such recommendations area-wide. Recent in order to identify how much and what kind of availability of acorn production data by tree land was needed to meet basal area requirements. size and age, and other silvicultural information For example, the oak requirement could be met on California black oak, has enabled biologists from combinations of marginal timber producing and foresters to estimate the oak basal area lands, isolated oak stands, stands in draws or required to support acorn production to meet the on poor soils, as well as from intensively needs of specific densities of deer. Using this managed timber lands where oak was one of the data, oak management guidelines to meet these managed species. This analysis was also nec- requirements can be developed. essary to measure present oak stocking levels in relationship to our objectives. Information was needed on the following topics to develop recommendations for an entire 5. An evaluation of the effect of meeting winter range: various oak retention levels on timber produc- tion.

-I/ Presented at the Symposium on Ecology, These interim oak management guidelines Management, and Utilization of California Oaks, were developed through field discussion with Claremont, California, June 26-28, 1979. foresters, silviculturists, and Forest Service and California Department of Fish and Game bi- -2/ Forest Silviculturist, and Forest Wildlife ologists. Although there are many other habitat Biologist, U.S. Forest Service, Stanislaus Na- elements which should be, and are being consider- tional Forest, 19777 Greenley Road, Sonora, ed in managing the Stanislaus herd, we are California 95370 addressing only the oak component on the winter MAST REQUIREMENTS FOR DEER AND OTHER CONSUMERS range in this presentation. Acorns in the total diet of wintering deer have been found to range from 11 percent STUDY AREA to 76 percent (Browning et al. 1973, Harlow et al. 1975). It is reasonable to assume acorns The winter ranee of the Stanislaus deer will constitute an average of SO percent of the herd (Odocoileus hemionus californicus) occupies October-through-December diet of deer in the about 143,000 acres (57,870 ha) in an area Sierra Nevada mountain range during good mast bounded onthe southby Highway 108 years (Barrett and Menke 3/, Goodrum and others between Sonora and Long Barn, on the north by 1971, Ashcraft A/). ~eerconsumeabout 5 pounds Highway 4 between Vallecito and Arnold, on the (2.3 kg) of food per day, of which 2.5 pounds west by the Parrott's Ferry road between (1.1 kg) are acorns. Vallecito and Sonora, and on the east by a line from Crandall Peak to Arnold. Approximately 45 Although deer management is of prime con- percent of the area is National Forest land. cern, mast requirements for other acorn users Elevations range from 800 feet (243 m) to nearly like valley and mountain quail (Lophortyx 5500 feet (1,676 m). Mean elevation is about californica and Oreortyx picta) and gray squir- 3200 feet (975 m). Vegetation types include rels (Sciurus griseus) also are considered. chaparral, oakwoodland, California black oak, The population objectives were set at 1 squir- ponderosa pine, and mixed conifer. Ponderosa rel per 2 acres (0.8 ha) and 1 quail per 5 acres pine (Pinus ponderosa) is the most abundant (2.0 ha) (Goodrum et al. 1971). The daily in- conifer species. Associated species include take of a gray squirrel is about 0.22 pounds canyon live oak (Quercus chrysolepis), buck (100 gms) of food (Hawkins 1937, Uhlig 1956); brush (Ceanothus cuneatus), deerbrush of a quail, 0.02 pounds (9 gms) of food (Ceanothus integerrimus), mariposa manzanita (Michael and others 1955). Asserson (1974) (Arctostaphylos mariposa), and toyon found acorns in the stomachs of gray squirrels (Heteromeles arbutifolia). Winter precipitation in California to range from a low of 9.6 percent falls both as rain and snow. A deep winter snow by volume in July to a high of 71.3 percent in pack generally does not develop, and southerly December with an average of 50.9 percent over slopes usually are open most of the winter. an eleven-month period. We are assuming acorns constitute about 50 percent of the diet of gray The area in which the guidelines were de- squirrels over a twelve-month period because veloped covers roughly 10 percent of the total of their acorn storage behavior,and about half winter range and is known as the Schaeffer com- the diet of quail over a three-month time span partment. Different guidelines were developed (Table 1). for southerly slopes. These slopes cover the quadrants from east through south to west and Because only 50 percent of the acorn crop receive the greatest amount of winter sun. Deer is likely to be sound and available to ground use is much more intensive on these slopes and consumers because of encapsulation, abortion, oaks are more abundant. North slopes cover and insect damage (Todd 1976, Barrett and Men- those quadrants between west through north to ke-),the 245 pounds (275 kg/ha) is arbitrarily east. North slopes receive much less deer use doubled to a requirement of 490 pounds per acre and have a higher conifer to oak' ratio. per year (549 kg/ha).

Black oak acorn production is cyclic at 2- POPULATION OBJECTIVES to 3-year intervals (Roy 1962). In intervening years acorn production often is low. In such Population objectives have not been estab- lished for the Stanislaus herd, because the California Department of Fish and Game has not -3/ Unpublished report (A review of the value yet completed its management plan. However, of hardwoods to wildlife in California with Fish and Game and U.S. Forest Service biologists recommendations for research). R. H. Barrett have developed an interim management objective and J.W. Menke, respectively, College of Natural on the winter range of 90 deer days use per acre Resources, Berkeley, and Department of Agronomy Der year on southerly facing slopes. Deer use and Range Science, Davis, University of Califor- has been measured as high as 90 deer days per nia.1976. acre by permanent transects in some areas in the Schaeffer compartment. -4/ Personal communication G.C. Ashcraft, California Department of Fish and Game, staff, December ,1978. deer squirrel auail total a. pounds of acornslday 2.5 0.1 0.01 freshweight 1 b. population objectives 1" 2 5 acres/animal

c. pounds of acorns required 90days 0.9 365days - d. pounds of acorns~acre~~earI225 20.1 0.18 245

J/ 90 deer days/acre/year also means 1 deerlacre for 90 days of use 40

-Table I--Estimated acorn requirements of deer, 110 squirrels and quail.

2 4 6 8 10 12 14 16 18 20 22

years, the diet of these and other acorn DBH - INCHES

consumers will shift to other food sources. TREES LESS THAN 80 YRS OLD TREES OLDER THAN 80 YRS Sometimes these are inadequate, as winter ' mortality is strongly correlated with years of AVERAGE 10 POUNDS OF I AVERAGE 60 POUNDS OF ACORNS ACORNS PER TREE PER TREE low acorn availability. I Once the mast requirements were estimated, No productive trees were sampled in the 26-inch and 30-inch d.b.h. classes. the next step was to determine the acorn pro- duction of oaks by age class to provide 490 pounds of acorns per acre. Data are extremely Figure I--Estimated number of pounds of fresh limited, although generalizations on expected California black oak acorns per tree per year mast production are available (U.S.F.S. 1969). as related to diameter at breast height. Perhaps the best data are from a study of Cal- ifornia black oaks by Graves (1977) on the Plumas and Tahoe National Forests in 1975 and of acorns needed by consumers. 1976 (fig.1). Black oaks do not produce large numbers of acorns until they are over 80 years First it was estimated that a 20-inch d.b.h. of age, and after 160 years, mast production open-grown tree would have a crown diameter of declines (McDonald 1969). Based on the above 36 feet (10.9 m)(U.S.F.S. 1969), and 8.2 open studies, a weighted average of 60 pounds (27.2 grown trees would occupy about 20 percent of Kg) acorns per tree was calculated for trees each acre. If an equivalent area was added to over 80 years old. provide for replacement of acorn producers by trees in the 0-80 year age class, then 40 per- cent of the area would be occupied by oak. STAND STRUCTURE TO MEET MAST REQUIREMENTS The second approach multiplied the basal The first step in developing the required area of a 20-inch d.b.h. tree by 8.2 trees to stand structure was to determine the amount of arrive at a basal area of 18 square feet per area that was to be occupied by oak. Acorn pro- acre (4.1 m2/ha) .needed in trees 80 years duction per tree was the starting point for this older (2.18 ft2/tree x 8.2 trees/ac.=18 ftmd /acre). determination. Because the Plumas-Tahoe study This figure was compared to the levels tenta- did not distinguish between acorn production of tively recommended or oak stands on above aver- open-grown trees and those grown in a closed age sites of 120 ft 5/acre (27.6 m 2 /ha) canopy, and because acorn production in this (Tappeiner and McDonald 1979) and found to be study was not correlated closely with size of about 15 percent. The assumption was then made tree, two different approaches were taken to that in a well-stocked oak stand older than 80 determine the basal area of oak needed. Both years, about 15 percent of the surface area methods relied on the observations that : (1) would be occupied by crowns. This figure was trees in the study area older than 80 years gen- doubled to provide for replacement by the 0-80 erally were 20 inches (54 cm) d.b.h. or larger year age class. The result was that 30% of the and (2) at 60 pounds of acorns per tree it would area would be occupied by oak. take 8.2 trees per acre to produce the 490 pounds Using these approaches then, the range On north slopes current Forest Service seemed to be 30-40 percent of the area would Region 5 guidelines for hardwood retention be occupied by oak, and this was established will be used. They specify 5 square feet of as a guideline. basal area per acre. If this is doubled to account for two age classes, it amounts to over 8 percent of a well-stocked oak stand SPATIAL ARRANGEMENTS for these sites. Individual trees or aggre- gations could be used on these slopes. The next step was to define an arrangement of oaks and conifers on the ground that could To maintain oaks in aggregations that be used for practical management purposes. consistently produce mast will require con- Oaks in association with conifers on the siderable effort. Better acorn production Stanislaus occur as single individuals, in data are needed by site, age, species, and pure aggregations of 0.1 to 1 acre (0.04 to 0.40 stocking density. For example, in the 1975 ha), or occasionally in small stands of 2 to 3 study of 110 black oaks on the Tahoe and Plumas acres (0.8 to 1.2 ha). Aggregations are small National Forest, 20 percent of the sample con- homogeneous units of oak in conifer stands. The sisted of non-acorn-producing oaks (Barrett main criterion used to identify oak aggregations and Menke 3/). Regeneration of California was at least 80 percent crown cover in oak. black oak by planting has never been seriously Canyon live oaks also occur in significant undertaken in California. If regeneration is number on the Stanislaus herd winter range. established either naturally or artifically, Where the two species occur together, both will protection of young seedlings from damage by be managed under these guidelines. deer will undoubtedly be necessary. Once young oak aggregations are established, thinning On south slopes oak occurs primarily as probably will be necessary to develop full- aggregations. It seemed reasonable to retain crowned mast producers. uniformly distributed oak aggregations because these aggregations are easily recognized on the ground by field crews, and because they are more IMPLEMENTATION OF GUIDELINES efficiently managed than single trees. Thus, the guidelines picture conifer-oak stands with a Four steps were followed for applying 30 to 40 percent oak component distributed as the oak guidelines to large units of the winter uniformly as possible in aggregations of 0.1 range. to 1 acre in size (fig. 2). The remaining area would be occupied by conifers. The oak aggre- Step 1. The angle of the winter sun was deter- gations should occur in roughly 2 age groups of mined and the slopes receiving the most winter 0 to 80 years and 80 to 160 years with a stocking sunlight, were identified on a topographic map. level of 18 square feet per acre in the 80 to 160 year age group. Step 2. An overlay showing the location and acreage- of accessible commercial timber lands was prepared. Those lands falling on southerly slopes were identified for 30-40% oak retention.

Step 3. Using aerial photos, an overlay of timber types was prepared. Stands were divided into ten acre grids and the oak component was shaded by 3 classes of 0 to 20 percent, 20 to SO percent and greater than 50 percent. This enabled us to ascertain the levels of oak stock- ing by stands, over the total compartment, relative to our stocking guidelines,and to se- lect specific stands for treatment on a priority basis.

DISCUSSION

This analysis would not be complete with- out discussing its effects on timber production. There are adequate predictions of conifer yields for ~aliforniaforest lands (Dunning and Reineke Figure 2--Area prepared for conifer plantation 1933). There is little doubt that conifer yields with black oak aggregations retained. will decrease using the proposed guidelines. However, using the management techniques devel- Graves, W.C. oped here and the existing timber yield data, 1977. The dependence of upland game on oak the impact of different deer population objec- mast production. California Department of tives can be evaluated by the land manager. Fish and Game progress report, project No. In this way, a desired balance between timber W-47-R-25, Job no. IV-1.4 21 pp. and deer production can be achieved where both resources occur in the same area. Harlow, R.F., J.B. Whelan, H.S. Crawford, and J.E. Skeen Oaks could yield a positive timber return 1975. Deer foods during years of oak mast in the near future. At present, oak is used abundance and scarcity. J. Wildl. Manage. primarily for fuel wood on the Stanislaus, and 39(2) : 330-336. it does not constitute a part of the regulated forest yield. Throughout the rest of the world Hawkins, A. S. this is not the case, where foresters look at 1937. Winter feeding at Faville Grove, yields of both conifers and hardwoods. Main- 1935-36. Am. Midland Naturalist l8(3) : taining oaks up to 160 years will likely produce 417-425. some high quality hardwood, and this would in- crease the value of the timber yield substantial- McDonald, P.M. 1969. Silvical characteristics of California ly. black oak (Quercus kelloggii Newb.) 2Opp. Quantification of deer population response U.S.D.A. Forest Service Research Paper-53, to various levels of oak retention is not Berkeley, Calif., Pacific SIV Forest and easily displayed for the decisionmaker. Al- Range Exp. Station. though deer numbers and acorn availability pro- bably do not form a direct linear relationship, Michael, V.C., and S.L. Beckwith we can safely assume that increased acorn yields 1955. Quail preference for seed of farm from managed oakstands will greatly increase the crops. J. Wildl. Manage. 19(2): 281-296. size, health, and stability of the Stanislaus deer herd. Tappeiner, J., and P.M. McDonald 1979. The silviculture of black oak (Quercus These guidelines were developed for a kelloggii) in the Sierra Nevada. Proceed- specific management problem on the Stanislaus ings of the symposium on the ecology and deer winter range. However, we feel the approach management of California oaks, Scripps can be applied to other vegetation complexes and College, Claremont. other wildlife species. Todd, P.H. 1976. Oak mast yields state-wide and on wild- REFERENCES CITED life management areas. Tenn. Wildlife Re- sources Agency, Tech. Report No. 76-5. 16 pp.

Asserson, W.C. I11 Uhlig, H.G. 1974. Western gray squirrel study in Kern 1956. The gray squirrel in West Virginia. County, California. California Dept. Fish West Virginia Conserv. Comm. Bull. 3, 83 pp. and Game, Wildlife Mgt. Branch Admin. Report 74-1. U.S. Forest Service 1969. The hospitable oak, coordination guide- Browning, B.R., W. Schulenberg and D. Brunetti lines for wildlife habitats, No. 3. 1973. The Railroad Flat deer herd. California California Region, 10 pp. Dept. Fish and Game, Wildlife Admin. Report NO. 73-1.

Dunning, D., and L.H. Reineke 1933. Preliminary yield tables for second growth stands in the California pine region. Technical Bulletin No. 354.

Goodrum, P.D., V.H. Reid, and C.E. Boyd 1971. Acorn yields, characteristics, and management criteria of oaks for wildlife. J. Wildl. Manage. 35(3): 520-453. Oak Management Harvest A: An Experimental Management and Utilization Project on Southern California Private Ownership1 lobata James E. Asher, A.C.F.-'2 1

Abstract: A large-acreage, corporate landowner has instituted a comprehensive, long-range, forest manage- ment program on its multiple-use wildlands under this Consulting Forester; the Plan ultimately includes bringing a sizeable mixed hardwood resource under management. In early 1979 we began: (1) a formal hardwood inventory of 7,680 acres (First Increment- Classification and Inventory), and (2) a 300-acre working "demonstration" oak management forest operation (Oak Management Harvest A) with all har- vested material to be utilized in the Ranch ongoing program.

INTRODUCTION Tejon Ranch consists of two hundred In 1975 Tejon Ranch Company agreed with seventy thousand acres forming the largest the Consulting Forester on the desirability contiguous Spanish land grant holdings in of long-range forest management whereby the California and is the setting for this report. forest and other resources could be improved. The Tejon Ranch Company, a farsighted land- The forest had the potential of contributing owner, is engaged in diversified agriculture, much more to the ongoing corporate picture and produces many crops ranging from cotton under planned utilization and not at the to pistachio nuts on its flat lowlands in the expense of the other natural resources and San Joaquin and Antelope Valleys, where the Ranch uses; in fact,sustaining forestry would elevation ranges from one hundred to three enhance all other values. thousand feet. Tejon Ranch contains working, non-renewable resources including oil and Softwood forest management, begun on a mineral leases and even a cement plant. A forest condition priority basis, soon made Tejon Ranch mainstay is its Livestock Division, evident the needs and the potentials of the historically running ten to fifteen thousand Ranch hardwood forest. Considerable acreage head of cattle on its ranges that go up to was found to support Upper Sonoran and Trans- 6,700 feet in elevation. Because of its ition life zone mixed oak stands. Densest awareness of renewable natural resources, the on northern exposures and on ridgetops above Tejon Ranch instituted wildlife management 4,000 feet is California black oak (Quercus over thirty years ago. Beneficial and profit- kello gii). Flats, ridgetops and some side- able controlled recreational hunting of deer, TT-^ills are forested with a "savannah" oak small game, and birds has helped to nurture forest composed mostly of blue oak ( ercus heavy and healthy game populations. douglasii) and California white oak f5is lobata). Scattered below 3,000 feet is interior live oak (Quercus wislizenii). Canyon live oak (Quercus ch m occurs Ñ~resenteat the Symposium on the Ecology, in dense stands on north slopes at middle and Management, and Utilization of California upper levels. Antelope-San Joaquin Divide Oaks, June 27, 1979, Claremont, California. ridge country, along the higher summits, contains approximately 15,000 acres of dense, -'consulting Forester, Lake Arrowhead, shrubby Brewer's oak (Quercus garryana var. California. breweri). Other hardwood species grow in resource is available on a continuing basis, selected arid to riparian sites, which include and (2) that the Tejon Ranch Company has a the chapparral representative scrub oak resource-oriented and long-range policy of (Quercus dumosa) . A hardwood forest inventory managed utilization of its assets, thus bye-delineated acreages is underway providing a potential of continuing sustained but incomplete. production of forest values including wood products. The selection of sample materials Initial hardwood forest management goals for the market search is deliberately varied, are (1) inventorying of the resource (which and consistently includes some materials of today presents many "unknowns"), and (2) the highest quality. It is felt that a tar- commencement of an experiment ("demonstration get of high per-unit monetary return must be forest") to (a) begin the development of obtained from the high-quality material to sound silviculture, and (b) determine the sustain a successful Program because the economic feasibilities. greater proportion of lesser quality products can and will be disposed of at lower profits. In keeping with the necessary sound 'Oak Management Harvest A" must show that oak corporate approach for such a long term forest management will pay for itself or the endeavor, the establishment of markets for concept cannot be considered feasible and be oak wood products to finance the management continued. Indications from one buyer are of oak woodlands is paramount. For the Tejon that a satisfactory recovery of high grade Ranch Company, until financially feasible lumber is possible provided that it is (1) markets are found and secured, no comprehensive milled properly for grade and at correct and forest management planning and activity is consistent dimension, and (2) is carefully practical (affordable). "Oak Management cured under exacting conditions (introducing Harvest A" is a start toward these initial some critical "unknowns"). This very pre- goals. The project is a test harvest and liminary reaction is encouraging though product manufacturing effort to develop indicative of the time and effort needed to techniques and establish their costs and to develop the project to feasibility. place various kinds of materials into poten- tial market channels; it is important also to Silviculture is being developed with put practical meaning into the evolving the input of several interested agencies such hardwood forest inventory. as the California Department of Forestry, the California Department of Fish and Game, Kern "Oak Management Harvest A" involved 300 County Fire Department. Thinning from below, acres of oak types within a 1,500-acre area aimed at a level of stocking control effec- in the Bear Trap Canyon section of Tejon tive in meeting the multiple-use guidelines Ranch. It was administered as a Tejon Ranch of Tejon Ranch natural resource management timber sale under standard controls and con- is being applied along with an "oak sanita- straints. A logging operator was contracted tion-salvage" approach. Crown dieback is the to harvest and mill a variety of species and principal indicator being used to rate "risk" products. A portable sawmill was installed oaks. A very light cut is resulting to date in the timber sale area which produced 30,000 in applying this prescription combination; bd. ft. of oak lumber (rough, green) grading compatible with the heavy Ranch emphasis on from Number three common (pallet stock) up continuing aesthetic value. through Number one common and better (furni- ture grades). Along with the lumber, 100,000 bd. ft. of logs, in variety, were prepared CONCLUSION for direct shipments. The attempt is being made to inject these materials into all "Oak Management Harvest A"; brought to possible markets across the United States and light several problems such as high harvesting, overseas. milling, and curkg costs; is in its comple- tion stage. A major problem is the slash and The expected market resistance is being debris accumulation; fuelwood contractors encountered with these "unproven" California have been brought in to accodplish cleanup on oaks; only long-standing traditional hardwood the Project. Evaluation of the results of supply sources are trusted. Meanwhile, we the silvicultural prescriptions is being done; are waiting for information from certain time will be needed, particularly to assess markets cooperating in testing the Tejon effects upon the regeneration problem. Cattle Ranch lumber and logs. and deer exclosures and other measures are to be installed on sample areas to further re- Key in gaining interest from and limited fine project effects. Market suitability of access to the cooperating hardwood consumers the oaks, the vital factor, has yet to be is (1) that a significant volume of oak interpreted and returned by the cooperating purchasers. Growth of Thinned and Unthinned Hardwood Stands in the Northern Sierra Nevada. . . Preliminary Findings1

Philip M. McDonald-2/

Abstract: Sixty-year-old stands of California black oak, tanoak, and Pacific padrone were thinned from a basal area of 198 ft /acre to 85 to 141 ft /acre, and their responses evaluated. Diameter growth of the three species doubled after 8 years and when averaged, increased from 0.46 to 0.98 inch. Larger trees and dominant trees grew best. Diameter growth of trees in clumps containing up to four members was equal to that of single stems of the same diameter. Average annual cu ic volume growth of thinned stands ranged from 66 to almost 89 ft5' /acre/year. Results are preliminary and any conclusions drawn from them are speculative.

INTRODUCTION These hardwood species are found growing singly, in small aggregations, or occasionally Among the hardwood tree species in Califor- covering an entire hillside. In many instances, nia,tanoak (Lithocarpus densiflorus / Hook. & they are the stepchildren of disturbance. Heavy Am:/ Rehd.) , California black oak (Quercus logging or fire reduces conifer competition and kelloggii Newb.), and Pacific madrone (Arbutus allows them to grow more freely. All have strong menziesii Pursh) show the most promise for sprouting ability and, even if killed above providing wood products, fuel, and fiber. In ground, usually remain viable below. Extensive northern and, to a lesser extent, central Cali- and rapidly-growing sprouts quickly occupy and fornia, these species are extensive and abundant. often take over disturbed areas. In 1975, volumes estimated for California wer about 2.55 billion board feet (14.5 million m 5 ) Because fire has been commonplace in the of California b 3ack oak, 1.97 billion board feet Sierra Nevada since the 18501s, nearly all hard- (11.2 million m ) of tan03 k, and 0.98 billion wood stands are of sprout oriqin. Some single board feet 5.5 million m ) of Pacific madrone trees show multiple centers when cut~presenting sawtimber.-3) evidence of former clumpiness. Because original stands often were dense to begin with, and ren- dered more so because of multiple sprouts, young- - Presented at the Symposium on the Ecology, growth stands also tend to be dense. Tree growth is slow and often decreases until mortality pro- Management, and Utilization of California Oaks. vides growing space for survivors. Claremont, California, June 26-28, 1979. Some landowners are asking questions on how - Research Forester, Pacific Southwest Forest to manage their hardwood resources. "What amount and Range Experiment Station, Forest Service, of yield can I expect," and "What is the best U.S. Department of Agriculture, Redding, Cali- spacing and thinning regime to maximize growth fornia. and yield" are the two questions most frequently asked. Little information is available, with - Personal communication from Charles L. almost none that quantifies the growth response to stand manipulation. Bolsinger, Forest Service, U.S. Department of Agriculture, Portland, Oregon, August 1978. This paper presents stand response infor- another. After the stand was marked to the mation. As such, it is an attempt to fill a prescribed basal area, crown thinning provided critical gap in the management of these species residual trees with "sky light" or room to of native California hardwoods. Results pro- expand. Straight, tall, thrifty, well-formed vided are tentative. They represent only a trees were favored (fig. 1). No more than four portion of a larger study, do not have enough stems per clump were allowed because additional duration to establish firm trends, and are not stems often were of poor form (fig. 2). Each statistically verified. They are presented to plot was surrounded with a buffer zone, 20 to show what is being attempted and to quantify 60 feet (6 to 18 m) wide, cut to its prescribed relationships to date. Any conclusions drawn basal area. from them are speculative and given only to provide an idea of "what might be." Local fuelwood cutters thinned the stand in return for the wood. Cutting rules required removal of all unmarked trees, stumps no higher THE STUDY than 8 inches (20 cm) above mean ground line, and the piling of slash. Utilization of the The setting for this study is the Challenge trees was to a 2-inch (5-cm) top. Experimental Forest, Yuba County, California, from 1968 to 1978. Here young-growth stands of In each growth plot, all leave trees larger California black oak, tanoak, and Pacific than 3.5 inches (9 cm) in diameter were numbered madrone are commonplace. The stands tend to be 2 inches (5 cm) above breast height. Tree even-aged, originating from sprouts after fire species, diameter, crown class, and clump den- or disturbance. In 1968, stand age was about 60 sity (one to four members per clump) were years. recorded annually. Diameter growth was calcu- lated first as basal area, averaged, and con- Site quality of the Experimental Forest is verted to a diameter basis. Cubic volumes to a high. Dominant California black oaks are about total top were taken from volume tables appli- 70 feet tall at age 60--indicating site index to cable to each species on high sites (McDonald be 60 at a reference age of 50 years (Powers 1978). Six plots with prescribed basal areas of 1972). The soil is deep and fertile, the mean 85 to 141 ft /acre 420 to 32 m /ha), and the annual temperature is 550 F (13 0 C), and precipi- control with 209 ft /acre (48 m /ha) had data tation averages 68 inches (1727 mm) per year. spanning 8 years (table 1). These plots are the basis for this report. The seven other growth To quantify the growth of individual plots were thinned at a later date and, there- species as well as that for mixed hardwood fore, had a shorter period of data collection. stands, 14 'È-acr (0.1-ha) circular plots w re Statistical analysis, however, was not possible established. They ranged from 60 to 150 ft5 / until sufficient data had accrued for all 14 acre of basal area. Somewhere within this range plots. would be a basal area that would balance the level of growing stock with the most efficient use of available resources, and therefore, RESULTS maximize growth. One plot was selected randomly as an uncut control. Prescribed basal areas Unthinned Stands were assigned randomly to the others. Data from the six %-acre growth plots and Lack of knowledge on hardwood growth control indicated that basal area of the un- response in general, and a probable need to thinned 60-year-old stang s ranged from 165 to establish a wide range of basal area levels, 230 ft /acre (38 to 53 m /ha). As a co5 posite each with several replications, suggested that stand, they averaged 198 ft /acre (46 m /ha) some form of replicated experimental design be and 659 stems per acre (1628 stems/ha) in the used. Lack of enough homogeneous area to estab- range of 2 to more than 16 inches (5 to more lish the large number of anticipated plots, than 41 cm) in diameter at breast height. however, plus difficulty in getting the stands Number of stems ranged from 832 to 416 per acre thinned at the same time, mandated that a dif- (2056 to 1028/ha) and were typical of unthinned ferent and, perhaps, more exploratory approach hardwood stands of these species in this area. be used. One plot for each prescribed basal Although these values indicate prethinning area was established. Statistical analysis of diversity, they also indicate that stands were growth response was to be by multiple regres- quite dense and growing slowly. To compare sion. thinned and unthinned stands, those that were thinned were combined and averaged to form a Marking guides were difficult to formulate. composite stand (plot). They are not strictly Leaning trees are common, particularly of Cali- combinable, however, and will be treated inde- fornia black oak, therefore, clumps can occupy pendently in future regression analyses. one piece of ground and their crowns influence For the composite plot, about 57 percent of cause of death. the total stems fell into the 4.1- to 8.0-inch (10- to 20-cm) diameter class, 27 percent into the 8.1- to 12.0-inch (21- to 31-cm) class, with Diameter Growth the remainder either larger or smaller. In terms of species composition, tanoak contributed Among species, tanoak had the best overall 63 percent of the total number of stems, Cali- diameter growth in both thinned plots and con- fornia black oak 23 percent, and Pacific madrone trol. Pacific madrone and California black oak the remaining 14 percent. The stands contained followed in decreasing order (table 2). As 3 about4090 ft or nearly 43 cords of wood per expected, large trees with wide crowns and large acre (274 m /ha) when utilized to a 2-inch (5- photosynthetic areas grew best. For example, cm) top. tanoak and California black oak more than 12 inches (30 cm) in diameter at breast height had the largest diameter increases for the 8-year Thinned Stands period. Small trees, however, responded mos relative to the control. In the 4.1- to 8.( An examination of cut stumps indicated inch (10- to 20-cm) diameter class, madrone that tree vigor generally had been poor. Trees trees in the thinned plots outgrew those in i averaged 12 to 15 growth rings per inch of control by more than three times; tanoak trees diameter (5 to 6 rings/cm) with the annual by more than two times. Overall, diameter growth rate in slow decline. growth of each species in the thinned plots was more than twice that of each species in the Thinning reduced the composite plot basal control. area by 41 percent and the number of stems per acre by nearly 70 percent. All stems less than When analyzed further by crown classes, 4 inches (10 cmj d.b.h. were eliminated and diameter growth in inches per tree, for 8 years, those in the 4.1- to 8-inch (11- to 20-cm) generally decreased as position in the stand class were reduced by 77 percent. Tanoak was declined (table 3). For all species, both in cut heavily and a more equitable mix of species thinned plots and control, dominant trees grew was achieved. best followed by codominant, intermediate, and suppressed. When diameter growth for all crown Thinning also increased the proportion of classes and species in thinned plots and control trees with more fully developed crowns. When was compared by t-test, it was found to be calculated as a percentage of the composite significantly better in the thinned plots (p = stand, the proportion of trees in the codom- -01) than in the control. inant crown class doubled; and in the dominant class, tripled. After thinning, trees in these The growth response to thinning of single two classes constituted 79 percent of all trees as compared with thinning of trees in trees. Also, average stand diameter was in- clumps needs to be evaluated. A forest manager creased by thinning, especially for tanoak and, needs to know whether or not leaving clumps of to a lesser extent, for California black oak trees will decrease total stand growth. and Pacific madrone. Diameter growth for single stems and clumps A total of almost 700 trees were removed having up to four members was determined for the from the growth plots. No heart rot was composite thinned stand and for the control observed in the stumps. Young-growth trees of (table 4). No trends in diameter growth by these species, either from seed or root crowns, species or by number of stems per clump devel- are usually free of this malady, at least in oped during the 8-year study. One reason for this area. the lack of trends was the wide range in di- ameter of stems within individual clumps. Mortality during the 8-year timespan was low in the thinned plots. One to five trees The relationship between original stem died in each plot--18 trees died altogether. diameters, number of stems in a clump, and stem The most common cause of death to tanoak and diameter growth was inconsistent. Growth of Pacific madrone apparently was disease (blight); individual members of two- and three-member for California black oak, suppression, and too clumps of tanoak and California black oak were much shade in the still too-dense plots often averaged for diameter growth each year for 8 led to mortality. Natural mortality during 8 years. For three-member California black oak years in the uncut control was 14 percent or clumps, the initially largest members grew more more than twice that of the thinned plots. slowly than other members at first, then at a Most of the trees that died in the control were medium rate, and were most rapidly adding girth small California black oaks less than 5 inches to their boles at the end of the study period (13 cm) d.b.h. Suppression was the prime (fin. 3). The initially smallest members of the Figure 1--Stands of California black oak, Figure 2--Tanoak clumps of sprout origin often tanoak, and Pacific madrone trees on the contain trees of both good and poor form. Challenge Experimental Forest tend to be even-aged, originating from sprouts after fire or disturbance.

Table I--Basal area of sample plots before and after thinning on the Challenge Experimental Forest

Basal area per acre

Plot before thinning after thinning Reduction -Ft2------Percent 1

2

3 5 6 7

Average

Control Table 2~Comparativediameter growth in thinned plots (T) and control (C) by species and diameter class during an 8-year study on the Challenge Experimental Forest

I 8-year diameter growth by diameter class 4.1 to 8.0 1 8.1 to 12.0 1 12.1 to 16.0 1 16.1 to 20.0 1 All sizes 1 I I I Species T C T C T C T C T C ...... Inches/tree ...... I/ Pacific - 0.58 0.15 0.83 0.48 1.09 1.02 0.87 0.40 madrone ------

California .SO .32 .80 .65 1.27 .74 -38 black oak ------All species .64 -33 .99 .69 1.25 1.13 1.25 ---- .98 .46

- Dashes indicate no trees present.

Table 3--Relationship of diameter growth to crown class in thinned plots and control for an 8-year study on the Challenge Experimental Forest

- --

8-year diameter

Thinned Species class Control --Inches tree--

Pacific madrone Dominant 1.00 0.87 Codominant ~90 -55 Intermediate - 521J .22 Suppressed ---- .12

Tanoak Dominant 1.32 1.23 Codominant 1.13 .67 Intermediate 1.13 .67 Suppressed ---- .29

California black oak Dominant -96 .60 Codominant -72 .35 Intermediate 36 .21 Suppressed ---- .10

Dashes indicate no trees present.

123 Table 4--Effect of clump density on diameter growth in composite thinned plot (T) and control (C) for an 8-year study on the Challenge Experimental Forest I 1 8-year diameter growth per stem when number of stems per clump was:

Species T C T C T C T C ...... Inches------

Pacific -I/ 0.89 0.36 0.65 0.58 0.20 0.40 madrone ------Tanoak 1 1.19 .78 1.20 .67 1.00 .42 1.25 .68 California black oak

Weighted average I - Dashes indicate no clumps present.

Table 5--Diameter growth by species and residual basal area during an 8-year study on the Challenge Experimental Forest 2 Eight-year diameter growth when basal area (ft /acre)was: I I I I I I Species 85 I 102 1 110 1 125 1 136 1 141 1 209 -Inches/tree------

Pacific -l/ madrone 0.7 --- 1.1 0.8 ------0.4

California black oak 1.1 1.0 .8 .8 .6 .6 3

Wei-nted average 1.2 1.3 1.1 - 9 .9 .7 .4 I Dashes indicate no trees present.

Table 6--Average annual and net cubic volume growth for all species combined by residual basal area, for 8-year period

2 Residual basal area level (Ft )

Thinned plots Control

Gross 66.3 87.6 77.2 88.8 70.3 77.6 81.8

Mortality 17.0 3.4 12.0 2.2 15.0 13.3 16.6

Net 49.3 84.2 65.2 86.6 55.3 64.3 65.2 -.64 -Initially largest --Initially median - .20 -.51 ----Initially smallest / - ?.. . A / : '. \

_c 3 .10 0 0 0 .05 J? i Q 0 Figure 3--Annual d.b.h. growth of .A2 I I I I I I .o 0 1 2 3 4 5 6 7 8 9 each member in California black Years after thinning oak clumps having three members.

-Initially largest --Initiallv median

Figure 4--Annual d.b.h. growth of each member in tanoak clumps having Years after thinning three members.

----California black oak -Tanoak

Figure 5--Annual trend of volume growth for California black oak 0 l I I I I I I I 1 lo 1968 1969 1970 1971 1972 1973 1974 1975 and tanoak in a stand cut to Year 141 ft2/acre of basal area. clumps grew rapidly at first, then moderately black oak, mostly because of less mortality. tinroughout. The initially medium-sized members Volume growth rate of tanoak appeared to be began with a modest diameter growth rate, fell steady or increasing slightly. behind, and then increased. For at least 1 year, however, they outgrew the other clump members. For three-member tanoak clumps, the DISCUSSION AND CONCLUSIONS initially largest members generally grew fastest, and the initially smallest members Limited data and one researcher's subjec- grew slowest (fig. 4). The initially medium- tive thoughts on the biological response of sized members indicated a wide range in annual tanoak, California black oak, and Pacific growth rate--best for 3 years, poorest for 1, madrone to manipulation are the basis for the and intermediate for 4. statements that follow.

For two-member California black oak and Each of these species occupies a specific tanoak clumps, the initially largest stems niche in the forest and each responds differ- generally outgew the smallest. Differences in ently to the biological and climatic forces annual growth rates between the two members, operating there. Tanoak grows fairly well in minimal throughout the study, were even less shady uncut stands and small trees respond well during the eighth year than the first. A in terms of diameter growth when thinned. similar analysis was done for four-member California black oak needs more sunlight. clumps. Results from this analysis are not Smaller trees grow poorly in the natural stand given because the number of clumps of this size andalm st as poorl9:in stands thinned to 130 or was small. Average diameter growth of indi- more ft9 /acre (30 m /ha) of basal area. vidual stems in four-member clumps, however, was no less than that for single trees of Tanoak, California black oak, and Pacific comparable size. madrone respond to thinning. Relative to trees in the unthinned control they doubled in di- Analysis of diameter growth for 8 years, ameter growth. For tanoak, indications are by residual basal area density, indicated that growth will stay the same or accelerate in species and stand response to thinning (table the years ahead. For California black oak, an 5). For tanoak, diameter growth ranged from increased growth rate is not certain. T ees in 2 1.0 to 1.6 inches (2.5 to 4.0 cm) per tree, for stand densities above 125 ft /acre (29 m 5 /ha) Pacific madrone 0.7 to 1.1 inches (1.6 to 2.8 seem to be declining. cm). Diameter growth of California black oak ranged from 0.6 to 1.1 inches (1.5 to 2.8 cm) The thinning trial was not replicated, but per tree and was progressively lower as resid- indicates cert in trends. Stands thinned at 2 ual basal area density increased. 102 and 125 ft5 /acre (23 and 29 m /ha) grew the mo t in cubic volume. At basal areas above 125 Another means of evaluating stand response ft3 stands have too many stems, a more shady to manipulation is by quantifying cubic volume environment and less available moisture--all of growth. For thinned plots and control, gross which could inhibit the vigor of California cubic volume growth for all species ranged from black oak. Below 102 ft /acre of basal area, a out 66 to almost 89 ft /acre/yr (4.6 to 6.2 stands were too open and seemed to be too warm m 9/ha/yr) (table 6). Natural mortality reduced for tanoak and Pacific madrone. Higher mor-2 average annual or gross growth from 2 to 22 tality in stands below 102 and above 125 ft / percent. Stand densities of 85 and 209 ft /acre acre, therefore, seems likely. (19 and 48 m /ha) suffered the highest mortality. Net g owth from the stands hinned to 102 Because diameter growth of California and 125 ft5 /acre was about 85 ft5 /acre (6 black oak seemed to be decli ing wh '5 n basal m /ha) each year. This is not a bad growth area density exceeded 125 fts (29 m ), analysis rate in its own right. If it consisted of of data from a representative plot examined quality wood from pruned trees, such stands this trend more closely. On the basis of 2 could be economically competitive with conifers. available information, the plot having 141 ft And because these hardwoods in characteristi- (32 m ) of basal area was considered to be cally dense stands prune naturally, pruning representative, recognizing tinat it may or may costs should be low. not be typical. The finding that California black oak and The trend of net cubic volume growth tanoak grow about equally whether as single during the 8 years indicated wide variation in trees or in clumps of two to four stems, at growth rate, and for California black oak, a least for the age of tree in this study, has generally declining growth trend (fig. 5). significance for the forester. It could mean Large declines in rate often resulted from that no penalty of decreased growth will result mortality. Tanoak showed less variation than from leaving clumps of well-formed stems (fig. Figure 7--Young-growth hardwood stands in north- central California yield a large volume of wood for product and energy use. Yield is almost 4090 ft3/acre or 43 cords per acre (274 m3/ha). Figure 6--Diameter growth of each member of this thinned clump will be about equal to that of four single trees of comparable size.

6) for possibly up to 70- to 80-year rotations. management guidelines specific to native Cali- Because two to four well-formed members per fornia hardwoods will need to be developed. tanoak and California black oak clump are commonplace in natural stands, foresters are The one sure conclusion at present is that free to leave them, if they wish. we are clarifying what we need to know. Much work, more studies, and more data are necessary For years, foresters have known that before firm guidelines for maximizing growth mixed-hardwood stands in the north-central from native California hardwoods will be avail- Sierra Nevada contained numerous stems. Perhaps able. they did not realize how muc wood these stands represented. Almost 4090 ft9 or 43 cords per acre (274 m /ha) is a lot of wood (fig. 7). LITERATURE CITED Little of it is rotton. Nearly all trees in the study area originate from root crowns. McDonald, Philip M. These structures apparently reduce greatly the 1978. Silviculture-ecology of three native incidence of heart rot bridging from rotting California hardwoods on high sites in north stump to pith of sprouts. central California. Ph.D. Dissertation. Oregon State University, Corvallis. 309 p. These early results indicate that the three species of native California hardwoods Powers, Robert F. studied are rather unusual. They often grow in 1972. Site index curves for unmanaged stands clumps, growth of 55- to 65-year-old trees is of California black oak. USDA Forest Serv. spread adequately over two to four members in Res. Note PSW-262, 5 p., illus. Pacific each clump, and response to release by thinning Southwest Forest and Range Exp. Stn., is variable. Such findings probably mean that Berkeley, Calif. Quercus Radial Growth of California Black Oak in the San kelloggii Bernardino Mountains1

Barbara Gemmill-2 I

Abstract: Hypotheses concerning growth of California black oak in the San Bernardino mountains were tested. Black oaks were found to grow radially in a slightly asymmetrical manner. Number of stems per clump decreased with age. Diameter of the largest stem and average radial growth for the previous 60 years increased with number of stems. Growth curves representing expected radial growth of black oaks in the San Bemardino mountains are presented. Possible air ~ollutioneffects on black oak radial growth are discussed.

INTRODUCTION

Oxidant air pollutants from the Los (Quercus ke'Ltogii Newb.), also exhibits Angeles Basin have been affecting the conif- symptoms of ozone damage, although not as erous forests of the San Bernardino mountains severely as the conifer species. The radial to a significant degree since World War 11. growth of five coniferous species and Cali- Symptoms of severe ozone damage to several fornia black oak with regard to air pollution conifer forest species have been noted. The in the San Bernardino mountains is currently chlorotic condition of the foliage and rate of being investigated as part of the Environ- needle shedding have suggested that a reduction mental Protection AgencyISan Bernardino in growth may be a consequence of high oxidant National Forest (EPAISBNF) Ecosystem Project. doses (McBride, Semion and Miller, 1975). A A preliminary analysis of the black oak portion hardwood associate, California black oak of the study is reported here.

The impact of photochemical oxidants on black oak radial growth is unknown. In order Ñ1~resente at the Symposium on the Ecology, to assess the magnitude of the likely growth Management and Utilization of California Oaks, depression brought about by air pollution, Claremont, California, June 26-28, 1979. more information is needed initially to portray the expected growth of a typical black ÑIProjec Leader, Tree Growth Study, EPAISBNF oak in the San Bernardino population of Ecosystem Project. Author's address: Univer- California black oak. In this analysis, I sity of California, Division of Biological have tested several suggestions and observa- Control, 1050 San Pablo Avenue, Albany, tions found in the literature relating to California 94706. black oak growth. It is important to note that since mostpublished information on ?This investigation was supported by EPA black oak growth consists of observations and Grant No. R805410-03. This report has been not data, my hypotheses are based on conjecture. reviewed by the Corvallis Environmental Research Where observations only suggested certain Laboratory, U.S. Environmental Protection relations, I have taken the liberty of Agency, and approved for publication. Approval proposing quantitative comparisons for the does not signify that the contents necessarily purpose of testing their possible validity. reflect the views and policies of the U.S. Also, the analysis is specific to the San Environmental Protection Agency, nor does Bernardino mountains and cannot be projected mention of trade names or commerical products to California black oak populations in constitute endorsement or recommendation for general at our given state of knowledge. use. Hypotheses to be tested include: (1) Two cores taken from opposite sides (7) The shape of generalized radial growth of a tree are proportional represent -----curve for black oak will according to site growth. Standard procedure in the dendro- factors, with variance seen in both the chronology field is to utilize two cores from location of the peak and the average growth opposite sides of a tree, perpendicular to the rate. direction of slope to avoid reaction wood (Fritts, 1976). The intention is to minimize The intention of this preliminary analysis variance in order to derive a single value is to establish which factors relate directly representative of radial growth. This pro- to the prediction of radial growth. The data cedure applies to all tree species. It is of used for this portion of the analysis should interest to know whether or not two cores be free from effects of air pollution. At taken by this method adequately represent the end of this paper, a discussion of air growth, given the often asymmetrical growth pollution effects on oak radial growth will be habit of an oak stem. presented, in light of information developed about expected black oak growth in the San (2) Growth rate of the main stem in 5 Bernardino mountains. multi-stemmed decreases increasing number of stems per clump. McDonald (1969) states that the number of sprouts per clump MATERIALS AND METHODS influences growth. For the purpose of this analysis, we will assume a negative influence. Black oaks were examined on six vegetation Each stem in a clump may be expected to have plots forming a portion of the study area of growth rates slower than a comparable single- the EPAISBNFEcosystem Project. All plots stemmed tree, and proportional to number of occurred within the conifer forest zone stems. As a corollary to this, (Horton, 1960) and were dominated by either Ponderosa pine (Pinus ponderosa Laws) or (3) Diameter of the main stem decreases Jeffrey pine (Pinus g'effreyi Grev. and Balf.). with increasing number of stems per clump. Species composition of the forest overstory is listed in Table 1. Plots varied in length (4) Tree height increases as number of from 100 to 300 meters, with uniform widths of stems per clump increases. Somewhat contra- 30 meters, and were located on variable slopes dictory to the above statement, Edwards (1957) and aspects. Plots extended in length until noted that stumps of large trees often produce 80 Ponderosa or Jeffrey pine of dbh greater than many stems of equal dominance along with other 10 cm were included. Site characteristics stems of lower importance. HcDonald (1969) and location of the plots are described in also found that sprout number and vigor in- Table 2 and Figure 1 respectively. The first creased as cut stump diameter increased up to four plots form a transect from the Crestline 20 inches, and that the many-stemmed clumps area (high pollution levels, low elevation, tended to grow the most vigorously. Vigorous relatively high precipitation) to Green growth and dominance, in both of these Valley (lower pollution, higher and drier). observations, probably refers to height. Both The last two plots form part of a similar of these examples refer to young (i.e. 4-yr- transect in the Barton Flats area. old) sprouts. However, since height is an important variable in competitive interactions, In the late summer of 1977, black oaks it is worthwhile to test whether this relation- greater than 10 cm dbh (diameter at breast ship is maintained among mature trees. height) on the six study plots were cored with a Swedish increment borer. Two cores (5) Number of stems per clump decreases were taken at a height of 1.5 m on opposite ~itJ9~ pf the clone. NcDonald (1969) found sides of each tree through a diameter running the number of sprouts per clump to decrease perpendicular to the direction of slope. The exponentially with age, from approximately 4 cores were returned to the laboratory, dried sprouts at age 20 to 2 at age 80 and 1 at age and mounted in wooden holders with the vessel 120, based on observations of black oak growing elements running vertically. Sanding tended throughout California. to clog the pores with sawdust and reduce visibility; consequently, cores were surfaced (6) Number of stems per clump increases with a razor blade. Cores were aged and with decreasing site quality. While initial growth rings were measured to the nearest numbers of sprouts may be related to size and 0.01 mm back to and including the year 1920, vigor of the parent tree, greater sprout using a Henson dendrochronometer. retention and more stems per clump at a given age have been observed on poorer sites (McDonald, Data utilized from other portions of the 1969). EPAISBNF study include: height, diameter and number of stems. Site indices for black oak Table I--Percent species composition of the study plots

Breezy Camp Deer Green Valley Schneider Camp Point 0-ongo Lick Creek Creek Osecola I Quercus ke l'tog'ii Libocedrus

ponderosa Qzlercus chpyso lepsis Pinus lambert'ianu Abies concolor

Table 2--Site characteristics of the study plots

Breezy Camp Deer Green Valley Schneider Camp Point 0-ongo Lick Creek Creek Osecola

No. trees 115 121 160 228 155 147 Density, treesiacre 155 96 108 102 86 124 Slope, percent 20 25 <5 30 20-45 <5 Aspect N,Nw N - W N - Elevation, feet 5000 6300 6300 6400 6000 7000 Average poten- tial soil rooting depth, m 4.75 4.31 1.09 3.74 7.16 5.64

Figure 1--Location of the study plots in the Sun Bernardino mountains (BP = Breezy Point, COO = Camp 0-ongo, DL = Deer Lick, GVC = Green Valley Creek, SCR = Schneider Creek, CAO = Camp OsceoZa) were calculated using the procedure of Powers correlation. Trees with crooked and leaning (1972), in which actual height is compared growth habits also tended to have weaker with expected height at a given age to evaluate correlations. growth potential of the site.

Ring widths corresponding to the same Predictors of Number of Stems, year on cores taken from opposite sides of the Radial Growth and Tree Height same tree were correlated using the Pearson correlation procedure (Nie, et al., 1975). For purposes of testing hypotheses 2-6 Age at breast height, height, diameter, average as outlined in the introduction, number of radial growth and site index were analyzed stems were regressed against other descriptive individually and in combinations against variables of diameter, height, site index, number of stems, by analysis of variance and average radial growth and age at breast height multiple regression procedures. A generalized Additionally, two other dependent variables growth curve was derived for each separate namely average radial growth and tree height plot by calculating the age at breast height were regressed against the remaining inde- of the tree at the time each growth ring was pendent variables. Results of the regression formed, and combining ring widths for each are indicated in Table 4. A breakdown of the age from year 0 to the oldest age of any tree data into charts is presented in Figure 2. on the plot. In the San Bernardino mountains, increasing number of stems correlate positively to the RESULTS AND DISCUSSION diameter of the largest stem and the average radial growth rate. Number of stems does Radial Growth Within Trees appear to decrease with increasing age, although the relationship is not strong. Average correlation coefficients per plot between cores taken from opposite sides of the The apparent increase in diameter and same tree are presented in Table 3. growth rate with number of stems, which is contrary to hypothesized results, appears to Table 3~Averagecorrelation coefficients, result from a third relationship: that number derived by comparing ring growth in sample of stems, in this area, increase with site cores taken from the opposite sides of a quality. Such an increase may well be due to single black oak. the younger ages of all trees in plots with high site indices, having no older trees to Average provide controls for age. However, even within one plot, i.e. Camp 0-ongo, average Plot name growth rates and diameter of the main stem Breezy Point increase with number of stems up to 4 stems per clump. Perhaps these data affirm Camp 0-ongo 38 .686 McDonald's (1968) observations that stumps 1 from larger trees produce both a larger number Deer Lick .428 of sprouts and more vigorous ones. In general, hypotheses relating diameter and site quality l5 I to number of stems can neither be upheld nor Green Valley Creek .694 I rejected with a large degree of certainty. Schneider Creek ,578 However, the fact that the poor sites had almost exclusively single-stemmed trees casts 27 I doubt on the statement that, for this area, Camp Osceola 7 .490 Average of all trees 1 104 .602 sprout retention is increased on poorer sites. The correlation is less than could be Age, diameter of the main stem, tree expected in arid-site conifers (Fritts, 1976) height, site index and average radial growth and suggests that two cores, while they may for the previous 60 years are all significantly still provide an estimate of growth, are not related to number of stems per clump, age consistently proportional to one another. In negatively and the remainder positively. general, most trees correlated fairly well Average radial growth has very strong cor- between cores, with a few extremely poor cor- relations with height, age and site index, relations bringing averages down. Poorest while height has a strong correlation with correlations were found among the older trees diameter. From this analysis, number of stems with very thin growth rings of all the same does not appear to be highly important predictor general magnitude; small variances in such of average radial growth, although a significant small rings will contribute to a poor relationship exists. Within a tree, many other relationships are stronger and more consistent. 1/ Table 4--Calculated f-values for each variable- , all plots

dependent independent direction of variable variable correlation f -value significance number of stems average diameter, per clump all stems average radial growth, previous 10 years age and average radial growth age diameter, main stem height site index average radial growth, previous 60 years average radial diameter, main stem growth, previous height 60 years age site index and age site index height age -- .47 -- diameter, main stem + 66.76 +++ ,A1111 variables refer to measurements on largest stem in the clump, unless otherwise noted. -" +significant at P = 0.10 level ++significant at P = 0.05 level +++significant at P = 0.01 level SITE HEIGHT DIAMETER AGE CLASS CLASS CLASS CLASS NUMBER OF I STEMS

AVG RADIAL1. GROWTH 2. (previous 60 years) m

Age classes: 1- 0 years through 60 years; 2- 61 years through 80 years; 3- 81 years through 100 years; 4- 101 years through 120 years; 5- 121 years through 140 years; 6- 140 years and above. --Site classes: 1- 0.0 site index value through 20.0 site index value; 2- 20.1 site index value through 30.0 site index value;3- 30.1 site index value through 40.0 site index value; 4- 40.0 site index value and above. Height classes: 1- 0.0 meters through 10.0 meters; 2- 10.1 meters through 15.0 meters; 3- 15.1 meters through 20.0 meters; 4- 20.1 meters and above. --Diameter classes: 1- 0.0 cm d.b.h. through 20.0 cm d.b.h.; 2- 20.1 cm d.b.h. through 30.0 cm d.b.h.; 3- 30.1 cm d.b.h. through 40.0 cm d.b.h.; 4- 40.1 cm d.b.h. through 50.0 cm d.b.h.; 5- 50.1 cm d.b.h. and above.

Figure 2--Breakdown of data into variable classes, all plots. The average value of tbso dependent variables corresponding to classes of the independent variable is presented. Expected Radial Growth Curves area especially in late summer (see Miller, these proceedings). Other oak defoliation Curves representing typical radial growth studies, generally concerning eastern North of black oak within each of the study plots American oaks, have noted that the degree of are presented in Figures 3-4. Since data growth reduction due to defoliation depends from different calendar years have been pooled on the extent, season and frequency with in deriving the curves, responses relating to which the defoliation takes place. Rexrode environmental variables such as yearly fluctu- (1971) noted that severe injury in one year ations in precipitation, temperature and air reduced wood production, while successive pollution are assumed to balance out, while annual defoliations led to branch dying and the expression of long-term site conditions tree mortality. Nichols (1968) found that (i.e., soil factors, gradients of average one year of moderate defoliation may reduce annual precipitation) remain. radial growth 20 to 30 percent, while one year of heavy defoliation may cause a growth Most notable features of these growth reduction of 40 to 70 percent. Two consecutive curves are the large early radial growth of years of 60 to 100 percent spring defoliation oaks on higher average rainfall sites (5.e. caused mortality. In contrast, Baker (1941) Breezy Point and Camp 0-ongo), and the small found that growth increment among oaks 81 to but consistent radial growth of old oaks on 100 percent defoliated was reduced only one- all sites. half of normal.

Air pollution defoliates black oak only Air Pollution Effects moderately, and chiefly in the late summer, on Radial Growth rather than during periods of rapid spring growth. Being deciduous there are no direct Air pollution may be thought of essen- carryover effects on the foliage from one tially as a defoliator, reducing viable leaf year to the next. However, it is conceivable

0.5

1 1 1 1 1 1 1 1 1 1 0.0 1 1 1 1 1 1 1 1 1 1 0.0 30 30 00 00 120 150 00 m 120 ISO AGE AGE Figure 3--Typical radial grouth curves for Figure 4-- Typiaal ¥radiagrouth curves for California black oak on two plots on the California black oak on four plots on dry moist end of a precipitation gradient in locations along a precipitation gradient the San Bernardino mountains. in the San Bemardino mountains. that air pollution may have a significant SUMMARY AND CONCLUSIONS impact on height growth of damaged oaks, since most of the height growth depends on The following discussion pertains solely carbohydrates produced and stored at the end to black oak in specific locales in the San of the summer. In contrast, the effect on Bernardino mountains. There is no data to radial growth of an oak exhibiting smog-damaged verify whether the San Bernardino population leaves might be hypothesized as one of a does or does not significantly differ from moderate growth diminution. Whereas conifers black oak populations elsewhere. may be greatly weakened and susceptible to mortality after a series of poor growth years, Two increment cores per tree may be oak species have the unique characteristic of adequate to describe radial growth of black being able to survive for extended periods at oak only when old and leaning trees are extremely small radial growth rates, and still excluded. Study trees should be selected for respond quickly to improved conditions relatively straight growth habits, and caution (Gingrich, 1971). At some point, however, should be exercised in deriving conclusions sustained damage must reach a point that from year to year variation in very old trees. exceeds even the resilient capabilities of the oaks. Figure 5 graphs the actual radial Increasing number of stems per clump does growth curves from two trees of the same age not appear to dampen radial growth rates, from the Camp 0-ongo plot, which experiences although the nature of the competitive severe oxidant doses. Both trees withstood a relationship between stems in a clump deserves period of drought in the late 194O7s, prior more study, particularly in relation to site to the presence of air pollution. Within the factors. Site factors and age are the smog period from approximately 1950 to the strongest determinants of radial growth. The present, one tree (#834) appears to have effect of age, or growth stage of the tree suffered little air pollution injury, while should be controlled for or removed before the other (#882) is in obvious decline. Leaf it is possible to compare radial growth rates injury ratings obtained from 1974 to 1978 between trees. The present analysis indicates (see Miller's contribution, these proceedings) that diameter cannot effectively replace age suggest that these trees are showing two in predictive equations for radial growth, extremes of responses to air pollution. At for obvious reasons. A tree may be small in present, the internal and external factors diameter either because it is young, in which responsible for the apparent differential case it is in its most rapid period of growth, response in radial growth is unknown. The or because it is growing very slowly. Height remainder of the Tree Growth Project's work and diameter should be modelled as the inter- with black oak will be designed to identify related results of the trees' internal growth and quantify these factors contributing to dynamics, with at least one important feedback these two different responses. Additionally, being that radial growth correlates possitively the magnitude of each response throughout the to height. San Bernardino mountains will be assessed. The site index utilized here to summarize TREE NO. 834 site factors is useful as an initial approxi- AVG. LEAF INJURY SCORE-7.6 mation to the importance of site. However, it merges together an assortment of diverse environmental features, such as the precipi-

AVG. LEAF INJURY SCORE-2 tation and temperature regime, stand density, and past history. The identification of site qualities contributing to growth differences needs considerably more analysis before radial growth can be described quantitatively.

California black oaks in the San Bernar- l ~ l l l ll,li, l I 10-40 Itso ID60 1070 Ism din0 mountains experience a rapid flush of YEAR radial growth as young trees, reaching growth Figure 5--Actual growth curves of tuo eqd- rates up to 3 mm per year within the first 25 aged black oaks on the Camp 0-ongo plot. years on the better sites. After 50 years of age, growth fluctuates closely around a much lower rate, also depending on site.

Although black oak may be expected to respond less severely to air pollution damage than coniferous species, damage is visible in the radial growth patterns of some individuals. Assessment of this damage awaits the identi- McBride, J. R., V. Semion, and P. R. Miller. fication and quantification of external and in- 1975. Impact of air pollution on the growth ternal factors, as mentioned above. of ponderosa pine. Cal. Agr. 29(12): 8-10.

McDonald, P. M. LITERATURE CITED 1969. Silvical characteristics of California black oak. USDA Forest Serv. Res. Paper Baker, W. L. PSW-53, 20 p. Pacific Southwest Forest and 1941. Effect of gypsy moth defoliation on Range Exp. Stn., Berkeley, CA. certain forest trees. J. For. 39: 1017-1022. Nichols, J. 0. Edwards, M. B. 1968. Oak mortality in Pennsylvania. 1957. California black oak - its management J. For. 66: 681-694. and economic possibilities. J. For. 55: 506-510. Nie, N. H., C. H. Hull, J. G. Jenkins, K. Steinbrenner, and D. H. Bent. Fritts, H. C. 1975. SPSS. 675 p. McGraw Hill, New York. 1976. Tree Rings and Climate. 567 p. Academic Press, New York. Powers, R. F. 1972. Site index curves for unmanaged Gingrich, S. F. stands of California black oak. USDA 1971. Stocking, growth and yield of oak Forest Serv Res. Note PSW-262, 5 p. Pacific stands. & Proc., Oak Symposium, North- Southwest Forest and Range Exp. Stn., eastern For. Exp. Stn., Upper Darby, PA, Berkeley, CA. p. 65-73. Rexrode, C. 0. Horton J. S. 1971. Insect damage to oaks. In Proc., 1960. Vegetation types of the San Bernardino Oak Symposium, Northeastern FO~~EX~.Stn., mountains. USDA Forest Serv. Res. Paper Upper Darby, PA, p. 129-134. PSW-44, 29 p. Pacific Southwest Forest and Range Exp. Stn., Berkeley, CA. Prescribed Burning in California Oak Management1 21 Lisle R. Green- Quercus agrifolia Abstract: Prescribed burning is aimed at reducing hazardous chaparral and other fuel accumulations, beneath or near trees. Because most California oaks have thin bark and almost any fire causes serious damage to boles or crowns, some hand cutting, or clearing with a small bulldozer, may be necessary before burning. Prescribed burning can be accomplished safely in fuels not directly under or adjacent to canopies. Prescription items discussed are ratio of dead-to-live fuels, fuel volume, green and dry fuel moisture, relative humidity, windspeed and direction, and air temperature. Other considerations are terrain, time of day, and season of year.

INTRODUCTION branches and litter from the oak trees (figs. 1, 2). When we talk of prescribed burning in California oak management, we are usually concerned about burning chaparral with as little damage to oak trees as possible. We want to remove brush fuels or, occasionally, other fuel accumulations that could threaten stately old oak trees or thickets of trees during wildfires. Another reason for a prescribed burn is to reduce numbers of oak trees, as when burning for range improvement.

THE FUELS PROBLEM

Oak frequently dominates on northerly exposures, as stringers along low elevation riparian zones, or it may mix with conifers or other woodland species at upper elevations. Usually we find an understory of brush, or brush surrounding and fingering through the oak Figure 1-Thick oak stands require hand or woodland. If the oak is dense enough to exclude mechanical thinning, or burns prescribed brush, the tree canopies often extend to the to remove only small amounts of fuel per ground. The fuel within the stand then consists burn, to prevent destruction of the trees. of dead or nearly dead shrubs and dead and live The brush~or "chaparral "-is frequent 1y dominated by chamise (Adenostoma fasciculatum H. Lipresented at the Symposium on the Ecology, & A.). Associated species and genera are Management, and Utilization of California Oaks, manzanitas (Arctostaphylos spp.) , ceanothus Claremont, California, June 26-28, 1979. (Ceanothus spp.) , mountain mahogany (Cercocarpus betuloides Nutt .), scrub oak (Quercus dumosa Li~ange Scientist, Pacific Southwest Forest and Nutt .), salvia (Salvia spp.), and others. These Range Experiment Station, Forest Service, U.S. shrubs contain fats, waxes, terpenes, and oils Department of Agriculture, Riverside, that are readily extracted in the laboratory as California. "ether extract." These materials are also readily driven off when heat is applied during During wildfire that sweeps across wild or prescribed fire and they burn violently thousands of acres (ha) of wildland vegetation, 5, 10. or 50 feet (1.5. 3, or 15 m) in the air. air temperatures are usually in excess of 100' F (38' C), relative humidities below 5 percent are not uncommon, and sustained winds from 20 to 70 miles per hour (32 to 112 km/h) are usually blowing. In late summer, dead fuels may contain from 3 to 10 percent moisture, and fine, green fuels 50 to 65 percent~lessthan one-half their green fuel moisture contents of early spring. With these conditions, fire spreads rapidly through the fuels that are within a few feet of the ground. Where these fuels are beneath the oak trees, a convection column of hot air and swirling, burning volatiles distilled from the green fuels will, as a minimum, burn holes through the canopy above. If the fuels near the ground are continuous under the canopies, and if the burning conditions are extreme-low relative humidity and fuel moisture, high air temperature, and windspeed-the entire canopy may explode into flames and consume the small Figure 2--Hand labor was used to prune trees branches. Strong winds, coupled with and pile underbrush, which was burned. Low undercanopy fuels, may move fire through the intensity broadcast burning can now be used canopies. to control fuel accumulations. During the Big Bear Fire on the San The chaparral may contain little dead fuel Bernardino National Forest in 1970, and in other in young stands, or from 35 to 50 percent in fires where forests or woodlands were destroyed, aged stands. Most of the dead material is dis- the damage to oaks was principally where trees tributed through the living shrub crowns. Brush were underlain by brush. The oaks survived the in southern California generally has relatively Big Bear Fire where brush fuel loading was at little fuel on the ground, so fires travel low levels. The vulnerability of an individual through the brush crowns, and into tree tree to fire appeared less related to canopies, if they are above or adjacent. attributes, such as bark thickness, crown stratification, or chemical content of the A herbaceous understory is usually lacking foliage, than to the distribution of brush fuels beneath dense chaparral, but a sparse stand of around it (Minnich 1973). In the Eastern United herbaceous plants, mostly annuals, is observed States, killing of oaks by wildfire was two to frequently where the brush stand is open. After four times greater in unburned forest than in fire or other clearing, seed from these plants prescribed burns conducted during the previous and from seed stored in the soil, sometimes for 10 years (Little and others 1948). Fires went decades, start to grow. Forbs--herbaceous, out in forested areas burned by prescribed fire nongrassy plants--are abundant at first, but 1 year before the wildfire. from 2 to 5 years after the initial clearing annual grasses and longer-lived forbs, such as There have been some favorable and some deerweed (Lotus scoparious Ottley), become abun- unfavorable data collected following fire in oak dant. After 5 to 7 years, woody vegetation from stands. On the positive side, oaks sometimes sprouts and seedlings occupies the site again, seem to be somewhat more fire resistant than and for the next 10 or 15 years the young, much of the chaparral. Scrub oak and shrub live succulent closed stand of brush does not burn oak (Quercus turbinella Greene) contain less of readily, except under the most adverse burning the volatiles, 3.7 and 6.2 percent respectively, conditions. Gradually, however, dead twigs than flammable chaparral, which contains from 7 accumulate, some litter builds up, short-lived to 20 percent volatiles (Rothemel 1976, species die or dieback during drought, and the Montgomery 1976). The oaks generally are ratio of dead-to-live plant material increases, somewhat higher in green fuel moisture than so that the stand becomes more and more chamise, and contain a lower proportion of flammable. Until the chaparral is about 20 dead-to-live fuel (Green 1970, Minnich 1973). years old, most fires are extinguished before Because of these and, perhaps, other variables, they reach 10 acres in size. As the brush ages the only group of sclerophyllous species that beyond 20 years, wildfires tend to get bigger showed resistance to fire during the Big Bear (Philpot 1973, Rogers 1942). The really big conflagration of 1970 was the oak woodlands fires occur when the chaparral is from 30 to 40 (Minnich 1973). In a prescribed burn in years old, or older. southern California, 85 percent of live chamise was consumed, 75 percent of live manzanita, but Hand labor was used to clear brush during only 45 percent of mountain mahogany and scrub the late 1950's and 1960's when prison labor was oak (Green 1970). available in quantity to agencies, and it is currently used to some extent &en firefighting The "bad" news is that California oaks, crews and other labor are not otherwise with the exception of coast live oak (Quercus occupied. Hand labor is environmentally accept- agrifolia Nee) (Plumb 1980) and, perhaps, able, but more expensive than other clearing Engelmann oak (9. engelmanni Greene) (Snow methods. This high cost might be justified 1980), are thin-barked and stems and canopies where the clearing is under or near valuable are sensitive to fire. Canyon live oak (9. trees but, generally, would be prohibitive on chrysolepis Liebm.), on the site of the 175,000 any extensive scale. acre (70,820 ha) Marble-Cone Fire in Monterey County, was described as "so sensitive and Bulldozers can sometimes be used in and flammable as to invite self-destruction" around oaks to push brush away from trees to be (Griffin 1978). A wildfire may have few or no protected, or a bulldozer can crush brush for beneficial effects on a black oak stand, but has burning under relatively safe burning many bad effects. It kills most small stems, conditions. Use of the bulldozer can also be and scorches the stems and roots of larger somewhat expensive because working around and trees, even though the bark is relatively thick. under canopies, using care not to damage trees, Scorching causes fire scars, which result in is not conducive to high rates of production. deformities, leave openings to admit rot and If the bulldozer is needed to save oaks, diseases, and serve as points of ignition when however, it may be justified. fire next goes through the area (Edwards 1957). Interior live oak (2. wislizenii A.DC.) has thin Herbicides may control or eliminate bark, and topkills readily when fuels burn unwanted vegetation in some oak stands. They around the base of the tree (Plumb 1979). In can be injected into tree trunks or applied to the Eastern United States, oaks and other stumps of cut brush or trees. Aerial broadcast hardwoods are so sensitive that fire is not applications of herbicides is seldom appropriate recommended for use in their management but, because of potential damage to desirable trees, rather, is directed toward hardwood control but tractor boom or hand spraying of brush (Fender 1976). sprouts within and around oak stands can be accomplished under appropriate wind, temperature, and humidity conditions. Use of HAZARD REDUCTION herbicides after prescribed burning or hand clearing should be considered. Because fire in chaparral located near oaks is one of the greatest threats to the oaks (fig. Prescribed burning will be needed to get 3). what can we do? Alternatives to wildfire rid of hand-cut brush piles, tractor-crushed removal of the brush include prescribed burning, brush, or standing chaparral. How is this to be mechanical clearing, herbicides, hand labor, or accomplished? some combination of these methods.

Prescribed Burning

Prescribed burning of mature chaparral without damaging oaks presents problems that are difficult, or sometimes impossible, and we have rather little experience with this type of burning. Repeat burns should be easier. Personnel then have more experience with prescribed burning, deal with less fine flashy fuel, less total fuel, and fires are less likely to crown.

Numerous variables affect fire behavior, that is, the way it burns. It is convenient to discuss these variables individually, but they are all interrelated and, integrated by the fire, determine burning behavior.

Figure 3--Securi ty against wildfire can be attempted by crushing the brush adjacent to trees, and burning under a low intensity burn prescription. Fuel Factors Lindenmuth 1971, Rothennel and Anderson 1966, Forest Service 1968, and Forest Service n.d.).

Ratio of Dead-to-Live Fuels Dead fuel moisture can be determined by laboratory procedures, but is usually estimated Young chaparral stands~thoseless than 20 from special fuel sticks that represent dead years old-will contain less than 20 percent fuels from 114 to 1 inch (0.6 to 2.5 cm) in dead material, and frequently only 5 or 10 diameter. Moisture readings of 6 to 12 percent, percent. Such a brush stand is nearly fire- depending on the proportion of dead fuel, are proof, and will burn only under extreme burning needed for burning mature standing brush. conditions. Of the brush stands we work with in oak management, most are older-20 to 50 years Green fuel moisture also influences fire of age. As brush ages, the proportion of dead behavior, although its effect may not be as fuel increases until aged stands may be from 35 obvious as that of dead fuels. Moisture content to 50 percent dead. Such mature brush generally of the green fuel is always too high, above 25 burns we1 1 under moderate burning conditions. percent, for the green twigs to sustain flaming If the brush has been crushed or treated with without an outside heat source; but during herbicide, or if snow breakage occurs, the summer and fall when moisture content of the proportion dead may be more than 50 percent. twigs may be as low as from 55 to 65 percent, heat from flaming dead fuel dries the green twigs until they, too, burn violently. From Fuel Volume experience and research we know that, if green fuel moisture is 90 percent or greater, burning Chaparral volume in California will vary these fuels is most difficult and much dead fuel from about 5 to 40 tons per acre (12 to 100 tons is needed to sustain the flaming. For mature per ha), and average about 18 tons (44 tons per brush, a green fuel moisture no greater than 65 ha). During hot prescribed burn or wildfire, 65 to 75 percent is generally needed for to 80 percent of fine-stemmed, flammable brush, satisfactory prescribed burning. such as chamise and coastal sage species in a mature stand will burn; but only about 50 percent of less flammable species, such as Weather Factors mountain mahogany and scrub oak will burn. From theoretical studies (Byram 1959) and from experience we know that, as available fuel Relative Humidity quantity increases beyond 2 to 3 tons per acre (5 to 7 tons per ha), the fire burns more and Humidity is the moisture in the atmosphere, more intensely. For this reason, reburns with and the relative humidity compares this moisture usually less flammable fuel, are generally to the amount the air would hold if it were easier to conduct safely than are initial burns. saturated, for example, 20 percent or 70 Ten tons per acre (25 tons per ha) of small percent. Humidity affects moisture content of flammable fuel-that which will burn during a small dead fuels, which absorb moisture when the f ire--are considered heavy fuel accumulation relative humidity is high, and release it when (McArthur 1962, Norm 1977). and we have that the relative humidity is low. The effect of much or more in most mature chaparral stands. humidity on fuels larger than an inch is small, This makes burning without damage to oaks except over long periods of time. difficult. To burn standing brush near trees, we like relative humidity to be 25 to 40 percent. When Fuel Moisture the brush is crushed or cut and piled, from 30 to 60 percent relative humidity, depending on Although the value varies somewhat the dead-to-live ratio, is desirable. depending on type of fuel, size of firebrand, windspeed, and other variables, a fuel moisture content of 25 percent of oven-dry weight is an Windspeed and Direction approximation of the value above which fuels will not burn (Rothennel 1972). Fire spread is Lack of ability to forecast local winds has generally slow in small fuels containing more been responsible for more prescribed burning than 15 percent moisture, unless steep slope or escapes than any other variable affecting fire strong winds boost the combustion rate (Britton behavior. Weak storm fronts sometimes move in and Wright 1971, Foster 1976, Heirman and Wright unexpectedly but, more frequently, erratic wind- 1973, Rothermel and Anderson 1966, Sneeuwjagt speed and direction because of local topography 1974, and Forest Service n.d.). As fuel and convect ion aid escapes. Wind accelerates moisture goes up, or down, fire intensity the oxygen supply to burning fuel, and changes proportionately (King 1973, Pace and contributes to heating of uphill or lee side of fuels. It carries away water vapor that dampens to burn from the top of the hill in a series of burning, and transfers firebrands beyond the narrow strips where the fire burns with the fire front. Ten miles (16 km) per hour winds slope. are usually considered the upper limit allowable for prescribed burning. If the slope has a southerly exposure, fuels will be somewhat more flammable than on a Although wind causes problems, it would be northerly exposure. Frequently, it is easier to difficult to burn without some air movement. prescribe burn on south slopes because, when Without a flammable understory, such as dry they will burn satisfactorily, northerly grass, several miles per hour of wind-four to exposures generally will not burn, and this eight (6 to 12 km)-is needed to move fire results in a natural fireline. If the exposure through brush canopies. A little wind is needed is northerly and ready for burning, the south to disperse heat when burning under tree exposures will burn intensely. canopies, and wind is needed to move fire through sparse fuels. If local terrain is irregular, the problems of gusty, turbulent windf low and direction changes conÂront the prescri bed-burn planner. Air Temperature

. Air ttemperature has less direct effect on Time of Day fire behavior than humidity, fuel moisture, or wind, but affects these and other variables, and Conservative prescribed burning calls for through them, fire behavior. reaching prescription and igniting during the hot part of the day, and burning into lowering High air temperatures warm fuels so that air temperature and rising relative humidity. less preheating by fire is needed before Fuels are as dry as they will be during this combustion occurs. Also, less heat energy is period, and as burning is extended into the late required to drive off moisture, and moisture part of the day, control problems are less. For evaporation proceeds more rapidly. Because of large burns, the objective might be to burn out heating near the ground, high air temperatures a safe fireline and to burn under clusters of can cause unstable air. This may result in trees during the morning hours or the previous strong convection currents and strong upslope day, then allow fire through the rest of the daytime winds, which sometimes cause fire burn when the air temperature is near maximum spotting and fire whirls. As temperature rises for the day. and relative humidity decreases, drying of fine fuels proceeds. Season Some studies have suggested that prescribed burning be done when maximum air temperatures Where dead fuel accumulations are massive are less than 70Â F (21' C), especially when within a stand of trees, the objective should be burning under tree canopies (Biswell and Schultz to burn during late winter or early spring, or 1956, Gaines and others 1958). A maximum of 80Â earlier during the winter if sufficient rain has F (26' C) was suggested for burning fuel breaks fallen to wet 100-hour timelag [up to 3-inch (Schimke and Green 1970). Minimum temperatures (7.6-cm) diameter] or larger fuels, as well as can be as low as 30' F (-lo C), but low tem- litter. By burning when the larger fuels and peratures are usually accompanied by high rela- deep litter will not burn, the flashy tive humidities and high moisture contents of fuels~pineneedles, fallen oak leaves, dry fine fuels. A temperature range of 60 to 70' F grass, and small twigs-can be removed with (15 to 21' C) would be nearly ideal for most minimum damage to trees. If burning in such a prescribed burning. Brush piles or crushed stand is delayed until moisture content within brush can be burned under low temperature the larger fuels is below 17 or 18 percent, they ranges. will add to the intensity and duration of the fire, and much more damage to tree boles and canopies will result. Other Factors

CONCLUSIONS Terrain California wildlands have been prescribe Slope has an effect on fire spread similar burned by permit since 1945, usually for range to windspeed: the steeper the slope, the more improvement. The objective frequently was to rapidly fire spreads uphill and the more slowly kill or severely damage stands of oaks. Only downhill. Prescribed fires usually are started during the last year or two has burning to near a ridgetop and allowed to back downhill, or enhance the appearance and chances for survival of oak stands during wildfire been an objective. Green, Lisle R. Experience in oak management burning, therefore, 1970. An experimental prescribed burn to is limited, but is being expanded rapidly. reduce hazard in chaparral. USDA Forest Practices and principles learned in burning Serv. Res. Note PSW-216, 6 p., illus. chaparral, ponderosa pine forests, and other Pacific Southwest Forest and Range Exp. fuel types are being modified to apply to Stn., Berkeley, Calif. prescribed burns in oak forests. Scientists in various disciplines are currently gathering Griffin, James R. knowledge about oak ecosystems, and this 1978. The Marble-Cone Fire 10 months later. knowledge will aid in reducing the hazards of Fremontia (July 1979), p. 8-10. Calif. fire to California's oak stands. Native Plant Soc., Berkeley, Calif.

Heirman, Alan L., and Henry A. Wright LITERATURE CITED 1973. Fire in medium fuels of West Texas. J. Range Manage. 26(5):331-335. Biswell, H. H., and A. M. Schultz 1956. Removal of tinder in Ponderosa. Calif. King, N. K. Agric. 10(2):6. 1973. The influence of water vapor on the emission spectra of flames. Combust. Sci. Britton, Carlton M., and Henry A. Wright and Techno1 . 6: 247-256. 1971. Correlation of weather variables to mesquite damage by fire. J. Range Manage. Little, S., J. P. Allen, and E. B. Moore 24:136-141. 1948. Controlled burning as a dual-purpose tool of forest management in New ~ersey's Byram, G. M. pine region. J. For. 46(ll) :810-819. 1959. Combustion of forest fuels. Chap. 3, p. 61 to 89. In Forest Fire: Control and McArthur, A. G. Use, by K. P. ~zis.McGraw-Hill, New York. 1962. Control burning in eucalypt forests. Commonwealth of Australia, For. and Timber Edwards, Milton B. Bur. Leafl. 80, 31 p., illus. Canberra, 1957. California black oak-i ts management and Australia. economic possibilities. J. For. 55(7):506-510. Minnich, Richard A. 1973. The impact of fire suppression on Fender, Darwin E. southern California conifer forests: a case 1976. Fire by prescription for managing study of the Big Bear Fire, Nov. 13-16, timber. In Proceedings of the Fire by Pre- 1970. Proc. Symp. on Living with the scription Symposium, p. 37-39. Fire Chaparral, Riverside, Calif., 1973:45-74. Management, Southern Region, Forest Service, Sierra Club, San Francisco, Calif. U.S. Dep. Agric., Atlanta, Ga. Montgomery, Kenneth Reid Forest Service, USDA 1976. Ether extractives and flammability of 1968. Rate of fuel consumption increases when Mediterranean-type shrubs. Master's thesis. fuel moisture drops. Progress Report of Calif. State Polytech. Univ., Pomona, Calif. Research, p. 129. Washington, D. C. Norum, Rodney A. Forest Service, USDA 1977. Preliminary guidelines for prescribed Fuel management planning and treatment burning under standing timber in western guide-prescribed burning guide. 56 p. U.S. larch/Douglas fir forests. USDA Forest Forest Service Northern Region, Missoula, Serv. Res. Note INT-229, 15 p., illus. Mont . Intermountain Forest and Range Exp. Stn., Ogden, . Foster, Ted 1976. Bushfire-history, prevention, and Pace, Charles P., and A. W. Lindenmuth, Jr. control. 247 p., illus. A. H. and A. W. 1971. Effects of prescribed fire on Reed, publ. 53 Myoora Rd., Sidney, vegetation and sediment in oak-mountain Australia. mahogany chaparral. J. For. 69 (11) :800-805.

Gaines, Edward M., Harry R. Kallander, and Joe Philpot, Charles W. A. Wagner 1973. The changing role of fire on chaparral 1958. Control led burning in southwestern lands. Proc. Symp. on Living with the ponderosa pine: results from the Blue Chaparral, Riverside, Calif ., 1973: 131-150. Mountain Plots, Ft. Indian Sierra Club, San Francisco, Calif. Reservation. J. For. 56 (5) ~323-327. Plumb, Tim R. Rothermel, Richard C., and Hal E. Anderson 1980. Response of oaks to fire. Symposium 1966. Fire spread characteristics determined on the Ecology, Management, and Utilization in the laboratory. USDA Forest Serv. Res. of California Oaks Proc. Scripps College, Paper, INT-30, 34 p., illus. Intermountain Claremont, Calif. June 26-28, 1979. Forest and Range Exp. Stn., Ogden, Utah.

Rogers, David H. Schimke, Harry E., and Lisle R. Green 1942. Measuring the efficiency of fire 1970. Prescribed fire for maintaining control in California chaparral. J. For. fuelbreaks in the central Sierra Nevada. 40(9):697-703. USDA Forest Serv., 9 p., illus. Pacific Southwest Forest and Range Exp. Stn., Rothermel, R. C. Berkeley, Calif. 1972. A mathematical model for predicting fire spread in wildland fuels. USDA Forest Sneeuwj agt , Richard John Serv. Res. Paper INT-115. Intermountain 1974. Evaluation of the grass fuel model of Forest and Range Exp. Stn., Ogden, Utah. the National Fire Danger Rating System. Master's thesis. Univ. of Washington, Rothermel, R. C. Seattle. 162 p. 1976. Forest fires and the chemistry of forest fuels. In Thermal uses and Snow, Gerald E. properties of carbohydrates and lignins. p. 1980. The fire resistance of Engelmann and 245-259. Academic Press, New York. coast live oak seedlings. In Symposium on the Ecology, Management andUtilization of California Oaks Proc. Scripps College, Claremont, Calif. June 26-28, 1979. Quercus lobata

Nursery Propagation of California Oaks1

Suzanne Schettler-2 I and Michael N. Smith-3I

ABSTRACT : California Oaks have been propagated by seed, cuttings, and grafting; but seed remains the most practical method. Initial planting of acorns in a bag or flat permits sorting and root-pruning before seedlings are planted into container or ground. Propagation and cultural practices vary with the purposes for which the oaks are produced.

INTRODUCTION GOALS

Propagation of California oaks by nursery Forestry methods is well suited to ornamental use. When it comes to forest and range plantings of oaks, For timber use, a forester seeks oaks with the costs and benefits of these methods must be consistently erect, straight boles, rapid rate weighed for the particular application. On the of growth, and more or less even size. Clonal one hand, direct broadcasting or dibbling into material may even be desirable. The strain the ground may seem more economical if acorns must be well adapted to the local soil and are abundant enough after sorting to cover climate. The trees must be of adequate size expected losses to foraging animals, drought, during the best planting season (mid-fall and other causes. On the other, a plant of through mid-winter in mild climates, early fall gallon-can or equivalent size is a known entity in snow country), and must be able to establish that has already survived many initial hurdles; themselves quickly and grow vigorously to and early maintenance is less expensive in one harvest size. nursery location than spread over acres of potentially rugged terrain. It may be promising, moreover, to borrow initial nursery Wildlife Management techniques and then plant out at an early stage. The decision to use or not to use A wildlife manager presumably seeks the nursery methods at a given stage of seedling full diversity of local ecotypes, and trees of development will depend on the economic value varied growth habit are not undesirable. of the trees and cost of alternative methods. Mature trees should bear abundant acorn crops Common principles apply to propagation for all to provide food for wildlife. The wildlife purposes. manager shares with the forester an interest in locally adapted trees and in matching optimum planting size to optimum planting date. For Lipresented at the Symposium on the Ecology, large-scale forest plantings, there is a Management, and Utilization of California Oaks, growing awareness that local genetic material Claremont, California, June 26-28, 1979. should be kept intact: propagation should be from local trees only. This also applies to L1~ropagation Manager, Saratoga Horticultural other large plantings such as along highways Foundation, Saratoga, California 95070. and in large housing subdivisions.

?'partner, Wintergreen Nursery, Watsonville, California 95076. Ornamental Horticulture but has not been tried extensively for California species. The type of graft is The typical ornamental nurseryman seeks dictated more by the preference of the predominantly aesthetic characteristics in a propagator than by the plant; one of us has had young oak, combined with potential for success very limited success with a simple side graft in varied landscapes. The tree should resist performed in January on coast live oak (Quercus disease and be adaptable to a wide range of agrifolia). However, grafting is a relatively climates and soil types. A given tree may be expensive technique, requiring a strong motive planted in a location hundreds of miles from for perpetuating an individual clone (as is its parent, on native soil, subsoil or fill, frequently the case for ornamental 'use). with drought or summer watering. It must be able to thrive in an artificial setting as well as in a natural one. Each tree should grow Tissue Culture vigorously, become established readily in the ground, and not vary too much in form from the Tissue culture has produced only limited "classic" image of the species. success with many woody plants, often resulting in proliferation and development of vegetative Thus, the goals of oak growers may vary. shoots without similar development of roots. But they all share an interest in plants with a We do not know of any sustained success with vigorous start, in the strongest possible state California oaks. Tissue culture is also fairly at planting time, and produced by the most expensive on a per-unit basis, especially with economical method. slower-growing plants; but there is potential for nearly unlimited numbers of "identical" trees if this method were perfected. VEGETATIVE PROPAGATION

Propagation by seed has been the only ACORN PROPAGATION method commercially successful thus far, and will be discussed in the next section. The The remarks that follow, unless otherwise considerable diversity inherent in this method credited, are based entirely upon our can be partly limited, where desired, by first-hand experience as commercial growers of selection of source trees, preferably within oaks in central and northern California. relatively uniform populations. The following are some methods of clonal propagation, applicable where the traits of specific Collection selected trees are to be perpetuated. Collecting acorns presents as large a challenge as any later stage of propagation. Cuttings Timing is crucial. The first wave of acorns to drop from a tree consists primarily of aborted Some propagation of oaks has been done and weevil-eaten acorns. Then, the good acorns from cuttings. However, most oak species are drop a few days or weeks later. Not all trees inherently difficult to root. Researchers to bear equally heavy acorn crops. A given tree date have rooted only a few species, using is not always consistent in its crop from year elaborate equipment and such exotic materials to year. And in some years, perhaps in as 2,4,5-T [(2,4,5-trichlorophenoxy) acetic response to aberrant weather during the acid]. And the numbers propagated by this previous season, a species may bear a poor or technique have been too small to hold much negligible crop throughout its range, as Q. promise for economical production on a lobata did in 1978 in much of northern commercial scale. However, it should be noted California. that many plant species thought to be difficult or impossible to propagate by this method in To physically collect acorns on the tree years past are now routinely and economically is slow and precarious, but gives the best reproduced in this manner. Often the percentage of sound acorns if they are gathered "breakthrough" has involved simple between the first and second drops and just as environmental, mechanical (as in hedging) or they loosen sufficiently from the cap to permit chemical manipulation of parent stock. removal without damage. Gathering acorns from the ground is far easier and faster, as they sometimes can be raked or swept up. But this Grafting method also has its drawbacks. Unless the first drop has been raked or otherwise removed, Grafting has been quite successful with the eaten and aborted acorns will be collected some European and eastern American species . It together with the good ones. And animals may could prove worthwhile in certain applications, beat the propagator in gathering their acorns. In addition, acorns of different species may be Sowing mixed on the ground unless the parent tree is well isolated or growing in a pure stand. For Two problems quickly develop after sowing. large producers, it would seem advisable to Oak roots grow rapidly while the tops grow maintain certain seed trees in the wild by slowly. The nurseryman, though perhaps not the spraying as needed against principal insect forester or wildlife manager, may seek to alter pests like the Oak Moth or California Oakworm the root-shoot ratio to prevent early root ( californica) and the Filbert or binding in containers. (All three growers may Acorn Weevil ( uniformis), and by one be deceived as to root growth by observing only or two deep waterings at the drip line during the tops.) And every batch of acorns will summers of extreme drought. exhibit mixed viability and vigor, producing a need to sort and cull at the earliest, most economical stage. Sorting

Two kinds of sorting are required. Broken Seed Beds and crushed acorns and those with weevil holes in the shell must be visually sorted. And One traditional method of sowing is to acorns that look good are generally floated as plant in seed beds. This allows for a rough test for viability--those that float unrestrained growth of strong roots, but unless are reliably bad, although those that sink are they are frequently undercut to prepare them in not always viable. advance, at lifting there is potential for mortal damage to the roots, at least in the case of evergreen species like Q. agrifolia. Storage Deciduous species can regenerate roots after heavy cutting if lifted while they are leaf less It may be necessary to store acorns if 1 and dormant. The seed bed method perinits the full year's growth would produce a plant too use of inexpensive space and ease of irrigation big for planting the following fall. Acorns and fertilization. With proper timing, can be dried and stored at cool or cold seedlings can be transferred directly from the temperatures, but in our experience, drying has seed bed to a permanent planting site. reduced viability to an unacceptable level, particularly with Q. agrifolia. It might be possible to delay sowing, if needed, through Seed Flats lower-temperature moist stratification or even freezing; we have not explored these Planting in seed flats is very possibilities. space-economical, although it is a two-step method. It permits easy handling and the sorting so essential at the earliest stage of Stratification seedling development. Growth rate can be manipulated inexpensively by moving a flat to a Cold stratification (in which seeds are warmer or cooler environment. In our central layered or mixed with a moist medium such as coast climate, outdoors is cooler than on the peat in a container and refrigerated) is greenhouse floor, which, in turn, is cooler sometimes used to break dormancy of the embryo, than on a greenhouse bench. Growth rate can to permeate the seed coat without rotting the also be manipulated by raising or lowering seed, and/or to even out the commencement of nutrient levels. But, unless seedlings are germination. However, with the possible transferred to individual containers soon after exception of high-elevation material, the need germination, roots become crowded and for stratification in California oaks is hopelessly tangled in the flat. With questionable~a batch of fresh acorns of ten refinements, we believe this could be one of includes quite a few that have begun to sprout the best methods for propagating oak plants. on the ground or surprisingly even on the tree. Deep flats that hold 3-1/2 inches (9 cm) or Even Q. kelloggii, a red oak species reported more of sowing medium are needed to provide in the literature to require stratification, uncramped root space. And a copper screen or has germinated well and rapidly for us without treated bottom on the flats causes air and/or such treatment. Chemical pretreatment with chemical pruning of the tap root which induces gibberellin or other chemicals might be tried, root-branching . but likewise seems unnecessary for California oaks. In our experience, every low-elevation California oak species has shown good Pots germination with no pretreatment other than careful sorting. Acorns are sometimes planted directly into individual pots, a method used extensively to grow coniferous species for timber use. The could provide the most effective shortcut for advantage of this method, if pots are deep forest planting in mild climates: acorns, enough and seed is of known high quality, is collected as they drop, could germinate in bags that it is theoretically a one-step process. quickly enough to plant directly into the However, the pots most commonly used in ground within a matter of weeks. Where losses nurseries are too shallow for oaks and acorn are high from feeding by jays and other viability may be unknown. The less vigorous acorn-eaters, once a root and top are producing individuals cannot be culled before a food for the seedling,- the acorn which is their considerable investment in materials has been main attraction can be clipped off.-41 made, and it is difficult in a pot to "correct" a root system. The best container for this purpose is one 2 to 4 inches (5 to 10 on) Transplanting square by at least 7 to 8 inches (18 to 20 on) deep, either a bottomless band or a fiber pot Transplanting from either a bag or a flat whose bottom decomposes after a few months. provides a prime opportunity to cull However, availability of pots this size is undesirable plants and to tend roots of select limited. They are also heavy and awkward to individuals. At this time, lateral roots handle in standard shallow flats. regenerate freely after the tap-root is cut, whereas to cut heavy roots at later stages tends to produce shock and setback. The kind Plastic Bags of root system ultimately desired can be partly determined by how hard and how frequently the The most successful method of starting roots are pruned while the seedlings are still acorns that we know was passed on to us by W. young. Here the ornamental nurseryman will Richard Hildreth while Director of Saratoga likely diverge from his forest or wildlife Horticultural Foundation. Sorted acorns are counterpart, deliberately forcing development mixed with damp sand, vermiculite, peat, or of a branched root system ideal for planting sphagnum in a plastic bag and kept between into successively larger containers. about 50 and 75' F (10 to 24' C). This is not the classic "cold stratification," which it superficially resembles, but a method of Container sowing. The acorns begin to sprout in the bag within a few months or even weeks. They will Selection of container may be a compromise continue to germinate over an extended period, of factors. For the forester or wildlife but in practice, the slow sprouters tend to manager, a deep root system that helps the remain less vigorous at all later stages and plant become established quickly in the ground are best discarded. (This, of course, means must be weighed against problems of digging a many more acorns have to be collected than the deep planting hole and the logistics of moving anticipated crop.) When the root is 2 to 3 heavy containers. Here, also, container cost inches (5 to 8 cm) long, it is tip-pinched to is critical, with cheaper materials such as induce branching (particularly desirable if the polyethylene film, cardboard, or tarpaper often plant is to be container-grown) and planted being preferred. For a nurseryman, container directly into a moderately large container such cost is less restricting. As mentioned before, as the one described above or a gallon can. At for any grower, it is possible (and desirable) this stage, shoot growth may still not have to transplant directly from the bag or flat to begun. The seedling may be sown with acorn on a 1-gallon can or its depth equivalent. the surface of the soil, or may be placed an inch or so below the surface. Medium The only disadvantages of this method occur when the seedlings are left in the bag Near1y any reasonable planting medium can too long: the shoot will grow bent after it be used with good results as long as it is reaches the light at the surface of the bag, well-drained. Planting mixes usually employed the roots will become tangled, and the whole in the ornamental nursery include various mixture can rot. But, properly timed and mixtures of conifer sawdust or shavings (most maintained, this technique is well adapted to frequently Redwood [Sequoia] or Douglas-fir the need to keep pace with rapidly-developing [Pseudotsuga]) and any of a wide variety of vigorous roots, to sort at the earliest sands, soils, or volcanic materials. Soil of opportunity, and to prune and straighten roots any sort should normally be sterilized, while at the most formative stage. It requires little environmental control and no pre-transplant feeding or watering. It is Ñl~ersona communication with Wayne Poderick, economical of space, as bags can be kept in Director, Botanic Garden, Tilden Park, unused space under greenhouse benches. And it Berkeley, California. the other materials tend to be acceptably low Staking in pathogenic fungi and other organisms. If the young plants will be outplanted into dense Staking is generally not necessary. A high-clay soils, it is advisable to use a grower may wish a tree for timber or ornament relatively dense nursery mix, with watering and to have a strongly upright lower trunk. other nursery care adjusted accordingly. Some However, staked trunks tend to be weaker and to clay content is highly desirable in any case develop less rapidly in girth than unstaked for retention of nutrients. trunks. Both single-trunked and multitrunked trees are desirable for landscape use, and a After this first potting, it is important gnarled trunk can increase an oak's aesthetic to minimize posttransplant shock. The value. If taller trees are desired, judicious seedlings should initially be kept in a cool pruning of weaker secondary trunks may be more location with an even supply of moisture, and useful than staking. given half shade, particularly if moved during the longer, hotter days of spring or summer. Pests and Diseases

Culture Young oaks in the nursery are as subject to pests and diseases as are other plants, and Culture of oak seedlings for ornamental early detection is important because treatment use is geared toward achieving maximum growth is most effective when these problems first at all stages. This is accomplished by giving appear. the seedlings constant optimum conditions and avoiding stress. The soil mix should always be Aphids frequently occur in closely packed moist (permitted by a porous, well-drained nursery blocks, particularly of Q. agrifolia mix). The presence or absence of nutrients and Q. kelloggii during April and mid-September seems to make little difference in growth until through midqctober. They can seriously seedlings are 2 or 3 inches (5 or 8 cm) high. distort growth, but seldom kill the plants. At later stages, most oak species are as Whiteflies occur occasionally in summer, again responsive to high fertility as most other where blocks of plants are overpacked so that woody plants; differences produced in growth much of the foliage is shaded. Both aphids and rates of Q. agrifolia, Q. wislizenii, and 9. whiteflies are treated effectively with such lobata can be spectacular. Temperatures should systemics as Orthene (safest to the user), be moderate; in theory a winter-heated house Cygon or Metasystox which give extended could permit year-round growth. Summer shade control. One application generally lasts 1 to permits more vigorous growth during the first 3 months. Quick knock-down without lasting year or two. And although probably not control can be obtained with Diazinon, economical, long-day lighting should accelerate Malathion, Sevin, or other short-residual growth. surf ace insecticides.

Oak Moth Caterpillars are not usually a Roo t-Pruning nursery problem. They, and similar species, can skeletonize young foliage but, again, are Root trimming may be necessary at each usually not lethal. Control is obtained with successive move to a larger container in order such materials as Orthene, or with Lindane to keep roots from growing cramped or coiled which is not systemic but leaves a long-term while the top reaches saleable size. It is crystalline residue effective where eggs hatch critical to keep roots growing actively and over a period of weeks. Dipel and other freely. As alternatives to screened containers formulations of Bacillus thuringiensis give or bottom-treated flats to prune and induce effective biological control. Broad-spectrum, early branching of newly-germinated roots, short-term, insecticides give control if all open-bottomed containers or plant bands produce the caterpillars have hatched at the time of the same effect at the transplanting stage; as application. the pots are moved from one location to another the roots are pruned in the process. Fiber Stem gall insects such as the Woody Twig pots tend to rot away at the bottom and become Gall (Callirhytis perdens) can do very serious open-bottomed containers with time. It is most damage, especially on Q. agrifolia and Q. desirable to transfer young plants rapidly to wislizenii, where they girdle twigs and the next larger container or to the ground, as virtually ruin many young trees. Chemical soon as roots have filled the current control is extremely difficult ; probably the container. most effective measure would be to enclose plant blocks with shade or other cloth of Outplanting sufficiently fine mesh to prevent entry by the adult insects. When it is time for final planting Into the ground, several factors must be taken into Powdery mildew may be a problem in late account. Is water available for a few deep summer, primarily in sprinkler-irrigated irrigations during the first dry season? If nurseries and in foggy coastal locations. It not, the young plant must be planted with, or can seriously distort new growth and cause just ahead of the first rains. Planting should "witches' brooms." Many chemicals are be timed and tended so that extremes of available specifically for it, although there temperature, wind, and drought are prevented. may be registration problems for use in oaks; Under ideal conditions, a vigorous oak seedling Dithane, Karathane, Kelthane, and Pipron are can be planted out and experience little or no registered for powdery mildew. Benlate is interruption in its growth. However, if the often effective only at increasingly high timing and situation of planting will be less concentrations. Repeated sprays of Captan, than ideal, the plant should be hardened off alone or in combination with other fungicides, well in advance to prepare for the new can give effective control. Benlate and Captan environment. Nutrients can be gradually also control Botrytis, which can be a problem reduced, periods between watering gradually under cool, wet conditions particularly in lengthened, and exposure to hot sun Increased early spring. so that a tougher plant goes out to compete in the wild, less dependent on human care. Fungus twig blights and root rots are often caused (especially in sprinkler-irrigated The propagator's success shows up not in nurseries) by Pythium and Phytophthora. Truban the nursery, but many years later when wildlife is probably the best currently registered or humans, with no thought of propagation, control, while Captan is a reliable standby. enjoy a healthy stand of oaks.

All these diseases are prevented by generous plant spacing, and hand- or other REFERENCES short-duration or non-overhead watering. Emery, Dara, and Winton Frey Under continuous good culture, it is not 1971. Native plants of California: seed unusual here for the low-elevation deciduous propagation information. Santa Barbara oaks (9. kelloggii, 9. douglasii, 9. lobata) to Botanic Garden leaf let. attain 1-112 to 2 feet (46 to 61 cm) of top growth by the end of the first summer in the Hartmann, Hudson T., and Dale E. Kester nursery. Q. agrifolia may reach 2 to 3 feet 1968. Plant propagation: principles and (61 to 91 cm). At the end of the second year, practices. Prentice-Hall , Inc., New he deciduous species will have grown to 3 to 5 Jersey. eet (91 to 152 cm) in 5-gallon cans and coast Lve oak to 5 to 8 feet (152 to 244 cm). Mirov, N. T., and Charles J. Kraebel 1939. Collecting and handling seeds of wild plants. Civ. Conserv. Corps, Forestry Publ. No. 5, Washington, D.C. Nutrient-Microbial Considerations in Oak

Paul H. Dunn-21

Abstract : Nutrient data for California Quercus woodlands has been extracted and is presented in table and graph form to facilitate comparison of individual sites with other sites. Nutrient cycles, with emphasis on carbon, nitrogen, and phosphorus, are reviewed for Quercus. Fertilizer use in Quercus woodlands is reviewed. Nonsymbiotic dinitrogen fixation and mycorrhizal associations with Quercus are discussed and four mycorrhizal fungi species producing hypogenous fruiting bodies in association with Q. dumosa are identified .

INTRODUCTION NUTRIENT BUDGETS IN OAK WOODLANDS

Recognizing the value of oak woodlands for Oaks rarely occur in pure stands. Most of recreation, wildlife, and wood production is the data presented here are therefore derived the impetus behind current oak outplanting from woodlands in which oak is the dominant programs. A major influence on the success of overstory species, but not the exclusive such oak productivity is the nutrient-microbial species on the site. The information has been condition of the soil. gleaned from many different scientific papers so the nutrient budget is not complete for Microbial activity in soils is generally every site; however, the budgets presented little understood but critical to the success hopefully will indicate a range of values of many management plans, particularly those against Which a site can be judged before involving outplanting. introduction of oaks, management activities are proposed and some and increasing productivity of oak-dominated prediction of success can be made. sites. For this reason, microbial conditions and the interrelationship to nutrient pools Much of the California oak data is must be taken into account. extracted from the California Soil Vegetation Survey which, though not complete for all areas This paper is designed principally to give of the State, provides some usable budget oak woodland managers a reference to compare values. These data include unpublished the nutrient status of their sites to nutrient and were made available by Paul levels in other oak woodlands and thereby Zirke3'of the University of California, predict results of proposed management Berkeley. The criterion used by the author to activities. Much of this information, which is classify a site as oak woodland-based on sparse and scattered throughout the scientific California Soil Vegetation Survey data~wasan literature, is summarized here with emphasis on excess of 50 percent cover of oak or an California oak woodlands, though other areas oak-grass savannah. are considered as well. Quantities of nutrients in various pools do not alone give complete information about Lipresented at the Symposium on the Ecology, the nutrient conditions of a site. The rate of Management, and Utilization of California Oaks, transfer between pools is also Important. A Claremont, California, June 26-28, 1979.

~~icrobiolo~ist, Pacific Southwest Forest and a~inke,Paul J. 1979. Unpublished chaparral Range Experiment Station, Forest Service, U.S . soil data, chaparral plant data, and Weibull Department of Agriculture, Glendora, probability density plots. Dep. of Forestry, California. Univ. of Calif ., Berkeley. site with high turnover rates between pools can and place, Ceanothus greggii foliage decomposed be as product:ive as that site with large 12.8 percent, Adenostoma fasciculatum nutrient pools but with slower recycling rates. decomposed 15.05 percent, A. sparsifolium decomposed 20.18 percent, Arctostaphylos glandulosa decomposed 18.81 percent, and The Carbon Cycle Cercocarpus betuloides decomposed 23.07 per- cent. Gross primary production, or energy, is fixed in carbon compounds during In oaks, decomposition takes place through photosynthesis. Oaks metabolize part of the a combination of micro-organisms and soil gross primary production as respiration; the invertebrates. But within a narrowly defined remainder generates biomass, or net primary system, some inherent differences in production. Each fall, deciduous oaks drop decomposition rates occur by species and site. most of their net primary production in the For example, the decomposition rate in form of leaves onto the litter layer. temperate oak woodlands is higher than the Conversely, evergreen oaks keep their leaves decomposition rate in San Diego chaparral sites 1-1/2 to 3 years, which means that less of recorded by Yielding, partly due to the dry their annual energy production is expended in climate of the chaparral which limits the regenerating leaves. The evergreen oaks do amount of time conditions are suitable for tend to drop their oldest leaves primarily decomposition (Winn 1977, Olson 1963, Yielding during the fall, but it is not a complete drop 1978). In England, foliage of Quercus robur L. (Wheeler 1975) as in deciduous species. decomposed 40 percent in 18 months (Edwards and Heath 1975). An oak-hickory forest in southern Prior to falling, leaves of many tree Illinois was estimated to decompose one-half of species are infected by initial decomposition the litter in 10.5 to 17 months (Akhtar and fungi (Jensen 1974). When the leaves are others 1976). Litter from a mixed oak forest deposited on the upper layers of litter, they in New Jersey had 65 percent decomposition in are invaded from below by soil fauna (Dickinson 18 months (Lang 1974). An oak-pine forest and Pugh 1974) which chew the leaves into even litter on Long Island lost 66 percent of its smaller pieces. Much of the leaf material is weight over 1 year (Woodwell and Marples 1968). left partly decomposed in fecal pellets. In 6 months, Q. underwent 28 percent Successive waves of microbes then decompose decomposition and Q. velutina had 29 percent leaves and fecal pellets with extracellular decomposition (Broadfoot and Pierre 1939). In enzymes. the same 6-month period, Q. petraea lost 26.20 percent in English mull, 23 percent in moder, Readily decomposed carbon-containing and 22 percent in peat. Q. & lost 17 compounds, such as sugar, are metabolized percent each on three separate sites in 6 first, mostly by sugar fungi such as Zygo- months (Bocock and Gilbert 1957). mycetes (Jensen 1974). Next, cellulolytic microbes slowly decompose the cellulose. The As a juvenile oak woodland ages, the depth resistant lignins which remain are then very of the litter layer changes. In juvenile slowly decomposed. The final links in the stages, the depth of the litter layer gradually decomposition chain are the humic compounds increases. In a mature temperate zone oak which, because of very long half-lives in the forest, a nearly steady state is achieved, with soil, take 100 to 1000 years to decompose. litter deposition equaling litter decomposition These humic compounds may originate directly (Lang 1974). Such may not be true for stands from the litter or from microbes involved in where nutrients become limiting or where the decomposition. Each step in the decomposition amount of resistant compounds in leaves process involves a different microhabitat and a increase. The result is a longer decomposition different complement of microbes. Near the time (Edwards and Heath 1975), offset only bottom of the litter layers only lignin and partly by better moisture retention in the humic compounds remain. This layer, which thicker litter layers. The dense, closed becomes anaerobic when wet, is referred to as canopy of older stands also decreases the the fermentation layer. temperature in the litter layer, thereby slowing decomposition. In some areas, The decomposition time of a leaf in litter environmental conditions are such that varies in proportion to resistant compounds in equilibrium is never achieved, mostly due to the leaf and the environmental conditions. For dryness (Olson 1963). For example, the example, Edwards and Heath (1975) found that California oak savannah does not develop deep increases in the polyphenol content of 2. robur litter layers, perhaps due to the high L. leaves decreased the decomposition rate. water-holding capacity of the soil and high Yielding (1978) showed that in San Diego County levels of rodent and activity which chaparral, Quercus dumosa foliage decomposed breaks up litter and moves it down into soil 21.12 percent in 18 months. In the same time where decomposition is rapid. Microbial respiration accounts for 99 For example, quantities for chaparral sites percent of the CO produced from the litter and (fig. 1) generally fit in the mid-to-lower soil (Ausmus an2 Witkamp 1974). The actual range. proportion of respiration attributable to bacteria, fungi, roots, and other soil organisms is not easily ascertained. Of the The Nitrogen Cycle microbe-produced CO, about 78 percent is due to fungi, about 22 percent is due to bacteria Nitrogen~essential to all living (Anderson and Domsch 1973). These percentages organisrns~isa component of the amino acids may attribute too much activity to bacteria in which make up protein. Nitrogen gas is the oak woodlands, since the acidic litter in the principal component of air (2 80 percent), oak woodland ecosystem selects in favor of however, it is not in a form usable by most acid-loving fungi. organisms. Through symbiotic association with a microbe, some plants are able to fix nitrogen Most microbes are dependent on photo- from the air into a usable form. The legumes synthetically fixed carbon as an energy source. and members of the genus Ceanothus are typical. The distribution of carbon, therefore, closely Dominant chaparral shrubs reflect this parallels the distribution of microbes, as nitrogen-fixing ability (fig. 3) in their demonstrated by selected California oak stands foliage nitrogen content. Ceanothus cannot (fig. 1). Although no microbial data was exist on sites which do not provide sufficient developed for this study, microbial activity nitrogen from soil or allow fixation to should parallel the carbon biomass in the upper maintain leaf tissue concentrations greater soil layers. This may not be true for the than 1 percent. Wercus dumosa, which does not carbon increase seen below 50 cm. fix its own nitrogen, reflects the available

Carbon (kg/m2) Nitrogen (g/m2) 2 2 Figure 1--Carbon (kglm ) and nitrogen (glm ) soil profiles from Quercus dumosa sites in southern California: (a) Kiethly Ranch, Lake County, Calif ., (b) Owl Canyon, Hollywood, Calif., (c) El Prieto Canyon, Los Angeles County, Calif., (d) Scissors Junction, San Diego County, Calif.. (e) Sunrise, San Diego County, Calif., (f) Descanso (4 mi NE), San Diego County, Calif ., and (g) Vista (5 mi S) San Diego County, Calif. (Data supplied by Paul Zinke, University of California, Berkeley).

Zinke-31 has developed Weibull nitrogen of a site in its foliage. Plants can distributions for the carbon content of soil to maintain the same foliage nitrogen level within 5 cm stands of Quercus dumosa throughout the a broad range of soil nitrogen levels. Changes State (fig. 2niVhis curve for in foliar nitrogen levels occur at the extremes comparison, the relative richness of any given of soil nitrogen concentrations. Soil nitrogen site to other sites in the State can be made. is the most direct measure of the nitrogen Any site which falls on the low end of this condition on a site. The Weibull distribution distribution should be considered marginal. of g. dumosa soil nitrogen content (fig. 4) range of carbon-nitrogen ratios occurring in provides a measure against which a site can be the top meter of soil (table 1). The Q. compared (fig. I). douglasii sites (oak savannahs) generally have lower carbon-nitrogen ratios than other Cali- fornia oak species. r-

L o .45 .do ' 1.35 1.80 2.25 2.70 Carbon (kg/m2) 0 I I I I I 1 Figure 2--Weibull function for carbon for Cali- 17.3 40.1 62.9 85.6 108.0 131.0 154.0 fornia Quercus dumosa soil (0-5 an) (Data Nitrogen (g/m2) supplied by Paul Zinke, University of Cali- Figure 4-Weibull function for nitrogen for fornia, Berkeley). California Quercus dumosa soil (0-5 cm) (Data supplied by Paul Zinke, University of Cali- fornia, Berkeley).

Leaves are an Important part of the nitrogen budget in an oak woodland. Depending on size, leaves were found to constitute 3 to 7 percent of the total tree biomass aboveground in the Georgia study performed by Monk and others (1970). Leaves in California are commonly 1 to 2 percent nitrogen (Wheeler 1975). Post oak-blackjack oak forests in Oklahoma have a nitrogen content of 2.4 percent in post oak and 3.4 percent in blackjack oak (Johnson and Risser 1974). The quantity of leaf nitrogen is related to nitrogen availability within the woodland. Leaves normally acquire all of their nitrogen early in their growth (Sampson and Samisch 1935). Before oaks drop their leaves (every year for deciduous species, every 1 to 3 years for evergreen species), much of the nitrogen in the Nitrogen (percent) leaf is translocated from the leaves to the woody tissue. The percentage retained by the Figure 3--Weibull function for California tree varies from 72 to 77 percent for Cali- chaparral f oliar nitrogen (Data supplied by fornia oaks (Wheeler 1975). Q. dynosa is an Paul Zinke, University of California, exception, with 27 percent retention (Sampson Berkeley). and Samisch 1935, Wheeler 1975). Much of the nitrogen left is in structural materials Another method of assessing site quali,ty resistant to microbial decomposition. is the carbon-nitrogen ratio (C:N) of leaf litter and soil on a site. Sites rich in Decomposition of nitrogenous compounds in nitrogen have a low carbon-nitrogen ratio. In leaf litter is similar to the decomposition of sites low in available nitrogen, the ratio carbon compounds. The nitrogen is made soluble increases. Profiles for several oak woodland by extracellular enzymes from microbes. From sites in southern California illustrate the there, the nitrogen may be leached into the Table 1-California Soil-Vegetation Survey data for the top 1 meter of soil in oak woodlands.

1 Carbon- 1 Plant 1 PPTN 1 Elevation

2 percent mglm

Quercus douglasii 20-50 23 Trimmer Fresno Grasses 80-100 (& douglasii 5-2 0 4122 (B) Supan Tuolumne Pinus sabiniana <5 Grasses 5 0-8 0 (& douglasii 20-50 578(B) Wishey lu Calaveras Grasses 50-80 & douglasii 20-50 10 6 Sacata Fresno Grasses 80-100 & douglasii 20-50 1759(B) Whiterock Calaveras Grasses 80-100 & douglasii 20-50 3991(B) White rock Calaveras Grasses 50-80 & douglasii 2 0-5 0 433 Laniger Tehama Grasses 5-20 & douglasii 20-50 617 (B) Argonaut Butte Grasses 80-100 & douglasii 20-50 101(B) Argonaut Yuba Grasses 20-50 Ceanothus 5-2 0 -Q. douglasii 20-50 353 (B) Amrogosa Butte Grasses 50-80 -Q. douglasii 20-50 439(B) Auburn Butte Grasses 50-80 -P. sabiniana 5-2 0 & douglasii 5-20 346 (B) Auburn Calaveras Grasses 80-100 -Q. douglasii 2 0-5 0 1722 (B) Exchequer Calaveras Grasses 80-100 & douglasii 20-50 824 (B) Exchequer Calaveras Grasses 80-100 & douglasii 20-50 0 Auberry Butte -Q. douglasii 20-50 2 0 Guenoc Shas ta Grasses 50-8 0 & douglasii 20-50 161(B) Sobrante Calaveras Grasses 50-80 --Q. lobata <5 286 7 (B) Chualar Yuba

Ñ'(B)=dat for bicarbonate extraction; otherwise water extraction Table 1-Continued

Carbon- Plant Cover Carbon Nitrogen Phos~y- nitrogen Soil County Quad/Plot PPTN Elevation rus- ratio

2 percent mglm

Q. wislizenii <5 Grasses 80-100 535 (B) Sobrante Yuba Q. wislizenii 20-50 12 Shaver Fresno Q. wislizenii 80-100 35 Ahwahnee Fresno Q. wislizenii 80-100 65 Auberry Fresno & wislizenii 80-100 Q. douglasii 5-2 0 Stover Tehama & wislizenii 20-50 95 0 & douglasii 5-20 Grasses 20-50 Sobrante Butte Q. wislizenii 5 0-8 0 2295 (B) & douglasii 20-50 Grasses 2 0-5 0 686 Ahwa hnee Fresno Q. wislizenii 80-100 & douglasii 5-20 579(B) Sierra Yuba Q. wislizenii 20-50 Q. douglasii 5-20 Grasses 5-2 0 Wisheylu Yuba Q. wislizenii 20-50 89(B) & douglasii 5-20 Grasses 20-50 84 7 (B) Rescue Yuba & wislizenii 5-2 0 & douglasii 20-50 Grasses N/A 15 To1 lhouse Fresno & wislizenii 20-50 Grasses 20-50 969(B) Dorado Calaveras & wislizenii 20-50 & douglasii 20-50 675 (B) Rancher ia Calaveras Q. wislizenii 5-2 0 Grasses 80-100 Q. wislizenii (shrub) 50-80 3019(B) Ahwahnee Yuba & wislizenii (shrub) 20-50 14 Sites Glenn 20-50

37 Weitchpec Humboldt Table 1--Continued

Carbon- Plant Cover Carbon Nitrogen PhosQo- nitrogen Soil County Quad/Plot PPTN Elevation rus~ ratio

2 percent kg/m2 & mg/m -c :N -mm -m -L . densif lora echinoides 50-80 33.48 837.21 438(B) 40.0 Hostler Yuba 39D4104 2032-2134 1220 Abies concolor 20-50 -L. densiflora 50-80 13.54 707.81 352 (B) 19.1 Salminas Sonoma 60D2/03 1778-1880 91 0 & kelloggii 50-80 18.35 921.74 791(B) 19.9 Challange Yuba 50A3/05 1270-1372 82 0 & kelloggii 20-50 6.23 282.62 22 22.0 Neuns Shasta 24D4/06 1270-1372 550 & kelloggii 20-50 11.36 848.58 , 32 13.4 Guenoc Sonoma 60C2/02 1270-1372 150 -Q. douglasii 20-50 & agrifolia 20-50 Grasses 20-5 0 & kelloggii 5 0-8 0 6.82 447.11 10 15.3 Mariposa Shasta 23A4/02 1270-1372 520 kelloggii 1 5-20 21.82 1713.60 27 12.7 Tyson Humboldt 26B1103 1778-1880 1040 Grasses 20-50 & sarryana 80-100 & ~arryana 80-100 16.93 1419.90 52 11.9 Tyson Humboldt 26B1116 1778-1880 1010 Douglas-f ir 5-20 Holodiscus discolor & kelloggii Douglas-f ir 1 & sarryana 1 20-50 6.78 433.12 72 15.7 Kilarc Shasta 15C3/01 1778-1880 5 80 &~arryana breweri 20-50 Grasses I root zone where it is taken up by the plant producing NO, is heterotrophic nitrification. root, the -root complex, or by In this process, a microbe takes an organic microbes for their own use. The microbes have compound with a nitrogen compound attached and life cycles of a few days at most after which changes the form of the nitrogen compound they are decomposed by other microbes. without ever releasing it from the attached Approximately 0.3 percent (Jensen 1932) of the organic compound. This process continues until microbial biomass in each life cycle is left in the organic compound has an NO3 attached. The microbial wall materials (humus), which is NO, is then split off and made available. No highly resistant to decomposition and also high free NH, or NO2 is produced in this process in nitrogen (C:N 10:l). Since there are (Focht and Verstraete 1977). several turnovers in microbial biomass each season, with 0.3 percent of the nitrogen lost Under anaerobic conditions, denitrifi- during each cycle, the amount of nitrogen cation, another step in the nitrogen cycle, can retained in resistant compounds steadily occur. NO3 can be converted to N 0 and N 2 2 increases. With each microbial generation, C02 which are subsequently lost to the atmosphere is produced through respiration and lost from (Focht and Verstraete 1977). The Importance of the soil. As the carbon is lost from the denitrification has not been determined, litter, the carbon-nitrogen ratio becomes although this chemical conversion appears to smaller. At ratios of 1:7 to 1:10, the provide a means of nitrogen loss under the remaining carbon is insufficient to continue litter where the soil is moist with anaerobic decomposition cycles. microsites . The mineralization of nitrogen in leaf Nitrogen in the roots (mostly fine) cannot litter to nitrogenous forms available for be ignored as an Important part of the oak root-mycorrhiza uptake proceeds through many nutrient budget~specifically, 21 percent of steps. Production of ammonium, NH,, from amino the total nitrogen held by an oak (Duvigneand acids is the first step in the process. The and Denaeyer-DeSinet 1970, Rolf e and others enzymes for ammonification are common in fungi 1978, Johnson and Risser 1974). Yet little and bacteria. Some plants and many microbes information is available on its dynamics. The can take up NH4 as a usable form, some cannot. fine roots are known to undergo seasonal cycles The transformation of nitrogen from ammonium to of growth and death, but no data are available the more available nitrate, NO,, is a two-step on the removal of nitrogen from these roots nitrification process carried out by bacteria before death. which use the energy released in the chemical process. In the first step, NH, is changed to More certain are the methods by which NO., by Nitrosomonas group bacteria. In the roots take up nitrogen. Root hairs, which second step, NO,, is converted to NO,, by occupy a limited area, take up nitrogen from ~itrobacteri bacteria. Both of these solution. Another effective means is through steps are sensitive to almost any disturbance, ectomycorrhizae which occur on all oaks (Trappe e .g., burning, plowing (Powlson 1975). The 1977). The sheath of ectomycorrhizal fungi acid pH of oak woodland litter and soil is not surrounds the active root tip, isolating it preferred by these two groups of bacteria. If from the soil and preventing production of root NH4 is the preferred form of nitrogen for hairs. The mycorrhizal sheath has mycelia plants being raised, the conversion of NH4 radiating from it which occupy the soil space can be blocked naturally by allelopathy more effectively than root hairs from the same (Rice and Paucholy 1972) or artificially by length of root. Surface area is increased ten N-Serve which is specific against Nitrosomonas times compared to root hairs. Mycorrhizal group bacteria (Goring 1967). Blocking this mycelia are also much more efficient than root conversion may be a major advantage in hairs in taking up water and nutrients, preventing the leaching of NO from the site. 3 including nitrogen. Many plants are unable to Pure culture studies have not determined a survive without the mycorrhizal association preference by oak for NO -N or NH4-N. Work on unless large amounts of fertilizer are added to Pseudotsuga menziesii (~irb.) Franco has shown make nutrients available, as in nursery that this ectomycorrhizal conifer cannot reduce operations (Menge and others 1978). NO N in its larger roots &i and others 1972); 3- however, subsequent study- revealed that the In wildland sites, adding nitrogen root tips of pure culture E. menziesii are very fertilizer may not be practical, so a natural efficient in reducing nitrate~bettereven than source of additional nitrogen is important. In the intact mycorrhiza. An alternate means of principle, both biological and nonbiological sources of additional nitrogen are available. Both rainwater and atmospheric dust contain i1~rapPe, James M. 1979. Personal considerable amounts of nitrogen. Air provides communication. U.S. Dep. Agric. For. Sen., another usable source of nitrogen derived from Pac. Northwest For. and Range Exp. Stn., volatilization of ammonia, NH , from soil, Portland, Oreg. lightning fixation, and industrial sources. Smog areas are also particularly heavy in Ecosystems efficiently conserve available nitrogen compounds (Appel and others 1978). nutrient supplies, particularly on low nutrient Though the amount of nitrogen from these sites. Few nutrients are lost with recycling. physical effects varies greatly, it cannot be Even the compounds resistant to decomposition ignored. are functional here, holding nitrogen which might otherwise be leached from the ecosystem. Three types of biological input of The rate of movement from one nutrient pool to nitrogen to oaks are recognized. In one the next determines the availability of method, animals which have grazed elsewhere nutrients for growth. Still unanswered is transport nitrogen into an oak savannah in the whether nitrogen added to the ecosystem is form of waste. These wastes are deposited and maintained over a period of time within that accumulate under trees which the animals use ecosystem or lost from it in order to maintain for shade and protection. The animals remove a fixed ratio between nitrogen and some other nitrogen from the same area in the form of element. acorns, browsed leaves, and grazed grasses. The net loss or gain from this exchange has not been measured, though Holland (1973) contends Phosphorus Cycle that removing cattle from an oak savannah does not change the nitrogen accumulation. Phosphorus is a nutrient known to be often in short supply, yet essential in the makeup of The second source of nitrogen accumulation compounds which transfer and hold energy, is from roots. Oak root systems extend out adenosine triphosphate (ATP) . Amounts present beyond the dip line of the canopy where, along in oak sites vary,,considerably (table 1). with their mycorrhizal associates, they remove Weibull distribution- of phosphorus values for nutrients from the entire area and concentrate 9. dumosa soil in California (fig. 5) provide a it around the tree by leaf fall. This should comparison of extractable phosphorus in the top result in a nutrient depletion of the area 5 on of soil for a given site. around the oak and an increase of nitrogen under the oak. But the area just outside the canopy in an oak savannah shows no decrease in nitrogen in the upper soil layers or grass production. Any root accumulation must therefore be from areas below the grass rooting zone.

The third nitrogen source in oak stands is nitrogen fixation. Biological nitrogen fixation can be symbiotic as in legumes and Ceanothus or nonsymbiotic as in many blue-green algae and some free-living bacteria species. Symbiotic nitrogen fixation associated with oaks has not been substantiated (Jain and Vlassak 1975). Nor are there reliable estimates of the importance of nonsymbiotic nitrogen fixation in oak woodlands, but it has the potential of being very important. One of the better documented cases of enhanced nitrogen fixation under oaks is with 9. dumosa lysimeters at Tanbark Flats, San Dimas Phosphorus (mg/m2) Experimental Forest. In these studies, there was no accumulation from surrounding areas and Figure 5-Weibull function for water-soluble aerial inputs to all lysimeters were the same, and bicarbonate-extractable phosphorus for but the oak showed increases over the controls California Quercus dumosa soil (0-5 an) (Data in nitrogen content (table 2) (Zinke 1969). supplied by Paul Zinke, University of Cali- This experiment suggests that Q. dumosa (and fornia, Berkeley). Eriogonum fasciculatum) probably enhances nonsymbiotic nitrogen fixation while Adenostoma Available phosphorus is often the problem, f asciculatum inhibits fixation. Ceanothus and not total phosphorus. Zinke's Weibull crassifolius is a symbiotic nitrogen-fixing probability distributions furnish two different species. A successful acorn crop provides a measures of available phosphorus. Mycorrhiza major sink of nitrogen which can be transported provides one means whereby the availability from the site by animals; however, a good problem is overcome. Root hairs inefficiently estimate of the amount of nitrogen in the acorn occupy a total soil volume and phosphorus crop is lacking and only poor knowledge exists diffuses very slowly in soil. In contrast, of the fate of this nitrogen in the ecosystem. mycorrhizal mycelia very capably occupy this Table 2--Nitrogen accumulation in the San Dimas lysimeters in 13 z- years (after Zinke 1969). Values are g/m of nitrogen.

Cover Type Original I/ 2/ 3/ 4/ Soil Barren Af- Ef f- Qd- Ccr

Vegetation 0 0 5.2 10.6 6.1 29.6 Litter 0 0 3.2 30.0 17.9 32.4 Mineral soil to 122 cm 318.0 283.8 -278.5 318.8 -343.6 320.1 Total 1 318.0 283.8 286.9 359.4 367.6 382.1 Change

I/ Adenostoma fasciculatum i;~d= quercus dumosa 7/Af = - Eff = Eriogonum fasciculatum - Ccr = Ceanothus crassifolius soil volume. Mycorrhizal fungi are very Microbes productive in phosphorus uptake. Citrus research shows a great increase in uptake Where oak roots are infected with efficiency when mycorrhizal fungi are present efficient strains of mycorrhizal fungi, much (Menge and others 1978). lower concentrations of available nitrogen and phosphorus can be tolerated. Enhanced nitrogen Availability of phosphorus is also changed availability through nonsymbiotic bacterial by the relationship between pH and phosphorus nitrogen fixation may also be possible in the solubility. More than 30 years of lysimeter future. These two types of microbes in measurements in the San Dimas Experimental particular need to be considered to preclude Forest show an increasing amount of available oak sites from reverting to grasslands or other phosphorus which correlates with decreasing non-oak areas. Nursery addition of good pH.- mycorrhizal strains could solve many problems (Trappe 1977).

Fertilization The amount of nutrient (such as nitrogen) on a site may also be important in determining Fertilization is currently an oak the spacing of oak trees, and may limit the woodlands management technique practiced biomass that a given site can support. outside of California to increase production. Phosphorus is particularly important because no Nitrogen fertilizer can be added to a site in biological way exists to fix this nutrient. two ways. Mineralized nitrogen fertilizer can The amount which is available on a site is all be added to a site, but on a large scale this the oak woodland will have. Fertilization may addition to low revenue producing oak woodlands figure Importantly in cases of low soil phos- is economically impractical; however, this may phorus. be very feasible in ornamental operations. A few principles are clear from fertilization Another impact of mycorrhiza on oak work done in the eastern United States. Most woodlands Is the production of subterranean studies show a response of eastern oak to fruiting bodies, or truffles (Gilkey 1916, nitrogen, but an N-P-K mixture gives a superior 1954). Truffles are important components of a' response (Auchmoody 1972, Farmer and others rodent's diet (Maser and others 1978, 1970, Broadfoot 1966, Buckley and Farmer 1974, Stienecker and Browning 1970) and are highly and Grandy and Pope 1978). The fertilization valued by Europeans for their flavor. Research response lasts 5 to 10 years (Buckley and is currently trying to introduce the European Farmer 1974). Fertilizer recommendations have mycorrhiza onto California oak for commercial to be made individually based on the unique production of truffles which would give oak requirements of each site. The implications .of woodlands a high economic value.Ñ In 1978, eastern United States oak fertilization experiments on western oak species is unknown. Oak fertilization and nitrogen cycling in the "~rappe, James M. Pers. commun. 1979. Mycor- eastern United States have been reviewed by rhizal applications in ecosystem management. Patric and Smith (1975). but no similar work U.S. Dep. Agric. For. Serv., Pac. Northwest exists for western oaks. For. and Range Exp. Stn., Portland, Oreg. the European black truffle brought $250 to $400 Broadfoot, W. M., and W. H. Pierre per pound. The production of edible truffles 1939. Forest soil studies: I. Relation of promises to provide more economic return than rate of decomposition of tree leaves to oak wood, and could increase wood production their acid-base balance and other chemical and provide a steady return until logging age. properties. Soil Sci. 48:329-348.

Native truffles also may be edible. Q. Buckley, W. B., and R. E. Farmer, Jr. dumosa at Kitchen Creek, San Diego County, 1974. Fertilization of Tennessee Valley California, has produced specimens of four pines and hardwoods: response during the different truffles: the Ascomycetes Geopora second 5 years after application. Tree clausa spp. Californica (Gilkey) Bards and Planters' Notes 25:14-15. --Tuber rufum var. nitidum (Vitt .) Fischer, and the hypogenous Basidiomycetes Gautieria Dickinson, C. H., and G. J. F. Pugh, eds. parksiana Zeller and Dodge and Hysterangium 1974. In Biology of plant litter spp. These fruiting bodies seem to be common decomposition, vol. 11. 530 p. Academic in the upper soil layers and are probably Press, New York. important to rodents and may be usable for human consumption. Duvigneand, P., and S. Denaeyer-DeSinet 1970. Biological cycling of minerals in temperate deciduous forests. In Analysis of temperate forest ecosystems. p. LITERATURE CITED 199-225. D. E. Reichle, ed. Springer-Verlag, New York. Akhtar, M. A., G. L. Rolfe, and L. E. Arnold 1976. Litter decomposition in oak-hickory Edwards, C. A., and G. W. Heath 1975. Studies in leaf litter breakdown: forests in southern Illinois. For. Res. 111. The influence of leaf age. Rep. No. 76-6, 3 p. Agric. Exp. Stn., Pedobiologia 15: 348-354. Univ. of Illinois, Urbana-Champaign. Farmer, R. E., Jr., G. W. Bengtson, and J. W. Anderson, J. P. E., and K. H. Domsch Curlin 1973. Quantification of bacterial and fungal 1970. Response of pine and mixed hardwood contributions to soil respiration. Arch. stands in the Tennessee Valley to nitrogen Mikrobiol. 93:113-127. and phosphorus fertilization. For. Sci. 16:130-136. Appel, B. R., E. L. Kothny, E. M. Hoffer, G. M. Hidy, and J. J. Wosolowski Focht, D. D., and W. Verstraete 1978. Sulfate and nitrate data from the 1977. Biochemical ecology of nitrification California aerosol characterization and denitrification. Adv. Microb. Ecol experiment (ACHEX). Environ. Sci. and . 1:135-214. Tech. 12 (4): 418-425. Gilkey, H. M. Auchmoody, L. R. 1916. A revision of the Tuberales of 1972. Effects of fertilizer-nutrient California. Univ. of Calif. Publ. in interactions on red oak seedling growth. Botany 6 (11) :275-356. U.S. Dep. Agric. For. Serv., Res. Pap. NE-239, 5 p. Northeast. Forest and Range Gilkey, H. M. Exp. Stn., Broomall, Penn. 1954. Tuberales. North American flora series 11, part 1. p. 1-29. Ausmus, B. S., and M. Witkamp 1974. Litter and soil microbial dynamics in Goring, C. A. a deciduous forest stand. Ph.D. dissertation. Univ. of Tenn., Knoxville. 1967. Control of nitrification of ammonium 202 p. fertilizers and urea by 2-chloro-6-(tri- chlormethy1)-pyridine. Soil Sci. 93 :431- Bocock, K. L., and 0. J. W. Gilbert 439. 1957. The disappearance of leaf litter under Grandy, D. L., and P. E. Pope different woodland conditions. Plant Soil 1978. Fertilization increases growth of 9:179-185. thinned and unthinned upland oak stands in the Boston Mountains of Arkansas. U.S. Broadfoot, W. M. Dep. Agric. For. Serv., Res. Note SO-243. 4 1966. Five years of nitrogen fertilization p. South. Forest Exp. Stn., New Orleans, in a sweetgum-oak stand. U.S. Dep. Agric. La. For. Serv. Res. Note SO-34, 3 p. South. Forest Exp. Stn., New Orleans, La. Holland, V. L. Patric, J. H., and D. W. Smith 1973. A study of soil and vegetation under 1975. Forest management and nutrient cycling Quercus douglasii H. & A. compared to open in eastern hardwoods. U.S. Dep. Agric. grassland. Ph .D. dissertation. Univ. of For. Serv., Res. Pap. NE-324. 12 p. Calif., Berkeley. 369 p. Northeast. Forest and Range Exp. Stn., Broomall, Penn. Jain, M. K., and K. Vlassak 1975. Study of nitiogenous activity in the Powlson, D. S. mycorrhizal rhizosphere of pine and oak. 1975. Effects of biocidal treatments on soil Ann. Microbiol. (Inst. Pasteur) organisms. p. 193-224 In Soil 126A:llg-122. microbiology. 262 p. N. Waker (ed). John Wiley & Sons, New York. Jensen, H. L. 1932. The microbiology of farmyard manure Rice, E. L., and S. K. Paucholy decomposition in soil: 111. Decomposition 1972. Inhibition of nitrification by climax of the cells of micro-organisms. J. Agric. ecosystems. Am. J. Bot. 59(10):1033-1040. Sci. 22:l-25. Rolfe, G. L., M. A. Akhtar, and L. E. Arnold Jensen, V. 1978. Nutrient distribution and flux in a 1974. Decomposition of angiosperm tree leaf mature oak-hickory forest. For. Sci. litter. p. 69-104. 2 Biology of Plant 24(1) :122-130. Litter Decomposition. Vol. I. 241 p. C. H. Dickinson and G. J. I. Pugh, eds. Sampson, A. W., and R. Samisch Academic Press, New York. 1935. Growth and seasonal changes in composition of oak leaves. Plant Physiol. Johnson, F. L., and P. G. Risser 10: 739-751. 1974. Biomass, annual net primary production, and dynamics of six mineral Stienecker, W., and B. M. Browning elements in a post oak-blackjack oak 1970. Food habits of the western grey forest. Ecology 55: 1246-1258. squirrel. Calif. Fish and Game 56:36-48.

Lang, Gerald E. Trappe, J. M. 1974. Litter dynamics in a mixed oak forest 1977. Selection of fungi for ectomycorrhizal on the New Jersey Piedmont. Bull. Torrey inoculation in nurseries. Ann. Rev. Bot. Club 101(5):277-286. Phytopathol . 15: 203-222.

Li, C. Y., K. C. Lu, J. M. Trappe, and W. B. Wheeler, N. C. Bolhen 1975. Foliar nutrient reabsorption 1972. Nitrate-reducing capacity of roots and efficiency in fire species of California modules of Ainus rubra and roots of oaks. M.S. thesis. Calif. State Univ., San Pseudotsuga menziesii. Plant and Soil Diego. 107 p. 37:409-414. Winn, C. Maser, C., J. M. Trappe, and R. A. Nussbaum 1977. Litter decomposition in the California 1978. Fungal-small interrelationships chaparral. M.S. thesis. Calif. State with emphasis on Oregon coniferous forest. Univ., Fullerton. 59 p. Ecology 59: 799-809. Woodwell, G. M., and T. G. Marples Merge, J. A., C. K. Labanauskas, E. L. V. 1968. The influence of chronic gamma Johnson, and K. G. Platt irradiation on production and decay of 1978. Partial substitution of mycorrhizal litter and humus in an oak-pine forest. fungi for phosphorus fertilization in the Ecology 49:456-464. greenhouse culture of citrus. Soil. Sci. Soc. Am. J. 42:926-930. Yielding, L. 1978. Decomposition of fire fuel components Monk, C. D., G. I. Child, and S. A. Nicholson of seven southern California chaparral 1970. Biomass, litter and leaf surface area plants. M.A. thesis. Univ. of Calif., estimates of an oak-hickory forest. Oikos Berkeley. 150 p. 21:138-141. Zinke, P. J. 1969. Nitrogen storage of several California Olson, Jerry S. forest soil-vegetation systems. In 1963. Energy storage and the balance of producers and decomposers in ecological Proceedings of a conference on Biology and Ecology of Nitrogen. p. 40-53. Natl. systems. Ecology 44 (2): 322-331. Acad. of Sci., Washington, D.C. Quercus kellogc~ii

Oaks and the California Landscape1

R. Burton Litton, Jr. 2

Abstract: Native oaks are important visual elements in the California landscape. Their significance is suggested by statewide distribution, by historic association, and the variety of visual roles played. Much of our local and regional landscape character is identified with different oak species and their visual arrangements; conservation of that character helps maintain scenic amenity. Oaks and landscape are discussed in regard to highways, recreation places, and urban forests. Some landscape research needs on native oaks are posed.

INTRODUCTION quality. Two of the patterns consist of highly contrasting mosaics of grass and oak Native oaks play a significant role in the woods with strong light to dark color con- California landscape. Oaks and their typi- trasts. In spring they display a marked cal visual arrangements contribute to the color brilliance. One of these two patterns distinctive identity of local and regional is the oak savannah, a continuous woodland landscapes. .Indigenous oaks are both numer- spread of scattered oaks, variable in den- ous and widely distributed. Historic ac- sity, through which the simple and flowing counts recognize the relationships of oak ground plane of grass remains apparent. The trees with such places as Oakland and with other pattern is a discontinuous mosaic of early Spanish exploration. The maintenance oaks in solid wedges, stringers, or whole of the esthetic character of California slope faces interspaced with clear grassland landscapes, some of it intimately dependent patches of various shapes. This contrasting upon oaks, should be recognized-as one part pattern of distinct oak and grass areas can of environmental quality protection. usually be correlated to facets of the topo- graphy and to exposure. The third major California oaks, as a group, occur in sev- pattern is that of occasional oaks--espe- eral sets of visual relationships which typ- cially black oaks (Quercus kelloggii Newb.) ify particular regional landscapes. Three --either grouped or alone within the domi- distinctive oak patterns contribute to scenic nant continuity of the mixed conifer for- est. This is a more subtle pattern than the preceding two but the scattered presence of Presented at the Symposium on the oaks makes local cells of contrast in color Ecology, Management, and Utilization of and light intensity compared to the more California Oaks, Claremont, California, June sombre, more abundant conifers. These par- 26-28, 1979. ticular oak patterns have special value in their contribution to scenic quality that Landscape Architect, Pacific Southwest has regional identity. They should serve as Forest and Range Experiment Station, Forest physical models to influence the form of Service, U.S. Department of Agriculture, development changes. Urbanization and land Berkeley, Calif.; Professor of Landscape use conversions are prone to make every Architecture, University of California, place look similar, leading toward mediocrity Berkeley, Calif. in our surroundings. Retention of Califor- tirely different species: Oakdale, Stanis- nia oak landscape as a physical, visual re- laus County, memorializes interior live oak source and responding to it ultimately (Q. wislizenii A. DC.); and Oakville, Napa serves environmental quality more broadly. County, recognizes its big valley oaks (9. It is logical to start by conserving local lobata Nee). It is apparent from these few and regional amenities. examples that oaks have strong enough visual images to be perpetuated in names. Kuchlerls vegetation map (1964) suggests we are never very far away from native The maintenance of local or regional land- oaks. The whole rim of the Central Valley, scape character built upon native oaks rep- save a small gap at the south end, is oak resents an extremely important and more ef- woodland. That ring is about 900 miles fective means of conserving scenic amenity long, includes some five oak species vari- than any attempt to provide a man-made sub- ously distributed north to south and east to stitute. The original landscape of an area west, but runs heavily to blue oak (9. w- is normally an extensive combination of re- -lasii Hook & Arn.). Then in the northern gionally typical landforms, vegetation pat- Coast Range from Eureka to the south of San terns, and water forms. To this will be Francisco - some 250 miles--we find oaks added new land use patterns, either urban or among the dominant trees within the mixed rural; but in usual situations no overall evergreen forest (Kuchlerls type 29). The man-made substitute takes the place of the southern Coast Range~Montereyto Santa Bar- earlier landscape. Physical signs of human bara--is again characterized by the Califor- activities,including clearing, grading, con- nia oak woods type. Canyon oak (9. chryso- struction, and new planting, are more apt to Liebm.) and black ~ak~especiallythe be seen as fragmenting rather than integra- latter, are visually important though subor- ting. The use of introduced trees is not dinate counterpoints within the very exten- automatically ~ondemned~becauseit can be sive mixed conifer forest of the Sierra-Cas- both efficient and attractive; but the sen- cade west side, the Klamath Mountains, and sitive use of indigenous oaks, along with the north end of the Coast Range. The pre- their perpetuation in place, is an important sence of oaks does not end there7because means of integrating new development with pockets of them grow on the ridge east of the broader surrounding landscape. San Diego,while at the extreme north end of the state, the Oregon white oak (2. garryana Dougl.) makes a token appearance. The Cen- Highways tral Valley, particularly the Sacramento portion, has its oak hummocks and riparian Highways are a primary way of showing us stringers, the last suffering serious reduc- the landscape. They pass through the coun- tions compared to an earlier time. The only try in one of two ways. They can thread sizeable part of California's landscape through the landscape in a way conforming to without the visual component of oaks or re- the landforms and tree cover typical of a mote from it is the southeastern desert locality, combining road and countryside country. into a satisfying experience. Or the high- way can more literally blast through terrain Some place names of the State suggest his- and vegetation providing a road foundation torical or cultural values based upon oaks without apparent regard for surroundings and being conspicuous in certain landscapes isolating road from place. Where the compo- (Gudde 1965). The Spanish were more dis- nents and scale of the landscape fit the criminating than later settlers, distin- scale and design of the highway, there may guishing live oak (encina) from the decid- still be failure to make compatible rela- uous oak (roble). Part of the city of Oak- tionships with the local vegetation mosaic. land was originally called I1Encinal de Tem- Not all highways include roadside planta- escaltf (Liveoak Grove by the Sweathouse), a tions, but all roads pass through the land- name reflecting Spanish, Mexican, and Indian scape. Some examples may suggest how Calif- influences. Both the earlier Spanish and ornia oaks can relate to highways and coun- the later Anglo-Saxons nonetheless observed tryside. that oak groves were distinguishing elements of this particular landscape. Paso Robles Freeway 24 leaves Walnut Creek and ap- (Pass through the Deciduous Oaks) in San proaches Oakland through several ranks of Luis Obispo County was first named by Padre hills. The dominant native vegetation is Pedro Font in 1776, later becoming the title live oaks in draws and on shadier slopes of a land grant and was finally adopted as while drier slopes are valley oak woodland the city name in 1889. Two other towns or mosaics of oak-chaparral. The roadside named for oaks in the 1870's refer to en- within the right of way is planted in a com- plete way, a relatively normal procedure for fenced line. By contrast, the freeway ap- an intensively traveled route in an urbani- proaching and leaving these blue oak hills zing area. The plantings are eucalyptus and runs with a straighter alignment through pine with introduced shrub cover which do flatter, open country. This kind of skill- not recognize the adjacent and distinctive ful highway design made responsive to a lo- native cover of oaks, grassland, and chapar- cal landscape gives the traveler an inter- ral. The plantation solves certain func- esting sequential change in an otherwise tional problems, such as light-motion rather monotonous stretch of road. The screening and erosion control. Yet the con- character of the oak woodland is observed cept of the roadside plantings totally ex- and no other roadside plantings are needed. cludes any influence by the original land- scape or linkage with it. A visual connec- The general policy for planting along tion with the surroundings could have been California highways is to be guided by the made with judicious placement of oaks, even vegetation adjacent to the right of way. It while allowing use of certain subordinate is a matter of design judgment as to what exotics if practical necessity demanded it. degree there is response to the local man- This particular freeway planting addresses altered landscape or to the native regional certain functional problems, but the amenity surrounding. California oak landscapes are provided is isolated from the broader land- distinctive and merit consistently sensitive scape seen from the road. response in highway design and construction phases. In a related counter example, live oaks are the major roadside trees planted along Highway 101 in the vicinity of Santa Maria. Parks and Recreation Places Roadside oaks correspond directly with the scattered oaks of the adjacent flat, then For parks and recreation places where oaks together they make a visual linkage with the dominate the landscape, two questions about local hillside mosaic of live oak-chaparral. visual quality arise. Are new plantings Highway 101--the Redwood Highway~between made with appropriate attention to surround- Petaluma and Santa Rosa runs through open ing oaks? Does silvicultural management agricultural country with considerable resi- assure perpetuation of oaks? dential development. The native landscape of flatter parts is grassland with widely A century ago, Grinding Rock State Park in spaced valley oaks. Hill slopes in the dis- the Mother Lode was a favored spot where the tance are grassland or evergreen forest with Miwok Indians gathered acorns from the val- live oak (2. agrifolia Nee) dominant. This ley oaks and black oaks. Farming later mod- being the Redwood Highway, widely spaced ified the area by clearing. Now old and clumps of redwood are planted along both mature oaks appear as landmark trees. Some sides of the roadway. Redwoods were never a of the oldest are decadent and falling a- part of this landscape. Those that are now part. Younger oaks grow in rather dense planted grow in an inhospitable climate of woods with some ponderosa pine and incense summer drought, heat, and wind. Tourism and cedar. There are almost no oaks of inter- the strength of a name have taken precedence mediate age and size. The purposes of the over a more appropriate useage of valley modern park use will be served well by main- oaks which belong in this place. Redwoods taining large, rather widely spaced oaks in will occur naturally along the highway fur- sizeable openings bounded by dense pine-oak ther north, a canopied landscape infinitely forest. The park is a handsome oak land- more impressive than this artificial planta- scape reflecting an early history of Indian tion. use. Yet it will not remain as it is, and a tree replacement program is needed. The South of Red Bluff, Interstate 5, the high- problem posed is one of recreational silvi- speed freeway passes through rolling low culture coupled with spatial design to suit hills covered with blue oak woodland, a rel- contemporary and future park needs. The atively small-scaled landscape. By modify- model to be followed is present in the land- ing horizontal and vertical alignments to scape as it may now be seen. fit the hills and adoption of a variable median area, the separated opposing lanes Glencliff campground in the Cleveland Na- approximate the visual scale of a two-lane tional Forest is in a flat with large and road. Continuity of the blue oak woodland scattered canyon live oak. The oaks are is maintained within the median as well as conspicuous for their size; their darkness along the right-of-way boundary. The out- contrasts to lighter enclosing hillsides side edges are cleared irregularly rather with thin and sear chaparral. While canyon than following the absolute edge of the live oaks are the primary visual key to the local landscape, they also afford the func- tageous soil-moisture conditions. Such up- tional amenities of shelter and shade; the land areas offer special visual values to a local climate is seasonally harsh. With the city because of their possible continuity openness of oak woods being less than ideal and their high degree of visibility from for a campground, plantations of Arizona lower parts of town. That wooded continuity cypress have been introduced for screening. can be maintained while containing low den- The pointed and glaucous forms of the cy- sity housing if carefully done or by concen- press have little in common with the origi- trating pockets of higher density housing nal surroundings, are visually competitive separated from areas of oak woods. Conser- with the oaks, and can not give the shelter vation of such oak areas can succeed only the oaks do. As an alternative--and in re- with early recognition of their value, and sponse to what may be seen--it would have sensitive planning and design. been possible to use heavy plantings of can- yon oak, first to give screening and later Other advantages of oaks in grouped pat- to grow selected oaks into tree form. terns extend amenity values into other in- herent relationships. Their adaption to At one level of consideration, the intro- place enhances survival potential. At the duced cypress at Glencliff are satisfactory same time, massed groupings are logical sub- in their growth and in improving the recrea- jects for application of silvicultural man- tional site. In a more urban place than agement which can assure their future. Yet this one, designed contrasts combining na- judging from the Berkeley campus of the Uni- tive and introduced vegetation may be ac- versity of California, the concept of main- cepted as interesting and appropriate~the taining oaks by silvicultural means is not context of a man-modified environment. At evident. Photographs from the year 1900 another level of consideration, this example show remarkable old and mature live oaks, shows no appreciation for the special visual perhaps 200 or more years old at that time. character of the surroundings, a point of Having reached the end of their life span, principle that bids ill for protecting a none of these old giants remain on campus. particular wildlands environment. Even so a form of recreational silviculture applied to existing oak groves and coupled with control of irrigation could give this Oaks in Urban Forests campus some historical ties to an earlier condition. In a recent paper on urban forestry empha- sizing visual landscape values, I defined Connected functional and aesthetic pur- "urban forestn as the general impression of poses are also served by oak woods. They forest within the city seen both close by include urban wildlife habitats, offering and in the distance (Litton 1978). To this sanctuary to birds and small mammals, and should be added the attendant values of var- the esthetic opportunity for wildlife obser- ied uses which apply to urban systems of vation. They provide watershed protection combined forested and open spaces. Oaks in by slowing up urban runoff and retaining the urban forest are apt to be remnants of water. Oak groupings, if of sufficient size an earlier rural landscape,and as such, of- and continuity, offer desirable opportuni- fer particular advantages. Since oaks nor- ties for recreational access, the location mally occur either as isolated individuals of limited park facilities, and connective or massed into woods, they can be considered routes. A function of oak management, coup- in these two ways in towns or cities. led with open space design objectives, may be the extension and consolidation of oak Oak Woods woods.

As part of the visual landscape, oaks are Single Oaks arranged (or were so originally) in discern- able patterns of woods intimately reflecting Individual and isolated oaks in the city-- the forms and aspects of local terrain. In largely remnants of an earlier time~appear turn, the local scene joins a larger region- to have greater threats to their survival al landscape. So oaks can contribute di- than do oak woods. Sheer competition for rectly and importantly to the amenity of the space is the central problem, but individual city, both locally and as tied to broader construction activities as well as the col- surroundings. In cities such as Berkeley lective impacts of urban development take and Santa Barbara, live oaks are found their toll of native oaks. Carelessness and grouped in stringers or wedges of upper wa- ignorance contribute, but even the most tersheds and defiles, massed on steeper up- careful measures meant to protect individual land faces and adapted to sites with advan- trees can eventually fail. New oaks planted after construction may have the best chance Landscape Research on Native Oaks for successful growth in altered site situa- tions. The need for Landscape research on Calif- ornia oaks can be posed by such questions Separated and single trees have visual as: How can we maintain oaks in urban influence only over local scenes--a differ- places? Can forms of recreational silvicul- ent scale relationship from that of massed ture be developed for perpetuation of oak oaks. Only if widely spaced trees are suf- woods? Would it be useful to find out how ficiently repeated do they endow notable oaks may be commonly appreciated in certain character to a town--a condition fulfilled California landscapes? Would the assembly by the valley oaks of Paso Robles. Even so, and dissemination of current information because oaks are generally long lived, the about oaks be useful to citizen's groups? enduring dominance of a single large tree in To urban planning departments? To environ- the local landscape is significant and with- mental planners and landscape architects? out substitute. Maintaining oaks in urban places means pro- Oak species have life spans ranging from tection of individuals as well as grouped 150 to 300 years (Harlow and Harrar 1950). trees. We need to understand how particular Therefore, protection of all but decadent species have been affected, and to what de- individuals is worthwhile. Problems of gree, by the urban stresses of grading and maintaining single oaks in town, for parks paving, changes in surface and groundwater or other purposes, can be represented by the supplies, and by microclimate modifica- example of constructing a single building tions. It appears, for example, that valley near an oak or oaks. A house may be archi- oaks are more sensitive to paving over the tecturally designed to fit the focal feature root zone than are live oaks, but such gen- of a single fine oak, with the tree working eralizations are not specifically helpful as a central link between house and garden. and may be misleading. Oaks, according to It is a grand and simple idea. The execu- species, have different but relatively long tion needs care at every step, followed by life spans; more accurate prediction of fu- proper water and garden management. Conven- ture life has a bearing on adoption of pro- tional experience indicates that avoiding tective measures. Does the urban environ- any changes within the drip line of an oak ment have a material effect on oak longevi- is the most desirable way to be safe, a ty? Oaks seem to grow slowly, and this as- safeguard frequently violated. The struc- sumed rate may be a misguided reason given ture must fit the tree level; grading must for discouraging their planting. We actual- be minimized. House walls cannot crowd the ly know little about growth rate of oaks in tree. Foundation design to avoid root dam- either urban or rural places; it may be fas- age may require bridging or piers in lieu of ter than assumed and cultural practices continuous walls. Any filling or paving could enhance growth rate. A slower growing within the tree canopy area can be threaten- oak as a street or park tree offers a real ing (decking, permeable paving or sharply advantage over faster growing trees in need- limited paving may succeed). Elaborate sys- ing a minimum of pruning maintenance. Avoid- tems of maintaining an air-water interface ing the impacts of some pruning practices between original ground grade and imposed used on fast growing trees suggests both fill are unlikely to succeed except tempor- economic and esthetic bonuses. Cities with arily. Roof water has to be removed inde- trees massed in woods could perpetuate those pendently from the tree root zone, and any trees by the adoption of silvicultural tech- under-canopy gardening should be modeled to niques. Even so, we do not know about how follow the preexisting condition of the mi- large an aggregation of oaks, or in what crosite and its climate. A successful end condition - may make it a suitable subject result means careful attention to a full of silvicultural research. array of factors. Experimentation with recreational silvi- Contemplating the place of oaks in urban- culture, that silviculture oriented to land- izing situations suggests several conclu- scape resources, may best start in rural and sions. What we may know about oak protec- wildlands areas. Grinding Rock State Park tion and culture is neither assembled in has been suggested as an appropriate place accessible form nor is it available for for such research. Bringing together sev- every day use. What we do not know about eral professional disciplines is needed~the oaks and their use in landscape is consider- plant ecologist-forester, the park adminis- able and a desirable research subject. trator, the landscape architect. And the social scientist is called upon to ascertain space agencies. As an example, there appears public values and to communicate with a pub- to be much popular interest in native plants; lic which can be hostile to misunderstood sometimes it takes a naive form, suggesting manipulations in park landscapes. It takes that all nativesare good plants,presenting a time for an interdisciplinary research and heaven-sent solution to maintenance-free planning team such as this to integrate landscapes. We know native plants, includ- their varied capabilities and to identify ing oaks,are an interesting class of plants goals. Silvicultural manipulations take which demand certain conditions for success- time to show effects. A long-term policy is ful growth, but research priorities about needed to assure that the undertaking is not oaks need identification. A working paper scuttled by neglect or adoption of new, should also be helpful in revealing a con- short-view policies. stituency interested in oak use and protec- tion along with what they need to know. In conclusion, the identification of oak Although a "state of the artw publication landscape values within this paper has been represents a modest kind of proposal, it based upon personal, professional judgment. should be both immediately informative and To confirm or deny the elements of profes- suggestive of what we need to find out about sional landscape judgment and to discover native oaks in the California landscape. other esthetic values that interested com- munities may have about the outdoors is pos- sible only with social science research. LITERATURE CITED This kind of research in wildlands is polit- ically unpopular and difficult to fund. Yet Gudde, Erwin G. it is needed to show what degree of public 1965. California place names. 383 p., support may exist to maintain the environ- Univ. Calif. Press, Berkeley, Calif. mental qualities of oak landscapes and their regional identity. Harlow, M., and Ellwood S. Harrar. 1950. Textbook of dendrology. 555 p., We as resource managers should strive to illus. McGraw-Hill Book Co., New York. bring together knowledge now fragmented and spread out among many different individuals. Kuchler, A. W. Information about California oaks is not 1964. Potential natural vegetation of the readily available in any concentrated or conterminous United States. Amer. Geog. easily available form. Certainly many indi- Soc., special publication no. 36. 155 viduals--researchers, academicians, plan- p., illus. Amer. Geog. Soc., New York. ners, foresters, landscape architects, to name some--have information about oaks based Litton, R. Burton, Jr. upon research and observation. A "state of 1978. Applying visual research concepts the artv publication about oaks would fill a and methods from forestry to the urban void at this time. Such a working paper scene. In Proc. Nat. Urban Forestry would be helpful to researchers, profession- Conf. ["Nov. 13-16, 1978, Washington, al practitioners, and local planning/open D.C. 1 (in press). Measures That Can Help Offset the Detrimental Effects That Urban Development Has on OakTreesl

Paul A. Roger- 21

Abstract: Land development is seriously encroaching upon our southern California oak woodlands. Urban development not only creates an unnatural environment, it also impacts these oak trees. Unless careful corrective measures are taken during construction, the trees ultimately decline and die. The effects that construction has on oak trees with regard to loss of air, water, and nutrients are discussed. The loss of roots and/or top foliage during construction is of major concern. Solutions center on the preservation of driplines during con- struction, special procedures for grading cuts and fills around oak trees, the use of specialized soillair drainage systems, and compensatory pruning and fertilization of impacted trees. This paper covers the practices currently used to preserve oak trees in highly developed areas.

All of us appreciate the native oak instance, drainage water from a car-wash rotted trees and are familiar with their majestic the roots of one oak tree so extensively that beauty. But as man continually develops their we were able to pull it straight out of the natural habitats in the coastal valleys and ground with a crane. foothills it is inevitable that he will en- croach upon them. This encroachment not only The oak problem in many sites to be creates an unnatural environment for these developed begins with the army of heavy trees but it often seriously impacts them un- equipment that is used during grading. This less careful corrective measures are taken. is damaging to the trees, as soil is removed This paper will provide an overview of some of and roots are either severed or filled over these problems and offer some mitigating and compacted. Additionally, water tables measures that can help to offset them. are changed and trees are often neglected during the entire construction period. Com- Urban development continually encroaches pounding this is the dust that accumulates on upon the oak trees' well-being by the con- the leaves. Compaction is often further in- struction of homes, roads and utility lines. creased as the trees offer shade to construction Additionally, grading changes most seriously workers and their vehicles. impact oak tree roots by both cuts and fills. Ultimately natural drainage courses are Once grading is completed the con- changed such that the tree is now forced into struction of buildings also takes its toll on an unnatural environment. From this point on, the trees. Utility trenching severs roots and decline is usual, and it is an eternal battle often such trenches are left open for extended to try to save a tree in this condition. For periods of time.

Building construction often requires Presented at the Symposium on Ecology, removal of some of a tree's upper structure. Management and Utilization of California Oaks, Disfiguration by limb breakage is a common June 26-28, 1979, Claremont, California. occurrence. When pruning is performed, large limbs are often removed or the tree may become somewhat pollarded, which obviously destroys its L' Landscape Consultant, Ojai, California. beauty. Such severe pruning further creates Figure I--Maintaining healthy oak trees on developed sites requires input from several disciplines.

problems with growth flushes and the subsequent their bases, improper pruning, and perhaps witches broom or powdery mildew diseases. further compaction. In time, it is inevitable that such trees will decline and eventually die. By far the greatest problem we encounter from development around oak trees are those So, those are the problems -- at least situations where soil is filled at the trees' some of them that confront us. It is possible bases. This is critical forair and water to have successful stands of oak trees in an drainage. Oftimes such fill soil located at urban scene. We have many such situations but the tree's trunk will retain moisture and in it does require expertise and money to achieve time will cause rot and eventually undermine success. Such an effort encompasses the inter- the tree. One declining tree that we in- facings of several disciplines (Fig. 1). A vestigated had seven feet of fill at its base. discussion of some of these follows- After its soil was removed we found that the basal area had already rotted two-thirds A good horticultural evaluation of all around the trunk. It appeared that former trees present on a proposed site is most im- construction had damaged the tree trunk and portant. Such an evaluation essentially that the presence of soil and its moisture separates the trees into removal and preser- retention had accelerated the demise of this vation categories. Some times we try to save tree. trees that shouldn't be saved. This is a costly decision because tree removal after Once site development is completed the construction has been completed is considerably tree problems do not end. This is a critical more expensive than earlier removal. time for them. Recognize that the trees have been removed from a natural environment, weak- A good horticultural evaluation en- ened by development and are now located in an compasses an investigation of all tree parts artificial environment. Such an environment by a knowledgeable person. Upper structure subjects them to overirrigation, planting at should be examined for cavities, physical weaknesses and possible pest problems. Such These examinations must be performed pest problems may have to be identified by a and recorded in order to accumulate as much pest control advisor and by pathological information as possible on each tree. Such testing. evaluations should include tree sizes relative to height and spread, and root locations so Basal parts of the tree must be in- that developers can plan around them to avoid spected in detail. Trunks should be examined serious impaction. for cavities or the presence of excessive amounts of fill soil. Not to be overlooked When evaluating the impact of con- are the trees' roots. Where are they? Are struction on trees, building and landscape are the trees deeply rooted such that construction of key importance. We try to save as many may not seriously impact them (Fig. 2)? Are trees as possible and to lessen the impact of they diseased? construction on them. For example, rather than construct a concrete wall which would disturb a tree's root systems, a wooden fence TYPICAL OAK TREE RHIZOSPHERE may suffice, as it would not require trenching for a foundation. Relocation of building pads or utility trenches can also be of great benefit to a tree. Perhaps several utility lines could be placed into one or two trenches -- thereby reducing tree root loss.

Pre-job conferences with all contract- ors can be of great benefit. Such meetings can enlighten these people about the trees and their care. Also the use of fences placed around oak tree drip lines can assist in assuring that compaction and the dumping of debris is lessened.

Ideally it is best to have all surgical or pruning work done prior to con- struction. This permits ease of arborcultural work and tree pruning performed often balances the roots lost during construction. TYPICAL WR PLAT CONDITIONS Should special tree wells, watering or feeding be required this is also an excellent time to perform them.

It is important that a knowledgeable person be present or available during all phases of construction. Such a person (usually a horticulturist or arborist) would be monitoring the trees and ensuring that they are properly maintained. Also such a person would have the capability to establish programs for future levels of maintenance.

In summary, then, protecting our oaks is the implementation of a complete program (Fig. 3). Such a program involves pre-site planning, horticultural evaluation and data collection design, and preparation and care of x - Distance of sensitive the trees prior to, during, and after con- IMIZOSMRIC CONDITIONS root zone beyond drip Tkst dramdeolct the line. struction around them. This program may inter- aver- rtiizospkm of the face many disciplines such as landscape two mjor Oak species found S, - Distance of sensltiv* within Ox . root zm downhill of architects, pathologists, entomologists, Th1Ã....- Infft-ttnn....-.-- .-. 1s.- based- - - -- tree~ - on slooe. upon 8 years of observation horticulturists and others as illustrated. during construction. CR - Remaining ennui radius I 10' critical Once these program items have been put into zone. effect, we will be able to have successful oak Figure 2--Typical distribution of root zones stands within urban development. under the canopy that are "sensitive" or "critical" to the trees' well being. OAK TREE MANAGEMENT FLOW DIAGRAM PROPOSED ENCROACHMENT TRANSFER TRANSFER Into sensitive root zone To new Homeowner's On-going oak tree maintenance occurs to Homeowner's Association = I I I I I I I I I I I I I I I I I I I I I I I I I I I I I - I m I ONE YEAR a ONE YEAR TWO YEARS I I a I I rn Figure 3--Flow diagram illustrating the critical periods of an oak tree management schedule. Aspects of Water Relations in Coast Live Oaks and Valley Oaks Subjected to Root Damage from Land Development Operations1 Stephen W. ~obert.8and Robin L. 3uith3' Quercus 1obata Abstract: Xylem pressure potentials and stomatal conductances were intensively monitored in individuals of coast live oak (Quercus agrifolia) and valley oak (Quercus .- lobata) in order to assess short-term effects on the tree water system resulting from root pruning and land grading operations. Increased water stress was measured in affected trees. The most negative potentials were approximate1y -30 bars in September and October in both species. Stomata1 conductances were typically quite low (0.02 to 0.10 cm s). Patterns of stomatal activity were measured which appeared to limit water stress. It was concluded that these oak species possess adaptations which may enhance survival following root system disturbances such as may occur during land development operations.

INTRODUCTION management areas. These individuals now face important challenges in regard to appropriate treatment of these oak communities. Southern oak woodland communities in southern California are being increasingly The oak trees in the study area represent utilized by land development projects. The species which have evolved a set of responses principal tree species in these communities are to external water availability under vegetationally, ecologically, and aesthetically environmental constraints which have operated important community components. In the area of over evolutionary time. Changing land use Thousand Oaks, California, Quercus agrifolia patterns which alter the water regime for these (coast live oak), 9. lobata (valley oak), and plants represent an important perturbation to a other oak species have undergone significant key environmental factor. In addition, the habitat modification from recent grazing and time scale of such perturbations is short farm practices and currently by changed relative to the generation time of the trees. land-use patterns from land developments. The which may live for hundreds of years. Thus, survival and reproduction of oak trees in this individual trees with a set of response rapidly changing environment is of concern to properties largely determined by past individuals working in the conservation and evolutionary history must now survive and reproduce under new conditions which may be quite different from conditions under which those properties evolved. I -/ Presented at the Symposium on the Ecology, Management, and Utilization of California Oaks, A working hypothesis of this study is that Claremont , California, June 26-28, 1979. site modification by land development will alter site water balance. The changed water Zl~esearchProfessor, Biology Department and balance should in turn affect a variety of Systems Ecology Research Group. San Diego State physiological processes in the oaks and other University, San Diego. California 92182 and plants. These effects may be detected in Chambers Consultants and Planners, 10557 Beach changed tree water use patterns through altered Boulevard, Stanton, California 90680. leaf stomatal conductances, which govern the exchange of water vapor, CO , and other gases, SPlant Ecologist, Chambers Consultants and and altered patterns of leaf water potentials, Planners. 10557 Beach Boulevard, Stanton, which are related to the ability of plants to California 90680. extract soil water and which affect rates of a number of metabolic processes. This study was and grading operations were assessed primarily designed to test this hypothesis and in so through measurements of xylem pressure doing provide needed data on water potentials. Pressure potentials were measured relationships of Q. agrifolia and 2. lobata. using a pressure chamber of the type described These data would then allow a preliminary by Scholander et al. (1965) and by Ritchie and evaluation of some effects of site modification Hinckley (1975). Stomata1 diffusion such as grading, drainage alteration, soil conductances were also measured with a loading by structures, irrigation, and other porometer of the type originally described by activities associated with land development. Kanemasu et al. (1969). During days of tree water relation measurements, air temperature and wet bulb temperature were measured with a shaded sling psychrometer. Photosynthetically METHODS active solar radiation (PAR) was also measured. Soil psychrometers were installed to measure soil water potentials at 5, 20, and 60 cm The study site was located on the depths. development known as Ben Johnson's Fairway Homes, near Thousand Oaks, California. The site is on gently rolling terrain dissected by Table 1--Brief characterization of study tree small drainages and intermittent streams. The settings. property is part of North Ranch, and the study area had been used in the past for grazing cattle. Individual tree Comments

The trees studied were all mature 18, 19, 20 (QL) Located on a ridgetop, in individuals roughly 80 to 100 years old. Tree well-drained, somewhat heights were generally between 20 and 30 feet. sandier soil than is ty- The trees for which data are presented are pical at the study site. characterized briefly in table 1. Water relations were measured in individuals of Q. 787 (QA) Located off the study agrifolia and Q. lobata which had varying site, used as one of the portions of the root system removed as a result control trees. of building retaining walls near the trees. 89, 92, 93, 94 (QL) Located in close proximi- The fraction of roots which were removed could ty to each other on gent- not be quantified because the root ly sloping terrain typi- distributions of the individual trees were not cal of the study site. known. However, an approximation of root system disturbance is given by the use of an index as described shortly. The walls involved vertical cuts typically 4-6 feet in depth. Table 2--Root Disturbance Index measured for located approximately 8-10 feet from the base the trees in this study. of a tree. Measurements were also made in undisturbed control trees as a reference by which to gauge the effects measured in the Tree Root Disturbance Index (RDI) disturbed trees. A crude index of disturbance to the root system was obtained by measuring -Inches - the length, depth, and distance from the tree base of the trenching cuts. These values were 0, 29837 then incorporated into a "root disturbance 510 indexw (RDI ) using 419 11 0, 1129- 340 229 0

&'When serving as a control tree, RDI = 0: final RDI was calculated following grading operations. where D is the depth of the cut, L is the length of the cut. and R is the radial distance of the cut from the tree base. All Daily courses of leaf water relations were measurements are in inches. Measurements were measured beginning at dawn. Pressure bomb leaf taken in increments around each tree and summed samples were obtained using a climber who to give the total RDI. These indices are given extensively sampled all levels and exposures in in table 2. The effects of these root-cutting the tree canopy. These data indicated that a major source of variability in pressure Measurements were made in late September potentials was the recent previous condition of to characterize short-term changes in the daily exposure of the leaves to solar radiation. course of pressure potentials in Q. agrifolia Analysis of these measurements revealed that subjected to root pruning. Two trees growing the horizontal variability was as great as the on even terrain approximately 120 feet apart vertical variability in the canopy. Thus, were selected. One, Q. agrifolia number 92 subsequent sampling was concentrated at lower (QA-92) had no root system disturbance and canopy levels, allowing more trees to be served as a control for Q. agrifolia number 94 studied. Leaves were systematically sampled (QA-94 ) which underwent root pruning. These from the four compass directions. While the data are presented in figure 1. On within-canopy variation was often significant, 19 September 1978, daily courses of xylem mean values and standard errors were calculated pressure potential were measured for both trees because our major interest in this study was in prior to root cutting. The root cutting on characterizing whole-tree responses. QA-94 was accomplished between 0840 and 0920 solar time on 20 September 1978. The daily All oak trees on the study property were courses for QA-92 were similar on both 19 and previous1~~surveyed, identified, and 20 September 1978, while QA-94 showed a midday cataloged- . All the tree identification negative shift of about 2 bars following the numbers mentioned in this study refer to those root cutting. Further measurements showed that assigned in the earlier studies. QA-94 achieved daily minimum pressure potentials similar to the control QA-92. but had generally high dawn potentials and RESULTS AND DISCUSSION apparent1y more rapid afternoon recovery. The major short-term effect, thus, appeared to be the development of more stressful midday A brief summary of climatic conditions is potentials, but overnight recovery, as presented in table 3. These are provided to indicated by the dawn potentials, did not assist in interpreting daily courses of plant appear to be affected. water relations which are presented later. Similar measurements were made before and following root cutting on 9. lobata tree A'~npublished reports by Jams Dean, Lee numbers 18 and 19 (QL-18, QL-19). These data New-man and Associates, Westlake Village, are presented in figure 2. On California. 28 September 1978, daily courses were measured in QL-18, which served as a short-term control, Table 3--Weather characteristics during days of tree water relation measurements. Given are maximum air temperature (T max) , maximum vapor pressure deficit of the air (VPD ), average dew point temperature 5- (T 7;average vapor pressure of the aire%), and soil water potentials at 60 cm depth (Y60). 215i5 b 28 SEP 78: Date I 'max 1 "Dmax 1 'dew I ' I '60 :5 "C mb "C mb -bars 20 19 Sep 78 26.0 29.4 - 5.6 4.02 - 21 SEP 78 20 Sep 78 27.1 31.8 - 5.5 4.07 - 25 21 Sep 78 31.2 42.6 - 5.1 4.18 - 28Sep78 35.1 44.1 +11.1 13.21 - "5: 6\, 12 30 SEP, 18,: 78 30 Sep 78 33.0 40.3 +12.3 14.28 - 04 Oct 78 25.7 16.8 +15.1 17.00 33 (2) SOLAR TIME 11 Oct 78 33.0 43.3 + 2.7 7.44 - 6 12 18 12 Oct 78 34.9 50.6 + 7.2 10.14 - (1) SOLAR TIME 13 Oct 78 36.5 55.2 + 7.3 10.19 - 240ct78 26.5 20.8 +9.5 11.81 21 Figure I--Daily courses of xylem potential with 06 Dec 78 7.9 8.6 - 8.5 3.21 standard errors for QA-92 (0)and QA-94 09 Feb 79 18.7 14.4 + 4.0 8.13 41 (@I.Vertical bars are standard errors. Figure 2--Daily courses of xylem potential with Ñ1~eadin close to zero bars, outside the standard errors for QL-18 (0)and QL-19 range of the psychrometer. (¥) and QL-19 on the day prior to root pruning. Data presented in figure 3 for 6 December The trees showed similar daily courses in 1978 and 9 February 1979 show daily courses of pressure potential, both in the dawn and midday pressure potentials during the winter wet minimum values. Root cutting and trenching season when soil moisture is replenished. were carried out on 29 September 1978, and Daily minimum potentials fell in the -10 to -15 measurements were again made on 30 September bar range and dawn potentials were in the -2 to 1978. Again, similar to the earlier data on -4 bar range. QA-787 is included in these QA-94, the dawn potentials were similar in data. This tree was located off the study site QL-18 and QL-19. However, the midday values and was used as a permanent control tree which were notably different, with QL-19 showing would not be affected by land development midday potentials of around -30 bars, while operations. QL-18 showed values of about -24 bars. The period of 11-13 October 1978 involved Data in figure 3 are presented to a study of short-term effects of large-scale illustrate a broader sample of trees over disruptions to root systems. QA-92, which was longer time periods. The daily courses scheduled for eventual removal . was selected measured on 4 October 1978 show QA-93, QA-94, for experimental root manipulations. In early and QA-89 with similar patterns. QL-18 and afternoon on 11 October 1978, a trench was dug QL-19 developed more negative daytime 8 to 10 feet deep around approximately 70% of a potentials than did the other study trees, circle formed at a radial distance of two feet probably because of local edaphic conditions at from the base of the tree. Morning values of the sandier ridgetop site of QL-18 and QL-19. potential in tree QA-92 (figwe 4) were 34 bars more negative than the other trees, similar to other measurements on this tree on earlier occasions. Root-cutting operations began shortly after 1200 solar time. Measurements at around 1540 revealed that potentials had decreased markedly in tree QA-92, reaching a mean value of -28 bars at a time when QA-94 showed a value of -14 bars. QA-92 then partially recovered in late afternoon to approximately -24 bars at 1750. The following day, 12 October 1978, the dawn potential measurements of -19 bars showed that tree 92 was unable to completely recover from the previous day's water deficit. QA-94 6 DEC 78 recovered to a dawn value of about -7 bars. QA-92 exhibited substantially more stressful midday potentials than QA-94. showing a minimum value of -31 bars while QA-94 developed minimum , 9 FEB 79 potentials of -17 to -18 bars. Measurements made on 13 October 1978 again revealed the same basic difference between the radically root-cut QA-92 and QA-94 which had a much smaller fraction of cut roots. Lack of 24 OCT 7 overnight recovery was again apparent in QA-92, which had a dawn potential of -19 bars, while 35 QA-94 showed values of about -7 bars. 6 12 18 Throughout the day tree 92 showed potentials (4) SOLAR TIME which were substantially more negative than QA-94. Minimum potential was -32 bars in Figure 3--Daily courses of xylem potential with QA-92, and -22 bars in QA-94. standard errors for QA-89 (01, QA-92 (01, QA-93 (@>, QA-94 (¥I QA-787 (A).QL-18 13 October 1978 was a high stress day in (Dl,and QL-19 0. terms of air temperature and the evaporative Figure 4--Daily courses of xylem potential with "demandw of the atmosphere (table 3). These standard errors for QA-92 (0)and QA-94 environmental conditions brought out a stomata1 (a). Also shown are leaf conductances in water stress response pattern which is shown in dashed lines on 13 October 1978. figure 4, and which is linked to the Cross-hatched area on 11 October 1978 development of leaf water potentials. The indicates the root cutting period on QA-92. daily course of potential in trees QA-92 and QA-94 all showed a midmorning minimum, then a (Griffin 1973). It must be stressed that these partial early afternoon recovery followed by a were carefully managed root pruning and grading midafternoon minimum and, finally, a partial operations and the same conclusions may not late afternoon recovery. These time trends in apply for trees subjected to more routine potential are related to the time course of trenching and grading operations in and near stomatal conductance. Midmorning conductances the tree root zone. Drastic root pruning on an were at a relative maximum, promoting higher experimental tree showed immediate disruptive rates of water loss by transpiration and the patterns of pressure potential, establishing subsequent development of decreasing that there are clearly limits as to the degree potentials. The midday decrease in stomatal of root damage these oaks can withstand in conductance, indicating a partial stomatal their present environment. closure under water stress, resulted in a partial midday recovery in potential. Stomata From these short-term data, it is not yet re-opened in midafternoon with a consequent possible to evaluate long-term effects of such decrease in potentials and began closure in a water stress regime. Plants have evolved a late afternoon with a corresponding increase in number of mechanisms to compensate for potentials. This linkage between stomatal environmental fluctuations in water activity and potential indicates that Q. availability, and this may be particularly true agrifolia is able to regulate water use in for these Quercus species presumably adapted to response to external environmental factors the med iterranean summer drought climate which affect tree water balance and internal pattern. Future measurements will clarify some factors of water stress which affect a number of the responses of these trees to root system of processes in plant tissues. disturbance and fluctuation in water availability, responses which must be understood before adequate oak management The effects of the root cutting on QA-92 programs can be developed. persisted through time as shown on 24 October 1978. It is not known if QA-92 could have survived this water stress regime because it ACKNOWLEDGEMENTS was removed for road construction in late October 1978. The indications are that the We thank Mr. James Dean for the foresight root disturbance in QA-92 produced much more to suggest these studies be undertaken and damaging and possibly irreversible effects when Mr. Ken Rattner for permitting measurements to compared to root disturbance effects measured be carried out at the study site. Dr. Phil in the other trees. Thus, there are limits in McDonald provided helpful criticism which the magnitude of root system disturbance which improved the manuscript. the trees can accomodate without major disruption in the tree water system.

LITERATURE CITED CONCLUSIONS Griffin, James R. 1973. Xylem sap tension in three woodland Water relations measurements taken at the oaks of central California. Bsology 54 study site over the period September 1978 (1): 152-159. through February 1979 indicate that increased Kanemasu, E. T., G. W. Thurtell, and C. B. water stress occurred in individuals of Q. Tanner. agrifolia and 2. lobata which have been 1969. Design, calibration, and field use of subjected to disturbances to the tree water a stomatal diffusion porometer . Plant system through root cutting and grading Physiol . 44: 881-885. operations. The measurements of water stress, Ritchie. Gary A., and Thomas M. Hinckley. as characterized by xylem pressure potentials, 1975. The pressure chamber as an instrument were not of such magnitude as to suggest for ecological research. Adv. Bsol. Res. impending lethal effects; rather, the trees 9: 165-254. incurred chronic water stresses which would Scholander, P. F., H. T. Hammel, Eida D. accumulate over time. The potentials of Bradstreet, and E. A. Hemmingsen. root-pruned trees fell within the range of 1965. Sap pressure in vascular plants. values reported elsewhere for these oaks Science 148: 339-346. Oak Tree Banks and Relocation1

21 Richard D. Cross- Quercus agrifolia

Abstract: A problem facing both developers and con- servationists is how to save valuable oaks in urban develop- ments when they are in a road right-of-way or future building space. Our unique solution is that if a tree is in good con- dition, it can be dug up and moved. Instead of boxing a tree we trench around it, dig it up, and move it to another location. In this way, many trees can be moved each day. Another facet of this operation is the temporary storage of trees in what we term "tree banks" for up to 3 years duration. The trees are laid in trenches and partially covered with soil. One-time relocation has been successful 85 to 95 per- cent of the time.

There is a tremendous amount of encroach- The ideal thing is to have the tree ment and urbanization that has a significant in the landscaping. In fact, you can remove effect on oak trees. Much of it is detrimental. the tree and relocate it back in again after What we have proposed in the last four years you have built that particular project. Say, is that many trees do not have to be cut down building a condominium or a roadway, or what if a road is going through. You can relocate have you. Trees can be moved -- small trees, the tree. It can be removed and taken -- large trees. Now, I should say oaks have been stored in the ground. If a roadway is going moved before, using a boxing technique. The through it's mainly a decision whether or not problem with this is that boxing is very ex- the tree should stay or go. Should we preserve pensive and time consuming. When the developer the tree by putting a costly well around it, gets that grading permit, he has a loan out or should we take the tree out? Now, if the from the bank and he wants to start grading. tree is in the middle of the roadway, or a He can't wait around for two or three months, condominium is going to be put in, in most six months, up to a year boxing trees. He has cases the tree is taken out. . It's expensive to move right away because time is money. He to redesign around trees. And in many cases wants to get the homes built and sold. So if you redesign around the tree, there are the developer needs to move in quickly. The serious consequences that you have to deal best way to do this is burying the tree or with later which involve more expense. digging the tree out with a bulldozer, not boxing it. This may sound radical, but it can All too often in Southern California we be done. We'll be working in conjunction with find a particular site where they're going to the City of Los Angeles on a pilot project. cut down a slope and fill a valley, so they We'll be taking some trees out that are about not only have to cut out the trees that are on 65 feet high with about a 70-foot spread. We the top, but they have to fill in and actually will move eight or ten of those in twelve hours. remove the trees on the bottom. The ideal way is to move the tree in one day, if you can. We have moved up to 12- Ñ Presented at the Symposium on Ecology, inch diameter trees. We have moved up to Management and Utilization of California Oaks, eighteen trees in a single day. June 26-28, 1979, Claremont, California. In some cases we store the trees for as long as a year. They'll build the pads, 21 Horticulture Evaluation and Research start putting up the frames on the house, then Systems, Encino, California. the trees can be taken out of the storage area. When they're laid we'll dig a ditch 8, 10, 12 the trees. This is probably the major pest feet deep, and lay the tree in, and then fill attacking relocated oak trees. in as much soil as possible on the tree. Also check for wind damage. You should Now, with pads that developers put up, prune the damaged branches because in many cases the soil is compacted; so you can't leave a you will put the tree near a building or near tree in its original position in many cases a place where a building will be erected. You because they have to compact to 90 percent. don't want to be liable for damage to the They have to dry the soil down hard so the building. structure will stand over the years. And this is a very severe trauma for your oak tree. What we're trying to say is there are That's why many of them in urban situations other alternatives. It's not a case of a tree will succumb even if you're building around has to go, or does it stay, and what do we do them. to preserve it? You can now take trees out. We feel that before you cut the tree down, you So if you've got the room, you store can relocate it. If you can't relocate it, your trees, and you move them later; and you store it for a year, two years, three years. can also take your oak trees and put them in Then take the tree out and put it back where more advantageous positions. An oak tree in you want it. You can do this, and I think front of a home is worth a great deal more that the landscapers, in the upcoming years money than it is in the back. will be able to use the environment we have, rather than bringing in trees that decline, If you're going to move an oak tree in that are not indigenous to this area, trees this fashion, there are certain things you such as eucalyptus that create a problem of have to take into consideration. One of them maintenance, pest problems and such. This is is, select a proper site. You have to be very a new approach, but it's going to find favor careful that you don't run into a situation with a lot of landscape architects. where a hole was dug to receive the tree, and underground water filled the hole. Just im- In storing, we lay trees down at an agine what would happen if the tree was put in angle depending on the type of tree. If the there! So site selection is very important. tree with multiple branches has a big spread, you really can't lay it down; but trees that Trees that are not weakened, and are come off hillsides and dense growth free from pests and fungus can be moved. grow straighter, so you can lay them down. We Insects such as the western sycamore borer tried it to conserve as much space as possible. (Ramosia resplendens) often hit trees weakened In the Calabasas area we stored 90 or 95 trees. by drought. Check for these. You don't want to move a tree that is severely hit or in a We can move the trees in the sunnner- state of decline. time or the wintertime. We prefer -- I know this sounds radical -- but we prefer to move the trees in the summer rather than the winter. The Pacific flatheaded borer (chrYso- If you've ever had a D-9 "Cat", a large piece --bothris mali) is a potential pest both before of machinery, if you get into soft soil, wet and after moving a tree. If you're going to soil, she'll go right to the belly pan, and relocate or store trees, you first have to you're stuck there with the machine. But we diagnose the trees' condition. Many trees are have found that in summertime it's ideal. We moved that shouldn't be, even boxed trees. If don't worry about the heat problem. I worry they're moved and not taken care of properly, more about my machinery getting in and out. a flight of borers will move in and take out Characteristics of Root Systems: California Oaks1 lobata

Abstract: Intensive examination of root systems for 21 oaks (Quercus lobata and Q. agrifolia), during excavation in a development project in the Conejo Valley (Ventura County, California), indicated that the major root zones were within 5 to 8 feet from the stem. Buttress roots within that distance send down sinker roots as far as 30 ft. with lateral feeder roots emanating at interfaces between different soil types in the soil profile. Shallow lateral roots with feeder roots only at the tips may extend as far as 90 ft. from the stem; these are assumed to be winter feeder roots. Tap roots on all trees, regardless of species, were degenerate and non-functional. Most roots had infections by Dothiorella querci and/or Phytophthora cinnamomi, many of which had been compartmentalized. Excision of up to 45% of entire root systems have met with no deleterious effects over six months; all roots were coated with Tree-Heal and wrapped with plastic until the excavations were backfilled.

This study was part of a research developers who are concerned with this problem, program at Thousand Oaks. North Ranch and the study is extremely valuable. Westlake Village comprise a very expensive development sponsored by my friend, Johnson Most of the impacted oaks are on an Holmes. The project is still not completed. area that has been rather highly grazed. Trees It will be two or three months before we can are scattered rather than occurring in large wrap up all our data. groups. In our study area we found 21 trees impacted by construction. At the time we did This has been one of the projects that not know it was possible to lift trees, bury tree men dream of because it gave us the rare them for a time, and then replace them. opportunity to study the characteristics of the oak roots. I entitle my talk "California We selected one of the oaks which was Oaks" because the eastern oaks have somewhat lost to construction activity. This became different characteristics. We are talking our study tree and we tore it completely apart. about trees that are adapted to long drought We dug it out and manicured the roots so we periods and then lengthy stretches of wet could study them. We had to give our help two weather, soaking rains, washing and so forth. or three lectures about roots so as to maintain a high level of interest on their part. Hence we see different characteristics than those which appear in either the eastern Now this tree appeared to be a very or southern oaks. But for the contractors and solid one. It was one of the most beautiful on the construction site. But as we dug around it we found it became weak from a loss of roots, and split at the crotch. Inside we Presented at the Symposium on Ecology, found a core of carbon. Apparently the tree Management,and Utilization of California Oaks, had grown around the parent which had been June 26-28, 1979, Claremont, California. damaged by fire a long time ago. The core was solid carbon and we detected no decay in this Forest-Ag, Lafayette, California area. Underneath the core, however, we found decay where the fire had not hit. the cut roots showed drying for about two inches up from the cut. Others dried for One of the characteristics of these three or four inches. But be that as it may. California oaks is a degenerate tap root. It the callus had formed around this area, almost appears to be active in the young oaks but immediately upon cutting. It is almost im- then for some reason which is not clear to us, possible to get there and treat that root it degenerates as the tree matures. It is before it callused to set up its own protective unusual to find old oaks with a solid tap root. mechanism. As we cut through we find that most of the roots occur within the two-to-three-foot zone. Other surprising things we found were As we penetrate below two to three feet the these -like winter feeder roots. One secondary roots are rarely found. particular feeder was rather neat. It lay about six or eight inches beneath the surface, We find that if we are going to en- running out as far as 90 feet. Except right counter mycorrhizal activity it will occur at the tip, there were no feeder roots on it. within the first foot or two of the stem. The small tip feeder roots looked much like Farther out we find a paucity of mycorrhiza. the tail of a poodle dog. The litter and everything that collects under the tree favors the development of fungi. Along the roots we found quite a bit of infection. We isolated Dothiorella querci Now one of the most striking observations and Phytophthora cinnamomi. In,many cases we make is the development of sinker roots. the roots had compartmentalized around these These sinkers will come as laterals, going infections and the tree had gone on to add down from the secondary or buttress roots additional roots. The natural mechanism the somewhere within five feet, or closer, to the trees have for withstanding many of these stem. Seldom do we encounter sinker roots infections is just amazing. In fact we also beyond five feet. But we could expect any- found Streptomycytes that were working on some where from three to ten sinker roots around a roots and an abundance of Trichoderma. tree, within three to four feet of the stem. Apparently these are the roots which provide On one root about 60 feet from the the survival mechanism for these trees during trunk we found Dothiorella and Fusarium and the dry seasons. clear out here the tree had compartmentalized around it. Looking at the map of the root zone of this particular tree it is evident that the As far as the depth is concerned, it's laterals which were found went clear out to fascinating because we found that at every 60 feet. If we look at the root zone of the layer of the soil zones we would see mats of profile, we find that on one side we see feeder roots. Then the root would go on down nothing beyond six feet from the stem. Coming and there would be another cluster of feeders. around on the south side of the tree we had a There was a beautiful layering of feeder roots group of laterals coming down to-three feet, in each transitional zone in the soil profile. but we had a great big, over-two-inch lateral, This continued to a depth of 30 feet. So down in the three-to-four-foot zone. Others these are the areas from which the tree is are less than two inches in size. Moving obtaining its sustenance. around the tree we find a little cluster of laterals probably coming from one major group. In the case of one particular tree Going around on the other side of the tree we where a wall was to be built, we cut out about find laterals out past the 50 foot marker as 45% of the root system and several people were well as a small cluster right around the stem of the opinion that it would die. We did the and another great big lateral down at the four cutting during the August dormancy. The tree, foot zone. however, had large roots, three feet deep, extending out as far as 80 to 90 feet in the This was the basic root structure of direction opposite the wall. The root system this particular tree which we sacrificed. which was left did the job. Next spring the tree leaved out before the others did and it Now during the process of our examination came out beautifully. all of the roots were hand-dug and cut, were wrapped with plastic and painted with tree- So much depends on the kind of care heal. There's some question in my mind about we give these oaks, and the protection they the value of this procedure. I think we receive. On the last check 11 months after probably could have sprayed the roots with cutting, we have yet to lose a tree on this paraffin just as well, because we found that development. We have not seen a tree really whatever the situation was, some drying wilt if we are giving it proper water. So you see it is possible to come out with beautiful trees in a well-developed program. Oaks and Outdoor

Quercus Sam S. Alfano agrifolia Recreation Management Officer Los Padres National Forest Goleta, California

Abstract: California oaks have played an important part in western Indian culture as well as the colonization of the State by the Spanish. The desires of farmers, ranchers, subdividers and other land users have caused a decline in the oak stands throughout the State. Some of the most desirable recreation sites located in California are located in oak groves. These oaks not only provide shade and shelter but also are the habitats of many wildlife species that provide visual enjoyment to the outdoor recreationist. It is essential that we retain, wherever possible, the remaining stands of oak, not only in our recreation sites throughout the State, but also in and adjacent to our growing communities. It is also essential that we pursue silvicultural practices that will assure growth of young trees in our old growth stands throughout the State.

It was Washington Irving who said, "He ancient trails to the oak groves. There was, who plants an oak looks forward to future no doubt, a feeling of pleasure and exhila- ages and plants for posterity. Nothing can ration to be in and among these ample pro- be less selfish than this." viders of food, who modified the heat of sum- mer, winds of fall, coldness of winter and If Gallup took a poll of the most scenic the rains of spring. and picturesque native trees of California, there is no doubt in my mind that California The oaks played an integral part in the oaks would head the list. Spanish culture, for the early Mission trail from San Diego to Monterey wound among the There is no question that oak species forests of oak. Beneath the outstretched had a special significance in early European limbs of a coast live oak, Padre Junipero Serra, culture. English oak, for example, provided in 1770, planted his cross and celebrated the fuel, timber for ship building, wood for first mass conducted on the Monterey Penin- housing and forests which generated such sula. The Spanish explorers interpreted the tales of hope, freedom and adventure as the coast live oak as an indicator of fertile land legend of Robin Hood. Strong, tough and and evidence of suitable location for resi- robust, the oak was a symbol of manhood. dences. American pioneers did so as well. And even today, in this time of stress and The California oaks were just as sig- pressure, just walking down a leaf-covered nificant to Indian culture. Although acorns lane brings serenity and peace of mind. provided a major footstuff for many Indian tribes, it can be assumed that they also Fifteen of America's 68 species of oak attached special aesthetic and perhaps spiritual grow in California. If one examines a distri- values to these bountiful trees. One can imag- bution map of the common species of California ine the joy and excitement that took place as oaks, it is evident that they are adaptable the women and children found their way along to a wide range of elevations, soils and climates.

There is no estimate of the acreage oc- Ñ'~resente at the Symposium on Ecology, cupied by oaks before the white man arrived in Management and Utilization of California Oaks, California. There is an estimate by some Claremont, California, June 26-28, 1979. experts, however, that originally 800,000 California black oak in southern California acres of riparian habitat occupied by oaks campgrounds and picnic areas is likely to in- existed in California and has now been re- crease in the future. A virulent fungus (fomes duced to some 12,000 acres. In the Coast annosus) attacks the roots of local conifers Ranges and Sierra Nevada foothills, ranchers and kills them in patches up to four or five burn, spray and bulldoze blue oaks to turn acres in size. New seedlings contract the dis- woodlands into grasslands under the question- ease and soon perish as well. Seedlings of able assumption that fewer oaks will mean more California black oak seem relatively immune grass for cattle. The continuing reduction to this pathogen and, consequently, are being of oak stands throughout California further used to replace the conifers. Likewise, photo- emphasizes the need to retain the remaining chemical smog is killing conifers while Cali- acreage for outdoor recreation purposes. fornia black oak is little damaged. The abil- ity to shed smog-laden leaves in the fall is Another point about conversion concerns one big advantage of being deciduous. water. A number of people today want to see the deciduous oak forests cut down and replaced The need for quickly establishing vigor- with conifers. They are forgetting one of the ous young black oak seedlings has stimulated big costs of conversion--the cost of water research in growing and outplanting this and lost by switching from deciduous hardwoods to other oak species. Nearly 100 acres on Liebre conifers. Conifers intercept rain and snow Mountain in the Angeles National Forest will in their crowns and much of it is lost by be set aside for tests aimed at developing evaporation. Deciduous hardwoods, on the planting stock and outplanting methodology for other hand, allow the precipitation to fall successful establishment of these oak species. through the crowns to the ground. Here the evaporative forces are much less. In a study The attractiveness of oak groves to the in the southeast, annual streamflow, which is outoor recreationist and to the recreation water available for reservoir storage, de- planner is understandable. Yet the desir- creased by 20% fifteen years after the area ability of these locations presents a rela- was converted from a mature deciduous hardwood tively minor but nevertheless certain amount forest to white pine (Swank and Douglass 1974). of risk to the user. The landscape architect This loss will continue and probably worsen as is careful to avoid the unnecessary removal of the pines grow larger and drink more water. trees when he designs a recreation facility. Other studies in the southeast and north cen- He avoids road locations that may necessitate tral states have shown similar results. the removal of large limbs and cut root systems. With all his carefulness, however, the problem Because water recreation is an inherent of tree (including oak) failure in campgrounds, part of outdoor recreation, and because I think parks and picnic sites has concerned many agen- Californians are going to need all the water cies throughout the State. they can get, this concerns me. In 1968 a California live oak fell across Adaptability to a harsh and variable a tent located in the Cerro Alto Campground environment makes these species extremely within the Los Padres National Forest. For- important to the outdoor recreationist. The tunately, no one was killed but an elderly valley oaks located on deep soils in the in- woman had to be hospitalized for nearly eight terior valleys are observed by the passing months. motorist as eye-catching silhouettes which break up the monotony of the landscape. The On a quiet spring day, what appeared to California black oak, which is found in a be a sound canyon live oak fell with a crash wide range of elevations throughout the State, into a campground unit within the Wheeler is known for its scenic beauty throughout the Gorge Campground. A young boy received minor year and especially when the species puts- on injuries and some $600 worth of damage was done its colorful fall display. to a recreation vehicle.

The coast live oaks are generally found An Easter Sunday almost turned into a day along our valleys and water courses throughout of tragedy as the heavy limb of a canyon live the State. These are mostly evergreen species oak within Tuckers Grove County Park collapsed and provide continuous shade and shelter to onto picnickers. Three persons were treated outdoor visitors. It is not by chance that at Goleta Valley Hospital for minor injuries. many of the campgrounds, parks and picnic sites In spite of these near misses, millions of throughout southern California and other parts visitor days have been spent in southern Cali- of the State, are located in oak groves'. fornia campgrounds without injury. Questions on oak soundness often are The importance of oaks in the valleys, raised by park rangers and campground foothills and forests has not drawn the at- attendants. Annual inspections of sites to tention that is needed. It is imperative note dead limbs and canker growth are that outdoor recreation managers begin to essential. Fkamination of core samples regenerate the valley and live oak species obtained from an increment borer can provide by pooling the latest information on oak signs of heart rot in the trees. Both are silviculture. being done in Forest Service campgrounds. Recently a 10-acre site was planted to The best information on tree failures canyon live oak seedlings on the Santa Barbara in recreation areas has been compiled by District on the Los Padres Forest. Stock in Dr. Lee A. Paine and his associates located five-gallon containers was outplanted using at the Pacific Southwest Forest and Range the latest techniques. Although the seedlings Fxperiment Station at Berkeley, California. were well cared for during the hot dry summer Dr. Paine's ~ublicationsentitled. "Tree ? - months, the roots provided succulent dinners Failure and Accidents in Recreation Areas: for hundreds of ground squirrels in the area. A Guide to Data Management for Hazard Control," "Accident Hazard Evaluation and Control De- To avoid this problem~theroots of oak cisions on Forested Recreation Sites," and seedlings planted in the Sage Hill Campground "Administrative Goals and Safety Standards located across the river were covered with a for Hazard Control on Forested Recreation 1-inch wire mesh. Hopefully, this technique Sites" constitute an extremely good basis for will allow the root systems to take hold be- evaluation of oak hazard problems. fore being eaten by ground squirrels.

This national computerized program pro- The successes and failures regarding oak vides for five classes of failure: upper hole, regeneration need to be shared by all concerned, lower bole, butt, limb and root system. A so that the least amount of time, effort, and query to the computer will show how many money is lost, and so that we can again re- failures injured people OL damaged property establish thrifty stands of oak throughout the and what costs are involved. Failures can valleys and foothills in this State. be related to species of oak, defects con- tributing to the failure, triggering environ- We should not overlook the outstanding mental factors, tree diameter, tree age, ele- aesthetic value provided by such oaks. Vast vation of the site, time of day and the year acreage throughout the valleys and foothills in which the failure occurred. Currently have been grazed by cattle to the extent that Los Padres National Forest personnel are con- young oak seedlings are nonexistent. Who is ducting annual reviews of recreation sites responsible for maintaining these last ves- to assess the hazardous tree situation. tiges of what was once an ocean of green? The aesthetic appreciation of oaks as a form of In our zeal to remove seemingly hazardous outdoor recreation is evident by the care trees, however, it has become necessary to use given to featured trees in urban areas. Un- a certain amount of good judgment. An ap- fortunately, too many oaks are eliminated for parently hollow oak may be the home of a subdivisions, shopping centers and other as- spotted owl, the refuge of the California phalt and concrete facilities. The quality grey squirrel, the nesting place of the Steller of the urban environment could be enhanced so jay or a perch for a sparrow hawk. In Cali- much more if only oaks, and plenty of them, fornia alone, more than 45 wildlife species were to grace the streets and buildings. consume acorns, including woodpeckers, band- tailed pigeons, Steller jays, raccoons and The sensitivity of the Indians for oaks is ground squirrels. Acorn mast also constitutes found in a statement made by Sitting Bull. He a significant percentage of the diet of many proclaimed, "1 wish all to know that I do not birds and mammals. It is this interrelation- propose to sell any part of my country, nor ship of wildlife to oak stands that draws the will I have the whites cutting our timber along outdoor visitor to see and hear themany wild- the river, more especially the oak. I love to life species that abound within these eco- look at them because they endure the wintry systems. This interrelationship appears to storms and summer heat, and not unlike ourselves, have been recognized by forest managers who seem to flourish by them." Let us heed Sitting manage the thousands of acres of California Bull's proclamation so that future generations black oak in the higher elevations throughout can see the magnificence of our native Cali- the State. fornia oaks and recreate under their spreading branches. LITEMTURE CITED AND REFERENCES Murray, Lynn. 1973. Black oak management plan. U.S. Barrett, Reginald H., and John W. Menke. Forest Serv., Mendocino National Forest. 1976. A review of the value of hardwoods to 40 p. wildlife in California with recommendations for research. Unpublished report. Paine, Lee A. 1971. Accident hazard-evaluation and control Behlen, Dorothy. decisions on forested recreation sites. 1979. Making the most of Arbor Day. USDA Forest Sen. Res. Paper PSW-68, 10 p. American Forests 85(3) :12. Paine, Lee A. Connell, D. L., and others. 1973. Administrative goals and safety stand- 1973. The hospitable oak. Coordination ards for hazard control on forested recrea- guideline for wildlife habitats, 3. U.S. tion sites. USDA Forest Serv. Res. Paper Forest Serv., California Region, 11 p. PSW-88, 11 p.

Cromwell, Gary. Paine, Lee A., and James W. Clarke. 1978. The majestic oaks. Garden, Nov./~ec., 1978. Tree failures and accidents in recrea- p. 5-8. (Author is plant taxonomist, tion areas. A guide to data management for County of Los Angeles, Dep. Arboreta and hazard control. USDA Forest Serv. Gen. Botanic Gardens. ) Tech. Rep. PSW-24, 30 p.

Griffin, James R., and William B. Critchfield. Pavlic, Bruce M. 1972. The distribution of forest trees in 1976. A natural history of southern Califor- California. USDA Forest Serv. Res. Paper nia oaks. West Los Angeles County Resource PSW-82, 113 p. Conservation District, Van Nuys, Calif. 73 p. Heritage Oaks Committee. 1976. Native oaks, our valley heritage. A Walters, Dirk, ed. guide to the botany, care and planting of 1977. Native plants: a viable option. native oaks in the Sacramento valley. Symposium proceedings, Special publica- Sacramento County Office of Education, 60 p. tion 3, California Native Plant Society, 213 p. McDonald, Philip M. 1969. Silvical characteristics of California black oak (Quercus kelloggii Newb.). USDA Forest Serv. Res. Paper PSW-53, 20 p. Damage Factors

Quercus wislizenii Abstract: The typical damage and the distinguishing characteristics of the injurious stage are described and illustrated for the following 11 important and/or common insects feeding on California oak trees, categorized as: Sucking insects: oak pit scales, crown whitefly; s- consuming insects: California oak moth, tent caterpillars, fruittree leafroller; Boring insects: western sycamore borer, oak twig girdler; Acorn insects: filbertworm, filbert weevil; and Gall insects: two-homed oak gall, dis- torted leaf gall. The management of these categories of injurious insects is discussed, emphasizing the philosophy and decision-making process.

INTRODUCTION homelot may require an immediate spraying of insecticide, whereas such an oak in a wild, Insects are one of the important cate- forested area may require observation and the gories of "damage factors" affecting oaks. encouragement of natural predators and para- In California well over 125 insect species sites. The final part of this paper will have been recorded feeding on various parts discuss what man can do to regulate popula- of oak trees. Approximately 15 of these tions of these injurious insects. insects are of major importance to oaks; a few of these important insects are discussed For a more detailed account of Cali- here. fornia oak insects and their management, the reader may wish to write the author for a For the person managing oaks it is copy of Brown and Eads (1965). Most species logical to categorize insect pests by the mentioned here are well covered by Furniss part of the oak they feed on. This subdi- and Carolin (1977) which is available to most vides the large number of oak insects into foresters. groups of less formidable size, and in large part these groups are natural in that sucking pests are together, chewing larvae of SUCKING INSECTS and are grouped, etc. Furthermore, control measures are frequently the same for Sucking insects include whiteflies, insects feeding the same way on the same aphids, leafhoppers, tree-hoppers, and scale plant part. Thus the sequence of insects insects. The long, stylet-like mouthparts of discussed here is as follows: sucking these insects are inserted into or near the insects; leaf-consuming insects; boring vascular system of the oak, generally the insects on trunks, limbs, and twigs; boring phloem, and the watery, sugar-containing sap insects in acorns; and gall insects. is withdrawn, sometimes in quantities that kill leaves and twigs. The plant cell struc- What the oak manager will do about ture is left intact. Often these sucking insects feeding on this tree may depend on insects inject into the plant some of their where it is. The infested tree on an urban saliva which may be toxic enough to kill tissue or cause it to be deformed. Sucking 1 insects seemingly have few defenses, except -'presented at the Symposium on the Ecology, their generally enormous reproductive powers. Management, and Utilization of California Honeydew may be dropped from infestations of Oaks, Claremont, California, June 26-28, some sucking insects, such as aphids and 1979. certain scales. Only two sucking insects are discussed in detail here: oak pit scales, L'~rofessor of Entomology, University of because of their great potential for harm, California, Riverside, CA 92521. and crown whitefly, because it is so common. Oak pit scales saliva, the bark around the scale begins to swell so that the mature, attached scale If the twigs and smaller branches of an appears to be residing in a pit. Three oak are leafless, and weakened or dead, like Asterolecanium species are present in Cali- those in figure 1, a close search should be fornia: 4. minus, A. quercicola, and A. made of the twig surfaces. If many shiny, variolosum with 4. minus being the most round, convex, yellowish-green, pin head- common. Insofar as known they have a single generation annually with peak hatch in late May. Of all the sucking insects affecting the oak tree, the pit scales can do the most harm because they frequently escape early detection, have a high reproductive poten- tial, and have toxic salivary secretions. Pit scale infestations can be devastating, particularly in addition to droughts.

Crown whitefly One of the most common sucking insects, especially on black oaks, is the crown white- fly, (Aleuroplatus coronatus, Homoptera: Aleyrodidae). Superficially it appears like a salt and pepper encrustation on the bottom side of the leaves; but when magnified, as in Figure I--Note generally weakened condition figure 3, each immature whitefly appears to of these branches of valley oak from a be a flat, scale-like, black body from which severe infestation of an oak pit scale, issue several large plates of white wax, Asterolecanium minus. somewhat in the form of a crown. The adults sized bodies are found in dimpled areas of the bark, as in figure 2, then most likely one of the oak pit scales, (Asterolecanium species, Homoptera: ) is present. The dimples or pits are especially noticeable when the scale is removed. When the young crawler scale first settles, the bark may be smooth, but with the insertion of the mouthparts and injection of its toxic

Figure 3--Immature forms of the crown whitefly, Aleuroplatus coronatus, on the lower leaf surface of coast live oak. 8.6X. appear more like a conventional insect in being winged and free of the leaf. The tiny adults are especially noticeable around oak stands in the spring of the year when they fly in such numbers as to resemble the swirl- ing flakes of a snow storm. At such times Figure 2--Numerous adults and pits of the gol- this whitefly is a nuisance pest. But at den oak scale, ~sterolecaniukvariolosum~ other times when the immature forms encrust on two twigs of Ouercus robur. 1.7X. the leaf in high numbers it is not obvious what the damage is to the leaf or tree. Other sucking pests of oaks 5 years. These population collapses may result from a depletion of oak leaf food Oak treehovpers (Homoptera: Membracidae) and/or a variety of insect parasites and ~elatinou~bhitefl~ fileuro latus gelatin- predators (Harville, 1955) that build up -oms. Homoptera:-----I Aleyrodidae during an oak moth epidemic. They are also Stanford's whitefly (~etr&eurodei stanfordi, subject to a naturally occurring wilt dis- Homovtera: Alevrodidael ease. The California oak moth (Phryganidia Woolly oak aphid (~ie~o~h~liaquercicola, californica, : Dioptidae) is also Homoptera: Aphididae) curious in that it is the only member of its Black-punctured kermes (Kermes nigropunc- family in the United States. Most of the tatus.. .- Homo~tera:Kermidael dioptids are tropical, but this one ranges Oak wax scale (Cerococcus quercus, Homoptera: into California, to north of San Francisco, Asterolecaniidae) and into Arizona. Ehrhornfsoak scale (Mycetococcus ehrhorni, Homoptera: Asterolecaniidae) The larva (fig. 4) when full-grown, is Oak lecanium scale (Lecanium quercitronis, about 25 mm long, without noticeable hairs, Homoptera: Coccidae) Oak scale (Quernaspis quercus, Homoptera: Diaspididae) Coast live oak erineum mite (Aceria mackiei, Acarina: Eriophyidae)

LEAF-CONSUMING INSECTS This category of insects is readily noticed because the forms themselves are relatively conspicuous as is the type of damage they do. Also, their defecated droppings may be in such quantities as to appear in windrows on the ground and sound like a light falling rain. These insects eat the cell walls and watery cell contents of the leaves. The loss of leaf tissue reduces the food-making capability and slows the Figure 4--Fourth-instar larvae of the Cali- growth of the oak. All of the leaf blade may fornia oak moth, Phryganidia californica, be consumed, leaving only the ribs, or only on injured leaves of coast live oak. 0.9X. one leaf surface, usually the lower, may be removed in spots. This is referred to as and it has a large, brown head. The body is 'skeletonizing." Also there are a number of mostly black but may have longitudinal insects on oak leaves that may spend a part, stripes of white, red, and yellow. Although or all, of their immature stage mining be- each larva is relatively slow-moving, it tween the upper and lower leaf epidermis. Larvae of moths are the most common oak leaf consumers, although there may be stages of beetles or wasps that attack the leaves. Three of the most common and important leaf consumers are discussed here: California oak moth, tent caterpillars, and fruittree leaf- roller.

California oak moth This voracious defoliator, also called the California oak worm, is perhaps the most important insect pest of oak trees during years of normal rainfall. During drought years the oak twig girdler probably equals it in importance. But it is typical of oak moth infestations to exist in extremely high Figure 5--Adult female of the California oak populations during one year; then these moth, Phryganidia californica; note populations will collapse and any stage of thread-like antennae. 1.7X. the insect will be difficult to find for 4 or consumes a great amount of oak foliage. The Fruittree leafroller adult female (fig. 5) is uniformly cream-tan except where the black cuticle is hairless on Archi s argyrospilus (Lepidoptera: the back of the thorax. The female has Tortrici-9- ae) is called "fruittree leafroller" thread-like antennae whereas the male's is since it is one of the most common and impor- feather-like; he also has a faint yellow spot tant pests of commercial , especially in the center of each forewing. In most of pome , but it has a wide host range and California there are two annual generations defoliates many woody ornamental plants. For of oak moth, but there may be as many as at least 30 years it has defoliated, with three in southern California. Usually larvae some regularity, the California black oak in will be present and feeding from mid-March to the San Bernardino Mountains. In common with mid-May and again from mid-July to mid- other members of this moth family the larvae September. tie the leaves together with silk in a kind of "nestu (fig. 7) and feed on these leaves. Tent caterpillars There are at least two tent caterpillars of the genus Malacosoma (Lepidoptera: Lasio- campidae) that may occasionally seriously defoliate oaks; included are x. californicum, the western tent caterpillar, and E. c- strictum, the Pacific tent caterpillar, see figure 6. Tent caterpillars are so-called

Figure 7--Larval injury and leafrolling of the fruittree leafroller, Archips argyrospilus, to terminal leaves of coast live oak. 0.5X.

As the larvae (fig. 8) become larger they tend to feed exposed, especially on the younger leaves. If disturbed they will usually spin a thread and hang tail downward. They wriggle violently at the least distur- bance. The 20 to 25 mm long larval body is Figure 6--Mature Pacific tent caterpillar, Malacosoma constrictum. 1.3X. because some of them spin great quantities of silk which they arrange in the crotches of twigs. They congregate on these tents to rest at certain times of the day. Although the species mentioned here will spin and lay down a silk line as they wander about the tree, they seldom if ever will form this silk into a tent. These mostly blackish cater- pillars are fairly large, being over 35 mm long when full grown. They are quite hairy with tufts sticking out their sides. These hairs are grayish or cream-colored, whereas some of the hair clumps protruding from the top are orangish. Most of these tent cater- pillars have a fair amount of speckled, light blue on their sides. The Pacific tent cater- Figure 8--Mature larva of the fruittree leaf- pillar has a dark blue head (fig. 6) .' There roller, Archips argyrospilus, on leaves of is a single, annual generation with larvae coast live oak. 2.1X. active from early to late spring. essentially free of hairs and is a light Damage from boring insects can be the pastel green, with the head a light, shiny most devastating type of insect damage. If brown. Populations of this leafroller can it is beneath the bark in the cambium tissue, become enormous and cause the complete de- usually the xylem and phloem tubes are cut, foliation of Quercus kelloggii. It is having a catastrophic effect on the tissue curious that Q. chrysolepis is hardly fed supplied by these vascular tubes. And, a upon in contrast to other local Quercus relatively small area of bored trunk can have species. Evidently there are few effective an effect on a relatively large area of natural parasites and predators. The larvae limbs, twigs and leaves. If the boring is in are most active from late March into May; the wood, or non-living part of the tree, the this may be later in the high elevations. immediate effect is less devastating; but the long-term effect may be a weakening of that structure, even to the point of its falling Other leaf-consuming insects to the ground. Live oak leaf cutter (Vespina quercivora, Another consequence of the insect's Lepidoptera: ) being buried in the tissue is that there is Oak ribbed case maker (Bucculatrix alber- almost always no way it can be reached; tiella, Lepidoptera: Lyonetiidae) eventually it, or usually a later life cycle Oak leaf blotch miner (Lithocolletis G- stage, will come out of the tree and then it foliella, Lepidoptera: Gracilariidae) can be treated with an insecticde or other Stenomid oak leaf tier (Setiostoma fernald-- - control measure. This means that when deal- -ella, Lepidoptera: Stenomidae) ing with boring insects, we must have a good Phycitid oak leaf tier (Rhodophaea cali- knowledge of its biology or life cycle ginella, Lepidoptera: ) development. But even with the most precise Western tussock moth (Hemerocampa vetusta, knowledge, variations in the rate of develop- ment of individuals of a boring insect popu- Lepidoptera:- - Liparidae) Salt-marsh caterpillar (Estigmene acrea, lation, together with vagaries of the ambient Lepidoptera: Arctiidae) temperature and its effects on this develop- Black oak woollybear (Hemihyalea edwardsii, ment, make the control of this insect cate- Lepidoptera: Arctiidae) gory the most difficult of all. A compli- Live oak weevil (Deporaus glastinus , cating factor with most boring insects Coleoptera: ) @uprestids, cerambycids, scolytids, as Oak leaf sawfly (Tericlista species, examples) is the attractiveness of water- Hymenoptera: Tenthredinidae) stressed trees. Often times supplying the tree with water is the most important insect control measure. BORING INSECTS Insects in this category bore or tunnel Western sycamore borer through any tissue of the oak except the leaves and acorns. The tissue cells and the Although this clear-winged moth (Synan- watery cells and the watery cell contents are thedon resplendens, Lepidoptera: Sesiidae), chewed with hard mandibles, ingested by the is well-known as a sycamore pest, it is also insect, and passed through its digestive very common and important on oaks. On either tract. These undigested parts are eventually of these trees a swelling, roughening, and defecated as fecal pellets or frass. This darkening of the bark or tunneling on the sand- or powder-like frass is loosely or trunk, larger limbs, or limb crotches is the tightly packed in the burrow behind the characteristic and readily visible damage. insect, where with some insects it remains, There is frequently an abundance of reddish- but with others an opening is made and the brown, sand-like frass in the crotches or on frass 'is eventually pushed to the outside. the ground surrounding the trunk. Sometimes An example of an insect employing both means the thin, paper-like pupal cases may be seen of frass disposal in its life cycle is the protruding from the bark, indicating that the bark or scolytid: the larvae pack the adults have emerged. If the roughened bark frass in the burrow, whereas the adults push is smoothed with a rasp or draw knife (fig. the frass to the outside. Because the 9), the numerous, meandering tunnels of the boring insect is hidden, it is not until the larvae will be exposed, appearance of frass on the outside, or the decline or death of tissue beyond the burrow, Generally only the less vigorously that it is discovered the oak is infested. growing bark is affected. On an oak used for Thus, considerable damage may occur before we ornament this damage is unsightly, but it is become aware of it. questionable how serious this damage is physiologically. The affected tissue is Figure 10--Notice many patches of whitish dead leaves on this coast live oak. Each patch has resulted from one year's mining of the oak twig girdler, Agrilus angelicus.

Figure 9--Trunk bark of sycamore scraped to chances are that it is infested with oak twig expose numerous meandering tunnels of the girdler (Agrilus angelicus, Coleoptera: larvae of the western sycamore borer, ~uprestid'mf one traces down the twig Synanthedon resplendens; oak bark so from one of these patches of dead leaves, to scraped is similar. 0.17X. the junction of the dead and living tissue, and carefully peels the bark, exposure of a flat tunnel girdling spirally down the twig in the cambium usually confirms the presence primarily bark, although tunneling into the of this insect. Further, if brown powder- cambium region is common, where the tunnels like frass and a 25-nun long, flat, whitish, may be moist. Attacks may also be associated legless larva, with expanded sides, is found with mechanical damage to the trunks or limbs in the tunnel (fig. 11) , it is certain the where equipment or automobiles have cut or twig girdler is present. This insect requires bruised the bark. Such injuries are attrac- tive egg-laying sites. The larvae causing the damage are whitish-pink with a light brown head and are mostly hairless. They are 18 mm long when full grown. The adult moths resemble small, black- and yellow-striped wasps. There is a single generation of moths annually; emer- gence occurs from May to early August, with a peak in June and July. Control on ornamental oaks is usually aimed at the exposed adults; a residual insecticide spray or paint may be effective. Scraping or rasping away the roughened bark, to improve the appearance, will also kill many larvae and pupae in their tunnels. Invigorating the oaks with judicious water- Figure 11--Mature larva of the oak twig gird- ing, fertilizing, and pruning may help, as ler, Agrilus angelicus, next to its mine in will the prevention of mechanical damage to the twig; bark at the junction of living the tree. and dead wood has been removed. 3.8X. two years to complete its life cycle. At the Oak twig girdler end of one year, twigs about 5 mm in diameter will have been girdled and killed; each will If one notices many small patches of include a relatively small number of brownish- dead leaves on an oak tree Qfig. lo), the white, dead leaves (fig. 10). At the end of about 22 to 23 months, the larva will have ACORN INSECTS girdled down into twigs 10 to 15 mm in diame- ter, and there will be many more dead leaves. Foresters and other tree managers often This girdling effectively cuts through the collect acorns for oak propagation. As much cambium and xylem layers, and stops the flow as 80 percent of these acorns may be wormy of water and nutrients to the leaves and (fig. 12). Two of the most common acorn- twigs beyond the girdle. boring insects are the larva of a moth--the filbe&worm (Melissopus latiferreanus, This twig girdler, like other buprestid Lepidoptera: Olethreutidae), and the larva of beetles, seems attracted to oaks suffering a weevil--the filbert weevil (Curculio occi- from drought. Much heavier girdler infesta- dent is, Coleoptera : ~urculionidae),e- tions follow one or more years of lower than figure 13. Either type of larva may tunnel normal rainfall. This girdling damage, and throughout the inside of the acorn and the persistent, dead leaves, on an oak tree grown for ornament, is unsightly and most owners want something done about it. How- ever, with oaks in the wild, forested envi- ronment such injury is of less concern to man. Physiologically such girdling damage may not be cause for concern, and conceivably could be even considered beneficial to the tree. It would in effect be like a pruning, which in a drought situation, could be beneficial. After 23 months, the twig girdler larva turns back into the wood it has killed, tunnels for 100 to 150 mm, chews out a cham- ber and pupates therein. The adult emerges in the chamber within a week or two and chews its way to the outside of the twig, thus being exposed for the first time in almost Figure 12--Three acorns cut open to show the two years. In warmer, inland areas the extensive larval tunneling and frass of period of adult emergence will be from late the filbertworm, Melissopus latiferreanus. May to late June; whereas in cooler, coastal 0.9X. areas, emergence will be from late June into late July. With such a two-year cycle, it should be noted that there will be even- numbered and odd-numbered year strains, with no interbreeding. To control twig girdler in valuable oaks, first invigorate the trees with suit- able irrigation, pruning, "or fertilization. Second, spray a residually effective insec- ticide on the oaks shortly prior to adult emergence from the twigs.

Other boring insects

Dry-wood termites (Kalotermes species, Isoptera: Kalotermitidae) Carpenterworm (Frionoxystus rabiniae, Lepidoptera: Cossidae) Pacific flatheaded borer (Chrysobothris *, Coleoptera: Buprestidae) Nautical borer ( nauticus, Coleoptera: Cerambycidae) Roundheaded oak twig borer [Styloms fulleri, Coleoutera: Cerambycidae) Figure 13--Sideview of the long-snouted adult Oak bark beetles (Fseudopityophthorus of the filbert weevil, Curculio occidentis, species, Coleoptera: Scolytidae) walking on the acorn cup of canyon live oak. 2.1X. deposit frass (fig. 12). The embryo may be destroyed and depletion of the endosperm may greatly reduce the vigor of a new oak tree. Another frequent symptom associated with insect-infested acorns is bleeding. Bleeding sap may have a sour, fermented odor from a bacterium introduced by the insect (Hilde- brand 6 Schroth, 1967). Bleeding may be so great and the odor so strong that some home- owners with oaks may want to have the insect controlled.

The filbertworm may be distinguished from the filbert weevil larva by the true legs on the thoracic segments and prolegs, with tiny hooks (crochets) on the abdominal segments; the weevil larva is legless. The Figure 14--Lower side of coast live oak leaf reddish-brown, metallic copper-marked fil- with two veins infested with the two-horned bertworm moth lays her eggs singly on the oak gall caused by Dryocosmus dubiosus; acorn and the newly hatched larva bores several other veins show slit marks where through the tough acorn coating. galls have fallen off. Dead tissue is due to ovipositional punctures. 1.5X. The yellowish-brown adult weevil (fig. 13) uses the tiny mouthparts at the end of her long, slender snout, to chew a small hole in the acorn coat, and then turns around, a reaction from the oviposition in the leaf deposits an egg and pushes it through the vein that soon causes the leaf beyond the hole. The weevil grub hatches inside of the puncture to die, even without a gall forming. acorn. The filbertworm has at least one It is common to observe coast live oak with annual generation and maybe two. The larvae all its leaves appearing partially whitish- may be boring in the acorns from July to brown, much in contrast to the normal dark September and again in the fall and through- green. This detracts from the tree if it is out the winter. The adults will be present primarily an ornamental. up to two months prior to these periods. The filbert weevil has only a single, annual From each gall emerges a female wasp and generation and may be present on the acorns many of these fly to the male flowers (cat- in the summer and early fall, with the larvae kins) and oviposit in them. Each oviposition feeding in the acorn from early fall through- causes the catkin to produce a club-shaped, out the winter. reddish-purple gall, one of which may contain a female wasp and another the male. Indi- viduals of this bisexual generation mate and OAK GALL INSECTS the females oviposit in the leaf veins, causing another crop of two-homed galls Oaks are the favorite host of the gall containing the unisexual generation. As a wasps (Hymenoptera: Cynipidae) . Over 140 timing device, it is worth remembering that species of these wasps lay their eggs in the two-homed gall is producing female wasps various tissues of oaks in the western United at about the time the are developing; States. The oak produces a growth (gall) this is about the time an insecticidal spray around the egg and developing larva that is should be applied. unique in form for each wasp species. Most of these galls are an interesting novelty and Distorted leaf gall cause no harm to the oak. The two leaf- infesting gall insects discussed here, how- The leaf, leaf , twig, and even ever, do cause economic damage. the acorn, may be involved by this very irregular, roughened, and many-celled gall on white oaks (fig. 15). It is caused by the Two-homed oak gall , Neuroterus varians (Hymenoptera: Cynipidae). Many of the valley oaks in the This name describes the small, wheat- , for example, have been grain-sized gall found on the lower leaf damaged, both ornamentally and physiologi- surface veins of coast live oak, caused by cally, by enormous populations of this gall. Dryocosmus dubiosus mymenoptera: Cynipidae). The leaves in particular may be so distorted, The gall frequently has a small, up-turned thickened, and reduced in size that they proj ection on each end (fig. 14) . There is cannot carry on their normal functions of the cost of the control measure? A single oak in a home yard, one that contributes considerable beauty and dollar value to the property, will easily be worth fairly costly and repeated treatment. But oaks in a wild, forest situation will probably have a much lower unit value, and cannot justify very costly pest control action. Spraying trees with insecticide, for example, may cost from $2 to $50 per tree depending on several factors. Phrasing the question differently: will the cost of doing something be less than the "costw of doing nothing?

Another related question to be decided is: will the control measure have side Figure IS--Severely distorted leaves and effects that are not acceptable? For exam- stems of valley oak resulting from galls ple, will spraying an insecticide kill the of Neuroterus varians. 0.9X. fish in a nearby lake or stream? Or, will spraying an insecticide create an unaccept- able public furor? Or, will spraying kill beneficial parasites and predators of the making food, transpiration, etc. Many home- pest insect? owners complained that they were deprived of the shade and beauty of their valley oaks by If it is assumed that something should this wasp's actions. Although considerable be done, the oak manager should get the spraying of insecticide had been done during services of a competent entomologist to aid the foliage season, it was of little effect. in the evaluation very early in the process. It was not until after discovering the wasp As a matter of principle the use of an was active before the leaves came out that insecticide should always be considered as control efforts became successful. The wasp the last resort, especially in situations oviposits in the developing leaf buds in where it is undesirable to be committed to February and early March. Insecticidal insecticide use year after year. Improving sprays at that time reduced the gall damage. the vigor of the oak tree should be con- sidered first, such as judicious irrigation, fertilization, and priming, especially when Other common cynipid gall insects dealing with the more damaging boring insects. Sanitation/salvage, removal of weak and dying California gallfly (Andricus californicus] trees as practiced in other types of forests, Irregular spindle gall wasp (Andricus may not only improve the appearance and vigor chrysolepidicola) of the oak stand, but may aid in insect oak gallfly ("Call control. Or the use of sanitation/salvage Twig ~lub-~allkaip (call&h) coupled with the use of insecticide, sharply White oak cone gall wasp . focussed both in space and time, may be the Spined turban gall wasp (Antron most desirable. Of the various means of Jumping oak gall wasp (Neuroteru applying insecticides to oak trees the toriusl method known as "high-pressure" or "hydraulic Woollybear gall wasp (Sphaeroteras trimacu- sprayingw is probably the most reliable. The losum1 spray equipment needed to treat a mature oak tree is large, heavy, and expensive. Com- mercial spray operators have such equipment MANAGING OAK INSECT PESTS for their business, and it is often least expensive to hire the job done by one of It is well to remember that the oak is a these operators. very tough tree and there is probably no insect species acting alone that will kill Until very recently, the use of insec- it. Very few insect problems compare in ticides for woody ornamental plants had to severity, for example, with drought or armil- conform exactly to what was printed on the laria root rot. After identifying the oak insecticide container label. The label had insect and its damage to the tree. and to state the specific rate that could be used learning pertinent points of the pest's on a particular oak insect pest. This has biology, the oak manager must decide whether meant that there were no legal recommenda- or not something should be done about it. A tions for similar oak insects not mentioned first question to ask is: are the oaks worth on the label. Recently these regulations were relaxed so that now an insecticide can An environmentally safer spray option for be registered: for oaks, or even just for California oak moth is the use of Bacillus woody ornamental plants; for a specified thuringiensis, which affects only certain insect pest, or for near species; for a rate insects and only at certain stages. Per 100 less than the maximum rate stated on the gallons of water use 1 gallon of Thuricida label; and for more than one method of appli- 90 TS, or 3 pounds of 25 percent BiotrolB cat ion. wettable BTB 183, when larvae are about half grown. There are not many alternatives to insecticides for the sucking insects men- Tree invigoration is a first line of tioned this paper. ~-i-n which defense against boring insects. This may be produces new growth tends to favor the pest by judicious watering, pruning, or fertil- insect. Pruning the tree, to the extent of izing. Second, a residually effective insec- good horticultural practice, opens the tree ticide spray can be applied shortly before crown so that insecticidal sprays can pene- the adult insect comes out of the bored trunk trate better. Parasitic or predatory insects or limb. On oak twig girdler or western have obviously not been an important factor sycamore borer this may be 2 pounds of 50 in the natural control of the sucking insects percent carbaryl wettable powder, or 1-1/4 of oaks; otherwise we would not have them as pounds of 80 percent carbaryl sprayable, per problems. 100 gallons of water. For twig girdler this should be applied about mid-May in inland To control pit scales, a single spray of areas to mid-June in cooler coastal areas. any one of the following insecticides in 100 Pruned, girdled twigs can be confined in a gallons of water can be used: (a) 1 pound of screen cage under the tree and watched for 50 percent diazinon wettable powder, (b) 2 adult emergence from the twig. For western pounds of 50 percent carbaryl wettable powder, sycamore borer this spray may be applied in or fc) 4 pounds of 25 percent malathion wet- late May; by observing the bored area the table powder plus 1 to 1-1/2 gallons of adults will begin revealing their presence by light-medium or supreme-type oil. Applica- the protruding pupal skins. Other boring tion should be made at peak hatch during mid- insects listed may have other adult emergence May to early June, or when seen. These dates. sprays and timing would also serve to control crown whitefly, or any of the other sucking For controlling acorn insects on the insects mentioned. tree, there is a legal registration for filbertworm using carbaryl spray, at the rate There are some natural enemies of the of 2 pounds of 50 percent wettable powder per leaf-consuming insects mentioned in this 100 gallons of water. This is for the adult paper, but it is questionable how well man moth which has been collected in mid-April, can control their beneficial actions. on oak gall apples, and again in mid-October California oak moth has a complement of on the acorn. This registration does not natural enemies (Harville, 1955) which un- mention the filbert weevil although carbaryl doubtedly keep this leaf-consumer in low is used to control other weevils. Control of populations during most years. During the these two insects in the acorns after they occasional year when the California oak moth are harvested can be accomplished with the populations explode, insecticidal spraying fumigant, methyl bromide, at the rate of 5 may be necessary. In those areas where pounds per 1000 cubic feet, at 70' to 7g°F fruittree leafroller has been damaging, with 4 hours exposure, at atmospheric pres- natural enemy activity has not been promi- sure, and in a chamber, van container, or nent, but leafroller itself exerts a built-in under a tarpaulin. Of course, methyl bromide control in that large, early-emerging worm is an odorless gas and is very toxic to populations consume the desirable foliage humans, so adequate precautions must be leaving none for the late emerging worms; but taken. The larvae can be killed in the this may be little solace for those owning acorns with wet or dry heat but this also the oaks. would likely kill the oak embryo. Acorns held in cold storage will retard the devel- If spraying of insecticides is accept- opment of the insects. able, carbaryl at the rate of 2 pounds of 50 percent wettable powder per 100 gallons of Carbaryl, at 2 pounds of 50 percent water may be used against oak moth; 1-1/4 wettable powder per 100 gallons of water, pounds of 80 percent carbaryl sprayable would also is effective against the adult stage of be an alternative. Either of these sprays the gall insects. Such a spray should be would also be useful against fruittree leaf- applied in early February for the distorted roller or tent caterpillars, or several of leaf gall wasp, and about mid-March to early the other leaf-consuming insects mentioned. April for the two-horned oak gall wasp. The timing of sprays for other gall wasps will Furniss, Robert L., and Valentine M. Carolin. vary depending on the species. 1977. Western forest insects. USDA Forest Serv. Misc. Pub. 1339. 654 p., 275 figs. Harville, John P . 1955. Ecology and population dynamics of LTCE RATURE CITED the California oak moth. Microentom. 20: 83-166. Brown, Leland R., and Clark 0. Eads. 1965. A technical study of insects af- Hildebrand, D. C., and M. N. Schroth. fecting the oak tree in southern Cali- 1967. A new species of Erwinia causing fornia. Calif. Agric. Expt. Sta. Bul. the drippy disease of live oaks. 810, 105 p., 144 figs, Berkeley. Phytopath. 57 (3) : 250-253. douglasii

Diseases of Oaks in California1

Robert D. Raabe

Abstract: Diseases of native oaks in California are of little importance under natural conditions. Root rots resulting in decline and/or death are very severe when na- tive oaks receive summer irrigation. Witches' broom may also be severe on oaks when pruned, fertilized,and irri- gated during the growing season.

Diseases of oak trees in California are tion moving up into the woody tissues. The relatively unimportant when the plantsaregrown disease results from the fact that native oaks, under natural or native conditions. This is because they have adapted to a climate where due in part to the fact that the soil-borne there is no summer rainfall, do not need irri- disease-producing organisms are not too impor- gation during that time. However, when grown tant under natural conditions. It is also due in containers where the root systems are con- in part to the long dry period in most of Cali- fined and cannot explore the open ground, the fornia. Most of the disease-producing organ- plants must be watered to keep them alive. isms which affect the foliage need condensed This weakens the plants. If water molds (spe- moisture on the leaves over a prolonged period cies of Pythium and Phytophthora) are present, in order for infection to occur. Dew formation they will invade the root systems and weaken is usually not of long enough duration to al- the trees resulting in stunting or maybe death. low such organisms to become established. The Control is difficult. Not overwatering, keep- most important diseases of oaks occur when the ing plants on the dry side,and using soil mixes trees are grown under cultivation and are with excellent drainage will help. Periodic treated improperly. Irrigation of trees dur- drenches with fungicides effective against such ing the summer favors certain disease-produc- fungi have given control in other native Cali- ing organisms. fornia plants and plants native to areas with dry summers (Raabe and Lert 1967). The diseases to be included here are sep- arated into those that are soil-borne and af- fect the root systems and those that infect the Decline and Trunk Canker above-ground parts of the plants. The impor- tance, general symptoms,and control measures, By far the most important disease problem if necessary, are mentioned for each disease. on native oaks is a decline in which the trees may die rapidly,or more commonly, in which the trees decline and linger a long time before SOIL-BORNE DISEASES they die. Symptoms include sparseness of fol- iage, loss of foliage color, death of variable Seedling Root Rot numbers of smaller branches, various size can- kers at the soil line,and death of the tree. This disease is most common in nurseries Cankers may be inconspicuous or may appear as when the seedlings are grown in containers. ruptures in the bark, at or near the soil line, Young trees die, usually during the summer sea- from which a dark sticky material may exude. son. An examination of the root system reveals many darkened and dead roots. Removal of the Little research has been done regarding bark on the main stem shows a brown discolora- the cause of the disease. Miller (1941) re- ported the isolation of Phytophthora cactorum (Lebert & Cohn) Schroet. from diseased trees Ñ'~resente at the Symposium on the Ecology, and in subsequent inoculations showed the fun- Management and Utilization of California Oaks, gus to be pathogenic to Q. agrifolia and Q. Claremont, California, June 25-27, 1979. virginiana. He also reported observing that excessively wet soil conditions due to pro- longed rains, overwatering, poor drainage and Ñl~rofessoof Plant Pathology, University of raising of the soil level on the main trunk California, Berkeley, California 94720. favor the disease Mircetich et al. (1977) reported the isolation of Phytophthora citri- the same as the fungus found in the oak roots -cola Sawada and c. cactorum from bark and roots left in the soil and because of this associa- of declining Q. agrifolia trees and from the tion, it received its name. soil around infected trees. They also isolated -P. cinnamomi Rands from cork oak, Quercus su- Although the oak root fungus is important -ber. In greenhouse inoculations using young as a disease-producing agent in many plants, seedlings, they found both Quercus sp. to be the amount of damage on California oaks has not infected by all three species of Phytophthora, been determined. Under natural conditions, the though the fungi did vary in their virulence fungus does not seem to damage California oak on the different oaks. trees. However, infected trees, in irrigated areas or in areas where the soil level has been In isolations from small roots of declin- changed, frequently die. The abundance of ing oaks taken from soil agar samples, uniden- layers of white fungus tissue between the bark tified species of Pythium and Phytophthora have and wood of the lower stems and larger roots been recoveredvindicating that they as well as (fig. 1) suggeststhe importance of the fungus the larger roots and stems may be infected by in weakening the trees. Recently a tree next these fungi. to a lawn in a large park blew down in a wind. Not only was the fungus present between the The importance of summer irrigation as bark and the wood of the roots but many of the the most important contributing factor cannot roots showed advanced stages of decay in which be over-emphasized and has been stressed by the wood had become quite soft and watery with Miller (19411, McCain and Raabe (in Brown et patches of fungus tissue scattered through it. al. 1975, Butterfield et al. 1963) and Mirce- Few other fungi produce similar fungus struc- tich (1977). tures when plants are infected. If in question as to whether the oak root fungus is the cause, On the U.C. Berkeley campus, excellent smelling the fungus tissue can help identify illustrations of this have been observed, the it, for theoakroot fungus has a distinct most striking of which occurred outside the mushroom-like odor. new Moffet Library. Two California live oak trees, each about 30 cm dbh,were left in place Another indication of the presence of the during construction of the building. Upon fungus includes the production of dark, root- completion, landscaping called for mounds on like strands on the outside of infected roots. either sides of trees, lawn planted up to the These rhizomorphs, as they are called, are im- trunks and sprinklers to irrigate the lawn. portant in the infection of roots. They are In 1971, this was completed. The tree nearest often similar to small roots but can be dis- the sprinkler immediately started to decline tinguished from them easily by soaking pieces and in 1974, the tree died and was removed. of rhizomorphs in household bleach diluted one The second tree showed a slower decline but by part in nine parts of water for 10 minutes. 1977 was very weak. Because of the drought If it is an active rhizomorph, the internal very little irrigation of the campus occurred portion will become bleached a pure white. that year. By early winter, the tree had re- The centers of roots will not do this. covered to the point where it did not look as though it had ever suffered decline. This is Other evidence of the presence of the oak a textbook example; it is known that withhold- root fungus is the production of mushrooms, ing irrigation for one summer does not always usually around the bases of infected plants. result in such a miraculous recovery but with- These mushrooms vary in color from pale tan to drawal of summer irrigation will help give con- red-brown and in size from 2.5 to 15 or 17.5 trol. cm in diameter. In California, they usually appear between the middle of November and the middle of January. Although spores are pro- Oak Root Fungus duced in abundance in these fruiting bodies, they are not important in the spread of the Another fungus which infects the roots of fungus. Spread is mainly by contact of roots oak trees is Armillaria mellea (Vahl ex Fr.) with other roots, either living or dead, in Kummer. This fungus is commonly called the which the fungus is active. oak root fungus, not because it often kills oaks but because the roots of native oaks fre- Many oaks have been listed as being in- quently are infected with little apparent dam- fected by the fungus throughout the world age to the trees under natural conditions. (Raabe 1963) but only a few have been tested The fungus received its name because orchard for resistance to the fungus (Raabe 1975). In and vineyard crops frequently died when planted such tests, Quercus ilex and 9. lobata have in land recently cleared of native oaks. The been found to be highly resistant, 9. chryso- fungus found in the dying and dead plants was lepis was found to be moderately resistant and --Q. dumosa and Q. virginiana (the only non-na- The more complete the removal, the better the tive oak to be tested) have been found to be control. The use of resistant plants also susceptible. ~dditionaloaks need to be will help control the fungus (Raabe 1975). tested in this program (Raabe 1966).

Verticillium and Fusarium Wilts

It should be mentioned that there are un- confirmed diagnoses of Verticillium wilt (K- ticillium albo-atrum Reinke 5 Berthe.) and Fu- sarium wilt (Fusarium oxysporum species as yet unnamed) in California live oak trees. Although there is a report (Ivanchenko 1957) of a 'wilt in oak trees in Russia in which a Fusarium sp. was found, it was isolated in conjunction with three other fungi, all four of which had to infect the tree before the wilt symptoms appeared. There is also a re- port of a vascular wilt of oak resulting from infection by Fusarium oxysporum in Romania and Russia (Georgescu and Mocanu 1956) but the fungus was found only in seedlings. In personal communication with Dr. W. C. Snyder and Dr. Shirley Smith of the University of California, Berkeley (recognized authorities on Fusarium wilts), they stated they knew of no Fusarium wilts in oak trees, particularly California oaks. In regard to Verticillium wilt, a survey revealed a report of Verticil- -lium on oak in Russia (Kranzouz 1958) and also a report from Hungary (Georgescu et al. 1959), but no reports of Verticillium on any oaks in the United States. This was corroborated by Dr. Stephen Wilhelm (an authority on Verticil- lium wilt) of the University of California, Berkeley. Trees reported to be infected by these fungi should be checked by the Univer- sity, State or Federal plant pathologists to determine the validity of the diagnoses.

DISEASES AFFECTING ABOVE-GROUND PARTS

Slime Flux Figure 1--A portion of a root with the bark removed showing the layer of white fungus This disease, which results from infec- tissue of ~rmiilariamillea between the bark tion of wounds by bacteria and various fungi, and the hard wood. occurs where sap or water can collect. It is usually more severe in large branches. As the Control of Armillaria mellea under urban organisms utilize the sap, they give off by- situations is very difficult. In orchards and products which prevent the cambium from heal- vineyards, methyl bromide fumigation has given ing the wound. More sap collects, more organ- some success. In urban areas, this is not isms develop and the process continues. Fre- feasible. Avoidance of summer irrigations and quently a dark liquid flows from such wounds the maintenance of existing soil levels around and may stain branches or the main trunk established trees will help. If changes in clear to the ground. soil levels are necessary, dry wells around the trunk should be made so that the soil level Control results from pruning in such a 60 to 90 cm away from the basss of the main way that no liquids can collect in the wounds. trunks will not be changed. In old wounds where this is occurring, the wound should be scraped to expose good wood Inasmuch as the fungus exists only in in- and should be fixed so that all liquids drain fected roots in the soil, the removal of such from it. It has been suggested that painting roots prior to planting will help give control. such wounds with Bordeaux or a fixed copper paste will help.

Powdery Mildews

The powdery mildews are a group of fungi which are completely external on the surfaces of infected plants except for small extensions into the epidermal cells for the purpose of nourishment. The fungi are so named because the vegetative growth including the spores has a powdery appearance. Unlike most fungi, the powdery mildews do not require condensed mois- ture for the spores to germinate. The powdery mildews actually are favored by warm days, cool nights and reduced light intensities. In California, there are four powdery mildews found on oaks and only the one which causes witches brooms is of importance. The causal fungus is Sphaerotheca lanestris Harkn., though it sometimes is listed as another fun- gus (Gardner et al. 1972). It frequently in- fects the new growth of plants (table 1) and when it does, it stimulates lower lateral buds to develop, resulting in a witches broom, all of which is covered by the white, powdery growth of the fungus (fig. 2). Infected leaves become distorted and somewhat brittle. This disease rarely occurs on trees growing under Figure 2--Quercus agrifolia branch tips, show- natural undisturbed conditions. It is favored ing powdery mildew witches broom on the right by conditions such as irrigation, fertiliza- and non-infected branch tip on the left. tion and pruning of trees, which promote new Photo courtesy of C. E. Yarwood. growth late in the growing period during sum- mer and fall. Sprouts following forest fires frequently are infected and develop witches brooms which may then become infected. Be- cause the disease results primarily from poor cultivation practices, control results from cultivation practices which do not favor the disease. Leaf infection by the same fungus results in the brown mildew which appears as a brown, felt-like growth on the undersides of the leaves. Though it is conspicuous, it does not damage infected trees. Many oaks are in- fected and those reported as susceptible are listed in table 1.

Erysiphe trina Harkn. is recorded only on two oaks. On these plants, it produces con- spicuous roundish infected areas on the upper surfaces of leaves (fig. 3). These infected areas frequently are covered with the sexual fruiting stages of the fungus, giving a grey Figure 3--Leaves of Quercus -agrifolia infect- appearance to the infected areas. Two other ed with the powdery mildew fungus Erysiphe powdery mildew fungi also are found on oaks in trina. .The infected portions on the leaf California. These form a white, powdery-like on the right are darker due to the produc- growth, sometimes interspersed with the small, tion of the sexual fruiting bodies of the dark, spherical sexual fruiting bodies of the fungus. The evidences of the fungus on fungi, usually on the older leaves of various these leaves are more pronounced than usu- oaks. Susceptible species are listed in table ally found. Photo courtesy of C. E. Yar- 1. Because these mildews do little damage, wood. control is not necessary. Table I--Susceptibility of oaks to four powdery mildew fungi in California (Bonar et al., Gardner and Yarwood 1978) A/

Erysiphe Sphaerotheca Microphaera Phyllactinia trina lanestris -alni corylea (Brown mildew and witches broom)

Native oaks

-Q. agrifolia -Q. agrifolia* -Q. agrifolia -Q. agrifolia -Q. chrysolepis -Q. chrysolepis* -Q. douglasii --Q. durata -Q. douglasii Q. durata --Q. lobata --Q. dunnii -Q, engelmanii Q. turbinella -Q. engelmann Q. --garryana -Q. garryana -Q. kelloggii -Q. keloggii* --Q. lobata --Q. lobata -Q. turbinella -Q. wislizenii Introduced oaks

Q. robur -Q. coccinea g. robur -Q. coccinea -Q. -Q. laurifolia* -Q. macrocarpa Q. mongolica Q. nigra* Q. obtusa -Q. palustris -Q. phellos* Q. robur Q. rubra Q. suber -Q. velutina 1 * species on which witches brooms have been reported (Gardner et al. 1972)

Ñ'~btaine from Bonar et al; Gardner and Yarwood, 1978.

Sooty Molds Leaf Blister

The sooty molds are dark fungi which grow This disease, resulting from infection by on the surfaces of plant parts, obtaining their the fungus caerulescens CMont. & nourishment from sugary materials either from Desm.) Tul., has been reported only on Quercus excretions of insects such as aphids, scale, agrifolia, Q. douglasii and --Q. lobata (USDA or white fly or from secretions of the plants. 1960). The symptoms appear as more or less They do not attack the plant tissues but they rounded, light green, slightly raised blisters are detrimental in that they may shade the about 6 to 12 mm in diameter on the upper sur- leaves,thus stunting the growth somewhat, and faces and concave areas on the undersides of they are not aesthetically pleasing. Control infected leaves. The layman may confuse these results from insect control. symptoms with those caused by an eriophyid gall mite. The blistered areas may be numer- ous enough to be confluent and, if so, leaf curl may result followed by defoliation. The fungus is favored by cool, wet weather after it to windthrow. Although this is a disease new growth has started in the spring. In of older trees, sometimes younger trees be- California it is of little consequence and come infected. In standing trees, heart rot control measures have not been determined. is evidenced principally by the production of fungus fruiting bodies on the outer sides of infected trees. These may be fleshy or they Rust may be woody. The importance of the disease is dependent upon the nearness to areas where The rust fungus, Cronartium quercum damage will result from falling trees or por- fBerk.1 Mivabe ex Shirai has been reported on tions of them. Control is based on this dan- ~uercuiairifolia, Q. chrysolepis, 6 dumosa, ger and removal of portions or all of infected trees may be necessary. Q. engelmanni, Q. garryana, Q. kelloggii, and Q. wislizenii in California (Bonar et al. un- pub.). ~hefun~usproduces yellow spores on the undersides of the leaves. These spores Drippy Nut are the repeating stage and can infect other oaks. Resting spores rarely are produced; This disease results from infection of however, when they germinate, the spores pro- developing acorns of Quercus agrifolia and 9. duced infect the alternate hosts which are 2- wislizenii by a bacterium which produces a or 3-needled pines. The rust is of little sticky material that drips from infected nuts. importance in California and control measures The material is unpleasant, especially when it are not needed. drips on cars, walks, driveways, garden furni- ture, patios, etc. The drippy stage of the disease is more prevalent during the warmer Anthracnose part of the year. The disease was first re- corded by McCain and Raabe (in Butterfield et This disease results from infection by al. 1963) and in studies by Hildebrand and the fungus Gleosporium quernum Harkn. (USDA Schroth (1977), the causal agent was named 1960). The fungus produces a leaf spot and a Erwinia quercina. According to Koehler (1978), twig blight on young twigs but is not important the causal bacteria gain entrance when acorns as a disease-producing agent in California. are stung by cynipid wasps, acorn curculios or probably other insects during egg-laying or feedings. No control is available at present though Koehler 1978 suggested finding a way of Septoria Leaf Spot defruiting landscape trees as a means of con- trol. This is another fungus leaf spot of oaks and in California is of little consequence. The fungus Septoria quercina Desm. has been Mistletoe reported on Quercus chrysolepis and Q. wislez- enii (Bonar munpub.) and quercicicola 5. In California, the leafy mistletoe Phora- Sacc. has been reported on Q. agrifolia (USDA dendron villosum Nutt. is found attackinmy 1960) on which they produce-small, circular oaks. This parasite produces a small branched spots on infected leaves. When severe, these plant with evergreen leaves. At the point of fungi may cause defoliation but generally, attachment, there may be a swelling of the they cause little or no problem in California. host branch and an occasional dying of portions of the infected branch distal to the point of attachment. The fruits of the mistletoe are Heart Rot attractive to birds and the seeds, which have Heart rot is a disease in which any of a a sticky mucilaginous coating, may go through number of fungi gain entrance to the heart- the digestive tracts unharmed or may stick to in this way. wood through wounds including those caused by the bills and be disseminated Even though the leaf mistletoes are perennial, fire or dead branches. In California, Ganoder- they do little damage to plants and control ma applanatum (Pers.) Pat., Polyporus rheades - generally is not necessary. Where desirable, (Pers.) Fr., sulphureus Bull. ex Fr., 5. r. infected branc es can be removed or, according gilous (Schw.) Fr., 5. versicolor L. ex Fr., s Poria andersonii fasciaturn Schw., 5. gauspatum to Milton Bell', they can be controlled by cut- ting the parasite from theplant and covering Fr., 2. hirsutum Willd. ex Fr. and 2. rugosum Pers. ex Fr. plus many other fungi have been reported as being associated with heart rots (Bonar et al. unpub., USDA 1960'). Once inside, -31 Personal communication with Milton Bell, for- they develop in the heartwood reducing its merly of Univ. Calif. Agricultural Ext. Service. strength and predisposing the tree or parts of the point of attachment by wrapping it with Ivanchenko, Y. N. roofing paper for an extended period of time. 1957. [The causes of oak wilt in the Lipetsky garden in the Savaltsky Forest]. Trud. vseyouz Inst. Zashch. Rost. 8:221-225. (Abstr. in Rev. Appl. Mycol. 37:342).

Koehl er, Carl 1978. Dripping acorns on live oak. Univ. LITERATURE CITED Calif. Ext. Serv. Growing Points July 1978: 2. Bonar, L. et al. Unpublished records of fungi found in Cali- Kranzouz, R. A. fornia. Univ. Calif. Dept. Botany Herbar- 1958. [New disease of oak seedlings in the ium. southeastern part of U.S.S.R.] [Shorn. Rub. lesn. Khoz.] 35:258-260. (Abstr. in Brown, L. R., C. S. Davis, C. S. Koehler, A. Rev. Appl. Mycol. 39:196). H. McCain 1975. Oaks on home grounds. Univ. Calif. Mircetich, Srecko M., R. N. Campbell and M. Div. Agric. Sci. Leafl. 2783, 7 p. E. Matheron 1977. Phytophthora trunk canker of coast Butterfield, H. M., C. S. Davis, A. H. McCain live oak and cork oak trees in California. and R. D. Raabe Plant Dis. Reptr. 61:66-70. 1963. Oaks on home grounds. Univ. Calif. Agric. Ext. Serv. Pub. AXT-89, 12 p. Miller, P. A. 1941. Bleeding canker of California trees. Gardner, M. W., C. E. Yarwood and T. Duafala Proc. 8th Western Shade Tree Conf. 8:39- 1972. Oak mildews. Plant Dis. Reptr. 56: 45. 313-317. Raabe, R. D. Gardner, M. W. and C. E. Yarwood 1963. Host list of the root rot fungus, &- 1978. Host list of powdery mildews of Cali- millaria mellea. Hilgardia 33: 25-88. fornia. Calif. Plant Pathol. 42:l-9. Raabe, R. D. Georgescu, C. C. and V. Mocanu 1966. Testing plants for res stance to oak 1956. Tracheomicoza puietilon de stejar. root fungus. Calif. Agric. 2O(3) :12. [Tracheosis of oak seedlings.] Rev. Padur- ilon 70:598-599. (Abstr. in Rev. Appl. Raabe, R. D. andP. J. Lert Mycol . 39: 743-744) . 1967. Root rot control in container stock. Flower and Nursery Notes for Commercial Georgescu, C. C., S. Orenschi and M. Petrescu Growers, March 1967:l. 1959. Cercetari asupra unei verticilioze la Quercus cerris L. In Omatiu lui T. Savu- Raabe, R. D. lescu prilejul implinirii a 70 de ani: 1975. Plants resistant or susceptible to k- 247-257. (Abstr. in Rev. Appl. Mycol. 39: millaria root rot. Univ. Calif. Div. Agric 743- 744) . Sci. Leafl. 2591, 9 p. (A new revision available in 1979.) Hildebrand, D. C. and M. N. Schroth 1967. A new species of Erwinia causing drip- United States Dept. of Agric. py nut of live oaks. ~h~to~atholo~~57:- 1960. Index of plant diseases in the United 250-253. States. U.S.D.A. Agric. Handbook No. 165. Quercus Response of Oaks to Fire1 aqrifolia 2 Tim R. Plumb- /

Abstract: Management of oaks requires knowledge of tree response to fire. This knowledge is gathered through visual and other evidence of damage and of recovery, or death of the tree under various conditions such as fire conditions, weather conditions, and tree characteristics, particularly bark properties. Published information and field observations of five southern California oak species indicate that significant differences in oak species' fire sensitivity warrant considera- tion. The degree of trunk damage sustained is important. Coast live oak (Quercus agrifolia Nee) is extremely fire resistant, while canyon live oak (9. chrysolepis Liebm.) almost self-destructs because of its dry, flaky bark. Bark thickness data are presented as well as methods for determining tissue viability. Recommendations for cutting or leaving damaged trees are based on species, size, and degree of trunk damage.

INTRODUCTION tree age and diameter, has been developed for some Eastern oak species (Johnson 1977). Various oak species make up a large part of the plant cover on 15 to 20 million acres (6 Historically, fire is considered a serious to 8 million ha) in California. They occupy a threat to oak trees (Edwards 1957, Sander wide range of sites as members of several 1977). This is understandable where the vegetation types (Munz and Keck 1959). In the primary forest product is a veneer or high hot, dry, summer climate typical of most of quality sawlog. Fire damage may immediately or California, oak trees are subject to wildfire eventually reduce the value of a tree. In wherever they grow. Consequently, management California, however, other "products"--such as of the oak resource must consider tree response wildlife enhancement, watershed protection, to wildfire. recreation, and aesthetic value--may be more important than potential wood products. Oak Although the effect of fire on oaks has trees may survive several damaging fires and been studied in eastern United States (Loomis live for 100 to 200 years or more. During this 1973, Hepting 1941, Toole and Furnival 1957), time, they may still provide many of the the only major report for California has nonwood values mentioned. concerned conifers (Wagener 1961). General studies have dealt with response of oak to Postfire oak management decisions must be damage from various sources, including fire, made on a basis of specific information. After and it is well documented that most oak species a severe crown fire, when all that remain are vigorously resprout from the root crown and the charred trunk and large branches of the below-ground bud zone (Longhurst 1956). Stump trees, it would seem obvious that the most sprouting potential, based on site index and appropriate action would be to cut the trees for firewood. On the other hand, after a low- intensity fire which causes little apparent Lipresented at the Symposium on the Ecology, injury to the trees, it would seem that they Management, and Utilization of California Oaks, could be left to grow to old age. However, the Claremont, California, June 26-28, 1979. apparent course of action may not always be the best postfire management decision. 'plant Physiologist, Pacific Southwest Forest and Range Experiment Station, Forest Service, This report, after some comments on U.S. Department of Agriculture, Berkeley, f ire-plant relationships, describes influences Calif., stationed at Riverside, Calif. on tree response to fire, and the specific fire response of five oak species, with respect to Visual Evidence the trunk and aerial crown. (Damage to the root crown and below-ground part of the tree is It can be assumed that the cambium of a not considered here.) A brief outline of tree trunk has been killed if the bark has been postfire oak management planning considerations completely consumed or if the bark has cracked is included. and separated from the wood. When the bark, although completely charred, is thick, intact, and firmly attached to the wood, It is DETECTION OF DAMAGED TISSUE necessary to cut through the bark to determine the condition of the cambium. If the inner To make an accurate assessment of fire bark has a yellow tone, not white or pink, the damage, the observer must be able to cambium is either dead or seriously injured. distinguish between live and dead tissue. It The cambium and wood may also be stained dark is readily apparent when leaves are heat killed brown or black, even though the inner bark by fire. Damage to buds (if present) and to appears healthy. It has not been determined the live inner bark and cambium of the trunk that stained tissue is definitely dead, nor how and branches is not always so obvious. Several long after the fire the staining occurs. methods of detecting damaged plant tissue are Because many other damage symptoms occur within listed in table 1. 3 weeks after a fire, it is probable that staining does also.

Table 1--Methods of detecting fire-killed plant tissue

Method of I/ detect ion General procedure Utility- Reference

Visual 1. Directly observe degree of Quick, simple, but success Loomis 1973 charring of tree trunk depends on species and d.b.h.

2. Cut through bark to wood; Time consuming, but simple Hare 1961 dead inner bark is yellow or and fairly definitive; time black, cambium black after fire for effect to develop is unknown

Aroma Cut through bark to wood; dead Time consuming, but simple; inner bark has distinct fermented confirms visual detection aroma

Chemical Cut into tissue, apply chemical Quick, but so far incon- solution: clusive

1. Urea peroxide plus ortho- Color response erratic or Hare 1965b tolidine (1 percent solution in none at a1 1 when tested 95 percent methanol); healthy tissue should turn blue or blue-black

2. Tetrazolium chloride; healthy No color response when Danielson 1972 tissue should turn red tested (for Douglas- fir seed)

Electrical 1. Measure difference in electrical Not tested; reported results Hare 1960 resistance of healthy and damaged in literature inconsistent Hare 1961 tissue with a voltmeter Skutt and others 1972

2. Use square wave generator and Not tested; can be done Ferguson and oscilloscope; to observe wave with a portable unit others 1975 (for pattern of live and dead wood dormancy in nursery stock)

Ñ~nlesotherwise indicated, evaluation is based on tests made for this report. Other Evidence Temperature (OF) Time (min) Effect

In the damaged inner bark of oak, the 10+ No injury aroma of a wine cask has been detected from 2 5 Death weeks to several months after a fire; neither 2 Death the minimum time it takes this aroma of fermentation to develop nor its duration is First, there is a threshold temperature below presently known. This test can be used when which continuous exposure will not cause death; the inner bark Is cut into to inspect for in this example, lethal temperature is tissue damage. somewhere between 120' F (49' C) and 125' F (52' C). Second, as the temperature increases, Under some conditions, healthy plant it takes less time to cause death. At 135' F tissue can be distinguished from damaged tissue (57' C) , seedling death is rapid. A by chemical reaction that produces a temperature of around 125' F is considered differential color response (table 1). With fatal to the cambium. the urea peroxide, ortho-tolidine, methanol method (Hare 1965b), healthy tissue should give a blue to blue-black response, whereas non- Fire Characteristics respiring, presumably dead tissue, should remain colorless. So far, I have not found the Fire behavior, in rate-of-spread, energy color differential clearcut. Often a mottled release rate, and residence time, affects the blue stain is obtained, so that it is time-temperature response, and thus the amount impossible to separate live and dead tissue of tree damage that occurs. The time- with any certainty. At present, I do not temperature relations for the fire, the bark recommend these chemicals for field use. surface, and the cambium are not the same (fig.

Tetrazolium (2,3,5-triphenyl tetrazolium chloride), used to determine viability of some seeds (Danielson 1972), is said to form an insoluble red pigment in live, respiring tissue. This chemical gave no color reaction in tests of either live or dead tissue, and is not recommended.

Measurement of electrical resistance has been used to identify live and dead tissue (Hare 1960, Various as cited in Hare 1961, Skutt and others 1972). Because the reported results are somewhat inconsistent and I did not test this method, I do not recommend it.

CONDITIONS AFFECTING TREE DAMAGE

The amount of damage that occurs in trees exposed to fire depends on the interaction of many conditions, the most important of which are briefly described here.

Temperature

The length of time that living tissue can withstand high temperature is inversely pro- portional to the temperature to which it is exposed (Martin and others 1969). Although there is some difference in heat sensitivity between individual cells and intact plants and between various plant species, a range of Figure 1--Time-temperature relations resulting fairly low temperatures is fatal to most plant from a passing fire can be predicted for two tissue. Lethal temperature for most intact different locations in the tree trunk plants ranges between 110 and 139' F (43 to (Martin 1963). 59' C), according to Hare (1961), who cites work with pine seedlings (Baker 1929): Differential Heating more resistant to fire at 35' F (2' C) than at 70' F (21' C). Not all sides of a tree are exposed to the same heat load. An eddy (chimney) effect develops on the lee side of a tree from the Season of the Year direction the fire Is moving. This has been amply demonstrated under laboratory conditions Work with California conifers indicates by Gill (1974) and duplicated in our laboratory that fire damage potential is greater in the (fig. 2). In the field, trees with basal growing season than later In the summer wounds on only one side of a tree, usually the (Wagener 1961). Both eastern conifers and uphill side, may be observed. hardwoods, including oaks, showed Increasing fire effects from winter to spring to summer (Ferguson 1957). This seasonal effect may be due to (1) differential physiological sen- sitivity to heat, (2) differences in fire intensity, and (3) differences in initial temperature, ambient temperatures being lower in spring than in summer.

Tree Characteristics

Predicting tree response to fire requires knowledge of certain facts about the tree, primarily. its species, age, diameter, and height; the tree part affected; and the hark characteristics.

In assessing fire damage, it is Important that the species of oak be identified correctly, because all oak species do not have the same resistance to fire or the same recuperative capacity after being burned (Hare 1961, Spalt and Reif Snyder 1962). Differences in heat tolerance are probably due to differences in bark thickness, composition, chemical content, and other traits. See the discussion of the specific response of five southern California oak species to fire in a later section.

Tree age influences resistance to heat damage-younger trees are more susceptible to stem and top kill than old trees. Directly correlated to tree age are tree height, d. b.h., and bark thickness. Bark composition also changes with age, and may increase or reduce a tree's susceptibility to fire.

Tree diameter, which is directly related to tree age and site quality, is important in Figure 2-Simulated fire behavior demonstrates determining trunk survival. Large trees are differential heating of a trunk. Above, base more resistant to fire damage than small trees of flame front is at base of "tree;" below, (Ferguson 1957). They have greater capacity as base of flame is completely past tree. a heat sink and usually have thicker bark. Most oaks, including coast live oak, if less than 6 in. d.b.h. will be top-killed by a hot Ambient Temperature fire. Seedlings and trees less than 2 in. diameter will be top-killed by most fires. The initial bark temperature may determine whether or not the cambium is killed. For Tree crown height directly affects amount example, Hare (1965a) found that longleaf pine of fire damage. Tree species which attain (g palustris Mill.) and sweetgum (Liquid- large size may suffer little or no crown damage - ambar styracif ha L.) were about 50 percent from a low intensity fire if the lower edge of the crown is 30 to 40 ft (9 to 12 m) above the rise of cambial temperature during a fire is ground. Shrubs and small trees usually sustain probably directly related to the flammability heavy crown damage or complete trunk and crown of the outer bark (Gill and Ashton 1968). I kill during most fires. have frequently seen coast live oak (smooth bark) show only surface charring while canyon Not all tree parts are equally sensitive live oak (flaky bark, fig. 4) was frequently to fire, although individual cells will be burnt through to the wood. Under intense killed at 125' F (52' C) . The size of a burning conditions, coast live oak is damaged material~itssurface to volume ratio~influ- only 112 to 314 in. (1.3 to 1.9 an) into the ences its susceptibility to heat damage. bark. Similar results from different bark Leaves with a high ratio are much more surf ace textures were reported for eucalyptus susceptible to damage than twigs and other (Gill and Ashton 1968). parts with much lower ratios. The trunk and branches are also protected by a corky layer of bark, which is a good insulator (Spalt and Reifsnyder 1962). Even a thin layer of bark will give good protection from high temperature for a short time--see the discussion below.

The roots are protected by a corky outer layer and by the soil itself. Oak root systems generally suffer little direct heat damage except possibly in feeder roots near the soil outer bark - inoctive phloem (rhytidome) surface. It is probable that part of a root system dies back in response to aboveground inner bork- damage, but this has not been verified in the field.

Dormant bud meristems have a thin protective covering of bud scales which reduces their sensitivity to heat damage as compared to Figure 3--Tree response to fire is partly leaves. I observed this after a prescribed determined by the nature of the primary fire in late spring in San Diego County in components of the bark and trunk. which the leaves of California black oak (9. kelloggii Newb.) trees were killed. New shoots emerged from the damaged branches within 2 weeks after the fire. Acorns are quite sensitive to heat; even those lying on the ground exposed to sun1igh t are soon damaged.

Bark Characteristics

Bark is the most important protection the cambium has against damage from fire, insects, cold, and mechanical injury. It is a natural insulator containing numerous air spaces and suberized corky tissue.

The bark develops into a complex structure as a tree matures, changing from a thin layer of epidermal cells in young tissue to a thick, complex, multilayered zone in old stems. The general internal structure of a tree is illustrated in figure 3.

The, outer bark varies greatly in surface texture from one species to another and is great1y affected by tree age. Surface texture may influence a tree's response to fire. A dry, flaky surface may actually contribute to a Figure 4-Bark surface texture may af fect fire fire's intensity and result in more damage than behavior. The dry, flaky outer bark of would occur to a tree with smooth bark exposed canyon live oak increases fire intensity and to the same external heat input. In fact, the amount of heat reaching the trunk. The most important single influence on The moisture content of bark varies from tree sensitivity to fire is thickness. species to species, seasonally, and between the Bark thickness is directly related to d .b.h. inner and outer bark (Vines 1968). The outer (Hare 1965a, Gill and Ashton 1968). and to tree bark forms a sheath of low moisture content and age (Spalt and Reifsnyder 1962). Hare (1965a) low thermal conductivity around a zone of high found, using a constant heat source, that it moisture content and conductivity , the inner took the cambium of an oak 30 seconds to reach bark; however, the thermal diffusivity of loth 140Â I? if the bark was 0.2 in. (5.0 mm) thick zones is similar (Martin 1963). Moisture and 136 seconds for bark 0.4 in. (10.0 mm) contents I measured for coast and canyon live thick. oak barks are as f 01 lows:

I collected bark thickness data for five Percent moisture southern California oak species. Differences Species Bark component content in bark thickness among the five species are apparent (fig. 5). Coast live oak not only has Coast Inner bark the thickest bark, but its living, inner bark live oak Wood is several times as thick as its dead, outer bark. Interior live oak (9. wislizenii A.DC.) Canyon Flaky outer bark 11 likewise has a high ratio of inner to outer live oak Inner bark 65 bark while the other species have about an Wood 60 equal amount of Inner and outer bark. Other work indicates the older trees have greater heat resistance, not only because the bark is These values are In line with other published thicker, but also because the proportion of data (Vines 1968, Martin 1963). The effect of dead bark is greater (Hare 1965a, ref. to moisture content on bark flammability may be thesis by D. D. Devet 1940). However, the high more important than its effect on heat transfer fire resistance of coast live oak contradicts (Gill and Ashton 1968). the idea that more dead bark is necessary for good fire resistance. The heat of combustion, the total amount of heat released during burning, for five QA(Coast live oak) southern California oaks is listed in table 2. QK(California black oak) With the exception of coast and interior live QC(Canyon live oak) oak outer bark, all of the heat values are less OD(Scrub oak) than the theoretical 8600 Btu per pound. In each species, the inner bark has the lowest heat content, probably reflecting a low component of waxes and resins. The outer bark has the highest percent of acetone extractable materials (oil, fats, and resins), which accounts for its high heat content. Much of this potential energy is not released during normal burning conditions, however, because combustion is incomplete and some heat is used to vaporize moisture.

Bark density significantly affects the thermal properties of the bark; reported density values range from 17 to 39 lb/ft3 for northeastern hardwoods and softwoods (Spalt and Reifsnyder 1962). Somewhat higher values were reported by Martin and Crist (1968). Based on a few observations, density values for five southern California oaks are listed in table 2. The outer bark of interior live oak at 61.3 lb/cu ft is very heavy and some pieces will sink in water. In contrast, the density of the 0 ~ " " ~ " " ~ ~ " ' ~ ' ~ " 0 5 10 15 flaky outer bark of canyon live oak is only 3 Tree diameter (dbh) in inches about 31 lb/ft . Figure 5-Total bark thickness of five southern California oak species was plotted in the The thermal properties of bark--its range of d.b.h. classes sampled in the field. insulating capaci ty~directly affect tree The curves are based on simple linear resistance to heat damage. Three such proper- regressions determined by least squares. ties are described by Martin (1963): 1. Conductivity-the ability of a regeneration; and wood degradation by insects material to transmit heat through itself. and disease.

2. Specific heat--the ability of a Methods have been developed in the East material to absorb heat. for estimating, soon after a fire, the probable tree mortality, and for surviving trees, the Table 2-Heat content and density of five south- probable wound size (Loomis 1973). Methods ern California oak species (theoretical were also developed for predicting future value for heat of combustion = 8600 sawtimber volume and quality loss, with dollar values (Loomis 1974). Procedures for predicting future amount of butt rot in Species and component Density Heat content-11 fire-scarred red oaks in the South and ways to estimate extent of existing rot behind old scars are also available (Toole and Furnival 1957). Hepting (1941) gives a method for predicting future volume loss due to basal fire Coast live oak wounds, for Appalachian oaks. Similar studies Outer bark Inner bark have not been made in California. However, by Wood applying results for oak in the East and South, we can obtain approximate damage estimates for California black oak the California oaks. Outer bark Inner bark Wood Estimating basal wound size and predicting tree mortality requires input about tree Canyon live oak species, d.b.h., and the width and height of Flaky outer bark tree charring (Loomis 1973). Immediately after Outer bark a fire, the width of a wound is fairly well Inner bark approximated by the width of the charred area; Wood however, wound height may exceed the charred Interior live oak area by several feet. The determination of Outer bark char height is complicated by the deliquescent Inner bark branching habit of some oaks; branching may Wood begin almost at ground level. Scrub oak Flaky outer bark Anticipated heart rot can be estimated for Outer bark- the present or predicted for the future using -Inner bark wound age and the ratio of wound width to tree Wood diameter at stump height (Toole and Furnival 1957). Reported rates of spread range from 1.5 Ñ'value rounded off to nearest 25 Btu. to 2.2 in. (3.8 to 5.5 cm) per year, with an overall average rate of upward spread of 1-114 3. Dif fusivity~the ratio of thermal ft (0.4 m) in 10 years. conductivity to the product of specific heat and density. Crown Damage

Diffusivity is useful for evaluating the Crown damage can range from no effect to temperature change in a material over time, as complete charring of the branches and total in the cambium during exposure of the bark to consumption of the leaves and small twigs. fire. However, Martin found that the thermal Often, different degrees of damage occur diffusivity of bark is nearly constant over throughout a crown; the lowest part or the side wide ranges of density, moisture content, and facing an understory of brush or heavy fuel temperature (because of compensating effects) suffers greatest damage. If damage from a and is about one-fifth that of water. spring fire is limited to heat kill of the leaves, new leaves may emerge within a few weeks. Sprouting usually occurs also from the TREE RESPONSE TO FIRE trunk and any branches that are not killed. Occasionally, some sprouts die back. In this section, the immediate and delayed response of the crown and trunk of a tree to fire are identified. Immediate tree effects Basal Trunk Damage range from no detectable damage to complete consumption or heavy charring, with tissue The most common fire damage to a tree death. Delayed effects include sprouting from trunk is a basal wound caused by death of the the tree base, trunk, and branches; cambial cambium (fig. 6). Wounds less than a few inches across may eventually heal over with no is not too wide, the cambium may be able to accompanying heart rot (Toole and Furnival reconnect. At any rate, trees with healthy- 1957), but larger wounds are responsible for looking crowns, but with girdled trunks, may the major loss of quality in eastern hardwoods. contribute to underestimation of fire damage. Establishment and spread of heart rot depends on many conditions, including resistance of the individual species, tree age, size of wound, RESPONSE OF SOUTHERN CALIFORNIA OAKS TO FIRE and the species of fungus (Hepting 1941, Toole and Furnival 1957). Field evaluation of wildfire effects on five prominent southern California oak species After a fire, a wound may also be attacked began in 1974 to aid in postfire management by various insects. As time goes by, new planning. It was well known that most cambium may eventually cover a wound. However, California oaks sprouted vigorously from the if decay is active and wood of the wound face base when the trunk or crown, or both, were is destroyed, the growing cambium may curve damaged; the study revealed important species inward and back on itself, forming a wound that differences. may remain open for many years. On the site of the 1974 Soboba Fire, on Subsequent fires may enlarge the wound the San Bernardino National Forest, almost 100 until all that remains of the trunk is a thin, trees that had suffered damage ranging from partial ring of mostly live wood. At this light, spotty char to complete trunk and upper stage, the tree is a mechanical risk-subject crown charring were selected, marked, and to wind breakage. One more fire may so weaken described. Postfire tree response (trunk and the tree that it falls. crown damage, resprouting, and death) was sampled for several years. Observations were Heat damage to a zone of cambium com- made between 1975 to 1979 on seven other pletely around the trunk girdles a tree and southern California National Forest areas eventually kills the crown. In a low intensity burned by wildfire. Two areas burned by ground fire, cambium damage may be restricted prescribed fire were also observed. to the lower 1 to 2 ft of the trunk however, with little or no immediate effect on the upper trunk or crown. I have seen trees girdled at Permanent belt transects were selectively this level still alive 8 years after the fire. established in stands of coast live oak and The root system is probably kept alive by food California black oak on the Soboba Fire area, supplied by the basal sprouts that develop and in canyon live oak on the Village Fire area after the fire. (Angeles National Forest). All trees in the transects were described by size, fire damage, How long the crowns of girdled trees will and amount of postfire recovery. Follow-up remain alive is not known. If the damaged zone sampling was done 1-112 to 2 years later.

Figure 6--Basal trunk damage Is the most common. Left, even a small charred area on a California black oak can indicate damage to the cambium; right, active cambium is rapidly growing over the wound. Coast Live Oak A subsequent tree survey on the Soboba Fire was run in June 1977 and May 1979, 34 and Coast live oak was studied on six burned 57 months after the fire. All the trees in a areas. The Soboba Fire was extremely hot, and belt transect 50 ft (15 m) wide and 565 ft (173 severely burnt several groves of coast live oak m) long were tagged and described. Data for (table 3, fig. 7). A number of completely the 57-month sample date (table 3) indicate charred trees were examined about 5 weeks after that: the fire. Initial evidence indicated that the cambium of many of the trees was not killed, 1. Only 4 percent of all the trees were and proposed sale of several hundred of the completely killed by fire. large trees for firewood was canceled. 2. Ninety percent of the trees less than The preliminary survey revealed coast live 3 in. d.b.h. were top-killed, but most had oak's ability to resprout from both the trunk sprouted from the base, and only 2 percent were and branches. Heavily charred trees resprouted complete1y dead. within a few weeks after the fire, and within 5 years, regrowth has filled out a good part of 3. The trunks and crowns of all but 5 the preburn crown area (fig. 7). percent of the trees larger than 6 in. d.b.h. survived the fire, and only two of 111 trees A followup survey of 75 completely charred were completely killed. trees in July 1976, 23 months after the fire, showed that all trees less than 3 in. (7.6 cm) The ability of the upper crown of coast d.b.h. were top-killed, but 87 percent had live oak to survive intense fires was observed basal sprouts. Most trees 3 to 6 in. d.b.h. on several other burned areas. Crown recovery were also top-killed, but about 20 percent had was dramatic on all of these areas, although it trunk or crown sprouts. None of the trees appears that percent mortality is occasionally larger than 6 in. d.b.h. were dead, and at greater than that after the Soboba Fire. least part of the trunk and crown of 60 percent Sometimes, the trunk and branch sprouts of a of the trees was still alive. coast live oak die back.

Figure 7--A tree may recover from extensive crown damage. x,3 weeks after a wildfire, a large coast live oak which was completely charred is sprouting along the tops of the lower branches; right, 5 years after the fire, a large part of the original crown has been replaced. Table 3--Condition of coast live oak trees on the Soboba area about 5 years after being completely charred in an intense wildfire

I I Tree condition, May 19 79 L Number of Basal Basal and Crown Tree diameter charred trees, Dead sprouts crown sprouts (d. b.h., inches) August 1974 only sprouts on1y

Other attributes than its outstanding fire trees is not expected. The most severe damage resistance favor use of fire in management of to this species occurs on the stand periphery, coast live oak. The trees are often large, where they are exposed to high temperatures making prescribed fire for hazard reduction from the surrounding brush. advisable; and the stands are often very dense, with a low fuel loading of shrubs and other The Cleveland National Forest successfully flammable material. used prescribed burning for hazard reduction under California black oak in May and June 1978. An understory of green grass often California Black Oak prevented direct burning of the tree trunks. Although the leaves on some of these trees were California black oak was studied on the heat killed, on most trees a crop of new leaves Soboba site and on a site of the Vista Fire emerged 2 weeks later. (San Bernardino National Forest) that occurred in 1972. A few trees in a small grove that suffered different degrees of fire damage were Canyon Live Oak marked for study a short time after the 1974 Soboba Fire. The trunks and upper crowns of Fire effect on canyon live oak was first the trees on the perimeter of the stand were studied on the Soboba area; this work indicated killed during the fire, but trees farther in that the trunk was relatively sensitive to heat the stand received proportionately less damage, damage. A more intensive investigation was although a few large, old, hollowed-out trees made after the November 1975 Village Fire. The fell over. condition of 198 trees with partially live crowns in a belt transect 50 f t (15 m) wide and In October 1978, a belt 'transect 25 ft 565 ft (172 m) long was determined 18 and 36 (7.6 m) by 300 ft (92 m) was established in months after the fire. Trees with girdled another grove , which had been partially trunks and dead crowns were tallied, but not surrounded by heavy brush. All 72 trees in the described. sample strip were tagged and their condition recorded (table 4). Almost 5 years after the The Village study site was in a dense, fire, only 9 trees were dead, and they were almost pure stand of canyon live oak. Most of evenly distributed throughout the 6 to 18 in. the trees were between 6 and 12 in. d.b.h. (15 to 46 cm) size classes. Trees less than 6 Fire damage was generally restricted to in. d. b.h. had the lowest percentage of live charring of the basal 1 to 5 feet of the trunk, crowns and highest percentage of basal sprout- and leaf kill of one-third to two-thirds of the ing. crown. The dead, flaky bark (fig. 4) often carried fire several feet up a trunk; leaves on A low intensity fire may kill the cambium branches a few feet from the ground were heat- of even very large California black oak trees killed, but not burned. It was common for the where the trunk is charred (fig. 6). Because bark of any size tree to be completely burnt ground cover is usually sparse under stands of through, exposing the wood underneath. This is large trees with closed canopies, high rare for the other species covered in this intensity fires and complete girdling of the report. Table 4~Conditionof a stand of California black oak 50 months after the 1975 Soboba Fire

I I Tree condition-11 Basal sprouting

Tree diameter Number of Dead Basal Live + (d.b.h., inches) trees sprouting crown-2/ live crown

--Percent --

Ñ~nitiafire damage ranged from no obvious effects to charring of the trunk and part of the crown.

2'~ncludes bth undamaged crown and regrowth since the fire.

Eighteen months after the fire, all trees several trees with different degrees of fire less than 3 in. d.b.h. were top-killed and 90 damage were monitored the first year after the percent had resprouted from the base (table 5). 1974 fire. Interior live oak was more Crown kill developed more slowly in the larger sensitive to fire than canyon live oak. trees and 55 percent were still alive at 18 Although the bark of these trees is mostly live months, although most were thought to be and doesn't burn well, total bark thickness is completely girdled at the base. Because the not very great (fig. 5). In addition, most tops of the trees were still green and growing, interior live oak trees in southern California it appeared that they were healthy and had are less than 12 in. d.b.h.; consequently, the successfully survived the fire. bark offers very little protection.

During the next 18 months, about one-half The effect of fire on large interior live of the "live" crowns turned brown (table 6). oak trees was observed in a recent survey on Many of the remaining live crowns will probably the Los Padres National Forest. Even trees die in the next 18 months. In general, canyon with bark an inch or more thick were thought to live oak trees that have complete basal char be girdled at the base where the fire appeared are probably girdled and eventually the crowns to be of moderate intensity. will die, although it may take several years. Successful use of prescribed fire in The use of prescribed fire in the interior live oak management does not seem management of canyon live oak does not appear promising. Not only is the bark thin, it seems to be promising. The trees are too sensitive to be less heat resistant than coast live oak to trunk girdling. The flaky outer bark bark of equal thickness. Where the bark is contributes to the fire, making even a low- charred, the cambium is almost certain to be intensity ground fire one of high intensity on ki 1led. Protect ion of large, individual trees the trunk surface. The rise of cambial might be feasible on small areas. temperature is probably directly related to the flammability of the outer bark (Gill and Ashton 1968). Prescribed fire might be safely used in Scrub Oak a stand of very large trees where fuel loading is low or where the trunks are protected from Scrub oak (Q. dumosa Nutt.) was included direct heat damage. In this report because it is an important component of the chaparral in southern California. Because of its small size and Interior Live Oak intimate association with highly flammable chaparral species, it is almost always Postfire response of interior live oak was top-killed by fire. initially studied on the Soboba area, where Table 5ÑConditio of canyon live oak trees 1-112 years after receiving basal trunk damage during the Village Fire, Angeles National Forest, 1975

Tree condition

Basal Basal sprouting Live Tree diameter Number of Apparent 1y sprouting + crown (d. b.h., inches) trees dead-1/ only live crown only

Ñà --- -- Percent ------

Ñ1~ evidence of live crown or sprouting.

Table 6~Declineover a 3-year period in the The recommendation to cut assumes that a percent of live crowns of canyon live oak tree has been completely girdled and there is trees burned during the Village Fire, little or no chance for survival of the trunk Angeles National Forest, 1975 and tree crown. The "leave" recommendation applies to trees in a range from those almost certain to survive to those which might Trees with live crowns survive. Among trees that may survive are those Tree diameter After After which have basal wounds. A wound is usually (d.b.h., inches) trees 18 months 36 months limited to one side of a tree. I have seen tree crowns survive when less than 10 percent of the trunk circumference was left undamaged. I -- percent - Canyon live oaks 12 in. d. b.h. with wounds up to 20 ft (6.1 m) in height have remained com- pletely functional. The question is, what percentage of a trunk circumference must be damaged before it should be cut? If a wound is narrow, the major portion of the trunk will remain intact, adequately supporting the crown PO STFIRE MANAGEMENT PLANNING of the tree. A prime consideration is whether or not the tree is presently or potentially a The information reported here leads to mechanical risk. As already noted, important some practical recommendations for postfire wildlife, watershed, and recreation values will management planning. The decision to cut or not be affected by serious trunk damage. not cut burnt trees as soon as a fire is out should be based on reliable information about A tentative cutting guide might be: anticipated tree survival. When possible, it is well to let at least one or preferably three 1. Cut trees less than 6 in. d.b.h. that growing seasons pass after a fire before making are more than 75 percent girdled. survival probability estimates and cutting decisions where survival is questionable. 2. Cut trees larger than 6 in. d.b.h. that are more than 50 percent girdled. The recommendations for cutting presented here (table 7) reflect only the expected response of trees to fire, and do not address CONCLUSIONS other management considerations. The recommen- dations are generalized for size classes and 1. Oak species response to fire is degree of charring. Except in a crown fire, variable. The trunk and upper crowns of coast when direct effects tend to be the same on all live oak trees are highly resistant to fire trees, there is usually considerable range in kill and most trees resprout soon after they degree of charring, and individual tree marking are burned. California black oak is less is appropriate. resistant to fire than coast live oak. Canyon Table 7~Recommendedguide to harvesting fire-damaged southern California oak trees, based on tree

size and degree of trunk char-1 /

Less than 6 in. d.b.h. 6-12 in. d.b.h. More than 12 in. d.b.h.

Species Light Medium Heavy Light Medium Heavy Light Medium Heavy char char char char char char char char char

Coast live oak Lv Lv Cut Lv Lv Lv Lv Lv Lv

California black oak Lv Cut Cut Lv Cut Cut Lv Lv Cut

Canyon live oak Cut Cut Cut Lv Cut Cut Lv Cut Cut

Interior live oak Cut Cut Cut Lv Cut Cut Lv Cut Cut Scrub oak Cut Cut Cut Lv Cut Cut -21 - --

Lj~ssumesthat 100 percent of the trunk circumference is affected, as follows: ---spotty char or scorch, scattered pitting; Medium-cont inuous charring, scattered areas of minor reduct ion in bark thickness; Heavy-continuous charring and pronounced reduction in bark thickness, with wood sometimes exposed. 5 means that the tree should ke left uncut for 3 years; means the tree can be cut immediately .

2/~cruboak does not reach 12 in. d.b.h.

live oak, interior live oak, and scrub oak are LITERATURE CITED more susceptible to fire damage than California black oak. Baker, F. S. 1929. Effect of excessively high tempera- 2. Large oak trees are generally more tures on coniferous reproduction. J. For. resistant to fire kill than small ones. Bark 27:949-975. is generally thicker and crowns are higher above the ground~both features reduce Danielson, H. R. vulnerability . 1972. Quick tests for determining viability of Douglas fir seed. p. 104-109. Proc. 3. Bark thickness and composition vary Joint Meeting, Western Forestry Nursery considerably among the five oak species studied Council and International Forest and appear to have a direct effect on fire Nurseryman's Assoc., Olympia, Wash., August damage to the cambium. Thick, live bark offers 8-10. best protection; dead, flaky, outer bark may directly contribute to a tree's destruction. Edwards, M. B. 1957. California black oak--I ts management 4. Discolored inner bark and cambium, and economic possibilities. J. For. 55: with an aroma of fermentation are the best 506-510. indicators of tissue damage. Ferguson, E. R. 5. Oak response to wildfire is complex 1957. Stem-kill and sprouting following and depends on actions and interactions of many prescribed fires in a pine-hardwood stand variables. Trees may not react as expected and in Texas. J. For. 55:426-429. without careful examination, sound or slightly damaged trees will be unnecessarily cut. Ferguson, R. B., R. A. Ryker, and E. D. Ballard Additional study of feasibility of prescribed 1975. Portable oscilloscope technique for burning in oak management is needed. detecting dormancy in nursery stock. USDA For. Sen. Gen. Tech. Rep. INT-26, 16 p. Intermountain Forest and Range Exp. Stn., Martin, R. E. Ogden, Utah. 1963. A basic approach to fire injury of tree stems. Proc. 2nd Annual Tall Timbers Gill, A. M. Fire Ecology Conf ., Tallahassee, Florida, 1974. Toward an understanding of fire-scar March 14-15, p. 151-162. formation: field observation and labora- tory simulation. For. Sci. 20:198205. Martin, R. E., and J. B. Crist 1968. Selected physical-mechanical proper- Gill, A. M., and D. H. Ashton ties of eastern tree barks. For. Prod. J. 1968. The role of bark type in relative 18(11):54-60. tolerance to fire of three central Victorian eucalypts. Aust. J. Bot. 16: Martin, R. E., C. T. Cushwa, and R. L. Miller 491-498. 1969. Fire as a physical factor in wildland management. Proc . 8th Annual Tall Timbers Hare, R. C. Fire Ecology Conf., April 10-11, 1969, p. 1960. Detecting dead cambium with a moisture 271-288. meter. J. For. 58:815-817. Munz, P. A., and D. D. Keck Hare, R. C. 1959. A California flora. Univ. Calif. 1961. Heat effect on living plants. USDA Press, Berkeley and Los Angeles. 1681 p. For. Serv. Occas. Pap. 183, 32 p. Southern Forest Exp. Stn., New Orleans, Louisiana. Sander, I. L. 1977. Manager's handbook for oaks in the Hare, R. C. north central States. USDA For. Sew. Gen. 1965a. Contribution of bark to fire Tech. Rep. NC-37, 35 p. North Central resistance of southern trees. J. For. 63: Forest Exp. Stn., St. Paul, Minn. 248-251. Skutt, H. R., A. L. Shigo, and R. A. Lessard Hare, R. C. 1972. Detection of discolored and decayed 1965b. Chemical test for fire damage. J. wood in living trees using a pulsed For. 63:939. electric current. Can. J. For. Res. 2:54-56. Hepting, G. H. 1941. Prediction of cull following fire in Spalt, K. W., and W. E. Reifsnyder Appalachian oaks. J. Agric. Res. 62:109- 1962. Bark characteristics and fire 120. resistance: a literature survey. USDA For. Serv. Occas. Pap. 193, 19 p. Southern Johnson, P. S. -,, Forest Exp. Stn., New Orleans, Louisiana. 1977. Predicting oak stump sprouting and sprout development in the Missouri Ozarks. Toole, E. R., and G. M. Furnival USDA For. Serv. Res. Pap. NC-149, 11 p. 1957. Progress of heart rot following fire North Central Forest Exp. Stn., St. Paul, in bottomland red oaks. J. For. 55:20-24. Minn. Vines, R. G. Longhurst, W. M. 1968. Heat transfer through bark, and the 1956. Stump sprouting of oaks in response to resistance of trees to fire. Aust. J. Bot. seasonal cutting. J. Range Manage. 9 :194- 16:499-514. 196. Wagener, W. W. Loomis, R. M. 1961. Guidelines for estimating the survival 1973. Estimating fire-caused mortality and of fire-damaged trees in California. USDA injury in oak-hickory forests. USDA For. For. Serv. Misc. Pap. 60, 11 p. Pacific Serv. Res. Pap. NC-94, 6 p. North Central Southwest Forest and Range Exp. Stn., Forest Exp. Stn., St. Paul, Minn. Berkeley, Calif.

Loomis, Robert M. 1974. Predicting the losses in sawtimber volume and quality from fires in oak-hickory forests. USDA For. Serv. Res. Pap. NC-104, 6 p., illus. North Central Forest Exp. Stn., St. Paul, Minn. Sprouting in Fire-Damaged Valley Oaks, Chews Ridge, California1

James R. Griffin 21

Abstract: Sproutingresponseof a total of 266 valley oaks was studied on plots representing three fire intensities in the Marble-Cone fire. In a crown fire plot all crowns were killed, but 53 pet of the roots survived to produce sprouts. After 1 year the crown fire plot sprouts averaged 59 cm in height. On a severe ground fire plot 82 pet of the oaks survived; 90 pet of the survivors had basal sprouts. Sprouts from trees with dead crowns emerged sooner and appear- ed more vigorous than sprouts from trees with live crowns. Mortality in a moderate ground fire plot was low; 57 pet of the survivors had basal sprouts. There was a trend in de- creasing basal sprout vigor with increasing tree size. Ninety-three pet of the basally sprouting oaks had diameters between 10 and 39 cm.

INTRODUCTION subjected to various degrees of crown damage. This report summarizes the sprouting response The Chews Ridge region in the Santa Lucia of over two hundred valley oaks during the Range of Monterey County supports many age- first growing season after the fire. classes of valley oak (Quercus lobata ~6e). Of particular interest are the younger trees, which are relatively well represented in this LITERATURE REVIEW area (Griffin 1976). These small valley oaks are currently uncommon or rare in much of the It is common knowledge that most Cali- oak woodland in California (Griffin 1977). fornia oaks sprout when cut or burned. The shrubby oak species in the chaparral send up During the Marble-Cone fire of August 1977 vigorous shoots after crown destruction, and all the valley oaks on the summit of Chews the evergreen oak trees sprout actively from Ridge burned to some extent (Griffin 1978). the base, sometimes from the crown as well. Damage ranged from incineration by crown fire However, the deciduous white oak trees (valley to light singeing by ground fire. oak; Oregon white oak, Q. garryana Dougl.; blue oak, 0. douglasii Hook. & Arn.) do not sprout While surveying vegetation recovery on as vigorously as the other California oaks. So parts of the burn, I noticed younger valley little has been published specifically about oaks sprouting throughout the burned woodland valley oak that these two other closely related on Chews Ridge. Knowing that few details of white oak trees are also reviewed here. valley oak sprouting were recorded in the lit- erature, I documented this interesting sprout Jepson7s (1910) early account of vegetat- situation where different age-classes had been ive reproduction in white oaks remains the most helpful general reference. The following items are taken from his oak regeneration notes 11 Presented at the Symposium on the Ecology, and individual species descriptions. All three Management, and Utilization of California Oaks, species wstump-sprout" when young, but sprout Claremont, Calif., June 26-28, 1979. vigor declines with age. Stumps of young white oaks are more likely to live than trees of the 21 Research Ecologist, Univ. Calif., Berkeley, same size basally girdled and left standing. Stationed at Hastings Reservation, Camel Oregon white oak may "weakly" stump-sprout in Valley, Calif. 93924 a few mature trees. Blue oak does not stump- sprout from mature trees, but it may wsuckerw from the trunk if cut several feet from the upper crowns remained green. Most valley oaks ground. Unfortunately, Jepson gave no sizes in light ground fire areas had so little dam- or ages at which sprouting declined in these age that they were not inventoried. Formal white oaks. plot boundaries were not set, but the study area was essentially a complete sample of val- Jepson stressed that natural valley oak ley oaks on three plots totalling about 2 ha. regeneration is almost exlcusively by seed and that valley oak has the least vegetative repro- All the smaller valley oaks which might ductive potential of any California oak. He be able to sprout were marked with numbered observed that: "Cutting off the trunk at the aluminum tags nailed at dbh level on the north ground ends the life history at once, unless it side of the trunk. The larger interspersed be a small sapling-like tree. Increasing the oaks were inventoried but not tagged unless height of the stump apparently makes no differ- they had damage features of special interest. ence so long as the cut is below the first main For both tagged and untagged oaks, dbh, height arms or branches, but if the short stubs of the of charred bark, condition of the 1977 leaves, main branches be left then sprouting ensues condition of the 1978 crown, and size and freely." nature of sprouts were recorded.

I found no significant modern reference to valley oak sprouting. The wildlife habitat RESULTS AND DISCUSSION improvement literature has one item on how to encourage sprout production from blue oak Valley oaks are seldom subjected to as stumps (Longhurst 1956). And the range im- hot a fire as these received in the oak-pine provement literature has a few notes on how to woodland on Chews Ridge. This portion of the eliminate blue oak sprouts with herbicides mountain last burned in 1928, so 49 years of (Leonard 1956, Leonard and Harvey 1956). fuel had accumulated. Although parts of the oak stands are still "savannaM with a ground The few references mentioned above deal cover of annual grasses or bracken (Pteridium with the response of white oaks to mechanical aquilinum Kuhn), much of the area had been in- or chemical crown damage. Even fewer referen- vaded by Coulter pines (Pinus coulteri D. Don] ces discuss sprouting induced by fire damage. (Griffin 1976). These thickets of pine sap- Benson (1962) did speculate that blue oaks lings and small trees with a deep litter of could not survive in chaparral habitats be- needles, branches, and cones greatly increased cause of their relatively poor sprouting vigor. the fire hazard to the oaks. In addition, two He stated: "Although the blue oak can survive consecutive drought seasons with only half of grass fires beneath them in the oak woodland, the expected precipitation added to the hazard. they are killed outright by a hot brush fire, so they are unable to invade the chaparral." From previous work I knew about several Benson was particularly contrasting savanna- dozen large valley oaks, up to 206 cm dbh, that grown blue oaks with white oak shrubs such as had been dead in the study area for some years. scrub oak (2. dumosa Nutt.) which thrive in These snags were completely consumed during the chaparral. fire. Only empty "root cavitiesw radiating out from large pits in the baked soil mark where the snags had been. Burning of these snags METHODS caused pockets of severe damage in otherwise moderate or light ground fire areas. I took general observations throughout a mosaic of fire damage conditions on Chews Ridge. The oaks inventoried for this report grew on Crown Fire the gentle summit between the U.S. Forest Ser- vice lookout tower and the Monterey Institute The fire entered the southern end of the for Research in Astronomy site. This area was study area on August 12, 1977 after crowning visited seven times between October 1977 and uphill through chaparral and scrubby hardwood December 1978. forest. Here the ground cover, shrub stratum, and tree leaves and small twigs were literally There was a general reduction in fire in- consumed. Trunks of the valley oaks, up to 22 tensity across the study area. Regardless of m tall, were charred to their tops. Crowns of location, however, each tree was classed indi- the oaks were completely killed; no epiconnic vidually into one of three damage groups on the sprouts appeared during the following year. basis of crown damage in 1977. "Crown fire" Many of the rootsystems of the oaks were also trees had all the leaves and smaller twigs con- killed. Crown fire mortality of valley oaks sumed. The "severe ground fire" trees still was 48 pet (Tables 1, 2). had leaves, but the leaves were dead. In "mod- erate ground fire" areas some leaves in the The first basal sprouts I noticed on the Table 1-- Diameter distribution of 53 valley Table 2-- Diameter distribution of 213 valley oaks killed by three degrees of fire damage oaks with basal sprouts (B) and/or epiconnic on the Chews Ridge study plots. sprouts (E) within three fire damage classes on the Chews Ridge study plots.

Severe Moderate Dbh class Crown ground ground Severe Moderate (cm) fire fire fire Dbh class Crown ground ground (cml fire fire fire

0-9 B BBE EIBBE E 10-19 20-29 30- 39 0-9 3 40-49 10-19 15 50-59 20-29 9 60-69 30- 39 2 70- 79 40-49 1 80- 89 50-59 1 90-99 60-69 100-109 70- 79 110-119 80-89 120-129 90-99 130-139 100-109 140-149 110-119 150-159 120-129 160-169 130-139 140-149 Total -

Total ' 31 study area were on these crown-fire-killed oaks. Within 60 days after the fire a few small val- sprouts (Table 2). After 1 year the browsed ley oaks had basal sprouts up to 20 cm tall. basal sprouts ranged in height from 10-115 cm These sprouts were already large enough to with a mean of 47 cm. Twenty-one pet of the attract browsing deer. One year after the fire, surviving valley oak trees had epicormic heights of the browsed sprouts ranged from sprouts on trunks or large branches. At the 15-120 cm with a mean of 59 cm. end of the first year some epicormic sprouts were dying, and it was not clear how many of the old crowns would survive or be rejuven- Severe Ground Fire ated by these sprouts. Most of the small trees that do survive by epicormic sprouts will have When the fire moved onto the gentler serious basal fire scars; strips of bark were slopes of the main summit, it no longer burned already peeling off where the cambium died by from crown to crown. Here the leaves were the end of the first year. The amount of fire heat-killed but not burned. Any burning that scars on the thick-barked large survivors was did occur in the crowns centered around the not evident during the first year. dead wood exposed at broken limbs and tops of large trees. On trees with extensive internal rot, burning so weakened the trunks that the Moderate Ground Fire trees broke apart. In a few hollow trees the internal fires killed the trees while the bark Direct mortality from the fire was low in remained unscorched. On small relatively thin- this area. Only two small trees and one large barked trees crown mortality resulted from heat- hollow tree out of 86 inventoried oaks died caused girdling through the bark. In many such (Table 1, 2). Fifty-seven pet of the surviv- trees the cambium died even though the bark was ing valley oaks have basal sprouts (Table 2). not charred. One year after the burn the browsed basal sprouts ranged in height from 10-120 cm with a Only 18 pet of the severe ground fire oaks mean of 45 cm. All trees with live crowns had died during the first year (Tables 1, 2). Of some degree of epicormic sprouting in the lower the surviving valley oaks 90 pet had basal crown. One year after the fire the large oaks had relatively normal-looking crowns. The small trees had mixtures of dead leaves, epi- comic sprouts, and normal twigs. Many of the LITERATURE CITED small trees will have basal fire scars. Benson, L. 1962. Plant taxonomy, methods and principles. Sprout Vigor Ronald Press, New York.

The dbh distributions in Table 2 strongly Griffin, J.R. support Jepson's (1910) generality that valley 1976. Regeneration in Quercus lobata savan- oak sprouting vigor declines with age. The nas, Santa Lucia Mountains, California. largest tree to have basal sprouts was 66 cm Amer. Mid. Nat. 95:422-435. dbh, and 93 pet of the trees with basal sprouts were between 10 and 39 cm dbh. Griffin, J.R. 1977. Oak Woodland. In Terrestrial vegetation Basal sprout heights could not be deter- of California. M.G. Barbour and J. Major,eds mined very precisely. The tips of some froze p. 385-415. Wiley-Interscience, New York. early in the season, and almost all sprouts suffered some die-back from mildew infection. Griffin, J.R. In 1978 mildew was abundant on sprouts of all 1978. The Marble-Cone fire ten months later. oak species over the entire Marble-Cone burn. Fremontia 6(2) :8-14. Black-tailed deer added even more problems in measuring sprouts, for over 90 pct of the Jepson, W. L . sprouts had been browsed. 1910. The silva of California. Univ. Calif. Mem. v. 2. I did not correlate sprout height with dbh, but smaller trees appeared to have larger Leonard, O.A. sprouts. The modal height class for basal 1956. Effect on blue oak (Quercus douglasii) sprouts was 40-59 cm. Of the 27 sprouts that of 2,4-D and 2,4,5-T concentrates to cuts were 70 cm or more tall only three were from in trunks. J. Range Manage. 9:15-19. trees greater than 25 cm dbh. Regardless of size, valley oaks with dead crowns appear to Leonard, O.A., and W.A. Harvey. sprout earlier, have longer sprouts, and pro- 1956. Chemical control of woody plants in duce more sprouts per trunk base than trees California. Calif. Agr. Exp. Sta. Bull. with live crowns. 755.

Longhurst, W.G. Fire Control Implications 1956. Stump sprouting of oaks in response to seasonal cutting. J. Range Manage. 9:194- Apparently the Marble-Cone fire caused a 196. rather high number of valley oaks to sprout. Even if heavy sprout mortality occurs in the next few years, an obvious number of sapling sprout clumps should develop. .This amount of basal sprouting has not occurred after pre- vious fires on Chews Ridge. The 1928 fire produced few if any successful sprout clumps on the study area. Pre-1928 fires caused only 3 pet of the stand to sprout; the 266 trees inventoried contained only eight sprout pairs andone sprout trio. Past fires also left basal fire scars on only 4 pet of the valley oaks on the study area.

Since the least sprouting after the Marble- Cone fire occurred in areas with no more than moderate ground fires, this study suggests that Chews Ridge did not have widespread crown or severe ground fires during the establishment of the present valley oak stands. Burns as serious as the Marble-Cone fire in the past should have caused a higher proportion of val- ley oak sprout clumps and more conspicuous basal fire scars on the surviving valley oaks. Quercus -kel loggii

Effect of Chronic Oxidant Air Pollution Exposure on California Black Oak in the San Bernardino

31 41 5 Paul R. Miller- , Gail J. Longbotham- , Robert E. Van Doren- I,

and Maureen A. Thomar61

Abstract: The effects of ambient oxidant air pollution exposure between 1974 and 1978 on California-black oak (Quercus Kelloggi Newb.) leaf injury development, stem diameter growth, acorn production, and relationships to insect pests and disease were studied in 15 vegetation plots located along a gradient of decreasing oxidant dose in the San Bernardino Mountains of southern California. Leaf injury decreased uniformly along the decreasing dose gradient. Year-to-year observations suggested that greater leaf Injury was related to lower air temperatures, concurrent with cumulative dose and higher precipitation during the preceding winter and spring. Greater leaf injury generally resulted in lower average stem diameter increases between 1975 and 1978 when the total tree population was considered; however, site quality obscured this difference in some plot comparisons. Distribution of the insect and disease complex did not appear related to the oxidant stress gradient; however, the fruit tree leaf roller and oxidant injury acted additively to injure foliage at several plots. Acorn production appeared depressed at these sites. The results of this study suggest that black oak will con- tinue to show diminished productivity if ambient oxidant air pollution remains at levels measured in recent years.

INTRODUCTION

California black oak (Quercus Kellog~i [Gord. and Glend.] Lindl.) , is positively Newb.) is an important species in the correlated with black oak crown cover in mixed-conifer and pine types of the San the San Bernardino Mountains (McBride 1978a) Bernardino Mountains. It is found in stands and the oxidant damaged ponderosa pine-black dominated by either ponderosa pine (Pinus oak type appears to be shifting towards a black ponderosa Laws.) or Jeffrey pine (P. oak type (McBride 1978b). Since 1974, data Jeffrey! Grev and Balf.). The seedling have been collected on a gradient of de- density of associated conifers, namely creasing oxidant dose in the San Bernardino ponderosa pine and white fir (Abies concolor, mountains (Miller and others, 1977).

'presented at the Symposium on Ecology, -3lResearch Plant Pathologist, Pacific South- Management and Utilization of California west Forest and Range Experiment Station, Oaks, June 26-28, 1979, Claremont, Forest Service, U.S. Department of Agri- California. culture, Riverside, Calif. li his investigation was supported in -4lFormerly Junior Statistician, Statewide part by EPA Contracts 68-03-0273 and Air Pollution Research Center, University 68-03-2442, and EPA Grants R805410-01 and of California, Riverside, Calif. 02, through the Corvallis Environmental Reseach Laboratory. This report has been -5lPhysical Sciences Technician, Pacific reviewed by the U.S. Environmental Protec- Southwest Station. tion Agency. -6/Formerly Senior Clerk, Statewide Air Pollution Research Center This report describes preliminary California Conference Center on the north results of work on the relationships shore of Lake Arrowhead. Plots were listed of within-season and end-of-season leaf in order of ascending elevation, with injury in black oak and radial growth to distances and azimuths from Camp Paivika, oxidant dose and weather variables. The the number of California black oak trees, frequency of acorn crops and the activity of and the principal pine associated in each defoliator insects and diseases along the plot (table 1). oxidant gradients are also reported. Plots were selected on the basis of relative homogeneity of tree cover. They METHODS AND MATERIALS were generally located on flat terrain or gently sloping north aspects. Plot width Study Sites was always 30 meters but length varied Fifteen permanent plots were estab- depending on the distance required to obtain lished in an east to west direction, the 50 ponderosa (PP) or Jeffrey (PJ) from 1515 to 2212 meters elevation, in the pines equal to or greater than 30 centimeter San Bernardino Mountains. Resultant plot diameter breast height (d.b.h.). All tree locations corresponded to a gradient of species equal to or larger than 10 centi- decreasing oxidant air pollution effect, meter d.b.h. were labeled with numbered with increasing distance to the east. The metal tags. oxidant gradient occurred within a 44.4 kilometer span between Camp Paivika at Oxidant Monitoring and the extreme west and Camp Osceloa at the Meteorological Measurements extreme east. Another dimension of the gradient was related to the south-to-north Hourly ozone measurements were obtained separation of plots, for example, the 3 to 4 from May through September, beginning in kilometer span between Sky Forest on the rim 1974, at three permanent stations~camp overlooking the basin and the University of Paivika, Sky Forest, and Barton Flats. The

Table I--Permanent plot characteristics with plots listed in order of increasing distance from the Camp Paivika plot.

Elevatio Location relative and pine-' to Camp Paivika Black oak Plot name Abbreviation , associate(s) Distance 1 Azimuth, trees I meters kilometers degrees Camp Paivika CF' Breezy Point BP Tunnel Two TUN2 Dogwood A DWA Univ. Cod. Cen. ucc Sky Forest SF Camp Oongo coo Green Valley Cr. GVC Deer Lick DL Snow Valley 1 SV1 Camp Angelus CA Schneider Cr. SCR Barton Flats BF Holcomb Valley HV Camp Osceola CAO

'pp - ponderosa pine; JP = Jeffrey pine DASIBI ultraviolet photometers used at these inserted into the orifice of the snow stations were calibrated by the California gauge. Air Resources Board in El Monte. Data were recorded on strip charts. Mast total Observation of Black Oak Responses oxidant meters (the instrument signal includes over 90 percent ozone and small Oxidant Injury--At two week intervals, amounts of NO2 and peroxyacetyl nitrate) starting in mid-June and ending by early were used at all sites prior to 1974; during September, within season measurement of leaf the 1974 to 1978 period they were located injury was evaluated at 5 of the 15 plots. for two to three week periods at or nearby Three branch tips were permanently tagged on each vegetation plot. These temporary plot each of five trees per plot; this labeling measurements were compared hourly by regres- provided assurance that the same leaves sion with the nearest of the three permanent would be observed each time. A five- stations so that missing hourly concentra- category descriptive scale was used to tions could be calculated. evaluate the symptom intensity represented by the aggregate of leaves on each branch Mast meters were calibrated against a tip: DASIBI ozone photometer that was maintained in the laboratory as a transfer standard. Scale Description Power was provided for Mast meters at plots with four 6 volt, 217 A/hr lead acid 4 Leaves completely green batteries that were replaced with newly charged batteries twice per week. DC to AC 3 First evidence of interveinal inverters were required. The Datamart strip chlorosis, chlorotic mottle, chart recorders used at plots had self- or necrotic lesions mainly on contained rechargeable gel cell batteries. upper surfaces

All oxidant and ozone data were ad- Moderate levels of inter- justed for the elevation difference between veinal chlorosis, chlorotic the calibration site and each mountain mottle, necrosis mainly on station or plot location by a factor ranging the upper surface from 1.16 at 1515 meters to 1.26 at 2212 meters. Cumulative ozone or oxidant dose More severe than category 2 was obtained by summing all hourly concen- with necrosis extending to trations equal to or greater than 0.03 the lower leaf surface ppm.(the natural background concentra- tion). 0 Leaves necrotic on both surf aces Air temperature and relative humidity were measured hourly at the three permanent An end-of-season evaluation of chronic stations and telemetered by radio or tele- leaf injury was made of all black oaks at phone line to the laboratory in Riverside. each of the 15 plots, during the first 10 The system was designed by Ball Brothers days of September, each year from 1974 to Research, Boulder, Colorado. At remote 1978. About half the plots were not visited vegetation plots, temperature and relative in 1977 due to scheduling problems. In this humidity were measured with hygrothermo- procedure the leaf canopy of each tree was graphs in standard weather instrument arbitrarily divided into upper and lower shelters. halves and leaf condition was described separately usually through wide-angle Winter precipitation was collected at binoculars. Year-to-year comparisons are vegetation plots using "Sacramento" storage thought of as relative levels of deteriora- gauges standing 147 centimeters high, with a tion from the healthy, symptomless score of 48 centimeter diamter base, and a 25 centi- 8 (4 each for upper and lower canopy). meter diameter orifice. The gauge was charged with antifreeze and a thin surface Stem Growth and Acorn Crops--In 1975, a layer of automatic transmission fluid. nail was placed at 1.4 meters d.b.h. on all Accumulations were measured monthly, when trees. In 1978, the d.b.h. was remeasured. possible. Standard rain gauges and, later, The diameter growth difference between the a modification of the snow gauge were used autumns of 1975 and 1978 (three growing to collect summer precipitation. The seasons) was compared from plot to plot and modification consisted of a 23 centimeter for all plots, with particular attention to diameter funnel and collection bottle the relationship between growth and leaf injury. Both the upper and lower crowns of each pollutant source is most evident for those tree were inspected for acorns during plots 40 to 44 kilometers east of CP and end-of-season observations. The frequency of above 2000 meters elevation, where average acorn crops for each tree was compared for leaf injury for each of the 5 .years at BF, the 1973-1978 period. CAO, SV1 and HV was > 7.0 (very slight to no injury Insect Activity, Diseases, and Other Environmental Stresses--At two plots, BLACK OAK PLOT LOCATIONS 4 LOCATION namely CP and BP, black oaks were infested m with the fruit tree leaf roller (Archips ar~yrospilusWalker) throughout the study period (Brown and Eads 1965). Eight other + + SV 1 CAO plots had minor infestations for at least 1 7.8 7 .a GVC year. Some of this early summer defoliation 6.5 was possibly due to the California oak moth (Phryeanidia californica Packard). The resultant defoliation was described as 1, DUA light; 2, moderate; and 3, severe. De- 5.3 SF foliation at the end of the season was + +Â¥'. comprised of a new flush of leaves that were produced following the activity of the insects in May and June. ------. 6 12 18 24 38 36 42 , True mistletoe (Phoradendron flavescens- DISTANCE

Plots in order Distance Average 1 Diameter of decreasing from injury-"' increase leaf in1ury CP (1974-1978) (1975-1978) kilometer centimeter

CP BP SF DWA coo SCR CA TUN2 DL GVC ucc BF CAO SV1 HV

-0 - 1.99 Very severe 2 - 3.99 Severe 4-5.99 Moderate 6 - 7.99 Very slight to slight 8 None

with greater leaf injury, but chronic de- population was divided into four stratifica- foliation of many trees by the fruit tree tions, or leaf injury categories, so that leaf roller at these plots may be partially the growth responses of each grouping could responsible for the smaller growth response. be tested using the two-sample t-test for unequal sample sizes. The test results show To further explore the effect of leaf substantial differences where the p values injury on growth, a regression was fitted were 0.000 for the first three groupings and for each plot but the R^ values did not 0.004 (separate) and .002 (paired) for the exceed 0.15. An analysis of variance was fourth, namely, 0-6.99 vs 7.0-8.0. used to test the regressions of growth on injury for all plots, showing that slopes The growth differences, evident from and intercepts differ beyond chance from these comparisons based on leaf Injury, are plot to plot. The importance of plot (as greatest when the 0-3.99 categories are expressed through characteristics like soil compared with the larger group of trees with depth, water holding capacity, and slope) on less leaf injury. The growth difference average radial growth is reported by Gemmill becomes smallest when trees in the 7.0-8.0 in this volume. leaf injury category are compared with the remaining population. The inÂluence of leaf injury on stem growth was examined by comparing four On the basis of leaf injury observa- samples from the total population (table 3). tions at six plots experiencing the heaviest Plot characteristics seem to dominate as the oxidant doses (CP, BP, TUN2, DWA, SF, and most important variables associated with COO) only 12 out of 170 trees in these plots stem growth; however, another method was could be considred oxidant tolerant, that used to investigate the relationship of leaf is, with a 7.0-8.0 injury score average for injury and growth in which the total tree the 1973-1978 period. population was examined without respect to plot characteristics. The total tree Table 3--Growth of four black oak samples from the total population when stratified by leaf injury category.

Leaf injury Trees Average diam Differences categories Per increase-!Qer be tween compared category (1915-1978) categories 1 centimeter centimeter

-'confidence interval of 95 percent

Examination of Conditions Affecting BP, DWA, SF and COO) had similar leaf injury Leaf Injury Development--Six of the plots for each year over the 5-year period. These receiving the greatest chronic exposure were plots are located on the ridgecrest over- compared for year-to-year variation of looking the polluted urban basin. TUN2 may average leaf injury for the 1974 to 1978 have had less injury because of the pollu- period (table 4). Five of the plots (CP, tant dilution resulting from its location

Table 4--Annual leaf injury to black oaks at six plots located within an 18 kilometer-long by 4 kilometer-wide zone at the heavily polluted western end of the Ran Bernardino Mountains.

Plot Year CP 1 BP I TUN2 1 DWA I SF I COO Av pi Average leaf injury score

1974 5.5 5.6 6.9 5.1 5.4 5.5 5.420-15

1975 5.5 5.2 5.7 5.4 4.9 5.5 5.220-15

19 76 4.7 4.3 6.0 4.6 4.3 4.7 4.620-15

1977 6.5 6.3 6.9 6.4 6.1 6.5 6.230-15

1978 4.6 4.1 5.6 5.0 5.0 4.6 4.6+0.15

Ave : t.8+0.11 5.1+0.16 6-29-20 5.320-22 5.220.34 5.420-11 5.2+0.06

"~verage injury for a single year for trees at the six plots could not be derived from averaging the six individual values for that year because plots must have the same number of trees

2'~onfidence interval of 95% 2.6 kilometers north of the first ridge- year of peak production was 1977, followed crest. The average injury at all plots by 1978. The general impression is that varied similarly from year to year. The trees with less leaf injury and more rapid most severe injury occurred in 1976 and growth also produce more acorns (table 6). 1978; 1977 had the least injury, while 1974 The small number of acorn bearing trees at and 1975 were intermediate. The data CP and BP may result from the combination of required to examine the different variables stresses imposed by oxidant pollution and associated with symptom development at all the fruit tree leaf roller. The locations six plots is not yet available for all where trees produced more acorn crops during years. the five-year period than the number of trees in the plot were DWA, TUN2, GVC, BF Sufficient data was available at plot and SV1. In some cases, this resulted from DWA to examine year-to-year changes of leaf the same tree producing acorns in successive injury. These data show the relationships or alternate years. The average diameter of cumulative oxidant dose and other vari- increases at these plots were all among the ables to injury, for the years 1976, 1977 highest, as seen from ranking of plots in and 1978. During these years, injury the column on the far right in table 6. development was measured biweekly throughout the growing season. The data suggest that Diseases and Insect Pests of Black Oak the larger amounts of injury in 1976 and Experiencing Chronic Oxidant Stress 1978 are associated with lower mean hourly June-September air temperatures and moderate The pest complex present on black oaks to high total seasonal precipitation (start- was described for each of the 15 plots in ing in October of the preceding year) (table order of decreasing leaf injury (table 7). 5). The correlation between cumulative During the 5 year observation period only oxidant dose and within-season development six of the original 428 trees in all the of leaf injury is greatest in 1978. The plots died due to pests or physical damage, negative correlation in 1977, when the dose and six were removed for firewood. The two was only slightly less than in 1978, coin- most prevalent problems were insect defoli- cides with lower precipitation and a higher ators (primarily the fruit tree leaf roller) mean seasonal temperature. These prelimi- present on 40 percent of the plot trees nary results suggest the hypothesis that for one or more years and a branch girdling higher temperatures coupled with lower soil canker observed on 24 percent of the trees. moisture availability are expressed as lower The fungal cause of the canker has not been daytime tree water potentials that, in turn, determined. The fruit tree leaf roller has limit both transpiration and pollutant been present in the western portion of the up take. San Bemardino Mountains for at least 10 to 15 years prior to our observations. Frequency of Acorn Crops--The number of The canker dieback was very scarce in the trees producing acorn crops during the 1974 four plots experiencing the most oxidant- to 1978 period were compared listing plots caused leaf injury. No evidence exists to in order of decreasing leaf injury. The suggest that the distributions of either the

Table 5--Variables that may have interacted to control leaf injury development of black oak at the DWA plot in 1976, 1977, and 1978.

Correlation Average End of Cumulative of dose and air season seasonal within- Precipitation, temp. Year leaf injury oxidant dose season injury 0ct.-Sept. June-Sept. (ppm-hr) (cm) (C) Table 6--Trees producing acorn crops between 1974 and 1978 (plots listed in order of decreasing leaf injury).

Total Plots in trees per plot Trees with acorns order of producing each year increasing Plot acorn crops diameter name 1974 - 1978 1974 1975 1976 -I/ 1977 1978 growth Acorn crops Trees

CP DL BP CP SF CAO DWA BP coo HV SCR SCR CA coo TUN2 GVC DL TUN2 GVC BF ucc CA BF SF CAO ucc SV 1 DWA HV (SVl=ND) Total 1 324 426 32 41 39 146 66 Percent 76.0 7.5 9.6 9.1 34.3 15.4

he 1977 data for GVC, DL, HV, CA, SCR, BF and CAO were contributed by Robert F. Luck, Division of Biological Control, University of California, Riverside

defoliator or the branch canker are influ- The relatively small size and small enced by oxidant stress. These agents more number of plots did not provide an optimal likely are to be controlled by existing air design for the best estimate of pest activ- temperature or soil moisture gradients. ity over the complete study area. The intensity levels (1, 2, and 3) to describe True mistletoe infections were present the defoliator, canker dieback, and true at only five plots, the most severe problem mistletoe severity on each tree provide a being at SCR. No direct effects of oxidant useful estimate of the severity of infesta- were recognizable on the mistletoe foliage tions or infections. and no observations were made of mistletoe fruiting.

Stem decay was detectable on only 2 percent of the trees, mainly those of large DISCUSSION diameter. The actual incidence of decay would probably be higher under a more This study was part of an interdis- thorough examination. ciplinary study to predict successional trends in forest stands subjected to several In spring 1974, a heavy snow caused a chronic oxidant dose levels (Miller and small amount of upper stem and branch others 1977). The trend in observed amounts breakage. The utilization of study plot of oxidant-caused leaf injury corresponded trees is indicated by the numbers removed to the injury to oxidant-sensitive conifer for firewood by 1978; one or two were species in the same plots oriented generally living at the time of removal. along a gradient of decreasing cumulative Table 7-Pest complex and other environmental factors affecting black oaks in the San Bernardino Mountains, 1974 to 1978.

Dead Plot rees trees Insect , Canker True Stem Snow Taken name 974 in 1978 defoliators-'-'! dieback I mistletoe decay damage for 1 1 2 13 111 2I3IlI2I3 firewood

CP

BP

SF

DWA coo

SCR

CA

TUN2

DL

GVC ucc

BF

CAO

SV1

HV

Total 4

Partial

Percentpercenf I

^l. Light 2. Moderate 3. Severe

seasonal dose. Oak leaf injury varied from Tests of the relationship between year to year; a high cumulative oxidant average leaf injury during 1974-1978 dose, moderate to high precipitation of the for all trees in a plot and average diameter preceding winter and spring, and low to increase during 1975-1978 were inconclusive moderate air temperature stress concurrent when plot comparisons were made. The with oxidant exposure during June-August variations of site index for black oak, as appeared to cause greater injury. Cumulative defined by Powers (1972), appeared to oxidant dose and the June-August transpira- obscure comparisons of leaf injury on growth tion pattern must be evaluated together in because intercepts were higher on the better order to develop a dose response simulation. sites; however, conclusive effects of leaf injury on growth were observed when the and the forest ecosystems of which it is a populations from all plots were pooled and, component. in effect, the influence of site index was averaged for 14 plots. The magnitude of this growth decrease relative to companion LITERATURE CITED species in the stand will be determined after further data analysis is completed. Brown, L. R., and C. 0. Eads McBride (1978b) has suggested a shift toward 1965. A technical study of insects black oak in the oxidant stressed ponderosa affecting the oak tree in southern pine-black oak type indicating that ponderosa California. Cal. Agric. Exp. Stn. Bull. pine experiences a larger decrease in 810, 105 p. growth and competitive ability. But, when oxidant stressed oaks are present on poor McBride, J. R. sites or when the effects of defoliator 1978a. Occurrence of forest tree seedlings insects and pathogens are coupled with in relation to variation in forest oxidant injury for several decades some overstory. &I Workshop Proc.: Simula- weakened trees may succumb to these combined tion modeling of oxidant air pollution stresses. This condition could develop in effects on mixed conifer forests and the the stands at the CP and BP plots; chaparral possible role of models in timber shrubs or grasses may eventually be the management planning for southern dominant cover type in this worst case California National Forests. p. 20 situation. Statewide Air Pollution Res. Cent., Univ. of Calif. , Riverside. Acorn production was very low at CP and BP during the study period. Thus, the McBride, J. R. combination of oxidant injury and defolia- 1978b. Predictions of changes in forest tion by the fruit tree leaf roller may have species composition associated with the an additive influence on both growth and effects of oxidant injury, pest com- reproduction. plexes and fire. In Workshop Proc.: Simulation modeling of oxidant air The number of trees producing acorns pollution effects on mixed conifer peaked in 1977, when all plots were con- forests and the possible role of models sidered. Roy (1962) reported that abundant in timber management planning for acorn crops for entire stands occurred every southern California National Forests. 2 to 3 years, but our data suggest a longer p. 12 Statewide Air Pollution Res. interval in the study area. A more detailed Cent., Univ. of Calif., Riverside. analysis of the size and frequency of acorn crops is being done by Robert F. Luck, the McDonald, P. M. principal investigator for this phase of the 1969. Silvical characteristics of interdisciplinary study. California black oak. U.S. Dep. Agric. Forest Serv. Res. Pap. PSW-53. The distributions of two other diseases, 20 p. U.S. Dept. Agric. Forest Serv. namely a branch dieback apparently caused by Pacific Southwest Forest and Range Exp. a fungus (not identified) and true mistletoe, Stn., Berkeley, Calif. do not appear related to the severity of oxidant stress. Their distribution appears Miller, P. R. and others. to be related to stand conditions and 1977. Photochemical oxidant air pollutant temperature-and-moisture gradients that effects on a mixed conifer forest existed prior to oxidant stress. The ecosystem--A progress report, 1975-1976. possible role of peroxyacetyl nitrate (PAN), EPA Contracts 68-03-0273 and 68-03-2442. a companion with ozone in the photochemical 338 pp. [Corvallis Environmental oxidant complex, has not been defined. At Research Laboratory, Corvallis, Oreg.] this time, it is not unreasonable to assume that ozone is the principal cause of the Powers, R. F. kinds of leaf injury symptoms observed. 1972. Site index curves for unmanaged stands of California black oak. U.S. McDonald (1969) described the resource Dep. Agric. Forest Serv. Res. Note values of black oak as a major component of PSW-262. 5 pp. U.S. Dep. Agric. six forest types in California and Oregon. Forest Service Pacific Southwest Forest Powers (1972) emphasized the economic and Range Exp. Stn., Berkeley, Calif. potential of the species. These descrip- tions provide a perspective from which it is Roy, D. F. possible to conclude that chronic oxidant 1962. California hardwoods: Management air pollution injury can have significant practices and problems. J. For. 60: primary and secondary effects on black oak 184-186. Sea-Salt Aerosol Damage to Quercus agrifolia and Quercus lobata in the Santa Ynez Valley, Quercus agrifolia

Gary L. Oqden-2/

abstract: This is a physiological ecology paper demonstrating the effect of far inland advection of sea salt aerosol on leaf damage symptoms and asym- metrical growth forms of two oak species (Quercus lobata, Ouercus aqrifolia) in a coastal valley in California. Foliar absorption of aerosol (chloride ion) produces leaf damage symptoms and asymmetrical growth forms on oaks up to 60 km inland under normal climatic conditions. Leaf morphological characteristics and environmental factors which cause a differential rate of Cl- foliar absorption by oak foliage is discussed.

INTRODUCTION

The study area is located in Southern the ocean. At 7.2 km inland Quercus agrifolia California in the Santa Ynez Valley. The W-E is more arborescent, ranging up to 3.6 m in orientation, mountain enclosure, and gradual height but still flagged away from the ocean. increase in elevation from the ocean inland At 16.1 km inland Ouercus agrifolia is a lean- make it an ideal area for aerosol advection ing single-trunked tree, with the angle of studies. The 2 principal oak species occur- lean less severe than at more coastal sites. ring on the alluvial flats and gentle slopes At 28.2 km, this species exhibits no lean and (Q. agrifolia and Q. lobata) have overlapping stands as a single-trunked specimen. distributions and differing growth forms (fig. 1). --Quercus lobata is only found 28.2 km or at greater distances from the coastline at -Ouercus agrifolia at a distance of 5.6 km Surf. Here, it takes on a pruned form with a inland is a prostrate pruned shrub approxi- severely leaning trunk. It resembles the form mately 1.8 m in height. The shrub is flagged of Quercus agrifolia at the 16.1 km site. from west to east. The trunks lean away from --Ouercus lobata still shows a flagged appear- ante at 48.3 km inland, but the severity of lean is less than at the 28.2 km site. Both Lipresented at the Symposium on the Ecology, oak species grow normally at distances of Management, and Utilization of California 72.4 km inland. Oaks, Scripps College, Claremont, California, June 26-28, 1979. These observations suggest that either the wind or something in the wind is causing LiB.A., M.A., Fresno State College, Ph.D., the differential growth form of the two oak U. C. Santa Barbara, Plant Ecologist and species. Wind dessication could cause an Taxonomist, Moorpark College, Moorpark, asymmetrical growth due to differential kill- California. ing of buds and leaves on the windward (west POINT CONCEPTION

Figure I--Map depicting location of the study area. Numbers beside each site represent distance inland from the w-facing coastline (Surf) in km. The valley is protected from a marine influence from the south by the Santa Ynez Mountains. Drawn figures depict the approximate growth forms of the two oak species.

facing) as opposed to the leeward (east fac- ing) portions of the tree. Sea salt aerosol (Cl-) could also produce a similar asymmetrical growth form. The trees, which act as wind filters, receive more sea salt deposition on windward than leeward leaves. The salt is fo- liarly absorbed with subsequent death of leaves and buds on the more exposed (windward) por- tions of the tree. The degree of lean is directly proportional to the long term inten- sity of salt spray damage.

Figure 2 diagrams the sequence of inju- ries that results in the formation of curved stems: (A) A twig which grew during a period of low spray intensity. The dark portion of the twig represents the dead tip which was killed when spray intensity increased to kill- ing proportions; (B) Represents two twigs which grew during the next period of low spray inten- Figure 2--Diaqram depicting the sequence of sity. During the next period of high intensity, injuries that result in the formation of the windward twig was killed since the leeward curved stems as a result of sea salt aerosol twig was protected by the seaward leaves and (Boyce 1954). branches; (C) The same type of injury has oc- curred during another period of growth; (D) and (E) The older dead twigs have begun to decay and expose some of the leeward twigs; (E) The living portion of the stem is composed of parts of several twigs which are oriented in the shape of an arc; (F) Represents the stem at some later time when radial growth has covered the dead twig scars (Boyce 1954). AEROSOL 0-----5.6 k m METHODS o-..-..- 7.2 km 0- 16.1 km Wind (anemometers) and salt aerosol sam- pling equipment were placed in the field at 0----28.2km selected sites (-27,5.6, 7.6, 16.1, 28.2, o-..-..- 322 k m 32.2, 48.3, 72.8 km) inland from the coast and -483k monitored on a weekly basis for 3 years (1971- ...... 72.4k m 1974). Salt aerosol was collected on 6.45 cm2 filter paper discs attached to microscope slides. The Cl ion was determined by mer- curic nitrate titration. For Cl- content in plant material the method of Brown and Jackson (1955) was used. ~a+ analysis was done by flame photometer.

AEROSOL ADVECTION

Salt aerosol was measured in significantly high quantities up to distances of 48.3 km in- land. Average weekly aerosol values for the 5.6, 16.1, 28.2, 48.3 and 72.8 km sites were 1.65, 0.49, 0.45, 0.2, and 0.02 mq ~l/20cm2/ week. Higher aerosol values were found during spring and early summer months than during late summer and fall (fig. 3). Normal sea breezes produce small amounts of Cl influx. Post- frontal onshore northwesterlies produce the greatest aerosol amounts, which occur during early spring months. Greatest aerosol values were found to be on ridge crests. Leeward ex- posures throughout the valley receive little aerosol. Figure 3--Salt aerosol values through time and space for 1973. Monthly values are derived FIELD OBSERVATIONS OF AEROSOL from averages of weekly totals from all DAMAGE ON NATIVE OAKS sources: impaction mq Cl-/20 cm2/wk + drip off + fog drip-sedimentation-precipitation. Leaf necrosis (salt burn) was observed on both oak species in the field. The symptoms were identical to those described in the lit- erature for ~l damage (Boyce 1951, Wells and Shunk 1938, Boyce 1954, Karschow 1958, -Q. agrifolia. Stroqonov 1964). 3. Windward exposed leaves on both tree spe- The patterns of foliage damage observed cies showed necrosis symptoms. None were were as follows: found on the leeward leaves.

1. Necrosis appears first at leaf tips as a 4. After the trees leaf out in February, browning area and proceeds along leaf symptoms occurred earlier in the season margins in an inverted V pattern from at sites located closer to the coast. leaf apex to petiole before leaf abscis- sion from the stem occurs. 5. On sites where both species occur, damage appeared first on Q. lobata. 2. Necrosis was found to distances up to 60 km inland on Q. lobata; and 28.2 km for 6. New necrotic leaves appeared more fre- leeward leaves. Cllevels were from 2X-8X quently on trees closer to the coast. higher in necrotic leaves than windward normal The quantity of leaves showing symptoms or leeward normal leaves. was greater at coastal than inland sites. Young foliage which has not been exposed 7. Leaf exposure time to salt-laden air to salt-laden winds is low in ~l (figs. 4 and before damage symptoms appeared is 5). With increased exposure time the Cl- shorter for sites at more coastal loca- levels for windward-normal foliage increase tions. until sufficient Clhas been absorbed to pro- duce observable salt burn symptoms. Note that 8. More apical and terminal buds die on at 32.2 km inland, it took 5 months of leaf windward as opposed to leeward portions exposure for Quercus agrifolia to produce a of. the tree. salt-burned leaf (fig. 4). One month less of leaf exposure was required to produce necrotic symptoms in Quercus lobata foliage at this FOLIAR ~l ABSORPTION VALUES IN same distance from the coast. Comparing both FIELD OAK SPECIES oak species at similar distances inland with equal topographic exposure, Quercus lobata had To determine rates of Clabsorption in a higher rate of foliar ~l absorption in field oak species,one study tree at each of the windward leaves than did Quercus agrifolia. 11 sites along the W-E transect was chosen. Equal exposure, vigor, size, maturity, and proximity to anemometers and aerosol sampling equipment were considered in tree selection.

Leaves were collected at 1-month intervals during the 1973 growing season. Three leaf 1Wind necrotic types were chosen (when present) for the dura- - 07 WB Wind normal tion of the growing season (February-September) mil Lee normal at each site: windward normal and necrotic leaves, plus leeward normal types. The wind- 06 ward side in all cases was facing the NW. For 1 each leaf type, 3 samples were taken of 20-25 leaves per sample. Through the 5-7-month sam- pling period, leaves were chosen which had ap- peared on the trees since the initiation of sampling. In this way, the effect of leaf ex- posure time to the prevailing winds could be evaluated. Samples were transported to the lab in small closed plastic bags in an ice chest. In the lab, after fresh weight was re- corded, each sample was placed in a 100-ml beaker with 50 ml of distilled water and swirled for 30 seconds to remove any external Clfrom the leaf surface. Leaf samples were A M J dried for 72 hours at 72-75OC after which dry J weights were recorded. The samples were then MONTH crushed with mortar and pestle and placed in Figure 4--Foliar Cl- values for Quercus agri- air tight containers. An analysis was then folia at a distance of 32.2 km inland from made of the Cl- and ~a+amount present in the the salt aerosol source. Note that increased leaf tissue. Clis calculated as percent sap leaf exposure time to the salt-laden winds instead of percent dry weight, so that overes- cause increasing amounts of chloride in wind timations of Clwould be avoided and also al- normal leaves. low comparison of different species and leaf ages (Cassidy 1966).

Internal Clvalues for both oak species were found to be from 0.01 to 0.11 percent sap Figure 5 shows that it took 6 months of for leeward normal leaves; 0.01 to 0.46 percent leaf exposure to the lower amounts of aerosol sap for windward normal foliage; and' for wind- contained in the wind at 48.3 km inland before ward leaves on which salt burn symptoms could enough Clcould be absorbed to produce visual be observed, values ranged from 0.51 to 3.02 signs of salt burn damage. This is a 2-month Cl- percent sap. Leaf moisture values were longer exposure time than for Quercus lobata also usually higher for windward leaves than at the 32.2 km site. Quercus agrifolia at the 48.3 km site showed no necrosis symptoms, with leaf morphological traits. windward normal leaf Clamounts being only slightly greater than the low Cllevels in the 1. When subjected to similar wind speeds, leeward leaves. the leaves of Quercus lobata tend to flutter more in the airstream than do leaves of Quercus agrifolia. This is due to the fact that Quercus agrifolia has a shorter petiole and is a more xeric leaf type than Quercus lobata. This action can cause cracks in the leaf cuticle and therefore increase the rate of Cluptake (Karschow 1958, Wind necrotic Boyce 1954). O7 1 Wind normal 2. Observation indicates that Quercus 11i1111 Lee normal 0.6- agrifolia leaves are not as wettable as those of Quercus lobata. This is 5; due to the smooth thick cuticular sur- y 05- - face and lack of dense concentrations u of stellate hairs on the upper and ;0.4- lower leaf surfaces of Quercus lobata. LLJd Salt solution beads up and runs off 0.3 - much more rapidly on Quercus agrifolia- This has been described by others 0.2- (Boyce 1954). 3. Leaves of Quercus agrifolia are more 0.1 - xeromorphic in nature than those of --Quercus lobata. The leaves are more rigid as a result of increased amounts A M J J A S of supportive tissue. They have a MONTH thicker epidermal layer. The fact that Figure 5--Foliar Clvalues for Quercus lobata xeric leaf morphology gives increased by month of leaf exposure time at a distance tolerance to salt spray has been ob- of 48.3 km inland from the salt aerosol served by others (Salisbury 1805, Wells source. and Shunk 1938, Wells 1939, Moss 1949, Edlin 1943 and 1957, Costing 1945, Kurauchi 1956, Martin 1959).

4. The difference in abundance of hairs At the 72.4 km control site where both oak found on the leaf surface of the two species show no asymmetrical growth,the foliar species suggests a mechanism for the Cl levels for both oak species remain identi- differences found in their relative cal for windward and leeward leaves,never be- tolerance to sea-salt aerosol. This coming greater than 0.04% Clpercent sap. hair covering which is much more abun- dant on Quercus lobata has a multipur- pose function in regard to foliar ab- MECHANISM FOR DIFFERENTIAL ~1-ABSORPTION sorption of salts. It provides more RATES BETWEEN THE TWO OAK SPECIES surface area for the impaction of aero- sol particles, plus more surface area The fact that at 28.2 km inland Quercus in contact with the salt solution for agrifolia has a normal canopy and Quercus subsequent possible absorption through lobata still exhibits an asymmetrical form the hairs. demonstrates that these two oaks have differing responses to similar aerosol levels. The leaf 5. Another possible explanation is that Cl- concentration required for necrotic symp- foliar absorption does not occur through toms to be produced is the same for both oak the hairs themselves but via the plen- species. The differing growth forms may there- tiful supply of ectodesmata provided at fore be explained in terms of varying rates of the base of these tufted hairs (Franke foliar Clabsorption. 1967). These structures are found only in certain regions of the cuticle in- The fact that Q. lobata has a faster rate cluding rich supplies found in epidermal of foliar ~l absorption and is thus more sen- cells at the base of hairs (Martin and sitive to salt laden winds is due to several Juniper 1972, Franke 1967, Hull 1964). Increased hair density would, there- fore, imply increased numbers of ec- todesmata. Quercus lobata with its greater hair density would thus poten- tially contain more sites for foliar absorption.

Besides the above morphological factors which could possibly cause Quercus lobata to have a greater foliar absorption rate, relative humidity also affects ion absorption rate. High relative humidities (above 75 percent) not only keep salt in solution on leaf surfaces but also permit the waxes of the cuticle to be in their most swollen state and thus more perme- able for entry of external solutions (Woodcock 1949, Cadle 1966, Jacobs 1937, Winkler and Junge 1971, Martin 1959, Roffman 1973). As humidity decreases, salts crystallize out, with Clremaining in solution the longest and hence providing a greater probability for leaf ab- sorption (Harding, Miller and Fireman 1958).

Relative humidities were measured in the Santa Ynez Valley for a 6-month period and found to be above 75 percent at coastal sites (16.1 km) 82 percent of the time and at inland sites (28.2 km) for only 69 percent of the time.

In order to test the possibility that Quercus lobata has a greater foliar Clab- C I 3 6 12 sorption rate than Quercus agrifolia and also DAYS to see if relative humidity plays a role in rate of Cluptake, a long-term differential relative humidity experiment was designed. Figure 6--Leaf Clconcentrations of oak foli- Oak seedlings of both oak species were grown age following various lengths of exposure to in the greenhouse until mature foliage was foliar applied sea water spray at 2 different produced. Seedlings were from 10-20 cm in humidity ranges. QA= Quercus aqrifolia; QL = height. Plants were sprayed with one applica- Ouercus lohata: RH = relative humidity; C = tion of undiluted sea water until their leaves control. were just moist but not dripping. (Application comparable to field conditions.) One-half the plants for each species were placed in differ- ent sections of the greenhouse under varying Similar experiments over 24-hour periods demon- humidity ranges. The high humidity greenhouse strated similar results. Others have found this ranged between 60-93 percent, while the low same phenomenon in crop plants (Swain 1972). humidity greenhouse was 38-60 percent. Thirty- six plants of each species were used. Three plants of each species were removed at specific CONCLUSION intervals, washed, weighted, dried and analyzed for Clcontent. Controls were sprayed with The routine far inland advection of sea- distilled water. Half the controls were ana- salt aerosol along N-S oriented coastlines in lyzed immediately after spraying; the other California by the prevailing westerlies and half were left in their respective environ- postfrontal high pressure ridges causes abnor- ments until the termination of the experiment. mally high Claerosol values up to 48 km in- The results appear in figure 6. land. The ~l ion is filtered out by the vegetation, NW-facing leaves receiving greater A differential foliar absorption of Cl" aerosol amounts than SE-facing leaves. High exists between Quercus lobata and Quercus relative humidities in the valleys keep the aqrifolia, the former species being less tol- aerosol in solution on leaf surfaces and main- erant. Higher humidities produced greater tain swollen leaf cuticles for maximum poten- rates of Cluptake than lower humidities. tial of Cl" foliar absorption. Once absorbed, the Cl- ion is transported to leaf margins and Edlin, H. L. leaf necrosis symptoms become visible. Other 1957. Salt burn following a summer gale in Clions are transported to apical buds with south-east England. Quar. Jour. Forestry resulting shoot tip death and leaf abscission. 51 :46-50. The same phenomenon continues, producing a pruned, asymmetrical growth form, the degree Franke , W. of lean proportional to the amount of salt 1967. Ectodesmata and foliar absorption. spray absorbed. g. lobata (Valley Oak) exhi- her. Jour. Bot. 48 :683-691. bits a greater degree of lean, away from the aerosol source, than Q. agrifolia (Coast Live Harding, R., M. P. Miller,and M. Fireman Oak) at similar distances and exposures inland. 1958. Absorption of salts by citrus leaves This effect is due to the more mesic nature of during sprinkling with water suitable for the leaf and the presence of stellate hairs on surface irrigation. Amer. Soc. Hort. Sci. the leaf surface. These morphological fea- (Pro) 71:248-256. tures cause Clto be more rapidly absorbed by Q. lobata leaves and this is reflected in Hull, H. M. greater death of windward leaves and twigs 1964. Proceedings for 7th Annual Symposium which eventually produces a greater degree of Southern Section of American Society of lean than observed in Q. agrifolia- Plant Physiologists. Emory University, p 45. Salt spray has been found to have an ef- fect on tree growth symmetry of Q. lobata up Jacobs, W. C. to 50 km inland and on foliage leaves up to 1937. Preliminary report of a study of at- 60 km inland on a seasonal basis. Sea salt mospheric chlorides. Mon. Wea. Rev. aerosol should not only be considered as a re- 65 :l47-151. tarding factor when analyzing coastal strand situations but also when studying areas such Karschow, R. as oak woodlands much further inland where 1958. Leaf absorption of wind-borne salt and vegetational responses can be observed. leaf scorch in Eucalyptus camaldulensis Dehn. Ilanoth 4:5-25.

LITERATURE CITED Kurauchi, Ichiji 1956. Salt spray damage to the coastal forest. Boyce, Steve G. Jap. Jour. Ecol. 5:123-127. 1951a. Source of atmospheric salts. Sci. 113: 620-621. Martin, J. J., and B. E. Juniper 1970. The cuticles of plants. St. Martins Boyce, Steve G. Press, 347 p. 1951b. Salt hypertrophy in succulent dune plants. Sci. 114:544-545. Martin, William E. 1959. The vegetation of Island Beach State Boyce, Steve G. Park, New Jersey. Ecol. Monogr. 29:l-46. 1954. The salt spray community. Ecol. Monogr. 24:29-67. Moss, A. E. 1949. Effect on trees of wind-driven salt Brown, J. D., and R. K. Jackson water. Jour. Forestry 38:421-425. 1955. A note on the potentiometric deter- mination of chloride. Amer. Society for Costing, H. J., and W. D. Billings Horticultural Sci. 65:187. 1942. Factors affecting vegetational zonation of coastal dunes. Ecol. 23:131-142. Cadle, Richard D. 1966. Particles in the atmosphere and space. Costing, Henry J. Chap. 2, Reinhold, N. Y. 226 p. 1945. Tolerance to salt spray of plants of coastal dunes. Ecol. 26:85-89. Cassidy, N. G. 1966. A rational method for recording and Costing, Henry J. comparing concentrations of plant consti- 1954. Ecological processes and vegetation tuents that are water soluble; with partic- of the maritime strand in the southeastern ular reference to Cl" and ~a+.Plant and United States. Bot. Rev. 20:226-262. Soil 25:372-384. Roffman, A., et al. Edlin, H. L. 1973. The state of the art of saltwater cool- 1943. A salt storm on the south coast (S. E. ing towers for steam electrical generating England) . Quart. Jour . Forestry 38 (1):24. plants. Westinghouse Environmental Systems Department. Pittsburgh, Pennsylvania. Wells, B. W.,and I. V. Shunk U. S. Dept. of Commerce, Springfield, Vir. 1938. Salt spray: an important factor in coastal ecology. Torrey Bot. Club Bull. Salisbury, R. 65 :485-492. 1805. An account of a storm of salt. Linn. Soc. London Trans. 8:286-290. Wells, B. W. 1939. A new forest climax: the salt spray Strogonov, B. P. climax of Smith Island, N. E. Torrey Bot. 1964. Physiological basis of salt tolerance Club Bull. 66:629-633. of plants (as affected by various types of salinity). Daniel Davey & Co., Inc. 279 p. Winkler, P., and C. E. Junge 1971. Comments on anomalous deliquescence Swain, R. L. of sea spray aerosols. Jour. of Appl. 1972. Unpublished thesis, Dept. of Horticul- Meteor. 10:159-165. ture and Forestry. College of Agriculture and Environmental Science, Rutgers Univer- Woodcock, A. H. sity, New Brunswick, New Jersey. 1949. Impact deposition of atmospheric sea salts on a test plate. Amer. Soc. for Testing Materials 50:1151-1166. Tolerance of Oaks to Flooding1 2 Richard Id. Harris, Andrew T. Leiser, and Robert E. Fi ssel 1 Quercus douglasii Abstract: Mature blue oaks (Quercus douglasi i ) and valley oaks (Q. lobata) growing on alluvial soils in central California withstood flooding for 50 to 98 days each of three years with little or no tree loss. Blue oak on shallower residual soils suffered 50 per cent mortality each year with similar flooding.

INTRODUCTION Most of the flooded trees at Black Butte were growing on a well-drained (when not Established native oaks have the reputa- flooded) alluvial fan. Most of the trees at tion of being sensitive to changes in their Terminus were on shallow, residual, hillside soil environment, even changes considered soil. Those in the Sacramento-San Joaquin improvements for many plants. Almost without delta were on a well-drained, fine-textured exception, moisture and aeration changes ac- organic soil . count for most of the difficulties. At the two reservoirs, the lower trees Oaks, therefore, were of particular in- were flooded beginning in early to mid-May. terest when we began studies in 1967 on the Andrus and Brannan islands were f 1ooded be- flood tolerance of woody plants in the draw- ginning June 21 , 1972. down zones of several central California reservoirs. The gross-pool levels of two reservoirs (Black Butte, north of Orlandsand RESULTS Terminus, east of Visalia) were raised (at least 13 and 25 feet respe~tively~abovetheir Black Butte Reservoir original designed levels. We also surveyed Andrus and Brannan Islands in the Sacramento- Fifteen of 16 mature blue oak trees sur- San Joaquin Delta two years after they were vived 50 to 98 days of flooding during three flooded in 1972. of the four years they were flooded to a max- imum depth of 8 to 10 feet of water over the Blue oak, Quercus douglasii , was the ground (Table 1, fig. 1). Sixty-nine per cent most numerous oak at the two reservoirs. Nine survived flooding 96 to 110 days two of the large valley oaks, Q. lobata, were at Black years. Butte and a few mature interior live oaks, -Q. wislizeni, grew at Terminus. Valley oak All of the valley oaks survived inunda- and pin oak, Q. palustris, were on Andrus and tion for periods ranging from 63 to 110 days Brannan islands. in 1967, Table 1. The maximum depth of water was' between 5 and 12 feet. -'presented at the Symposium on the Ecology, 1 Shoot growth of blue oak averaged about Management, and Utilization of California 25% more during each of the first three Oaks, Claremont, California, June 26-28, 1979. years of flooding than they did each of the two years before being flooded. Shoot growth y~rofessor,Professor, and Staff Research was complete each year in early May before Associate. Department of Environmental Horti- the trees were flooded. Trees on higher culture, University of California, Davis. ground not subject to flooding but within 10 This report based on a cooperative research feet (elevation) of the 1967 high-water mark program between the U.S. Army Corps of Engi- made at least 50 per cent more growth after neers, the U.S. Forest Service, and the Uni- flooding began than they did previous1 y. versity of California, Davis, under U.S.F.S. Vertical areas of bark were killed on trunks Research Grant Supplement #70 to Contract of many blue oaks subjected to flooding. NO. A 5fs-16565. Callus growth was vigorous, cracking the dead bark on surviving trees (fig. 2). Fig. 1. Valley oak (Quercus lobata), left, and blue oak (Q. douqlasn) ~uvialsoil at Black ButteTeservoir in April 1969. The two trees were flooded at least ninety days in 1965 and 1967 and forty days in 1966 and 1969. Valley oaks leaf out earlier than blue oak. Fig. 2. The bark on a number of flooded blue oak died in vertical strips. Note ridges of bark between two dead areas. Callus growth is vigorous. Black Butte, 1969.

Terminus Reservoir Other United States Studies Flooding for 68-86 days (20-30 ft. depth) in 1967 and 72-76 days (10-15 ft. depth) in Five species of oak tolerant to flooding 1969 killed half of the blue oak trees each were reported in two to six studies reviewed year, Table 2. The maximum depth of water was in a survey of such studies in the United 20 to 25 feet in 1967 but only 5 to 10 feet in States (Whitlow and Harris, 1978), Table 3. 1969. Seven species were found to be intolerant to flooding in 1 to 4 reports. Reports on six Shoot growth of surviving blue oaks was other species were either inconclusive, con- greater on flooded trees compared to that of tradictive, or indicated the species were the same trees on higher ground not flooded. only slightly tolerant. Number of shoots were not noticeably affected unless the branch was submerged. Branches Several oak species appear to be tolerant died if completely submerged longer than two to prolonged periods of flooding; others quite weeks. Bark was killed on flooded trees sensitive. Even though the soils were satur- similar to those at Black Butte. ated for these long periods, the water was not stagnate so that aeration apparently was The few interior live oaks all died if sufficient. water covered the soil around their trunks for longer than one week. RECOMMENDATIONS

Andrus-Brannan Islands Recommendations made in 1969 have been supported by observations since. These were Both pin oaks survived flooding to a for recreation site specifications based on depth of 10 feet for 92 days. All nine of an expected 50% survival of trees flooded at the valley oak trees survived 61 days of maximum gross pool levels for newly constructed flooding to a depth of 4 feet. reservoirs. 1. Remove all interior live oak. Quercus 4. Limbs at elevations where 2 weeks or wislizenii. below expected maximum gross pool. more of flooding is likely could be removed at time of site development or after death 2. Leave blue oak, Q. gu~lasii. which by flooding. will not be flooded to more than 75% of their height at the mean gross pool in the drawdown areas on previously dry (xeric) hi 11 sides which may be flooded for 80 days or less and on more moist (mesic) alluvial fans which LITERATURE CITED may be flooded for 100 days or less. Whitlow. T. H., and R. H. Harris 3. Valley oak, g. lobata, should take 1978. Flood tolerance in plants: a state- equal or greater flooding than blue oak. Its of-the-art review. Environmental and maximum tolerance was not reached by 100 days Water Qua1i ty Operational Studies. U.S. of flooding of trees on an alluvial fan. Army Engineers Technical Report E-79-1.

Table 1. Survival of blue and valley oaks following inundation of Black Butte Reservoir, Cal ifornia , 1965-70

Maximum I I I I Blue oak 1 Valley oak waterdepth 1 Days water covered soil 1 Live I , I Live I 0 I (1967) under trees trees survivalc-' trees ~urvivalg ft. 1965 1 1966 1 1967 1969 1965 1967 1 1969 1965 1969 no. no. no. no. no. 0 0 0-15 0 11 11 11 0-1 0 16-62 0-6 24 24 24 2-56 0 63-71 7-39 18 18 18 57-90 0 72-87 40-54 11 11 11 91 -95 0-51 88-98 55-64 16 15 15 96-100 52-65 99-110 65-74 13 9 9 101-103 66-72 111-123 75-80 5 2 2

u~reeswere grouped into different elevation groups based on the 1967 flooding. Length of flooding and tree numbers within an elevation group row are for the same trees. Ñ'~urviva was determined the spring after the year of flooding indicated.

Table 2. Survival of blue oaks following inundation at Terminus Reservoir, 1967-70 Maximum water Live Survival , spring after depth trees flooding (1 967) ft. 1965 1967 1969 1966 1967 I 1969 no. %Ll no. % 31 0-5u 0 0-34 0 6 6 100 7 100- 5-10 0 35-47 44-47 8 7 90 5 71 10-15 0-1 7 48-56 72-76 11 10 91 5 50 15-20 18-28 57-67 80-87 7 6 86 2 33 20-30 29-1 4 68-86 93-114 12 6 50 1 16

^(#I above) ?'per cent of trees alive in 1966. -'per cent of trees a1 ive in 1967. Table 3. Observations in the United States as to flooding tolerance of oak species in native stands, or laboratory and field tests (Whitlow and Harris, 1978). Number of reports Species Common name Tolerant 1 Slight Tolerance 1 Intolerant 1 Uncertain Q. lyrata Overcup 6 Q. nigra Water 3 Q. nuttallii Nuttall 's 2 Q. palustris Pin 4 Q. macracarpa Bur 3 1 Q. rubra Red 1 4 Q. alba White 1 Q. biocolor Swamp White Q. falcata Spanish 3 Q. marlandica Black jack 2 Q. montane Chestnut 1 Q. muehlenbergii Chinquapin 3 Q. prinoides Dwarf Chinquapin 1 Q.stellata Post 4 Q. velutina Black 3 Q. shumardii Shumard 2 Animal Damage to Valley Oak Acorns and Seedlings, Carmel Valley, California1

James R. Griffin 2'

Abstract: I sampled acorn production by mature valley oaks and studied predation on the acorn crop and resulting seedlings. Birds harvested much of the crop from the tree crowns. Insects ruined 20 pet of the mature acorns that hit the ground. Still some 200 viable acorns/m2 may fall under productive trees in good years. In absence of cattle and deer these acorns remain on the ground until rodents harvest most of them in the winter. Inside a deer exclosure access- ible to rodents about one seedling/m2 germinated and grew, but these seedlings rarely survived rodent predation for more than 4 years. Pocket gophers were the most important pred- ator in this area. When rodents were excluded, as many as 24 seedlings/m2 grew; over half survived for 3 years.

INTRODUCTION Predation

Public concern about the shortage of young Birds remove much of the maturing acorn valley oaks (Quercus lobata ~6e)is growing. crop from valley oak crowns. In poor years In large portions of California's oak woodland they may harvest all the crop before it falls. few saplings are present to replace the veteran Acorns picked by acorn woodpeckers (Melanerpes valley oaks dying of natural causes or being formicivorus) are lost to oak regeneration; destroyed by urban and agricultural development woodpeckers drop few acorns while eating them (Griffin 1977, Steinhart 1978). Although the fresh or when storing them where they cannot problem of low natural regeneration has been germinate. Throughout the oak woodland scrub publicized, only limited research has been de- jays (Aphelocoma coerulescens) are important voted to its causes. acorn consumers. Other Corvidae are locally important. At Hastings scrub jays have re- Oak woodlands around Carmel Valley typify moved acorns from individual valley oaks at the regeneration problem. Since 1967 I have rates exceeding 400/hour. These acorns how- studied valley oak reproduction on a variety ever, are not all lost to regeneration. Scrub of small plots at the Hastings Natural History jays store acorns in the ground and litter, Reservation. In this paper I discuss acorn and and the numerous acorns which are not found and seedling conditions on these plots over a long- eaten later are effectively "planted.'I er time span than previously reported (Griffin 1971, 1976) and add new data obtained from rodent exclosures. Insect Losses

Several types of insects damage valley DAMAGE TO ACORNS oak acorns (Brown and Eads 1965). Filbert- worms (Melissopus latiferreanus) and filbert weevils (Curculio occidentis) infest many mat- I/ Presented at the Symposium on the Ecology, ure acorns; however, such larvae in the acorns Management, and Utilization of California Oaks, do not always prevent germination. The only Claremont, Calif., June 26-28, 1979. data I have on the extent of crop loss to in- sects is from one set of long-term acorn traps 21 Research Ecologist, Univ. Calif., Berkeley, (four 0.25 m2 traps under each of four trees). Stationed at Hastings Reservation, Carmel Over an 8-year period about 21 pet of the fully Valley, Calif. 93924. developed acorns that dropped into the traps were clearly non-viable due to insect damage. Seasonal losses, mainly due to filbert weevils, nearby open rodent exclosures at this time. ranged from 0 to 31 pet. Possibly deer mice ( spp.) foraged over the unscreened areas sooner than the screened areas, although they had no trouble Mammal Damage getting under the screens. In the third study deer mice left partially eaten acorns in 10 of Despite insect and bird losses, acorns 25 screened quadrats. There were active accumulate beneath valley oaks during October holes in eight of the 25 screened quadrats in and November of good seasons. Trap data show the third study and active holes in 20 out of that more than 200 viable acorns/m2 may fall 25 quadrats in the last study. from productive trees. The four trees in the acorn trap survey averaged 34 viable acorns/m2 Of the 933 acorns monitored in these (range 7-74 acorns/m2) over a 9-year period. studies 756 (81 pet) were eaten on the spot or But these acorns do not remain on the ground carried away. Most of the remaining acorns long if unprotected. In pastures cattle eat germinated. Seventy of the germinating acorns many, and over the entire oak woodland black- effectively rooted and produced seedlings, but tailed deer (Odocileus hemionus) aggressively none of the seedlings survived continuing forage for acorns. At Hastings only rarely are rodent predation. valley oak acorns lying on the ground by Janu- ary, even after bumper acorn crops. DAMAGE TO SEEDLINGS My predation studies give some data on the loss of acorns on the ground in the absence of cattle and deer. All studies were run under Planted Seedlings the same valley oak within a large deer exclo- sure (Griffin 1976). In the first study 233 In 1967 during a dry winter, 16 germinat- naturally occurring acorns on four 25 X 25 cm ing acorns were planted in a grass plot (Grif- quadrats were watched starting in Novmeber fin 1976). The seedlings in this south slope 1970. Few acorns disappeared until pocket go- savanna died by early summer. The following phers (Thomomys bottae) became active near the autumn I planted 160 acorns in the same grass quadrats in ~ebr-971. By March only 103 plot. Despite starting in a wet winter, seed- (44 pct) of the acorns remained. ling survival was poor, and by the eleventh season no seedlings remained. In the winter In the second study 200 acorns from under of 1967 I also planted 16 acorns in an adjacent the tree were arranged into five groups of 40; cleared plot. These seedlings without grass half of each group was covered by a screen cage competition grew large enough to attract pests. to exclude birds. Most of the unscreened a- Browsing by brush rabbits (Sylvilagus bachmani) corns were damaged soon after placement in and stem girdling by flatheaded borers November 1971. Although the punctures on these (Chrysobathris e)contributed to the death acorns looked like scrub jay pecks, no jays of all seedlings in this plot by the eighth were ever seen "pecking." This type of damage season. did not occur again. Pocket gophers were also active at the start of this study. By March On a north-facing woodland site I planted 1972 no acorns remained on the quadrats. 16 acorns in 1967 in a cleared exclosure (Grif- fin 1976). In this cool, shady plot all the In the last two studies 250 acorns were seedlings grew well for two seasons, but later arranged into 25 groups of 10 with half of stem damage by borers and browsing by rabbits each group covered to exclude birds. The num- caused some mortality and slowed height growth. bers of acorns on the quadrats were: In the eleventh season survival was 38 pet; heights averaged 19 cm (range 7-39 cm). Date Open quadrats Covered quadrats In 1973 I planted 960 acorns using three Nov. 1975 125 treatments in five habitats. Two treatments Jan. 1976 1 were within rodent exclosures at each habitat. March 1976 1 However, rodents penetrated the exclosures and compromised the results. The unprotected Nov. 1976 125 treatments in which deer and small mammals had Jan. 1977 31 free access are worth mentioning. Sixty-four March 1977 16 acorns were planted in each of five unprotected plots. At the end of the fifth season no seed- In these last two studies acorns disappeared lings remained in four plots. In the fifth sooner from the open than from the screened plot, on the north-facing woodland mentioned quadrats, but there was no evidence that birds above, five heavily browsed seedlings survived. were involved. Birds did not take acorns from Thus, less than 2 pet of 320 unprotected seedlings remain; the tallest is 7 cm high. frequent records on the condition of every seedling year after year. The most detailed data on the fate of seedlings was from the Natural Seedlings 1975 acorn crop (Table 2). Few of these seed- lings died because of competitive or allelo- My study of natural valley oak seedling pathic effects of the grass cover; they died survival involved a healthy mature tree in a because predators ate them. Outside the ex- savanna habitat (Griffin 1976). This area was closure only four of 120 seedlings germinating part of an old hayfield which had been unculti- in 1976 were found dead in "intactv condition. vated and ungrazed for 40 years. Despite this Gopher digging was associated with all other lack of "ranching" disturbance, the oaks in missing seedlings. Some seedlings in poor this habitat have produced no saplings during health may have been eaten by gophers before those 40 years. The study tree is now within they could die, and gophers may have dug up a 0.2 ha deer exclosure and has an 11 m2 ro- and destroyed some dead seedlings before I dent exclosure under the outer edge of its could count them as dead. But the circumstant- canopy. This oak is consistently the most pro- ial evidence suggests that gophers are by far ductive tree monitored in the acorn trap sur- the major source of seedling mortality here. vey. Even though the crop failed in two out of nine seasons,it averaged 74 viable acorns/m^ Within the exclosure 106 out of 251 seed- (range 0-207 viable acorns/m2) . lings germinating in 1976 died during the fol- lowing three seasons. Many of the dead seed- In 1971 I started marking each seedling lings had been browsed by grasshoppers. Since with plastic flagging and aluminum tag on a the first two seasons were the driest on record small stake offset from the stem. The 1970 at Hastings, the 58 pet survival in dense grass acorn crop was so abundant that I could not cover is impressive. As of 1978 this tiny ex- keep up with all the new seedlings, but over closure had 192 live seedlings. Even with 300 were marked. Virtually all seedlings ap- heavy insect mortality in the future, the plot pearing each season since have been inventoried is vastly overstocked. Just one of the large (Table 1). Seedlings were checked several healthy seedlings that started in 1974 should times each season, and those with live root- be able to replace the parent tree. crowns in the fall, regardless of shoot condit- ion, were counted as survivors. Since 1971 I marked a total of 825 seedlings in the large CONCLUSIONS area accessible to rodents under the tree. At least 330 seedlings started in the small rodent Under Camel Valley conditions viable exclosure during the same period (the exclo- acorns fall from many trees in many seasons in sure was not fully rodent-proof until 1974). spite of heavy losses to birds and insects. When cattle and deer are excluded, the acorn Too many seedlings were involved to keep supply often exceeds the capacity of rodent

Table I-- Valley oak seedling survival inside and outside a rodent exclosure surrounded by a deer exclosure; maximum number starting in a given season and surviving in successive seasons

RODENTS NO RODENTS

Survivors, end of season Survivors, end of season

Date Start 1 2 3 4 5 Start 1 2 3 4 5

NO. /m2 1971 1.3 0.7 0.4 0.3 c0.1 0 1972 0.2 0.1 0.1 <0.1 0 1973 0.1 0.1 <0.1 0 1974 40.1 <0.1 0.6 0.6 0.6 0.6 0.6 0.6 1975 9 0 0 0 1976 0.5 0.3 0.1 0.1 23.7 19.0 16.4 13.7 1977 0.6 0.4 0.1 3.0 0.8 0.5 1978 0.7 0.5 4.1 3.4 Table 2-- Condition of valley oak seedlings from the 1975 acorn crop inside and outside a rodent exclosure surrounded by a deer exclosure during three growing seasons

I RODENTS NO RODENTS

DEAD OR MISSING Positive gopher damage, seedling within fresh gopher hole Probable gopher damage, fresh gopher hole near marker, seedling missing Possible gopher damage, seedlings and marker lost in gopher digging No rodent damage, seedling intact

ALIVE Stem dead, root alive Leaves dead or browsed, stem alive Stem with live leaves predators. The remaining acorns germinate, rodents. Whether the current seedling preda- and seedlings grow. On exposed south aspects tion problem is a permanent threat to valley seedling survival is nil; on north aspects or oaks is not clear. These trees which grow for in partial shade seedlings are able to survive centuries can wait a long time for the right in grass cover even in dry years, up to l/m2. combination of regeneration conditions. But the seedling supply seldom exceeds the ca- pacity of rodent predators. Rarely do unpro- LITERATURE CITED tected seedlings survive for more than a few years. Although several rodents and other Brown, L.R., and C.O. Eads small mammals browse seedlings, pocket gophers 1965. A technical study of insects affecting cause the greatest damage. When rodents are the oak tree in southern California. Calif. excluded, seedling survival is much higher. Agr. Exp. Sta. Bull. 810. In favorable habitats seedling density in ro- dent exclosures soon exceeds 10/m2. Even Griffin, J.R. though these seedlings will experience insect 1971. Oak regeneration in the upper Camel losses, an excess of saplings will result. Valley, California. Ecology 52:862-868.

Local seedling damage by small mammals, Griffin. J.R. particularly by pocket gophers, can prevent the 1976. Regeneration in Quercus lobata savan- development of valley oak saplings. When seed- nas, Santa Lucia Mountains, California. lings did achieve sapling size in the past, ~mer.Mid. Nat. 95:422-435 either the supply of acorns and seedlings must have been great, the small mammal damage to Griffin, J.R. seedlings must have been less, or some combin- 1977. Oak Woodland. Terrestrial Vegetation ation of the two. I doubt that the acorn sup- of California. M.G. Barbour and J. Major, ply was greater then unless insect losses were eds. p. 385-415. Wiley-Interscience, New lower. My opinion is that small mammal damage York. is now at a very high level. Steinhart, P Why small mammal levels are now so high . 1978. As the old oaks fall. Audubon 80(5): must remain speculative, but the introduction 30-40. of highly nutritious herbs (seeds of Avena spp., roots of Erodium spp., etc.) into the oak wood- land may have improved the habitat for many Products

Birds of California Oak Habitats-Management Implications1

Jared Verne? 21 Quercus

Abstract: About 110 species of birds can be observed during the breeding season in California habitats where oaks form a significant part of the tree or shrub canopy. Many of these birds use the oaks for foraging, nesting, or perching, and many regularly eat acorns. A guild approach to management, with selection of appropriate indicator species, is recommended. Management of oak habitats for birds should emphasize maintenance of mixed-species, un- even-aged stands where sites permit, and should provide for a continuing, abundant supply of acorns. Large, old trees are particularly important to birds, because they provide a wider array of foraging sites, tend to produce more acorns, and are best suited to excavation of cavity nests. Where present, a shrub layer should be maintained. Management plans for oak stands must consider adjacent, non-oak sites, because many bird species found there regularly exploit oaks.

INTRODUCTION The several species of oaks represent a wide variety of sizes and shapes, from shrubs to An estimated 15 to 20 percent of Cali- large trees. Some species are deciduous, others f ornia' s land base supports plant communities are evergreen. Some have dense crowns, allowing in which oaks (Quercus spp.) comprise a little light to penetrate to the ground, significant portion, of the tree or shrub although light easily filters through the canopies, or both.- About 110 bird species canopies of other species. The various species occupy California oak habitats during the differ in bark texture, leaf sizes and shapes, breeding season, so that the management of oak and in many features of their flowers and stands in a manner that will not unduly depress fruits. Students of avian ecology know that any bird species' numbers is truly a formidable differences of these kinds are vital to habitat task. selection by different species of birds, particularly with reference to their foraging ecologies. Each bird species differs in one or more ways from all others in the kinds of places it seeks its food, or in the manner it obtains Ñ'presente at the Symposium on the Ecology, the food, or both. In spite of the variety Management, and Utilization of California Oaks, within and between oak habitats, however, Small Claremont, California, June 26-28, 1979. (1974, p. 205) writes that "the differences in the quality of bird life are not as great ." In I~esearch Wildlife Biologist, Pacific a general sense, Small's statement is true, but Southwest Forest and Range Experiment Station, differences do exist in the bird species con+ Forest Service, U. S. Department of position of different types of oak woodlands, Agriculture, Fresno, California. and birds use different oak species in different ways. Perhaps more than anything else, Small's 21~lumb, T. R., and P. M. McDonald. Current statement serves to underscore our general lack ---status of oak management in California. of knowledge about the important relationships Proceedings of Symposium on establishment and between birds and oaks in California. treatment of high quality hardwood forest in the temperate climatic region. In preparing this report, I was repeatedly 1.N.R.A.-C.N.R.F. Nancy-Champenoux, France, disappointed by the lack of adequate September 11-15, 1978. (In press.) information. It seems that the most valuable contribution to be made here is to catalog the first preference for chaparral. In my opinion, areas in which our limited knowledge prevents because chaparral so frequently intermixes with sound management of California oaks for the oak stands, all of these species should be maintenance of bird populations. considered in plans for oak management. Censuses of breeding birds in oak habitats This paper is confined to those species of (table L), for example, reported breeding by birds that use California oak habitats during nine of 14 species assigned first preference for the breeding season. I believe proper chaparral by Miller (1951). Censuses did not management of oaks for breeding birds only include the ranges of two other chaparral should provide adequately for those species birds--California condor and mountain quail--and that use oaks at other times of the year. the California thrasher probably had finished Densities of birds in oak habitats are nesting by the time censuses were begun. considered~thedata show this to be one of the weakest points in the knowledge needed by Twenty-f our species, including the green managers. Information is provided on the ways heron, wood duck, and black phoebe, were classed in which birds use oaks, and management of oak by Miller to have primary affiliation with habitats for maximum benefit to birds is riparian sites. Breeding was confirmed for 13, discussed. My approach is necessarily and only three were not observed on any census. qualitative, as the required quantitative Use of oak stands by most of these species de- information simply is not available for the pends on an associated riparian habitat. vast majority of questions of interest to land managers. Species that show primary preference for conifer forests--Mil ler's coastal, montane, and subalpine types--somet imes include available oak BIRDS OF CALIFORNIA OAK HABITATS stands within their territories. We find some species on the list, therefore, that may be a Assembling a list of bird species that use surprise to some ornithologists; for example, oak habitats in California is complicated by the pileated and white-headed woodpeckers, the realities of vegetation. Oak habitats olive-sided flycatcher, mountain chickadee, common1y are adjacent to other quite different pygmy nuthatch, brown creeper, winter wren, habitats with different complements of birds golden-crowned kinglet, and pine siskin. Some that make use of the oaks. Oaks often share of these species were observed~evenconf irmed the canopy with other species of trees that as breeders~on a number of the censuses of attract bird species that might otherwise be breeding birds in oak habitats, particularly in absent. The nature of the understory vegeta- habitats along the coast (table 1). tion-percent cover by shrubs and herbs~pro- foundly affects the composition of the avian If we consider the variety of growth forms community. Seasonal availability of water is taken by oaks, the widespread distribution of a1so important. oak habitats in California, and the frequent association of oak habitats with other types, it The list of bird species (table 1) was is not possible to put together an unambiguous compiled from a number of sources. Miller's list of bird species dependent upon oak habitats (1951) assignment of California birds to in California. Given the list in table 1, an various habitat types was the primary ref- ornithologist experienced with California birds erence. Included are all species he specified might wish to begin dropping out those species as using oak woodlands and savannahs. A few whose association with oak types is clearly additional species were added from Small peripheral. These might include, for example, (1974), and from annual breeding bird censuses the green heron, ring-necked pheasant, black taken in cooperation with the National Audubon phoebe, cliff and rough-winged swallows, cactus Society. Because they are not usually regarded wren, golden-crowned kinglet, ye1 low-rumped as birds of oak habitats, several species on warbler, ye1 low-breasted chat, and whi te-crowned the list require explanation. sparrow. Another ornithologist might have different choices. Perhaps some would even Many birds occur regularly in oak stands expand the list to include such species as the because their preferred habitat type regularly great blue heron (Ardea herodias) and great occurs together with oaks (table L). For egret (Casmerodius albus) because they sometimes example. Miller did not indicate that establi h rookeries in valley oaks (w California thrashers or wrentits exhibit any 1obata)b1 and live oaks (Quercus agrifol~a).- selectivity for savannah or oak woodland types. Both species show first preference for Another approach would be to compile a list chaparral. Miller, however, did include based on the frequency of occurrence of species Bewick's wren and rufous-sided towhee in his in the various sites sampled for breeding birds oak woodland list; these species also show (table 1). Rufous-sided towhees, for example, Table 1--Breeding bird species associated with California habitats in which oaks (wspp) comprise a substantial part of the canopy.

abitat selection-' Breeding censuses'' Oaks used for.. . Species ~eerenceS3~ Rank Preferred A B C D E Food Nesting we

Green Heron Lacustrine Open nest Dawson 1923 (Butor ides virescens) waters

Wood Duck Lacustrine Secondary Bent 1923, Dawson 1923, (Aix sponsa) waters cavities 1940, Barrett and 0ther2~~Dersal

Turkey Vulture Savannah (Cathartes aura)

California Condor Cliffs, (Gymnogyps californianus) chiipcirral

Whitetailed Kite Riparian Open nest Dawson 1923, Bent 1937, Waian 1973 (Elanus Ieucurus) woodland

Sharp-shinned Hawk Montane (Accipiter striatus) forest

Cooper's Hawk Riparian Open nest Dawson 1923, Grinnell and Miller (Acciniter cmperii) woodland 1944, Fitch and others 1946

Red-tailed Hawk Savannah Open nest (wjamaicensis)

Red-shouldered Hawk Riparian Open nest Dawson 1923, ~itter^ (Buteo lineatus) woodland

Swainson's Hawk Savannah Open nest Bent 1937 (Buteo swainsoni) (uncommon)

Golden Eagle Savannah Open nest Dawson 1923. Bent 1937 (uchrysaetos)

American Kestrel Savannah Secondary (usparverius) cavity

California Quail Chaparral Van Dersal 1940, Martin and others (Lophortyx californicus) 1951, Leopold 1977

Mountain Quail Chaparral Bent 1932, Martin and others 1951 (Oreortyx e)

Ring-necked Pheasant Grassland Bent 1932, Van Dersal 1940, Barrett (Phasianus colchicus) and others'-'

Turkey Oak Bent 1932, Van Dersal 1940, Martin (Meleagris gallopavo) wood land and others 1951

Band-tailed Pigeon Oak corns, new Open nest Dawson 1923. Bent 1932, Van Deraal (Columba fasciata) woodland leaf buds 1940, Grinnell and Miller 1944, Neff 1947, Martin and others 1951. Fry and Vaughn 1977

Mourning Dove Savannah Open nest Van Daraal 1940 (Zenaida macroura)

Roadrunner Desert Open nest Dawson 1923, Grinnell and Miller (Geococcyx californianus scrub 1944

Barn Owl Cliffs, Secondary Bent 1938 ('Cyto alba) grassland cavities

Screech Owl Oak Secondary Dawson 1923, Grinnell and Miller (Otus asio) woodland cavities 1944

Great Horned Owl Oak Open nest Bent 1938 (wvirginianus) woodland

Pygmy Owl Coastal Secondary Bent 1938 (Glaucidium gnoma) forest cavities

Spotted Owl Coastal Open nest. Bent 1938 (eoccidentalis) forest secondary cavities

Long-eared Owl Riparian (Asio otus) woodland

Saw-whet Owl Montane (Aegolius acadicus) forest

Black-chinned Hummingbird Riparian Open nest Dawson 1923, Bent 1940, Grinnell (Archilochus alexandri) woodland and Miller 1944

Anna's Hummingbird Chaparral Foliage Open nest Dawson 1923, Bent 1940, ~rvin8I (Calv~teanna) insects, sap Table 1--Breediw bird species associated with California habitats in which oak (- spp) comprise a substantial part of the Canopy. continued),

ibitat selection-' Breeding censuses^' Oaks used for... Species eeenced' lank Preferred A B C D E Food Nesting type

Allen's Hummingbird Chaparral Open nest Bent 1940 (Selasphorus e)

Common Flicker Riparian corns^, Primary Dawson 1923, Bent 1939, Van Dersal (Colaptes -) woodland insects from cavities 1940, Grinnell and Miller 1944, bark 6 wood Martin and others 1951

Pileated Woodpecker Subalpine corns^, Van De a1 1940, Barrett and (Uryocopus pileatus) forest insects from o r 3 bark & wood

Acorn Woodpecker Oak corns^, sap, Primary Beal 1911, Dawson 1923, ~eff1928, (Melanerpes formicivorus; woodland bark insects, cavities Bent, 1939, Grinnell and Miller perch for 1944, Martin and others 1951, hawking Bock 1970, MacRoberts and MacRoberts 1976

Lewis' Woodpecker Oak corns. Primary & Bent 1939, Van Dersal 1940, Martin (Melanerpes w) woodland perch for secondary and others 1951, Bock 1970 hawking cavities

Hairy Woodpecker Montane corns^, Bent 1939, Van Der 71 1940, (Dendrocopos villosus) forest insects from Barrett and others- bark 6 wood

Downy Woodpecker Riparian corns. Primary Bent 1939, Van Dersal 1940, Martin (Dendrocopos pubescens) woodland insects from cavities and others 1951 bark 6 wood

Nuttall's Woodpecker Oak corns^, sap, Primary Dawson 1923, Bent 1939, Mille and (Dendrocopos nuttallii) woodland insects from cavities Bock 1972. Barrett and others" bark 6 wood

White-headed Woodpecker Montane Primary Bent 1939, verner7.l (Dendrocopos albolarvatus forest cavities

Eastern Kingbird Savannah (Tyrannus tyrannus)

Western Kingbird Savannah Perch for Open nest Dawson 1923, Bent 1942 (Tyrannus verticalis) hawking

Cass-ln's Kingbird Savannah Perch for Open nest Dawson 1923. Bent 1942 (Tyrannus vociferans) hawking

Ash-throated Flycatcher Pinyon- Foliage insects, Secondary Bent 1942, Grinnell and Miller (Myiarchus cinerascens) juniper perch for cavities, 1944 woodland hawking natural cavities

Black Phoebe Cliffs, (Sayornis nigricans) riparian woodland

Western Flycatcher Coastal Perch for Knot holes Dawson 1923, Bent 1942, Root 1967 (mpidonax difficilis) forest hawking

Western Wood Peewee Montane Perch for Open nest Dawson 1923, Bent 1942 (Contopus sordidulus) forest hawking

Olive-sided Flycatcher Montane Open nest Bent 1942 (Nuttallornis borealis) forest

Violet-green Swallow Montane Secondary Nevman and Duncan 1973, vernerÑ (Tachycineta thalassina) forest cavities

Tree Swallow Riparian (Iridoprocne -) woodland

Rough-winged Swallow Cliffs, (Stelgidopteryx ruficolli grassland

Cliff Swallow Cliffs, (Petrochelidon pyrrhonota grassland

Purple Mar tin Coastal Secondary Grinnell and Miller 1944 (Progne subis) forest cavities

Steller's Jay Montane corns, Open nest Beal 1910. Van Dersal 1940, Bent (Cyanocitta stelleri) forest foliage insects 1946, Martin and others 1951

Scrub Jay Oak corns, bark & Open nest Beal 1910, Dawson 1923, Van Dersal (Aphelocoma caerulescens) woodland foliage insects 1940, Gcinnell and Miller 1944, Bent 1946. Martin and others 1951, Root 1967 Table 1--Breeding bird species associated with California habitats in which oaks (Quercus spp) comprise a substantial part of the canopy.

abitat selectid' Breeding censusesÑ Oaks used for.. . Species ~eferencesÑ Rank Preferred A B C D E Food Nesting type Yellow-billed Magpie Savannah s corns^ Open nest Dawson 1923, Lindsdale 1937, Van (Pica nuttalli) Dersal 1940, Grinnell and Miller 1944, nt 1946, Barrett and other3

Common Raven Cliffs, corns^ Open nest Dawson 1923. Barrett and others" (COKVUScorax) grassland (rare)

Common Crow Riparian corns^ Open nest Dawson 1923, Van Dersal 1940, (ebrachyrhynchos) woodland Grinnell and Miller 1944, Bent 1946, Martin and others 1951

Mountain Chickadee Subalpine corns, Secondary Van Dersal 1940, Grinnell and (Parus gambeli) forest foliage insects cavities Miller 1944, Bent 1946, Martin and others 1951

Chestnut-backed Chickadee Coastal Bark 6 foliage Secondary Grinnell and Miller 1944, Bent (Parus rufescens) forest insects cavities 1946, Dixon 1954, Root 1964, Hertz and others 1976

Plain Titmouse Oak corns, bark Secondary Dawson 1923, Van Dersal 1940, (Parus inornatus) wood land and foliage cavities Grinnell and Miller 1944, Bent insects 1946, Martin and others 1951, Dixon 1954, Root 1964, 1967

Bushtit Oak Foliage insects Suspended Grinnell and Miller 1944, Bent (Psaltriparus -) woodland "sock" 1946, Root 1967, Hertz and others 1976

White-breasted Nuthatch Montane corns^, bark Secondary Van Dersal 1940, Grinnell and (S&& carolinensis) forest insects cavities Miller 1944, Bent 1 8, Martin and others 1951, Verner-%'

Pygmy Nuthatch Montane (Sitta pygmaea) forest

Brown Creeper Subalpine Bark insects Natural Dawson 1923, Grinnell and Miller (Certhia familiaris) forest cavities 1944 under bark scales

Chaparral Foliage liiiieccs Open nest Mailliard 1902, Dawson 1923, Bent 1948

Winter Wren Coastal (Troglodytes troglodytes forest

House Wren Oak Foliage insects Secondary Grinnell and Miller 1944, Root (Troglodytes &) woodland or natural 1967 cavities

Bewick's Wren Chaparral Foliage insects Natural Root 1967, vernerL1 (Thrymanes bewickii) cavities

Cactus Wren Desert (Campylorhynchus scrub brunneicapillus)

canon Wren Inland (Catherpes mexicanus) cliffs

Mockingbird Savannah Foliage insects Open nest Dawson 1923 (W polyglottos)

California Thrasher Chaparral corns' Open nest Dawson 1923, Van Dersal 1940, (Toxostoma redivivum) Martin and others 1951

American Robin Montane Foliage insects Open nest ~itter6' (- migratorius) forest

Hermit Thrush Subalpine corns^ Open nest Van Dersal 1940, Bent 1949, (Cathams guttata) forest Barrett and others-

Swainson's Thrush Riparian (Catharus ustulata) woodland

Western Bluebird Oak Mistletoe Secondary Bent 1949, ~ernerl' (Sialia mexicam) woodland berries, perch cavities for hawking

Coastal forest

Blue-gray Gnatca tcher Oak Foliage 6 Open nest Dawson 1923, Bent 1949, Root (Polioptila caerulea) woodland twig insects 1967, 1969 Table 1--Breeding bird species associated with California habitats in which oaks (- spp) comprise a substantial part of the canopy. (continued).

ibitat selection-' Breeding censusesÑ Oaks used for... Species ~eferencesÑ Rank Preferred A B C D E Food Nesting type Phainopepla Desert Mistletoe Open nest Dawson 1923, Bent 1950, Walsberg (Phainopepla e) scrub berries, perch 1977 for hawking

Loggerhead Shrike Savannah Open nest Bent 1950 (eludovicianus) Starling Riparian corns, Secondary Van De a1 1940, 7Fttand (- vulgaris) woodland foliage insects cavities otberz', Verner-

Button's Vireo Oak Foliage 6 twig Open nest Dawson 1923, Bent 1950, Root 1967 (Vireo huttoni) woodland insects solitary Vireo Montane Foliage insects Open nest Dawson 1923. Grinnell and Miller (Vireo solitarius) forest 1944

Warbling Vireo Riparian Foliage insects Open nest Bent 1950, Root 1967 (Vireo gilvus) woodland

Orange-crowned Warbler Chaparral Foliage insects Open nest Bent 1953, Root 1967 (Vermivora celata)

Nashville Warbler Montane Foliage insects Bent 1953 (Vermivora ruf icapilla) forest

Yellow Warbler Riparian Foliage insects Root 1967 (Dendroica petechia) woodland

Yellow-rumped Warbler Subalpine Foliage insects Bent 1953 (Dendroica coronata) forest

Black-throated Gray Warbler Oak Foliage insects Open nest Dawson 1923, Grinnell and Miller (Dendroica nigrescens) woodland 1944, Bent 1953, Root 1967

Yellow-breas ted Chat Riparian (Icteria virens) woodland

Wilson's Warbler Riparian (Wilsonia pusilla) woodland

Western Meadowlark Grassland Barrett and othersÑ (Sturnella neglec ta)

Hooded Oriole Riparian Foliage insects (Icterus cucullatus) woodland

Northern Oriole Riparian Foliage Insects Pendant Dawson 1923, Grinnell and Miller (Icterus galbula) woodland nest 1944, Bent 1958, Newman and Duncan 1973

Brewer's Blackbird Savannah Open nest Dawson 1923, Nevman and Duncan (Euphagus cyanocephalus) 1973

Brown-headed Cowbird Riparian (Molothrus ater) woodland

Western Tanager Montane Open nest Bent 1958 (Piranga ludoviciana) forest

Black-headed Grosbeak Riparian Catkins, Open nest Bent 1968 (Pheuc ticus melanocephalt woodland foliage insects

Lazuli Bunting Chaparral Foliage insects Open nest Dawson 1923, Bent 1968 (Passerina aaoena) (rarely)

Purple Finch Coastal corns, Open nest Dawson 1923, Van Dersal 1940, Bent (Carpodacus purpureus) forest foliage insects 1968, Barrett and others-

House Finch Savannah Foliage insects Open nest, Dawson 1923, Bent 1968 (Carpodacus mexicanus) secondary cavities

Pine Siskin Subalpine Foliage Open nest Bent 1968 (Carduelis pinus) forest

American Goldfinch Riparian Acornsa Open nest (Carduelis tristis) woodland (uncommon) Dawson 1923 Lesser Goldfinch Savannah Open nest (Carduelis psaltria) Dawson 1923, Grinnell and Miller Lawrence's Goldfinch Oak Oak gall Open nest 1944, Bent 1968 (Carduelis lawrencei) woodland insects Van Dersal 1940, Martin and others Rufous-sided Towhee Chaparral corns', foliage insects 1951, Davis 1957, Bent 1968 (werythrophthalmus; Table 1--Breeding bird species associated with California habitats in which oaks (euzspp) comprise a substantial part of the canopy. (continued).

Habitat selec tionÑ Breeding censuses'-' Oaks used for.. . Species ~eferences^' Rank Preferred A B O D E Food Nesting type

Brown Towhee 2 Chaparral 50 rn corns^, open nest ~avis1957, Bent 1968, ~othsted' (Pipilo fuscus) foliage insects

Rufous-crowned Sparrow Chaparral 20 20 33 18 Foliage insects Bent 1968 (Aimophila ruficeps)

Dark-eyed Junco 5 Subalpine -50 100 % -53 Foliage insects Root 1967 (= hyemalis) forest

White-crowned Sparrow Chaparral Open nest in Bent 1968 (7.onotrichia leucophrys) scrub oaks

Chipping Sparrow 3 Montane 6 Foliage insects Root 1967 (Spizella passerina) forest

Song Sparrow Riparian -50 20 40 -29 Foliage insects (Melospiza s) woodland

Habitat types classified and ranked by Miller (1951) according to bird species preferences. If no number is entered in the "rank" column, it indicates that Miller did not consider the species to show any preference for oak woodland or savannah.

Percent of sites where each species was recorded during the breeding season; values underlined indicate breeding detected. A - Coastal Marin Co., 4 sites, 8 counts; B - San Francisco Bay Area, 5 sites, 10 counts; C - South Coastal Area, 5 sites, 8 counts; D = Central Valley Area, 3 sites, 7 counts; E = All sites combined. Sources: Hutchinson and Hutchinson (1944, 1945, 1946, 1947), Pugh (1956, 1961). Shepard (1962, 1963). Cogswell (1966, 1973). Robert (1966). Perrone (1970), Remsen (1971), Tangren (1971, 1972), Koenig (1972), Manolis (1972, 1974). Stewart (1972a, 1972b, 1973a, 1973b. 1974, 1975, 1977), Steiker and Maas (1973). Winkler (1973). Bontrager (1974), McKinnie (1974), Loveless and Loveless (1977). In addition, two counts done in 1978 in digger pinelblue oak woodlands in Madera County have been included in the Central Valley Area data (J. Verner and L. V. Ritter, unpubl.) . 31 References pertain to food habits or to nest sites, or both. $1 Designate proportions of the species' annual diets comprised of acorns, as follows: a - undetermined proportion, b = 0.5 to 2 percent, c - 2 to 5 percent, d - 5 to 10 percent, e - 10 to 25 percent, f - 25 to 50 percent, g - greater than 50 percent. 51 Barrett, R. H., J. W. Menke. M. E. Fry, and D. Mangold. 1976. A review of the value of hardwoods to wildlife In California with recommendations for research. Final report, submitted to Tahoe National Forest, USDA Forest Serv. Unpubl. typescript. 45 p.

^L' Personal communication. Lyman V. Ritter, PSW Forest and Range Experiment Station, Fresno, (March, 1979).

Personal observations of the author. San Joaquin Experimental Range, Madera Co., Spring, 1978.

8/ Personal communication. Stephen H. Ervin. Calif. State Univ., Resno, (March, 1979) -91 Personal communication. Stephen I. Rothstein, Univ. of Calif ., Santa Barbara, (March, 1979).

were observed on 15 of 17 sites (88 percent) Bewick's wren, mourning dove, scrub jay, brown and in all four zones-Coastal Marin County, towhee, California quail, plain titmouse, San Francisco Bay Area, South Coastal Area, and Hut ton's vireo, , red-shafted Central Valley Area (table 1). Fourteen other flicker, black-headed grosbeak, warbling vireo, species were observed in all four zones. These and downy woodpecker. Certainly these are among are, in descending order of percent of sites the most ubiquitous of the species that utilize where seen, Anna's hummingbird, bushtit, oak habitats. Twenty-seven species were observed in three of the four zones, and another 21 were recorded in two zones. i'~age, D. .I. 1970. San Joaquin River rookery study. Special wildlife investigations report. DENSITIES OF BIRD SPECIES Project W-54-R-2, Calif. Dep. Fish and Game. FOUND IN OAK HABITATS Unpubl. typescript. 9 p. Management options ideally should consider ¥^~ilburn J. W. 1970. Lincoln great blue densities of animal populations that are subject heron rookery study. Special wildlife in- to management activities. The breeding bird vestigations report. Project W-54-R-2, Calif. censuses (table 1) used the "mapping method,'' Dep. Fish and Game. Unpubl. typescript. 20 p. approved by the National Audubn Society and designed to estimate densities of bird Ñ'~ersona communication. Stephen H. Ervin, populations. One source of bias affecting these California State University, Fresno (March estimates, however, is that of individual pairs 1979). of birds whose territories overlap the boundary of the study plot. Seldom are overlapping territories mapped out completely, although some value is assigned to them in computing total density of any given species on the plot. The effect of this bias decreases with increasing numbers of territories that are completely within the boundaries of the plot. The bias is exaggerated, therefore, by decreasing plot size, and by large mean territory size in relation to plot size, for any given species. Both effects should influence estimated densities in breeding bird censuses cited (table I), because some plots were as small as 8.0 acres (3.24 ha), and many bird species breeding in California oak woodlands have territories larger than that.-

The possibility of bias in the censuses cited here was tested by regression analysis (a.L). Estimated total densities of breeding birds, as a function of plot size, were fitted to linear, exponential, and power Plot size [acres] curve regression models. Statistically significant (P < 0.001) negative correlations were found in each case: linear model, -0.80; Figure 1~Relationship between plot size and exponential model, -0.81; power curve model, estimated density of territorial -0.80. The best fit to the data, therefore, males, as calculated from breeding bird cannot be judged by the correlation coeffi- censuses (table L). Dashed portions of cient. By visual inspection, the power curve the curve are calculated extrapolations fit is the best fit to the data points (a. from the data. -1). This analysis suggests that estimated HOW BIRDS USE OAKS breeding bird densities reported in the censuses used (table 1) probably are subject to Oaks are used by birds for feeding and substantial bias from plot size variation. nesting. They also provide elevated perches for Reducing plot size from 32 to 8 acres (13 to resting, surveillance of territory, or watching 3.2 ha), for example, would inflate estimated for prey. Of all the species listed (table 11, bird densities by about 2.7 times. Calculated at least 30 include acorns in their diet, and at extrapolation of the curve (a.L) shows some least 45 obtain insects from oak foliage, twigs, tendency for the curve to flatten out as the bark, or wood. Nine species catch aerial plot size approaches 50 acres (20 ha), but even insects by launching from perches in oaks, at plots as large as 32 acres are too small to least three eat sap, and at least two consume escape the bias. significant quantities of berries from mistletoe growing on oak trees. The list identifies 49 The curve (a.L) suggests that total species that build open-cup nests in oaks, two density of territorial males in California oak that build suspended nests, six that excavate woodlands during the breeding season probably their own nest cavities, and 20 that use natural is on nthe order of 1295 per square mile cavities or cavities excavated by other species. (500lkm ). Estimated density by species, Altogether the list specifies feeding or nesting however, is beyond the scope of this paper. We uses of oaks for 91 different species of birds need further analyses of the effects of plot (82 percent of the total). No doubt many of the size and other variables that can influence remaining species a1so use oaks, but because density estimates. We also need samples from many writers omit reference to the kinds of more sites in each of the various. identifiable trees used for feeding or nesting, this types of oak habitats in California, so that information is not available. Moreover, the each type can be analyzed individual1y. data on use of oaks were derived from only a partial survey of the literature and personal knowledge. Several species indirectly derive value from oaks. Hawks and owls, for example, Ñ1~ersona observation of the author. San consume many prey species that obtain food or Joaquin Experimental Range, Madera County, nesting cover from oaks, or both. Spring 1978. A general overview such as this un- Members of a group, except young fortunately does not quantitatively assess fledglings, collectively defended the group's avian use of oaks. We have little information all-purpose territory, which usually was on the details of foraging by birds in oaks, occupied permanently, and which ranged in size although proper management of oak stands for from 8.7 to 22.2 acres (3.5 to 9 ha). birds requires that we know which oak species "Territory size is probably determined by the are most important to foliage gleaners (species nutritional requirements of the group.. .(as) it that pick insects from foliage surfaces), bark correlated with group size." When the acorn feeders, and others, and whether or not sea- crop failed within a group's territory, the sonal variations affect species' preferences. group abandoned its territory. We need to know more about bird preferences for acorns of different oak species, and the The birds bred cooperatively, each group quantity of acorns consumed by birds in various typically having only one active nest at a time California oak types. We need to know within its territory. The majority of group preferred nest trees, either for open or cavity members participated in incubation, brooding, nesters, and what characteristics tend to make and feeding young. Yearlings were less an oak of a given species better for excavation attentive at the nest than were older birds. of nest cavities. All of these areas are "At Hastings the reproductive rate was between fertile for research into how we might better 0.2 and 0.3 young fledged per adult per year. incorporate the needs of birds into management Only about 60% of the groups breed and only plans for oaks. about 40% of the groups fledged young." About half of the fledged young disappeared within Al-though the literature on details of the their first year, and most of these losses were ecology of birds in relation to oaks is meagre, probably attributable to hawks. some out standing except ions exist. Two examples are briefly mentioned here, because Nestling diet consisted almost exclusively they set the standard of quantitative of insects, although acorns comprised the major excellence we should seek in future studies of share of the diet of acorn woodpeckers during bird species and bird communities in California most of the year (=.2). The acorn woodpecker oaks. The first example considers a single is best known for its fascinating acorn storing species, the acorn woodpecker, which is behavior. Acorns of all oak species were used. probably the most oak-dependent bird in North The birds excavated storage holes just large America and one that has received considerable enough to house one acorn each, concentrating attention from students of avian biology. The the holes in "granaries" consisting of large, second example involves analysis of a portion living or dead trees. A sample of 26 groups at of an avian community, specifically the foliage Hastings averaged about 4100 functional storage gleaners in a coastal oak forest in Monterey holes in their granaries, with a maximum of County. about 11,000. Granaries there averaged 2.1 per group, with a range from one to seven. Eighty-eight were located in valley oaks The Acorn Woodpecker (Quercus lobata), 17 in blue oaks (Quercus doug- lasii), five in California sycamores (Platanus Acorn woodpeckers have been studied in racemosa) , two in black oaks (Quercus detail in California (Ritter 1938, MacRoberts kelloggii), and one in willow (Salix spp.). and MacRoberts 1976). Only selected portions Granary trees were measured (table 2). Utility from the MacRobertsl study are mentioned here, poles and fence posts also were used as these relate more directly to the kinds of &casionally, and other types of granary trees questions addressed in preparing management have been reported in the literature, including guidelines. Unless otherwise cited, the data pines (Pinus spp.), true firs (Abies), redwoods used here are from MacRoberts and MacRoberts (Sequoia sempervirens) , and eucalyptus (1976). (Eucalyptus spp.). Ritter (1938) suggested that almost any dead tree, tree with deep dry bark, Acorn woodpeckers are high1 y social birds, or building was selected as a granary. forming cooperative groups ranging in size from two to 15 individuals (mean between five and Gutierrez and Koenig (1978) analyzed six) at the Hastings Natural History characteristics of acorn woodpecker granary Reservation, Monterey County. An area of about trees in two California pine-oak woodlands. 4.25 square miles (11 km ) supported 50 to 60 They reported that each group territory always such groups, yielding a rough, estimate of 71 included at least one main storage tree and birds per square mile (28/km ). This number "of ten one or more secondary storage trees. did not vary much during the MacRobertsl four They prefer pines but use oaks where pines are seasons of study. scarce." Storage trees usually were dead or dying. "When initially selected, granary trees Table 2~Dimensionsof trees used as granaries by acorn woodpeckers at stings Reservation, Monterey County (from MacRoberts and MacRoberts 1976)-??

D.B.H. Height

Mean Range Mean Range Inches -Feet Valley oak 11.0 to 60.2 (28 to 153)

Blue oak

Sycamore 14.2 to 50.4 (36 to 128)

Black oak 24.4 18.9 to 29.9 (48 to 76)

Ñ'~alue in parentheses are centimeters for D.B.H. and meters for height.

are often living, but because they are the with a few new ones added. Sap hole largest and often the oldest trees in the area construction is a communal affair and all they are likely to contain rotten limbs in members of the group use them." All oak species which roosts as well as storage holes can in the Hastings Reservation study area were easily be drilled. Such a tree is also likely exploited for sap. to die before its neighbors, thus providing the birds with additional storage space and increasing the percentage of dead storage trees in use at any one time."

Gutierrez and Koenig took several à ¥. .Â- measurements from trees in nine group ter- Storage hole construction ritories at Plaskett Ridge and ten at Cone ^B ¥¥   Peak, Monterey County. Their measurements Restorage of acorns included all storage trees and the largest *¥¥ *** - nonstorage pine tree in each group's territory. Feeding on stored acorns They concluded that "the woodpeckers select the .  4 largest tree in a given area" as their primary Acorn storage granary. "Such a choice not only provides the 0.  à most space for storage holes to be drilled.., Green acorns but also locates the granaries either in open - areas or (as in pine-oak woodlands) above the Oats surrounding canopy; acorn woodpeckers are Â¥* ...  rarely found in areas which do not provide such Insects openness."  ¥ ..Â¥ Sa P Acorn woodpeckers also eat significant **.-.a* quantities of sap from about early February Buds, Catkins through early September (a.2), drilling Jan1FeblMar I~pr'May 'JuneJuly ~ u '~ept'g Oct 'NOV '~ec holes in selected oaks specifically for gathering sap. "Each group has within its Months territory several localized areas where brings Figure 2--Annual food cycle of acorn wood- are made. The same holes are used each year peckers at Hastings Reservation (adapted from MacRoberts and MacRoberts 1976). Acorn woodpeckers also consume significant Bewick's wrens, dark-eyed juncos, and chipping numbers of insects, mainly in spring and sparrows, typically ground feeders, a1so summer. Beal (1911) and Neff (1928) found 23 occasionally foraged in oak foliage. percent insects in stomach samples of acorn woodpeckers taken at all times of the year. The blue-gray gnatcatcher, warbling vireo, Insects are captured mainly by flycatching, as and orange-crowned warbler migrated from the these woodpeckers rarely glean insects from Hastings Reservation for the winter. The wood or foliage surfaces or bore into wood to resident plain titmouse and Button's vireo were obtain subsurf ace insects. Minor amounts of joined in the foliage-gleaning guild for the other foods are eaten, such as oat seeds, oak winter months by ruby-crowned kinglets and catkins, fruit and, perhaps also, leaf buds and yellow-rumped warblers. Root's quantitative pistillate flowers. Grit is consumed daily and analysis of the foraging activities of the guild often comprises a significant portion of the was confined to the breeding season. A section stomach contents. of his study area covering about 70 acres (28.3 ha) had seven pairs of plain titmice, ten to These studies of the acorn woodpecker eleven pairs of blue-gray gnatcatchers (based on provide the kinds of facts needed in manage- maps for May 1 and June 27, 1963), two pairs of ment. Population densities are estimated; Hutton's vireos, four pairs of warbling vireos, general biology is outlined; food resources are and four pairs of orange-crowned warblers. identified (quantitative data are given in Beal [I9111 and Neff [1928]); and characteristics of All five species subsisted primarily on trees selected for acorn storage are discussed. insects of the orders , Coleoptera, At the community level, management requires Lepidoptera, and Hymenoptera, and a11 regular1y many of the same details. The study by Root foraged in both deciduous and live oaks. Only (1967) of f oliage-gleaning species at Hast ings the plain titmouse "regularly fed upon plant Reservation gives useful details about the material: seeds and plant fragments were found food resources of several bird species and lim- in 13 of the 16 stomachs examined." ited information on population densities. Root's paper is possibly the best commu- Foraging maneuvers were gleaning (prey nity-level analysis in California oak resting on substrate, bird standing on a perch), woodlands. hovering (prey resting on substrate, bird in the air), and hawking (both prey and bird in the air). In terms of foraging strategies, the The Foliage-gleaning Guild plain titmouse and the orange-crowned warbler were nearly identical (m.2). The two vireo Root (1967) defines a guild "as a group of species were very similar, but the blue-gray species that exploit the same class of gnatcatcher stood apart from the other two environmental resources in a similar way." A species pairs. The pairs, however, were not guild groups together species that are not similar in preferred foraging substrates (table necessarily closely related taxonomically. -3) and prey selection (table 4). Foraging Members of a guild overlap in one or more niches among members of the same foraging guild dimensions of their ecologic niche. The were diversified, as we see in this example, species Root studied in oak woodlands at and, in ecological studies, this is the rule Hastings all spent significant amounts of time rather than the exception. This sort of picking insects from surfaces of oak leaves or diversification is thought by many ecologists to bark, or both. "To be considered a member of result from interspecific competition, although the foliage-gleaning guild in the oak woodland, this is a debated issue. The fact that concerns the major portion of a bird species' diet had us here, however, is that, as a result of to consist of obtained from the diversification, birds harvest insects and other foliage zone of oaks" (Root 1967). invertebrates from all or nearly all of their refugia in any given ecosystem, whether it be an Five species identified as members of the oak woodland or a marsh. guild during the breeding season were the plain titrnouse~butit barely met Root's criteria for The two studies summarized here highlight this guild, because such a large proportion of some of the kinds of information--population its food consisted of "plant material and densities, feeding habits, and nesting arthropods living on bark1'--the blue-gray habits-needed to effectively manage California gnatcatcher, Hutton's vireo, warbling vireo, oak habitats for maintenance of avian and orange-crowned warbler. Other communities. More importantly, however, Root's foliage-gleaners occasionally foraged in the (1967) study of the foliage-gleaning guild at oaks adjacent to their preferred chaparral or Hastings Reservation provides a way of looking riparian sites. Included in this group were at animal communities that can substantial1 y the bushtit, black-throated gray warbler, and facilitate their management. The guild approach yellow warbler. Scrub jays, house wrens, allows us to group species according to common ecologic requirements, so it should be possible Hastings Reservation, and ~aptists' believes to identify indicator species for each of the plain titmice also may bury some acorns. Many various guilds distinguishable in the animal of these acorns, however, are never recovered by community. The orange-crowned warbler may be a the birds and later may germinate. The actual suitable indicator for the foliage-gleaning significance of this behavior in maintaining oak guild at Hastings Reservation, for example, stands is totally unknown, although Grinnell because more than 90 percent of its foraging (1936) discussed the potential significance of attacks are directed at the foliage. It might birds as up-hill planters of oaks. even be a good indicator for bark feeders, because maintenance of plenty of foliage will Because birds consume insects, damage to necessarily include maintenance of bark. By trees by insects may be reduced. Literature assuring that populations of the indicator that relates this point specifically to species are being properly maintained, the California oaks is not available. Studies in manager may be reasonably assured that guild other timber types are available, however, and associates of those indicator species are also many of these have been summarized by Wiens doing well, and the management task is (1975) and DeGraaf (1978). The general simplified. conclusion is that birds probably do not control insect populations or even suppress serious outbreaks of damaging insects once such outbreaks are in full swing. The main effect may be the prevention of serious outbreaks (DeGraaf 1978).

Possible negative effects of birds on oaks also have been neglected by researchers. Birds consume mistletoe berries and probably disperse the parasite in their feces. Excavation of oaks by birds for insects, nest cavities, acorn storage holes, or sap collecting holes probably increases tree vulnerability to invasion by pathogens and insects. Oaks and birds, however, have coexisted for millions of years, so it is difficult to imagine that these negative effects need give us much cause for concern. Nevertheless, research needs to be done to assess possible negative effects of birds on oaks.

Gleaning MANAGEMENT CONSIDERATIONS Figure 3~Foraging maneuvers of birds in the foliage-gleaning guild in oak wood- Effective management of California's oak lands at Hastings Reservation (PT-- habitats must provide for the rich avifaunas plain titmouse, BGGÑblue-gra gnat- associated with them. We need to know how avian catcher, HV--Hu t ton' s vireo, WV-- communities respond to various manipulations of warbling vireo, OCW--orange-crowned oak habitats. Limited research in this field warbler). The length of each arm of the has been done in the Eastern United States, but coordinates is in direct proportion to practically none has been done in the West. the percentage of each species' use of Most oak types in the East receive substantially the three designated foraging tactics more precipitation than most oak woodlands in (adapted from Root 1967). California. Moreover, Eastern oaks are managed for timber production on a scale much larger than in California. These facts suggest that we EFFECTS OF BIRDS ON OAKS: should not apply results of Eastern studies to A NEGLECTED AREA management of Western oaks.

Virtually no systematic studies have been Oaks provide numerous, varied resources, as done on the effects of birds on California discussed so forcefully in this symposium. oaks. On the positive side, a few bird species Priorities among the products and values store acorns for later consumption by burying them, usually singly, in widely scattered spots. Griffin (1971, 1976) reported that scrub jays, Steller's jays, and yellow-billed E'~ersona1 communication. Luis Baptista, magpies bury large numbers of acorns at the Occidental College, Los Angeles (March 1979). Table 3--Attacks at various substrates in oak tsees during the breeding season by members of the foliage-gleaning guild- (from Root 1967)

Herbs Twigs Air Foliage

Plain titmouse 11.2 47.6-21 0 41.3 Blue-gray gnatcatcher I 0 3.2 13.3 83.5 Button's vireo I 0 19.6 6.5 73.8 Warbling vireo I 0 6.6 1.6 91.8 Orange-crowned warbler I 0.6 1.9 0.6 96.9

Ñ'~h foliage-gleaning guild includes all species that obtain a significant portion of their food supply by picking insects from surfaces in the foliage layer.

L1~ncludes picking at lichens and fruit.

Table 4--Arthropods in diets of foliage-gleaning species, based on prey identified in stomach samples (from Root 1967)

Prey identified Hemiptera Coleoptera Lepidoptera Hymenoptera Other

Number ------Percent ------

Plain 81 13.2 55.3 6.5 10.2 14.8 titmouse

Blue-gray gnatcatcher

Buttons vireo

Warbling vireo

Orange-crowned warbler

associated with oaks must be established and Provision for birds in managed oak stands clearly stated in plans for any given requires that sufficient numbers of trees be management unit. That is, goals must be set. available to supply the foraging, nesting, It is not my purpose to build a case for perching, and cover needs of birds in the managing all our oak habitats for maximum community. Especially important also is that benefit of birds, although this may be a there be enough acorns. I believe, however, selected goal in some instances. Rather, I that we tend to overemphasize management of oaks believe that negative effects on all resources, for acorn production as wildlife food, for- including birds, should be minimized whenever getting that oaks provide important habitats for we choose to manipulate our native environments more bird species that do not depend on acorns in any manner. than for species that do. Proper timing of project activities on a management unit also is Acorn Consumption important because of the annual cycles of bir and the regenerat ion capabilities of oaks.-9 Acorn consumption by birds in California Management must also concentrate on foraging oak habitats has not yet been quantified and nest site requirements of birds, as adequately, partly because we lack suitable adequate provision of these needs most likely estimates of the densities of bird species that will provide adequate perches and cover for eat acorns, and partly because we lack accurate birds in our oak woodlands. figures on the weight of acorns normally consumed by various species during a year. Several researchers have attempted to estimate Foraging Requirements minimum acorn needs for wildlife (including mammals as well as birds) in Eastern and Birds find food on all parts of oaks--the Southeastern oak forests. Shaw (1972) trunks, branches, twigs, buds, flowers, and summarized this work, and concluded that about foliage. The full spectrum of potential 100 lb per acre (112 kglha) of acorns "(total foraging substrates is best provided by tree-crown production) is a reasonable goal when mixed-species, uneven-aged stands. Live oaks acorn-consuming game and nongame species are particularly should be maintained in those considered." Whether or not this value is a stands now containing them, as they provide realistic ball-park figure for California foliage for cover and as an important foraging habitats is not known. As in many of the substrate for many species during the winter Eastern studies, however, wildlife in months. California's oak habitats have been observed to remove all acorns from traps even in heavy pro- Reid and Goodrum (1957) suggest the need duction years (Griffin 1976). This heavy use of to provide suitable oaks of mixed ages within acorns suggests that the needs of animals in the the home ranges of species using them. Because West may not be too different from those in the some bird species in California oak woodlands East. may have territories as small as 2 or 3 acres, a properly managed stand should have a If this is true, then, we may next ask continuing supply of oaks suitable to birds on whether or not managers can reasonably set a every 1- or 2-acre parcel. In some instances, goal of producing an annual yield of acorns for however, even widely scattered trees in wildlife at 100 lb per acre in California's oak savannah habitats may meet the nesting woodlands. Recent studies the California requirements for several pairs of the same Department of Fish and Game" show that acorn species, particularly ound feeders that nest production on that order of magnitude probably in trees. Rothstein,Ã for example, reported is a modest expectation, on most sites at least. finding single oaks near Shandon, San Luis Dry weight yields of fallen acorns in blue oak Obispo County, with three or four northern stands ranged from 9 to 191 lb per acre (10.1 to oriole nests and several nests of Brewer's 214 kglha), and in interior live oak (Quercus blackbirds. "On the other hand, the only tree wislizenii) stands from zero to 97 lb per acre in such areas may consistently have a western (109 kglha). One canyon live oak (Quercus king bi rd nest , but on1 y one. " chrysolepis) stand produced 1960 lb per acre (2195 kglha), and black oak stands ranged from Mistletoes that parasitize oaks supply zero to 1543 lb per acre (1727 kg/ha). Values berries as an important source of food for some differed enormous1 y between years on the same species, most notably the phainopepla. Control site, but further work is needed to adequately of mistletoe in oaks may be vital to characterize this variability. If wildlife maintaining tree vigor, but complete consume most or all fallen acorns, even when elimination of mistletoe could have a sig- yields approach 2000 lb per acre, production of nif icant negative effect on ,populations of at 100 lb per acre may not be an adequate goal. least a few bird species. Some compromise may Before we accept this value uncritically. it be necessary. must be thoroughly researched for wildlife in California oak types.

Acorn production by most California oak 21~urray, L., J. A. Lorenzana, W. J. Bradley, species is not high every year. Pro- and W. R. Thornton. 1973. Black oak management plan, Mendocino National Forest. Unpubl. typescript. 23 p. Ñ1~raves W. C. 1976. The dependency of upland game on oak mast production. Progress Ñl~ersona communication. Stephen I. report on upland game investigations. Project Rothstein. University of California, Santa W-47-R-24, Calif. Dep. Fish and Game. Unpubl. Barbara (March 1979). typescript. 16 p. duction tends to be high at 2-year, 3-year, or tree species and optimum tree sizes, shapes, and irregular intervals (Sudworth 1908, Wolf 1945) . states of decadence. As with adequate provision Different species are not necessarily of foraging substrates and acorn production, synchronized in the timing of high and low maintenance of mixed-species stands is production years. Management to ensure important, because different bird species adequate acorn production on any given site, exhibit different preferences for nest cover. therefore, can be increased by mixed-species Older, larger trees should be available for stands of oaks. cavity nesters, and uneven-aged stands should be planned to provide for replacement of fa1len Barrett and other&' suggest that sources cavity trees. In my experience, snags~deador of measured variation in acorn production partly dead trees--are less critical to cavity "probably include at least: 1) tree , nesters in oak woodlands than they are in other 2) trap position under canopy, 3) tree size timber types; most nest cavities at the San (crown cover), 4) tree shape (dominance), 5) Joaquin Experimental Range, in Madera County, tree age (DBH), 6) site (plot), 7) regional are in living blue oaks. environment (area), 8) annual weather." At least some of these variables may be incorporated into management planning to The Guild Approach increase acorn production. Size and shape of the crowns of more productive trees (genetic After enough data have been accumulated on differences?, site differences?), for example, the feeding and nesting behaviors of birds in might be improved for acorn production by California oak habitats, we should classify the selective removal of appropriate neighboring bird species by guilds and take a guild approach trees. Stands may be managed to assure a to management. The next step is to select sufficient number of older trees, which tend to suitable indicator species for each guild, and be the most productive (Shaw 1972). McDonald regularly inventory populations of indicator (1969) found that black oaks do not produce species to determine population trends over long viable seeds before 30 years of age, and not periods of time. until they are about 80 years old do they pro- duce acorns in large quantities. High pro- This presupposes suitable inventorying duction levels may then be maintained at least methods for oak habitats. Such methods need to to an age of 200 years. be researched within constraints of providing reliable population trends, if not reliable As to acorn consumption, Gutierrez and estimates of densities, and being time and cost Koenig (1978) recommend that acorn granary efficient . Inventorying should be done before trees be maintained for acorn woodpeckers. and after all sorts of management treatments in This recommendation is not restricted to oaks, all sorts of oak habitats to assess impacts. because the woodpeckers use other species of Particularly important in this regard may be any trees too. Existing granary trees should be activity that affects understory vegetation, identified and spared whenever tree cutting or especially the shrub layer. Shrubs are required removal of any kind is planned. Because the by a number of bird species commonly associated birds apparently prefer the largest trees in an with oaks, so shrub removal may have a large area as granaries, old, large living trees impact on the number of bird species able to use should be spared. "The number of potential an oak stand. storage trees retained in an area should at least be equal to, and preferably located near, snags presently in use as granaries." Consideration of Adjacent and Included Habitats

Nest Site Requirements Plans for management units that include, or are adjacent to, other habitat types must Managing oak stands to provide ample consider the additional bird species such nesting sites for birds suffers presently from habitats attract. Earlier discussions pointed a lack of quantitative information on preferred out that several species of birds regularly exploiting oak habitats do so only because their preferred habitat is available in the area. Twenty species listed in table show first E'~arrett, R. H., .J. W. Menke, M. E. Fry, and preference for riparian sites and another 14 D. Mangold. 1976. A review of the value of show first preference for chaparral. These two hardwoods to wildlife in California with habitats are frequently associated with oak recommendations for research. Final report, woodlands in California, and some bird species submitted to Tahoe National Forest, USDA Forest preferring them are exhibiting downward Serv. Unpubl. typescript. 45 p. population trends. The National Audubon Society publishes in alternate years a "Blue List" of ACKNOWLEDGMENTS species for which available field data indicate declines of a magnitude deserving attention. Lyman V. Ritter assisted with the Those from table 1 that are cited in the 1978 literature review. Drs. Luis Baptists, Stephen Blue List (Arbib 1977) for the Pacific coastal H. Ervin, and Stephen I. Rothstein critically area are, by preferred habitat type: 1) reviewed the manuscript and supplied some of the Riparian woodland - Cooper's hawk, information used in table 1. Gary P. Eberlein red-shouldered hawk, ye1 low warbler, and yel- did the regression analyses that formed the low-breasted chat ; 2) Savannah - Swainson's basis for figure 1. To all I express my sincere hawk; 3) Coastal forest - purple martin. appreciation.

Summary of Specific Recommendations LITERATURE CITED

Multiple-use management of oak stands Arbib, R. likely can accommodate the requirements of 1977. The Blue List for 1978. Amer. Birds birds if all of the following general rec- 31: 1087-1096. ommendations are incorporated into the man- agement plans. Beal, F. E. L. 1910. Birds of California in relation to the Concentrate on the feeding and fruit industry. Part 11. USDA Biol. Surv. nesting requirements of breeding Bull. 34:l-96. birds, as adequate provision for them will likely satisfy the other needs Beal, F. E. L. of birds in oak woodlands--including 1911. Food of the woodpeckers of the United those of migrants and winter States. USDA Biol. Surv. Bull. 37:1-64. residents. Bent, A. C. a Use the guild approach, including 1923. Life histories of North American selection of suitable indicator Wildfowl. Part I. U. S. Natl. Mus. Bull. species. 126, 244 p.

Maintain mixed-species, uneven-aged Bent, A. C. stands, especially allowing for live 1932. Life histories of North American oak retention. gallinaceous birds. U. S. Natl. Mus. Bull. 162, 490 p. Provide a continuing supply of oaks, generally distributed on every acre Bent, A. C. or 2-acre parcel of the management 1937. Life histories of North American birds unit that presently supports oaks. of prey. Part I. U. S. Natl. Mus. Bull. 167, 409 p. Provide a continuing supply of large, old trees, especially those with a Bent, A. C. good record of high acorn production. 1938. Life histories of North American birds of prey. Part 11. U. S. Natl. Mus. Bull. a Manage for a mean annual production 170, 482 p. of at least 100 lb of acorns per acre, until further research Bent, A. C. establishes a better estimate of 1939. Life histories of North American wildlife's needs. woodpeckers. U. S. Natl. Mus. Bull. 174, 334 p. Provide an ample shrub layer where one occurs in existing oak stands, Bent, A. C. and consider the possibility of 1940. Life histories of North American establishing shrubs in stands from cuckoos., goat suckers, hummingbirds, and which they were removed in the past. their allies. U. S. Natl. Mus. Bull. 176, 506 p. Consider needs of oak-using species from different, adjacent habitat Bent, A. C. types. 1942. Life histories of North American flycatchers, larks, swallows, and their allies. U. S. Natl. Mus. Bull. 179, 555 p. Bent, A. C. Dawson, W. L. 1946. Life histories of North American jays, 1923. The birds of California. 2121 p. (4 crows, and titmice. U. S. Natl. Mus. Bull. vols.). South Moulton Co., San Diego, 191, 495 p. Calif.

Bent, A. C. DeGraaf, R. M. 1948. Life histories of North American 1978. The importance of birds in ecosystems. nuthatches, wrens, thrashers, and their -In Proc., Workshop on nongame bird habitat allies. U. S. Natl. Mus. Bull. 195, 475 p. management in the coniferous forests of the . R. M. DeGraff, tech. Bent, A. C. coord. Gen. Tech. Rep. PNW-64, p. 5-11. 1949. Life histories of North American Pacific Northwest Forest and Range Exp. thrushes, kinglets, and their allies. U. Stn., Forest Serv., U. S. Dep. Agric., S. Natl. Mus. Bull. 196, 452 p. Port land, Oreg.

Bent, A. C. Dixon, K. L. 1950. Life histories of North American 1954. Some ecological relations of chickadees wagtails, shrikes, vireos, and their and titmice in central California. Condor allies. U. S. Natl. Mus. Bull. 197, 400 p. 56:113-124.

Bent, A. C. Fitch, H. S., B. Glading, and V. House 1953. Life histories of North American wood 1946. Observations on Cooper hawk nesting and warblers. U. S. Natl. Mus. Bull. 203, 733 predation. Calif. Fish and Game 32: 144-154. P. Fry, M. E., and C. E. Vaughn Bent, A. C. 1977. Acorn selection by band-tailed pigeons. 1958. Life histories of North American Calif. Fish and Game 63:59-60. blackbirds, orioles, tanagers, and allies. U. S. Natl. Mus. Bull. 211, 549 p. Griffin, J. R. 1971. Oak regeneration in the upper Camel Bent, A. C. Valley, California. Ecology 52:862-868. 1968. Life histories of North American cardinals, grosbeaks, buntings, towhees, Griffin, J. R. finches, sparrows, and allies. 0. L. 1976. Regeneration in Quercus lobata Austin, Jr., comp. and ed. U. S. Natl. savannas, Santa Lucia Mountains, California. Mus. Bull. 237, Parts 1, 2, and 3. 1889 p. her. Midi. Nat. 95:422-435.

Bock, C. E. Grinnell, J. 1970. The ecology and behavior of the Lewis 1936. Up-hi1 1 planters. Condor 38:80-82. woodpecker (Asyndesmus lewis) . Univ. Calif. Publ. in 2001. 92:l-100. Grinnell, J., and A. H. Miller 1944. The distribution of the birds of Bontrager, D. R. California. Pacific Coast Avifauna No. 27. 1974. Breeding bird census. Sycamore-coast Mus. Vertebr. Zool., Univ. Calif., Berkeley. live oak riparian woodland. her. Birds 608 p. 28:1035-1036. Gutierrez, R. J., and W. D. Koenig Cogswell, H. L. 1978. Characteristics of storage trees used 1966. Breeding bird census. Broad-leaf by acorn woodpeckers in two California evergreen forest with shrub-f illed woodlands. J. For. 86: 162-164. openings. Audubon Field Notes 20:633-634, 642-643. Hertz, P. E., J. V. Remsen, Jr., and S. I. Jones 1976. Ecological complementarity of three Cogswell, H. L. sympatric parids in a California oak 1973. Breeding bird census. Broad-leaf woodland. Condor 78:307-316. evergreen forest with shrub-f illed openings. Amer. Birds 27 :992-993. Hutchinson, A., and M. Hutchinson 1944. Breeding bird census. Mature stand of Davis, J. live oaks along canyon creek. Audubon Mag. 1957. Comparative foraging behavior of the 46 (Section 2): 18. spotted and brown towhees. Auk 74: 129-166. Hutchinson, A., and M. Hutchinson McKinnie, I. R. , Jr . 1945. Breeding bird census. Mature stand of 1974. Breeding bird census. Sycamore-coast live oaks along canyon creek. Audubon Mag. live oak riparian woodland. Amer. Birds 47 (Section 2):61. 28: 1036.

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Koenig, W. Neff, J. A. 1972. Breeding bird census. Deciduous oak 1928. Economic status of the common woodland. Amer. Birds 26:1001-1002. woodpeckers in relation to Oregon horticulture. Marionville, Missouri, Free Leopold, A. S. Press Print. 1977. The California quail. 281 p. Univ. Calif. Press: Berkeley, Los Angeles, Neff, J. A. London. 1947. Habits, food and economic status of the band-tailed pigeon. North Amer. Fauna 58. Linsdale, J. M. 76 p. U. S. Fish and Wildl. Serv., 1937. The natural history of magpies. Washington, D. C. Pacific Coast Avifauna 25. 234 p. Cooper Ornithol. Club, Berkeley, Calif. Newman, T. F., and D. A. Duncan 1973. Vertebrate fauna of the San Joaquin Loveless, B., and R. Loveless Experimental Range, California: a 1977. Breeding bird census. Sycamore-coast checklist. USDA Forest Serv. Gen. Tech. live oak-riparian woodland. Amer. Birds Rep. PSW-6, 17 p. Pacific Southwest Forest 31:70. and Range Exp. Stn., Berkeley, Calif.

MacRoberts, M. H., and B. R. MacRoberts Perrone, M., Jr. 1976. Social organization and behavior of 1970. Breeding bird census. Deciduous oak the acorn woodpecker in central coastal woodland. Audubon Field Notes 24: 749-750. California. Ornithol. Monogr. 21, 115 p. her. Ornithol. Union. Pugh, E. A. 1956. Breeding bird census. Sycamore-live Mailliard, J. oak dry wash. Audubon Field Notes 1902. Wren-tit building in a tree. Condor 10:433-434. 4:95. Pugh, E. A. Manolis, T. 1961. Breeding bird census. Oak wooded 1972. Breeding bird census. Mixed canyon. Audubon Field Notes 15: 505-506. oak-digger pine woodland. her. Birds 26: 981-983. Reid, V. H., and P. D. Goodrum 1957. The effect of hardwood removal on Manolis, T. wildlife. Proc. Soc. Amer. For. 57: 1974. Breeding bird census. Mixed 141-147. oak-digger pine woodland. Amer. Birds 28: 1043-1044. Remsen, V. 1971. Breeding bird census. Deciduous oak Martin, A. C., H. S. Zim, and A. L. Nelson woodland. Amer. Birds 25:983-984. 1951. American wildlife and plants. 500 p. McGraw-Hill Book Co.. New York and Toronto. Ritter, W. E. 1938. The California woodpecker and I. 340 McDonald, P. M. p. Univ. Calif. Press, Berkeley. 1969. Silvical characteristics of California black oak (Quercus kelloggii Newb.). USDA Robert, H. Forest Serv. Res. Paper PSW-53. 20 p. 1966. Breeding bird census. Mixed evergreen Pacific Southwest Forest and Range Exp. forest. Audubon Field Notes 20: 629-630. Stn., Berkeley, Calif. Root, R. B. Stewart, R. M. 1964. Ecological interactions of the 1975. Breeding bird census. California chestnut-backed chickadee f 01lowing a range bay-buckeye-mixed forest. Amer. Birds extension. Condor 66:229-238. 29:1123.

Root, R. B. Stewart, R. M. 1967. The niche exploitation pattern of the 1977. Breeding bird census. California blue-gray gnatcatcher. Ecol. Monogr. bay-bishop pine-mixed forest. Amer. Birds 37:317-350. 31:72.

Root, R. B. Sudworth, G. B. 1969. The behavior and reproductive success 1908. Forest trees of the Pacific slope. 441 of the blue-gray gnatcatcher. Condor p. U. S. Gov. Print. Off ., Washington, D. 71:16-31.

Shaw, S. P. Tangren, G. 1972. Wildlife and oak management. In 1971. Breeding bird census. Riparian oak Proc ., Oak symposium [Morgantown, west woodland. Amer. Birds 25:967-969. Virginia, Aug. 16-20, 19711, p. 84-89. USDA Forest Serv., Northeastern Forest and Tangren, G. Range Exp. Stn., Upper Darby, Penn. 1972. Breeding bird census. Riparian oak woodland. Amer. Birds 26:977-978. Shepard, M. 1962. Breeding bird census. Coastal forest. Van Dersal , W. R. Audubon Field Notes 16:529-530. 1940. Utilization of oaks by birds and mammals. J. Wildl. Manage. 4:404-428. Shepard, M. 1963. Breeding bird census. Coastal forest. Waian, L. B. Audubon Field Notes 17:503. 1973. The behavioral ecology of the North American white-tailed kite (Elanus leucurus Small, A. majusculus) of the Santa Barbara Coastal 1974. The birds of California. 310 p. Plain. Ph.D. Dissert., Univ. Calif. Collier Books, New York. Library, Santa Barbara.

Steiker, E., and S. Maas Walsberg, G. E. 1973. Breeding bird census. Deciduous oak 1977. Ecology and energetics of contrasting woodland. Amer. Birds 27:993-994. social systems in Phainopepla nitens (Aves : Ptilogonatidae) . Univ. ~alif.bl. in Stewart, R. M. Zool. 108: 1-63. 1972a. Breeding bird census. Oak-Cali fornia bay-buckeye-mixed forest. Amer. Birds Wiens, J. A. 26:979. 1975. Avian communities, energetics, and functions in coniferous forest habitats. 2 Stewart, R. M. Proc., Symposium on management of forest and 1972b. Breeding bird census. California range habitats for nongame birds [Tucson, bay-bishop pine-mixed forest. her. Birds Arizona, May 6-9, 19751. USDA Forest Serv. 26:98l. Gen. Tech. Rep. WO-1, p. 226-261.

Stewart, R. M. Winkler, D. 1973a. Breeding bird census. Oak-California 1973. Breeding bird census. Riparian oak bay-buckeye-mixed forest. Amer. Birds woodland. her. Birds 27:996. 27:995-996. Wolf, C. B. Stewart, R. M. 1945. California wild tree crops. Rancho 1973b. Breeding bird census. California Santa Ana Botanic Garden, Santa Ana Canyon, bay-bishop pine-mixed forest. her. Birds Orange County, Calif . 27:997-998.

Stewart, R. M. 1974. Breeding bird census. Oak-Cali fornia bay-buckeye-mixed forest. Amer. Birds 28: 1035. Walter D. ~oeni~u

Abstract: Acorn woodpeckers (Melanerpes formicivorus) are a major harvester of acorns throughout California, eating them as they mature and caching them in storage trees each fall. At Hastings Reservation in central coastal California, a population of 120 to 130 birds stored an average of 43,600 acorns (344 per bird) each year. These acorns provide an estimated caloric content of edible material of 180,500 kcal, only about 6 to 7 percent of the total yearly metabolic requirements of the woodpecker population. These data are sufficient to indirectly provide a reasonable estimate of average acorn production in the study area. The pattern of acorn storage by the acorn woodpecker and other major acorn harvesters in California contrasts with harvesters of piiion pine nuts (primarily Clark's nutcrackers and pinon jays) in the Southwest. Nut storage by both these species apparently results in significant dispersal of seeds, whereas most of the acorn harvesters in California effectively predate the acorns they pick. Equally contrasting are the adaptations of the mast-producing trees in the two communities. Pition pines exhibit characteristics promoting seed dispersal by birds, while oaks in California do not appear to have evolved comparable mechanisms.

remains. In addition, acorn woodpeckers have a unique way of INTRODUCTION coping with food shortage during the winter. Each group of birds defends a storage tree, or granary, within which acorns are stored individually in holes (MacRoberts and MacRoberts The pattern of energy flow within natural ecosystems can 1976, Gutierrez and Koenig 1978). Stored acorns are a crucial provide useful insights into the factors influencing population resource. Not only are birds unable to remain resident on dynamics and community organization (Wiens and Innis 1974). their territories through most winters without access to them, Here I present an energetics analysis of one component of the but also reproduction the following spring is impossible for community. The approach I will take groups whose stores have been exhausted during the winter is preliminary and limited, but could readily be expanded to (Kocnig 1978). Acorn woodpeckers are most dependent on include more species in the acorn consumer guild, leading to a acorns during the fall and winter (approximately September to more complete evaluation of their impact on oak ecology and March), but groups with stored acorns remaining continue to population dynamics. use them through the spring and summer. The acorn woodpecker (Melanerpesformicivorus) is one of the most characteristic birds of oak and pine-oak woodlands throughout western North America. The birds live in METHODS permanently territorial family groups of between two and fifteen individuals: their diet is diverse. including flying and bark-crawling insects, sap, wild oats, fruit, vertebrates, oak buds Data were collected as part of a study of the ecology and and flowers, and acorns. They do not bore into wood as do social behavior of the acorn woodpecker at Hastings Natural most other woodpecker species. Acorns, which are the single History Reservation. Monterey Co.. central coastal California. most important item of their total diet, are eaten directly off Approximately 25 groups of acorn woodpeckers were banded the trees from the time they ripen in the fall until none and censused beginning in fall of 1971, permitting accurate estimates of population size. Between July 1974 and Presented at the Symposium on the Ecology, Management, September 1978 the number of stored acorns in each granary at and Utilization of California Oaks, Claremont,California, June Hastings was counted at bimonthly intervals. Beginning in the 26-28, 1979. winter of 1975-76. I took random samples of stored acorns from accessible sections of each granary. These were identified 2/~ost-doctoral Research Zoologist, Hastings Reservation and Museum of Vertebrate Zoology, University of California, to species (five are common in the area: Quercus lobata Nk, Carmcl Valley, California 93924. Q. agnyolia Nee, Q. douglasii H. & A., Q. kelloggii Newb., and Q. chrysolepis Liebm.), dried for several months, shelled, and Table 1-- Yearly variation in species compositionof acorns stored the cleaned cotyledons weighed. In 1975-76, only the total by acorn woodpeckers at Hastings Reservation weight of the acorn sample was taken for each group of acorn woodpeckers. In the other two years acorns were divided first by species and then by degree of insect damage. Each set thus Year Percent of all stored acorns Total(N) Q. Q. Q. Q. Q. obtained was then weighed separately. These data permitted agrifolia lobata douglasii kelloggii chrysolepis estimation of the total number and proportion of acorns of 1975-76 5.0 17.0 51.4 18.1 8.4 45470 each species stored by the woodpecker population, the mean 15.2 7.9 41927 weight of undamaged acorns, and the average amount of insect 1976-77 27.1 34.3 15.6 0.6 43425 damage that occurred to stored acorns of each species. 1977-78 19.5 50.3 21.6 8.0 Mean 16.9 33.7 30.0 13.8 5.6 43607 The energy consumption of acorn woodpeckers was estimated from values of existence metabolism (Pimm 1976) These data are readily convertible to energy flux per unit corrected for the increased costs of normal activity and area. The approximate size of the study area is 247 ha, of digestive inefficiency (Wiens and Innis 1974). The caloric which about 70 percent consists of oak woodland or forest in content of acorns was estimated using an average 9.7 kcallgm which oaks are common. Thus, given an average TMR for for lipid content and 4.2 kcal/gm for the remaining material; acorn woodpeckers at Hastings of 2,810,000 kcallyear and average lipid content for acorns of each species are from acorn reserves of 180,000 kcal/year (tables 2 and 3). the mean Tuckcr~. Estimates of acorn production were gleaned from TMR of the population is about 11,400 kcal/ha/year while the the literature. energy stored in granaries amounts to 730 kcal/ha/year. Table 4 lists the percent of total acorn production which would be stored in granaries given these estimates and an acorn crop of RESULTS four different orders of magnitude. The proportion of the acorn production stored in granaries ranges from a high of 22 percent given a crop of 1 kg/ha to 0.02 percent if the crop Table 1 lists the estimated total numbers of stored acorns were 1000 kg/ha. cached by acorn woodpeckers at Hastings for each of the three years. The relative proportion of the total made up by each of Using these values the relationship between acorn the five species of oaks varied considerably from year to year; production and the TMR of the acorn woodpecker population however, the total number of stored acorns was relatively can also be estimated (table 4). In this case, given an average constant, ranging between 42,000 and 45,000 (X=43,607), or crop of 1 kg/ha, the TMR of the population would be over about 344 acorns/bird/year. Table 2 summarizes the total three times the total acorn production. Given a crop of 1000 estimated number of acorns of each species stored, along with kglha, the TMR of the population would be only 0.3 percent the mean weight, amount of insect damage, total weight of of the acorn production. stored acorns, caloric content per gram and per acorn for each The actual fraction of the total acorn production which is species, and total caloric content of all stored acorns averaged used by acorn woodpeckers is dependent not only on the for all data. After correcting for insect damage, the total production itself but also on the proportion of their diet made average weight of stored acorns was 39 kg/year. In total, the estimated caloric content of stored edible material averaged up of acorns. Earlv studies based on stomach content analyses suggested that this proportion might be as high as 50 to 60 180,500 kcallyear. pcrcent (Beal 1911, Neff 1928), far higher than the proportion These values represent the average maximum total suggested by the data on acorn storage discussed above. energetic content of stores. Maxima were generally counted in However, I feel that these early figures are certainly December or January when acorn fall was complete. Prior to overestimates, both because of the relatively slow digestive rate this, during a period of about four months beginning when for seeds such as acorns compared to other softer material acorns first begin to mature, acorns are eaten directly off the consumed by acorn woodpeckers, thereby biasing stomach trees rather than from the granary (or, alternatively, those taken content analyses (see Custer and Pitelka 1976), and also from the granary are replaced by newly harvested acorns). because of the difficulty in assessing the importance of sap, a food resource only recently shown to be important for acorn The estimated metabolic requirement of the acorn woodpeckers (MacRoberts 1970). If half the diet of the woodpecker population at Hastings was compared with the population during the storing months of September to caloric value of stored acorns (table 3). The proportion of the total metabolic requirement (TMR) of the population December is made up of acorns and only stored acorns remain after that time, acorns would then make up about 25 percent of accountable in stored acorns is surprisingly low--only 6 to 7 their total diet. Then, if the acorn crop averaged 10 kg/ha, pcrcent. Even considering only the eight months of the year woodpeckers would consume approximately 9 percent of the during which acorns are not available directly from the trees, stores account for only 10 or 11 percent of their remaining total crop, and less than 1 percent if the crop averaged 100 kg/ha (table 4). TMR. The relatively constant proportion of the TMR met by stored acorns during the study suggests that this proportion is usually not limited by the acorn supply itself, which varied DISCUSSION considerably during the three yearsu.

Unpublished data; J. Tucker, Dept. Botany, Univ. California, Problems in Estimates of Acorn Production Davis. ^Unpublished data; J. Griffin, Hastings Reservation, Univ. Though each step of this analysis is an approximation, the California, Carmel Valley, California. greatest uncertainty is in the estimation of acorn production Table 2 -- Mean weight, insect damage, and caloric content of acorns stored by acorn woodpeckers

Q. agrifolia Q. lobata Q. douglasii Q. kelloggii Q. chrysolepis Total Total number of acorns stored 7,370 14,696 13,082 6,018 2,442 43,607 Mean weight of undamaged acorns (gm) Mean percent of cotyledon eaten by insects Mean edible weight (gm) Total weight of stored acorns (kg) 6.10 13.73 10.69 5.71 2.75 38.97 Kcal/gm 1 5.16 4.44 4.41 5.01 4.51 --- KcaVstored acorn 4.27 4.15 3.60 4.75 5.08 --. Total caloric content of stored 31,500 60.900 47,100 28,600 12,400 180,500

(table 4). Obtaining such estimates is a difficult but essential These data indicate wide variation in production from year challenge to future ecologists interested in oak communities. to year, species to species, and even from tree to tree. These Values reported by Wolf (1945) suggest that in good years fluctuations vary over at least two to three orders of magnitude acorn production of California oaks may reach 2000-6000 and range up to a maximum of possibly over 1000 kg/ha. It is kg/ha wet weight, or about 1300-3500 kg/ha dry weight. More unlikely, however, that acorn fall would average this high over recently, Graves (1976, 1977) reported preliminary values of an area of mixed terrain and habitat covering several hundred acorn fall in Sierra foothill communities of 0 to 2200 kg/ha hectares such as is of interest here. On the other hand, the dry weight. At Hastings Reservation, acorn falls of 0 to 98 values cited are for acorn fall, after crown-harvesters have acorns/m2 (about 0 to 1100 kg/ha of edible cotyledons) below already removed all the acorns they were able to take. Thus, four valley oaks (Quercus lobata Nee) over a 9-year period though the range in production values used in Table 4 are have been recordedg . probably representative of the variability shown in oak woodlands in California, there is as yet no data with which to estimate the average production over a relatively wide area of Table 3 - Energetic requirements of acorn woodpeckers at any California habitat. Hastings Reservation However, the data presented here on the metabolic requirement of the acorn woodpeckers allow a rough estimation of probable average acorn production. If 25 percent of the diet of acorn woodpeckers consists of acorns, a Mean number of birds in the proportion which no doubt varies from year to year but is study area Total metabolic Table 4 -- Relation of acorn production to use by acorn requirements of woodpeckers the population (kcaVyear)17 Caloric content Mean acorn production (dry weight) of stored acorns 1 kg/ha 1 10 kg/ha 1 100 kg/ha 1 1000 kg/ha (kcal) Edible Percent of TMR production met by stored (kcal/ha)17 acorns Percent of Percent of MR production met by stored stored by acorns during acorn period when woodpeckers acorns are not TMR of the available population Estimated using divided by total acorn temperature 13OC, and 13 hr photoperiod. Digestive production efficiency was estimated as 70 percent and the cost of -!-/ Estimated using an inedible shell weight averaging 30 normal free ranging activity as 40 percent above existence percent of dry weight and an average caloric content of 4.8 metabolism, kcal/gm for cotyledons. probably a reasonable estimate, the woodpecker population dispersal (Grinnell 1936). Three other crown-harvesting acorn would have to consume 85 percent of a total acorn crop consumers in California, Lewis' woodpeckers (Melanerpes averaging 1 kg/ha. This is clearly unrealistic. At 10 kg/ha, lewis), band-tailed pigeons (Columbu fasciata), and common woodpeckers would consume about 9 percent of the total acorn crows (Corvus brachyrhvnchos), are similar to nutcrackers and crop, still improbably high but low enough to allow at least a pinon jays in that they are nomadic and aggregate into flocks few other acorn consumers to coexist with them. Consideration in the fall (Bock 1970, Grinnell et al. 1918). However, none of, of the metabolic requirements of these other acorn users, these species store acorns in the ground or in a way likely to including crown harvesters (other birds and squirrels), ground result in acorn dispersal. predators (deer, rats, and mice), and parasites (various insects), There also appear to be striking adaptive differences would provide an excellent means of estimating total average between the oaks and piiion pines. Piiion pines exhibit acorn production. characteristics which can be interpreted as adaptations for seed dispersal by nutcrackers and pinon jays. Among these characteristics are a high lipid content of seeds (about 60 Contrast of Oak and Piiion Pine Communities percent compared to less than 20 percent for acoms), high visibility and distinct seed coloration, relatively large seed size compared to other pines, and synchronized production of seed A fascinating comparison of these data is possible with crops over wide geographic areas (Vander Wall and Balda that of Vander Wall and Balda (1977) for the harvesting and 1977, Ligon 1978). No comparable coadaptations are evident caching of piiion pine (Pinus edulis Engelm.) by Clark's among California oaks: if anything, the tannins of acorns are nutcrackers (Nucfraga columbiana) in northern Arizona. likely to have evolved as a deterrent to avian harvest and These authors estimated that a population of about 150 birds dispersal. Little investigation has been done on any of these cached between 3,300,000 and 5,000,000 nuts/year, compared factors in oak communities, however. It would clearly be to only 44,000 acorns/year stored by the Hastings population of profitable to examine interspecific variation in acorn size, lipid about 125 acorn woodpeckers. The total weight of harvested content, tannin content, and synchrony of acorn production in nuts was calculated to be between 685 and 1028 kg for the nutcrackers compared to only 39 kg for the woodpeckers. terms of the potential role of these factors in either promoting Finally, Vander Wall and Balda estimated that each bird stored or hampering harvest and dispersal. between 26,000 and 39,000 kcal/year in nuts, 2.2 to 3.3 times In conclusion, I wish to emphasize the importance of two the amount of energy needed to survive through the six factors to the understanding of oak ecology. First is the months of winter during which they eat the seeds. In contrast, potential usefulness of an energetics approach, preferrably each acorn woodpecker stored on the average only 1,420 quantifying the energetic investments and constraints of both kcal/year in acorns, only 10 to 11 percent of the MR for the producers (the oaks) and consumers (acorn harvesters). Second remaining eight months during which acorns are not available is the importance of coadaptations between producers and in the trees. consumers in determining the observed pattern of the energetic These differences suggest that the acorn woodpecker-oak investment of the oaks. We cannot understand the ecology of interaction is very different from that of Clark's nutcrackers oaks nor manage them intelligently without consideration of and piiion pines. Nutcrackers harvest more energy than they the species which live off them and disperse them. need and presumably the recovery rate of seeds they cache is low. Acorn woodpeckers harvest only a fraction of their TMR, ACKNOWLEDGMENTS invest a great deal in maintenance of these stores, and recover virtually all the material they originally store. These contrasts are reflected in the life-histories of both J. Davis and J. Griffin read the manuscript and offered the birds and of the trees. In terms of the former, both Clark's helpful comments. Access to the unpublished data of J. nutcrackers and pifion jays (Gymnorhinus cyanocephalus), a Griffin and J. Tucker was appreciated. Final preparation of second major harvester of pifion nuts (Balda and Bateman the manuscript was made possible by T. Kaehler and the Shy 1971, Ligon 1978). harvest nuts in large flocks of 100 to 300 Computer Corporation. Financial assistance was provided by birds. Flocks of both species are nomadic and may move long the National Science Foundation and the Museum of distances to find and store nuts. Recovery rate of cached nuts Vertebrate Zoology, University of California, Berkeley. is low and at least some eventually germinate. The major crown-harvesting acorn consumers in California follow different exploitation patterns. Acorn LITERATURE CITED woodpeckers, as discussed above, live in relatively small, stable family groups which defend permanent territories. Only if the acorn crop fails entirely within a group's home range do they Balda, R.P., and G.C. Bateman move elsewhere. Few acorns stored by acorn woodpeckers 1971. Flocking and annual cycle of the pinon jay, gain the chance to germinate, though a small number are Gymnorhinus cyanocephalus. Condor 73:287-302. dropped by the birds prior to being stored in a granary. Scrub jays (Aphelocoma coemlescens) are also territorial Beal, F.E.L. and sedentary, though temporary feeding assemblages of 50 or 1911. Food of the woodpeckers of the United States. U.S. more birds may form in order to harvest acorns from localized Dept. Agr. Biol. Surv. Bull. 37. areas with heavy cropsg. Scrub jays cache acorns in the Bock, C.E. ground, however. and thus are probably important to acorn 1970. The ecology and behavior of the Lewis woodpecker ^ Personal observation. (Asyndesmus lewis). Univ. Calif. Publ. Zool. 92:l-91. Custer, T.W., and F.A. Pitelka MacRoberts, M.H. 1976. Correction factors for digestion rates for prey taken 1970. Notes on the food habits and food defense of the by snow buntings (Plectrophenax nivalis). Condor acorn woodpecker. Condor 72:196-204. 77:210-212. MacRoberts, M.H., and B.R. MacRoberts Graves, W.C. 1976. Social organization and behavior of the acorn 1976. The dependency of upland game on oak mast woodpecker in central coastal California. Ornith: production. Calif. Dept. Fish and Game job progress Monogr. 21:l-115. report. 1977. The dependency of upland game on oak mast Neff, J.A. production. Calif. Dept. Fish and Game job progress 1928. Economic status of the common woodpeckers in report. relation to Oregon horticulture. Free Press Print. Marionville, Mo. Grinnell, J. 1936. Up-hill planters. Condor 3890-82. Pimm, S.L. 1976. Existence metabolism. Condor 78:121-124. Grinnell, J., H.C. Bryant, and T.I. Storer 1918. The game birds of California. Univ. Calif. Press, Vander Wall. S.B., and R.P. Balda Berkeley. 1977. Coadaptations of the Clark's nutcracker and die pinon pine for efficient seed harvest and dispersal. Gutierrez, R.J., and W.D. Koenig Ecol. Monogr. 47:89-111. 1978. Characteristics of storage trees used by acorn woodpeckers in two California woodlands. J. Forest. Wiens, LA., and G.S. Innis 78:162-164. 1974. Estimation of energy flow in bird communities: a population bioenergetics model. Ecology 55:730-746. Koenig, W.D. 1978. Ecological and evolutionary aspects of cooperative Wolf, C.B. breeding in acorn woodpeckers of central coastal 1945. California wild tree crops. Rancho Santa Ana California. Ph.D. thesis, Univ. Calif., Berkeley. Botanic Garden, Santa Ana Canyon, Calif. Ligon, J.D. 1978. Reproductive interdependence of pinon jays and pinon pines. Ecol. Monogr. 48:lll-126. Quercus kelloggii

Annual Oak Mast Yields from Visual Estimates1

Walter C. ~ravesg~

Abstract: A method for visually estimating mast yields is described. Results of three yeam of field testing and application are listed. Wactical application of the method for management and research is discussed.

been reported in other states on other species of oaks (Goodrum et al. 1971). Seventeen species of oaks occur in California. !Chey provide an important element The first step toward meeting the study of habitat association for many wildlife species. objective was to monitor annual acorn produc- The annual mast or acorn crop produced by a tion per individual tree and per area. Indi- single species or in combination with associ- vidual tree production data were to be ated species contributes significantly to the correlated with physical tree measurementsy food supply of wildlife. Dependent species while area production data was to be corre- include tree squirrels (Sciurus griseus) lated with annual changes in selected wildliye wild turkeys (~eleagrisgalloparo ) band-tailed species and wildlife population levels. Seed pigeons (columba faseiata) mountain quail traps (Downs and McQuilkin 1944) were used to (0reortyxmYvalley quail (Lophortyx obtain initial production data from randomly californicu~)~wood ducks (Aix sponsa)* selected trees. Acorn yield data collected w a s Platyrhynchos) wild pigs (& in this manner were extremely variable and led scrofa) bear (ursus americanus ) deer to several modifications in the study Gileushemionus ) , acorn woodpeckers (Graves 1977 ) . (~elanerpesformicivorus) Stellerrs jays (Cyanocitta stelleri), and scrub jays One major change was to select sampled (Aphelocoma coerulescens 1. trees based on some knowledge of potential to produce acorns. This was accomplished by Because of the recognized importance of designing and field testing a method to oak associations and acorns to wildlife* the visually classify acorn production. mis California Department of Fish and Game has paper describes that procedure. been conducting an oak-wildlife relationship study since 1975. The major objective is to develop oak management plans for both public and private lands that provide proper cover and food for wildlife. Similar studies have 1. Four classes for acorn production of indi- vidual trees were defined as follows: Class #l - No visible acorns (Score 1) Class #2 - Acorns visible after very -1IPresented at the Symposium on the Ecologyy close examination. Maybe only Management, and Utilization of California one or two are observed (Score 2) Oaks, Claremont , California* June 26-28Â 1979. Class #3 - Acorns readily visible, but they do not cover the entire -2/Wildlife Biologist California Department of tree and the limbs do not appear Fish and Gamey Chicoy California. to bend from their weight (Score 3) Class #4 - Acorns readily visible and species throughout the state was initially covering the entire tree; tested in 1976 with continued surveys in 1977 limbs appear to sag from and 1978~using the described classes with weight of acorns (Score 4) the following instructions : a. Based on your subjective knowledge 2. Instructions for classifying each indi- of oak distribution in your area, select vidual tree were as follows: representative area or areas for each a. Walk up to the tree and note that oak species. Mast production varies acorns are either readily visible or from one slope to another. Therefore* not visible. the sample should include trees from various slopes and elevations. b. If acorns are not readily observed* the tree is either a Class 1or a b. Selection of trees should be on a Class 2. Walk around the tree and look random basis at preselected stops along for acorns. Use field glasses if neces- roads or equal distances along walking sary. If no acorns are observed* the transects. Do not select trees because tree is a Class 1. If one or more acorns of size, formy or obvious presence of are observed* the tree is a Class 2. acorns. Trees should be away from road- Record the class on a data sheet and go ways to avoid unnatural edge effect. to the next tree. c. Classify 100 trees of each species c. If acorns are readily observed* the per wildlife management unit. tree is either a Class 3 or 4. Walk around the tree to see if acorns are found all over the tree. If they are well distributed around the tree* the tree is a Class 3. Also* if the acorns Variation in classifying individual are only on one side or in one area, the blue oak trees occurred with three observers. tree is a Class 3. If the acorns occur in They independently classified the same 150 clusters of two* three or more* all trees* and all three classified 74 percent around the tree, is a Class it 4. In of the trees the same. Two observers were this class, the limbs are often bending in agreement on the classification for the from the weight of acorns. Record data remaining 26 percent with the third observer and go to the next tree. placing the tree one class above or below the other observers. The most frequent 3. Three or more observers classified the discrepancy occurred between Class l and same sample of 150 trees to determine varia- Class 2 trees. This variation between obser- tion between observers. vers in individual tree classification became insignificant in the overall average produc- 4. Blue oak (Quercus douglasii) trees on a tion class for the 150 trees with averages 60~000-acre ranch were randomly selected(by of 2.25, 2.23, and 2.25. driving along roads* stopping at .2 mile intervals, and classifying the nearest five Variation in the average tree class of treesland sampled in groups of 100 to deter- 100 trees was less than one percent as addi- mine adequate sample size needed to estimate tional groups of 100 randomly selected trees acorn production for a given area. were classified. me first group of 100 trees had an average production class of 2.25. 5. Visual classes were compared to samples men the second 100 trees were added to this for a of acorns collected in 0.2 m2 seed traps to sample of 200 trees* the average class was 2.27 relate the visual classes to some quantita- and remained the same with the addition of tive value. Wire-framed seed traps with another 100 trees. burlap sacks were placed under two Class ly sixteen class 2* 46 class 3* and 36 class 4 There was a significant (t test with trees. The number of trees sampled per class P=.05) difference based on both sample weight were predetermined from the expected range in and number of acorns per sample between dry weight of acorns collected per tree per Class 2, 3 and 4 trees (table 1). No acorns class, expressed as a percentage of the total were collected from Class 1trees. The expected range for all classes. F'hysical number of acorns collected per trap correlated tree measurements were recorded for each of positively (r=0.59* ~=.05)with the visual these sampled trees. class. There was no significant difference in the range of the DBH (Diameter Breast 6. Application of the method to obtain trend High-a measurement of basal area) for trees data for various geographic areas and oak Table 1--Acorn trap summary data per tree class

class 2(16)-11 Class 3(46) Class 4(36)

Mean acorns/trap standard error (Range Mean wt. gn /trap (Range

-l/Nmber of trees sampled.

Table 2--Average acorn yield class by species, county, and region, 1978

Brewer Canyon Coast Garry Interior Scrub Valley County Ul Species Blue Oak Black Oak Oak L. Oak L.0ak Oak L. Oak oak oak

Tehama 1.35( 328)Ll

mAL

El brad Glenn- Colusa

TOTAL

Napa Mendocin Lake San Luis Obispo Monterey Santa Clara Sonoma

TOTm

Stanis- laus Madera

TOTAL

COMBINED TOTALS

1978

1977

1976

LI~umberin parentheses indicates sample size.

gl~ample size unknown. in each visual class, with ranges of 32-132 shows an observed decline in mast production for Class 2, 98-162 for Class 3, and 124-236 for most species and administrative regions for Class 4 trees. (tables 2 and 3). Sampling intensity varied between observers, and only limited data was Application of the visual method to available for some species. Therefore, no monitor acorn yields on a statewide basis statistical analysis of the data was attempted. Table 3--Combined average yield classes of class and measured acorn production suggests all oak species by county and region for that the visual classification system could l976Â 1977, and 1978 be used to quantify annual acorn production, providing some information including basal areay stems per acrey average canopy heighty COUNTY and crown cover per acre on the tree stand and area is available. We intend to collect Siskiyou quantitative data and visually classify trees Humboldt on our blue oak study area through at least Trinity one more good acorn year in order to correlate Tehama the visual classification to quantitative mast production. We also intend to follow the same procedure with black oak (9. ~elloggii) during a good mast year. Questions asked are: El. brado What constitutes an average or above average Placer mast crop? Are the same trees that produce Glenn- one good year the same ones that produce during Colusa the next good year? These questions can be answered only afier several years of data are available.

Mendocino Assuming that the strong correlation Lake. exists between visual class and quantitative San Luis measurement of mast production for all oak Obispo speciesy the visual method can be used as a Monterey research and management tool. The researcher Santa Clar can use it to measure mast production in con- Napa junction with food habits, body condition, Sonoma reproductive levelsy and population trends of selected wildlife species. The visud classification can be used to sample a larger number of trees over a much larger area than Stanislaus 1.48( 100) 1.42( 260) 1.03( 240) the more expensive and time-consuming con- Madera 2.56( 1001 1.37( loo) l.oo( loo) ventional seed trap method. Provided that trees are classified and marked during good REGION 4 mast years, the land manager can use the method as a tool for selecting good mast-producing San trees of various sizes and age classes to be Bernardin, retained during logging and thinning operations San Diego for the benefit of wildlife and for natural Riverside reseeding of the area.

!the Department of Fish and Game will con- tinue to use this method to monitor acorn * = Sample size unknown. production throughout the state. The annual Number in parentheses indicates sample size. data and trend information will be used in conjunction with deery bear, and pigeon research. It will be used to forecast trends in squirrel DISCUSSION AND RECOMMENDATIONS populations and pigeon concentrations. h more data become available through our research, we intend to incorporate the visual classifica- The visual classification method for tion method into oak management plans for estimating acorn production for a given tree public and private lands as a tool for selecting or area is easily adapted to many oak manage- good mast-producing trees to be left during ment or research needs. With very little thinning and logging operations. direction or trainingy several observers can classify acorn production in a given geogra- phical area or in several areas using a uni- form classification system. The method works LITERATURE CITED well on all mast-producing species that were sampled. The untrained observers found the bwnsy A. A., and W. E. McQuilken. method easy to follow and applicable to their 1944. Seed production of southern areas and various species of oaks. The Appalachian Oaks. J. Forestry bz(l2) : significant correlation between the visual 913-920, Goodrum, P. D., V. H. Reid, and C. E. Boyd. Graves, W. C. 1971. Acorn yields, characteristics, 1977. !The dependence of upland game on and management criteria of oaks for oak mast production. Progress Rep., wildlife. J. Wildl. Mgmt. 35(3) ~520-532. Calif. Dept. Fish and Game. 21 p. Mammals of California Oak Habitats-Management Implications1 2/ Reginald H. Barrett- Quercus kelloqqi i

Abstract: A review of published literature on 169 terrestrial mammal species and 15 species of oaks in California established that at least 60 mammals may use oaks in some way. Thirty-eight mammals cannot or do not utilize oaks and 71 species need further study. It is proposed that ongoing land management practices affecting oaks be monitored to determine the effect of such practices on mammal popula- tions. There are no published studies clearly documenting the effect on a mammal population- of removing oaks from a site in California.

INTRODUCTION RANGE OVERLAP

Approximately 20 million acres or 20 per- On the assumption that to interact two cent of California is vegetated with some com- organisms must have overlapping distributions, bination of 6 species of oaks and related mast I compared the ranges of 15 oaks (including producing trees and shrubs. It is not sur- tan oak- (Sampson and Jesperson 1963, Griffin prising then that a major proportion of the and Critchfield 1972) with those of 169 terres- state's mammalian fauna utilizes oaks for food trial mammals including 11 introduced species and cover. (Ingles 1965, Burt and Grossenheider 1976). Of the 2,535 potential interactions (Appendix I), A number of vegetation or habitat classi- 56 percent could be considered as cases in which fication schemes has been devised for the a mammal species might interact with an oak state (Jensen 1947, Munz and Keck 1959, (table 1). Forty-four percent were cases in Cheatham and Haller 1975, Kuchler 1977, Barbour which the respective ranges did not overlap, and Major 1977), and one can find lists of consequently interactions are impossible. How- mammals that may be associated with most of ever, only 3 percent of all cases, or 5 percent these habitat types (Grinnell and Storer 1924, of the cases with some overlap, could be docu- Grinnell and Linsdale 1930, Grinnell 1933, mented from the literature as ones in which the Grinnell et al.1937, Hamilton 1939, Sumner and mammal species actually utilized the specific Dixon 1953, Brown 1957, Ingles 1965). Rather oak for food or cover. Thus 53 percent of all than repeat such lists here, I will review the cases need further study. Some additional relationships of oaks and mammals in California information may exist but not in published form by extracting from the published literature on readily available to land managers. both oaks and mammals of the state information on: 1) the overlap in the ranges of 15 oak For many mammals the literature indicated species and 169 terrestrial mammal species; use of oak in general, or documentation was and 2) the type and degree of utilization of available for use of oaks outside of California oaks by these mammals. An important result of (Van Dersal 1940, Martin et al.1951, Ingles this exercise has been the realization that for 1965). Considering this information as well as most of these 169 mammals we do not know whether that above, 60 mammals or 35 percent of the they utilize a given oak species, much less if 169 total may use oaks directly or indirectly they are strongly dependent on any of them. (table 2). This group includes the 21 mammals listed by Barrett et al.(1976). Thirty-eight mammals cannot or do not utilize oaks and 71 -'presented at the Symposium on the Ecology, species need further study according to this Management, and Utilization of California Oaks, analysis. Claremont, Calif., June 26-28, 1979. - 2~cientificnames of oak species are given in Assistant Professor, Department of Forestry Appendix 1. and Resource Management, University of Califor- nia, Berkeley, Calif. Types of Utilization eliminated, no satisfactory substitutes are Oaks provide thermal or escape cover for available. Gray squirrels and fox squirrels at least 55 California mammals (Ingles 1965, are probably the California mammals most Barrett et al.1976, Vgrner and Boss, in press). dependent on oaks for cover, but even they may For example, grey fox- and bobcat may use use trees other than oaks for den sites. dense oak chaparral as thermal cover (Grinnell Oaks provide considerable browse for many et al. 1937). small and large mammals despite the fact that most oaks have substantial amounts of tannins Table I~Interactionsand potential interactions or essential oils in their leaves (Mackie between 169 terrestrial California mammal species 1903, Van Dersal 1940). Voles, pocket gophers, and 15 California oak species, including tan oak and deer all forage on the leaves and twigs of many oak species, especially young seedlings (Martin et al.1951, Griffin 1971). Even dry leaves of the deciduous oaks may provide food POTENTIAL INTERACTIONS for deer (Leach and Hiehle 1957). As Griffin (15 x 169) has illustrated elsewhere in this symposium, the foraging of mammals may be a significant DOCUMENTED STRONG DEPENDENCE factor inhibiting growth and even survival of OF 5 MAMMALS ON OAK SPECIES oaks, particularly in the case of young trees FOR COVER OR FOOD (Mellanby 1968, Griffin 1971). The browsing DOCUMENTED UTILIZATION OF OAK domestic livestock and deer may be the most SPECIES BY 55 MA_MMALS FOR significant factor inhibiting t!ie regeneration COVER OR FOOD of oaks on California rangelands (Longhurst (EXCLUDING CASES OF STRONG et al. 1979.). DEPENDENCE) Clearly the greatest importance of oaks DOCUMENTED INTERACTION to mammals lies in their production of large, edible seeds (Martin et al.1951, Christensen OVERLAP OF MAMMAL AND OAK and Korschgen 1955, Reid and Goodrum 1957). SP3CIES RANGES BUT NO Acorns have a high caloric density (Ofcarcik DOC'JIIENTED USE OR OTHER and Burns 1971, Barrett et al.1976), and since INTERACTIONS (CASES IN they are relatively large, it is worthwhile NEED OF FURTHER STUDY) for many mammals to expend considerable energy foraging for them. At least 37 (22 percent) MINIMAL OVERLAP OF MAMMAL AND OAK SPECIES RANGES Table 2 --Utilization of oak by 169 terrestrial NO PUBLISHED DATA California mammals NO OVERLAP OF MAMMALS' RANGE < WITH OAK SPECIES' RANGE (EXCLUDING CASES BELOW) DOCUMENTED USE OF OAK FOR FOOD NO OVERLAP OF 12 MAMMALS' OR COVER, DIRECTLY OR INDIRECTL' RANGES WITH ANY OF 15 USE OF OAK FOR COVER OAK SPECIES USE OF OAK FOR FOOD NO INTERACTION USE OF OAK FOR BOTH FOOD AND COVER Raccoons may use hollow oaks as den sites or POSSIBLE BUT UNDOCUMENTED USE OF escape cover (Grinnell et a1 1937). Black bears OAK may den under the roots of large oaks (Piekielek and Burton 1975). Fallen oaks make good cover NO APPARENT USE OF OAK for deer mice and striped skunks (Ingles 1965). NO POSSIBLE USE OF OAK Of course, in most of these cases the mammal is not restricted to oaks and could substitute TOTAL similar vegetation. In this sense these species are not dependent on oaks per se. However, in of California's terrestrial mammals are known many cases where oaks are being altered or to utilize acorns. No species may be absolute- ly dependent on acorns if alternate foods are i'scientific names of mammal species are given available, but several species--especially in Appendix 1. bears, deer, pigs and squirrels--could not maintain normal densities without a fairly regular supply of acorns (Piekielek and Burton 1975, Dasmann 1971, Goodrum 1940, Barrett 1978), Over much of their range these mammals tend to relationship. fluctuate in density according to the annual crop of mast, indicating they are limited by In the analysis of oak-mammal interactions this source of food (Allen 1943, Burns et al. I also considered which oak species seemed to 1954, Uhlig 1956, Duvendeck 1962, Matschke 1964, be utilized most commonly by California mammals Barrett 1978). (Appendix I). The top 6 oak species included valley oak, interior live oak, California The utilization rate of mast crops by black oak, canyon oak, coast live oak and blue mammals has rarely been measured, but my own oak (table 3). Of these, apparently the most observations throughout California suggest likely to be reduced by human activities are that acorns other than those of tan oak rapidly valley oak, black oak and blue oak. The human disappear once they have dropped. Acorn utili- activities concerned are agricultural crop zation usually approaches 100 percent where production, timber production, and livestock deer, pigs or bear occur. Consequently, the production respectively. density, age structure, dispersion pattern, and species composition of oaks within the home range of a mammal strongly dependent on acorns Table 3. Importance of oak species to Cali- will undoubtedly influence the density and fornia mammals based on the number of docu- productivity of that species. mented interactions between each oak and 169 mammals. With this in mind, wildlife biologists have provided the following recommendation for OAK SPECIES NO. CASES PERCENT maintaining oak dependent wildlife: VALLEY OAK 1) maintain a 25 to 50 percent canopy cover in oaks, INTERIOR LIVE OAK 2) maintain a basal area of 200 to 2000 ft2 per each CALIFORNIA BLACK OAK 40 acres, CANYON OAK 3) maintain a mixture of age classes including older, more COAST LIVE OAK prolific seeders, BLUE OAK 4) disperse oaks in 0.5 to 5-acre aggregations. SCRUB OAK A mixture of deciduous and evergreen oaks is OREGON OAK preferable because this tends to provide a LEATHER OAK more even production of mast (Reynolds et al. 1970, Goodrum et al.1971, Connell et al.1973). HUCKLEBERRY OAK From the viewpoint of oak regeneration, however, ENGELMAN OAK a pulsed seed crop is desirable. The wide- spread occurrence of irregular seed production DEER OAK (SADLER OAK) is presumably a result of long coevolution of TAN OAK both oaks and their seed predators (Sudworth 1908, USFS 1948, Harper 1977). Squirrels, like TURBIN OAK (SHRUB LIVE 0AK . jays, not only eat acorns but disperse them, PALMER OAK (DUNN OAK) -0 -0 thus playing a double role in the ecology of oaks. TOTAL 67 100 Oaks may be important to some mammals by supporting oak dependent fungi, lichens, MANAGEMENT IMPLICATIONS mistletoe, galls or insect species required or Several California mammals are strongly preferred by these mammals (Van dersal 1940, dependent on oaks, many others utilize oaks to Ingles 1965). There is much more to be learned some degree, and even more species simply are about such relationships. Another indirect not known well enough to make conclusions relationship is that between the larger mammal- about their relationships with oaks. Several ian carnivores and oaks. Although carnivores important oak species, while still common now, in general are relatively catholic in their may be significantly reduced in numbers in the food preferences, some species such as the foreseeable future due to human activities and mountain lion prefer deer which may be depen- to influences of domestic and wild mammals. dent on oaks. Thus a productive oak woodland Therefore, land managers should reconsider their or shrubland should support not only a dense objectives in light of societies' future needs deer herd but a healthy lion population as well. and modify their programs accordingly. If it A comparison of mountain lion distribution in is determined that a reasonable population of California (Koford 1977) with that of oaks each native California mammal should be main- (Griffin and Critchfield 1972) suggests this tained in most portions of their pristine ranges, land managers must Brown, V. 1957. The California wildlife region. 1) determine cause and Naturegraph Publishers, Healdsburg, effect relationships Calif. 128 pp. between oaks and mammals (not to mention wildlife Burns, P. Y., D. M. Christisen and J. M. in general), and Nichols. 2) develop management pro- 1954. Acorn production in the Missouri grams to interface Ozarks. Missouri Agric. Exp. Sta. Bull. societies' needs for 611, 8 pp. crops, timber and Burt, W. H., and R. P. Grossenheider. livestock production 1976. field guide to the mammals (3rd with needs for wildlife A ed). Houghton Mifflin Co., Boston. conservation. 289 pp. Isuggestthat the primary need at this Cheatam, N. and J. R. Haller. time is to document the requirements of H., 1975. An annotated list of California California wildlife for oaks. The most prac- habitat types. Univ. California Natural tical and efficient way to do this is to moni- land and Water Reserve System. n.p. tor present oak manipulation practices as well as the proposed practices outlined above. Christisen, D. M., and L. J. Korschgen. Such a program of monitoring wildlife responses 1955. Acorn yields and wildlife usage in should be considered part of management costs Missouri. Trans. N.A. Wildl. Conf. (Leopold 1978). Monitoring must be carried 20:337-357. out with proper consideration for experimental Connell, D. L., G. Davis, and S. McCormick. design, adequate sample size and appropriate 1973. The hospitable oak, coordination criteria for measurements. I suggest the guidelines for wildlife habitats, Number 3. relative abundance of each mammal species USDA Forest Service, California Region, should be considered as a minimum. San Francisco. 11 pp. I am not aware of any published studies Dasmann, W. that have adequately determined cause and effect relationships between oaks and mammals 1971. If deer are to survive. Stackpole Books, Harrisburg, Pa. 128 pp. in California. The present is the time to begin a series of monitoring studies if there Duvendeck, J. P. is to be any time to modify existing manage- 1962. The value of acorns in the diet of, ment procedures before many alternatives are Michigan deer. J. Wildl. Manage. 26(4): foreclosed. In the meantime, managers must 371-379. be satisfied with a hodgepodge of subjective Goodrum, P. D. recommendations based on generally unsubstan- A population study of the gray tiated claims. 1940. squirrel in eastern Texas. Texas Agric. LITERATURE CITED Exp. Sta. Bull. 591. 34 pp. Allen, D. L. Goodrum, P. D., V. H. Reid, and C. E. Boyd. 1943. Michigan fox squirrel management.. 1971. Acorn yields, characteristics and Dept. of Conservation, ~ameDivision, management criteria of oaks for wildlife. Publ. 100, Lansing, Mich. 404 pp. J. Wildl. Manage. 35(3):520-532. Barbour, M. G., and J. Major (eds.). Griffin, J. R. 1977. Terrestrial vegetation of California, 1971. Oak regeneration in the upper Carmel John Wiley & Sons, N. Y. 1002 pp. Valley, California. Ecology 52(5): 862-868. Barrett, R. H. 1978. The feral hog at the Dye Creek Ranch. Griffin, J. R. and W. B. Critchfield. Hilgardia 46(9):283-355. 1972. The distribution of forest trees in California. USDA Forest Service, Res. Barrett, R. H., J. W. Menke, M. E. Fry and Paper PSW-82, 114 pp. D. Mangold. 1976. A review of the value of hardwoods to Grinnell, J. wildlife in California with recommendations 1933. Review of the recent mammal fauna of for research. A report of research per- California. Univ. Calif. Publ. Zool. formed for the Tahoe National Forest, 40(2):71-234. USDA. RO Supplement Number 8, Part A Grinnell, J., and J. M. Linsdale. under Master Agreement Number 21-395. 1930. Vertebrate natural history in a sec- 45 PP. tion of northern California, through the region. Univ. of Calif. Publ. Zool. 35:l-594. Grinnell, J., and T. I. Storer. Mellanby, K. 1924. Animal life in the Yosemite. Univ. 1968. The effects of some mammals and birds Calif. Press, Berkeley. 752 pp. on regeneration of oak. J. Appl. Ecol. 5(4) :359-366. Grinnell, J., J. S. Dixon and J. M. Linsdale. 1937. Fur-bearing mammals of California. Munz, P. A., and D. D. Keck. (2 vols.). Univ. Calif. Press, Berkeley. 1959. A California flora. University of 777 pp. California Press, Berkeley 1681 pp. Hamilton, W. J., Jr. Ofcarcik, R. P. and E. E. Burns. 1939. American mammals~theirlives, habits 1971. Chemical and physical properties of and economic relations. McGraw-Hill selected acorns. J. Food Sci. 36(4): Book Co., N. Y. 434 pp. 576-578. Harper, J. L. Piekielek, W. and T. S. Burton. 1977. Population biology of plants. 1975. A black bear population study in Academic Press, N. Y. 892 pp. northern California. Calif. Fish and Game 61(1):4-25. Ingles, L. G. 1965. Mammals of the Pacific states. Reid, V. H. and P. D. Goodrum. Stanford University Press, Stanford, CA. 1957. Factors influencing the yield and 506 pp. wildlife use of acorns. Louisiana State Univ. and A. M. College, School of Forestry. Jensen, H. A. Proc. Annual For. Symposium. 6:46-63. 1947. A system for classifying vegetation in California. Calif. Fish and Game 33(4): Reynolds, H. G., W. P. Clary, and P. F. 199-266. Ffolliott. 1970. Gambel oak for southwestern wildlife. Koford, C. B. J. Forestry 68(9):545-547. 1977. Status and welfare of the puma (Felis concolor) in California 1973-1976. Sampson, A. W. and B. S. Jesperson. Report to the Defenders of Wildlife and 1963. California range brushlands and National Audubon Society. 57 pp. browse plants. Univ. Calif. Agric. Exp. Sta. Manual 33. 162 pp. Kuchler, A. W. 1977. Map of the natural vegetation of Sudworth, G. B. California. & M. G. Barbour and J. 1908. Forest trees of the Pacific slope. Major (eds.). Terrestrial vegetation of U. S. Gov't. Printing Office, Wash., D. C. California. John Wiley & Sons, N. Y. 441 pp. 1002 pp. Sumner, L. and J. S. Dixon. Leach, H. R. and J. L. Hiehle. 1953. Birds and mammals of the Sierra Nevada; 1957. Food habits of the Tehama deer herd. with records from Sequoia and Kings Calif. Fish and Game 43(3):161-178. Canyon National Parks. Univ. Calif. Press, Berkeley. 484 pp. Leopold, A. S. 1978. Wildlife and forest practice pp. 108-120 H. P. Brokaw (ed). Uhlig, H. G. Wildlife and America. Council on Environ- 1956. The gray squirrel in West Virginia. mental Quality, USGPO, Wash. 'D. C. 532 pp. West Virginia Cons. Comm., Div. Game Mgmt., Bull. 3, 83 pp. .Longhurst, W. M., G. E. Connolly, B. M. Browning and E. 0. Garton. U.S.F.S. 1979. Food interrelationships of deer and 1948. Woody plant seed manual. USDA Misc sheep in parts of Mendocino and Lake Publ. 654. 416 pp. Counties, California. Hilgardia (in press) Van Dersal, W. R. Mackie, W. W. 1940. Utilization of oaks by birds and 1903. The value of oak leaves for forage. mammals. J. Wildl. Manage 4(4):404-428. Calif. Agric. Ext. Sta. Bull. 150. 21 pp. Verner, J. and A. Boss Martin, A. C., H. S. Zim, and A. L. Nelson. 1980. California wildlife and their habitats: 1951. American wildlife and plants - a western Sierra Nevada. Forest Serv., U.S. guide to wildlife food habits. McGraw Dep. Agric., Gen. Tech. Rep. PSW-37, 439 p. Hill Book Co., N. Y. 500 pp. Matschke, G. H. 1964. The influence of oak mast in European wild hog reproduction. Proc. Ann. Conf. S. E. Assoc. Game and Fish Comm. 18:35-39. 0) -1-1 H f-l 52 3l 1Ñ1-1 f-l a) x ha) i-3 1-1 . to 4-1

Appendix I--page 3

Hairy-winged myotis Myotis volans

California myotis Myotis californicus

Small-footed myotis Myotis subulatus

Silvery-haired bat Lasionycteris noctivagans

Western pipestrelle Pipistrellus hesperus

Big brown bat Eptesicus fuscus

Red bat Lasiurus borealis

Hoary bat Lasiurus cinnreus

Western yellow bat Lasiurus ega

Spotted bat Euderma maculata

Lump-nosed bat Plecotus townsendii

Pallid bat Antrozous pallidus

Brizilian free-tailed bat Tadarida braziliensis

Pocketed free-tailed bat Tadarida femorosacca Appendix I--Page 4

Big free-tailed bat Tadarida mol ossa

Western mastiff bat Eumops perotis

Pika Ochotona princeps

White-tailed hare Lepus townsendii

Snowshoe hare Lepus adcanus

Black-tailed hare Lepus californicus w00Is) Nuttall cottontail Sylvilaqus nuttallii Audubon cottontail Sylvilaqus audubonii Sylvilaqus bachmani

Pigmy rabbit Sylvilaqus idahoensis Mountain Aplodontia rufa

Yellow-bellied marmot Marmota flaviventris

Townsend ground squirrel Citellus tomsendii

Washington ground squirrel Citellus washinqtoni IT] Appendix I--page 6

Townsend chipmunk Eutamius townsendii

Long-eared chipmunk Eutamius quadrimaculatus

Sonoma chipmunk Eutamius sonomae

Merriam chipmunk Eutamius merriami

Western gray squirrel Sciurus griseus

Fox squirrel Sciurus niger

Douglas squirrel Tamiasci urus douglasii

Northern flying squirrel Glaucomys sabrinus

Botta pocket gopher Thomomys bottae

Northern pocket gopher Thomomys talpoides

Townsend pocket gopher Thomomys townsendii

Mountain pocket gopher Thomomys mcenticola

Mazana pocket gopher Thomomys mazana

Little pocket mouse Perognathus longimembrfs

San Joaquin pocket mouse Perognathus inornatus Appendix I--page 7

Great basin pocket mouse Perognathus parvus

Yellow-eared pocket mouse Perognathus xanthonotus

White-eared pocket mouse Perognathus alticolus

Long-tailed pocket mouse Perognathus formosus

Bailey pocket mouse Perognathus baileyi

Desert pocket mouse Perognathus penicillatus

San Diego pocket mouse Perognathus fallax

California pocket mouse Perognathus californicus

Spiny pocket mouse Peroqnathus spinatus

Heermann kangaroo rat Dipodomys heermanni

Panamint kangaroo rat Dipodomys panamintinus

Stephens kangaroo rat Dipocomys stephensi

Merriam kangaroo rat Dipodomys merriami

San Joaquin kangaroo rat Dipodomys ni tratoides

Giant kangaroo rat Dipodomys inqens

van

VAH

HX

vsn

nJ,n

van

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N3n

oan

van via svn

IMn

3m sai sw

Appendix I--page 11

Gray fox ¥ Urocyon cinere~argenteus B 1 C1

Island fox Urocyon littoralis

Black bear Euarctos ameri canus

Ringtail Bassariscus astutus

Raccoon Procyon lotor

Mart en Martes americana t4 ^0 Fisher Martes pennanti

Ermine Mustela ermines

Long-tailed weasel Mustela frenata

Mink Mustela vison

Wolverine Gulo luscus

Badger Taxidea taxus

Spotted skunk Spirogale putorius

Striped skunk Mephitis mephitis Appendix I--page 12

River otter Lutra canadensis

Mountain lion Fells concolor

Bobcat Lynx rufus

Burro Equus asinus

Horse Equus caballus

Wild boar Sus scrofa K> ^0 Elk Cervus canadensis

Mule deer Odocoileus hemionus

Pronghorn An tilocapra americana

Goat Capra hircus

Mountain sheep Orvis canadensis

Cow Bos taurus

N - No range overlap with any oaks 0- No apparent use of oaks despite range overlap mi- Minor range overlap with oak species Substantial range overlap with oak species, numerator indicates documented use as cover, denominator indicates documented use as food (1 = light use; 2 = moderate use; 3 = heavy use; A = foliage, roots, fungi; B = mast; C = indirect use) Quercus - Ecological Relationships Between Southern Mule kelloggii Deer and California Black Oak1

R. Terry Bowyer-2/ and Vernon C, Bleich-3/

Abstract: Some ecological relationships between southern mule deer (~docoileushemionus fuliginatus) and California black oakvkelloggii) are examined in the Cuyamaca Mountains, San Diego County, California. Data are presented suggesting that high deer densities adversely affect regeneration of California black oak. Mule deer consume nearly all acorns produced, and have a substantial negative impact on seedlings and sprouts which arise from fallen trees. A hypothesis is advanced to explain the probable evolution of existing deer-oak relationships. The ramifications of the continued decline of black oak stands are discussed.

STUDY AEEA

There is a vast 'body of literature dealing This study was carried out on East Mesa, with the ecology of mule deer (~docoileus Cuyamaca Rancho State Park, San Diego County, hemionus) in California (for example, see Dixon California. East Mesa is located in the 193^.opold et al. 1951, Linsdale and Tomich Cuyamaca Mountains at an elevation of 1,525 mi 1953, Longhurst et al. 1952, and Taber and and receives approximately 1,000 mm of precip- Dasmann 1958). Most researchers have noted the itation annually, including 950 mm of snow fall. importance of oaks (~uercusspp.) in the diet of Summer temperatures rarely exceed 35 C and winter these ; however, there is little quanti- lows seldom fall below - 10 C. fied information concerning the impact of deer on oaks. Moreover, the most complete studies have East Mesa encompasses 800 ha and consists dealtwith deer inhabiting the Sierra Nevada, and of extensive upland meadows interspersed with North Coast Ranges, while comparative data for thin fingers of oak and pine habitats. The deer occupying ranges in southern California are entire area is surrounded by dense, old-growth unavailable. The purpose of this paper is to chaparral. Upland meadows are situated in hydric examine and quantify specific ecological re- areas and oak and pine stands occur on rocky, lationships between southern mule deer (2.b. mesic sites. Old-growth chaparral predominates and California black oak (Q. in xeric areas. montane southern California. The meadows are characterized by annual -/.Resented at the Symposium on the Ecology grasses and f orbs , including cheatgrass (Bromus Management, and Utilization of California Oaks, tectorum) , ripgut (2. diandrus) , six-weeks Claremont, California, June 26-28, 1979. m~estucaoctof 1-d-stemmed f ilarree (Erodium cicutan-um),le mustard. (~isymbrium altissimum),rn ragweed (Ambrosia 'school of Natural Resources, The psil~stach~a),and slender-wooly 'buckwheat University of Michigan, Ann Arbor, MI 48109. lo onum racile). Deer grass (~uhlenberla Lwebrexsp . , and && c u rin wet portions of meadow habitat. ^calif ornia Department of Fish and Game, Large concentrations of tumble mustard, a valu- P.O. Box 1741, Hemet, CA 92343. able deer forage species, also are found in meadows with high soil moisture. Wild oats termined by counting the number of "bites" avail- (~vena'barbata) are common on drier sites ad- able to deer, and noting the actual number of jacent to oak and pine stands. California "bites" removed (~ackie1970). Furthermore, 200 buckwheat (~riogonumfesciculatum) occurs on the samples of black oak new growth were clipped, and periphery of meadows. Isolated patches of rose leader lengths as well as weights of new growth (M californica) and chokecherry runus us removed by deer were determined. virginiana) also are present in meadow habitat. Small islands of native perennial grasses, The abundance and timing of drop for the Agropyron trachycaulum, Bromus marginatus, black oak acorn crop was estimated using five Calamagrostis densa, Elymu: glaucus, and protected 0.22 m plots and 20 unprotected plots Sitanion hystrix, occur amid broad expanses of of the same size. Data on acorn removal b deer annual exotics, 'but only rarely. wee obtained by sampling within a 49.21 m2 ex- closure that allowed the entry of all wildlife Oak habitat is comprised predominantly of except deer. Estimates of the summer densities California black oak, 'but coast live oak of southern mule deer are 'based on direct ob- (~uercusa rifolia) and a scrub form of interior servation of 1,401 deer. Plant nomenclature is SEXE &TZEzenii fmtescens) also are according to Munz (1974). present. Squaw bush (= trilobata) and snowberry (Symphoricarpus m-minate under- story shrubs. Soft chess (Bromus-- mollis) and RESULTS ripgut occur beneath the oaks and in forest open- ings. Mexican manzanita Density estimates 'based on nearest neighbor and occasionally Jeffrey calculations suggest there are 3,500 California also occur in this habitat type. Coffeeberry black oaks on East Mesa. In oak habitat, these co ham nus calif ornica) of ten inhabits ecotonal trees occur at a mean density of 48 oaks/ha, zones between oak and meadow. while in pine habitat the mean density is 12 oaks/ha. A.pproximately 200 southern mule deer Pine habitat is composed largely of Jeffrey inhabit East Mesa. pine. Within pine stands, California black oak and coast live oak occur at low densities, the The most apparent Impact of mule deer on latter being more common. Mexican manzanita black oaks is the conspicuous browse lines on also is present. Yarrow (Achillea millef olium) , many of these trees (fig. I). Of the 93 black phlox (Leptodactylon ens),calif ornia oaks examined at the end of summer, 96 percent brome (~romusmargin?~cur beneath the exhibited signs of deer browsing. New growth on pines. the remaining 4 percent of these oaks was too high to be available to deer. Black oaks pro- Chaparral habitat is characterized by vided a mean of 289 leaders of new growth avail- chamise (A,denostoma fasciculatum) , mountain able to deer on each tree. Forty-six percent of mahogany (Cercous betuloides) , mountain all available leaders showed evidence of deer utilization. The mean length and dry weight of lilac (~eanothus re ' ' C. leucodernis and g. -palmrredbemyT' Fhamnus crocea), holly- unutilized black oak leaders were 59 nun and leaved cherry (P~USilicifolinnk-bmcted 0.31 g respectively. The mean length and dry manzanita (Arctosta h 10spinglei), and white weight of utilized leaders were 39 nun and 0.18 g. sage (Salvie Thus, deer use of new growth totaled 34 percent by length and 43 percent by dry weight. In

METHODS

Oak densities were estimated using a combi- nation of toe point (Wood et al. 1960) and near- est neighbor (cottam and Curtis 1956) sampling techniques. Results are 'based on 1,944 toe points. Diameter at breast height (DBH)and browse line height (BLH) measurements were ob- tained for 210 California black oaks from seven areas on East Mesa. DBH measurements were made at a height of 150 cm. If an oak branched below that height, only the largest branch was mea- sured. BLH was obtained by recording the lowest new growth available to deer. DBH measurements also were taken from 60 dead California black oaks. Figure 1~Californiablack oafc with a conspicuous Deer utilization of 93 black oaks was de- browse line from deer overutilization. aggregate, deer removed 20 percent (by dry wt) of all available new growth. We have calculated that 17 g (dry wt) of new growth per oak, or 58-83 kg (dry wt) of black oak in toto were eaten by deer on East Mesa during summer (~ul- ~ep). These data suggest that an average deer consumes about 3.2 g (dry wt) of black oak foliage and twigs during this period.

It is evident that black oak stems and leaves are not preferred forage. Almost all browsing by these mule deer occurs during summer when forbs (primarily tumble mustard, and red- stemmed filaree) dry out and become unpalatable-.4/ Even during summer, southern mule de r take less than 30 percent browse in their diet-.^ Yet, deer densities are sufficiently high that even OCT I NOV ' DEC this low level of utilization causes considerable damage to black oaks. In addition to removing Figure 2--Percentage of total acorns dropped by new growth from mature trees, deer adversely 10-day periods from 1 October through 10 De- affect black oak seedlings. During the spring cember, 1978 (open circles), and the cumula- of 1977, these seedlings numbered 6/ha in oak tive percentage of available acorns removed habitat. However, in areas of heavy deer use, by wildlife during this same period (open no seedlings survived past early July. Moreover, squares). our data suggest that there has been almost no seedling survival in these oak stands in the last Root rot (Armillaria sp.) is evident on 25 years. Only when acorns germinate within many older black oaks on East ~esai'! This con- dense patches of squaw bush or snowberry are they dition may predispose these decadent oaks to not substantially damaged or completely consumed severe damage during wind and ice storms. by deer. Indeed, Staley (1965) has implicated Armillaria as a secondary factor contributing to the decline Where oak and pine habitats adjoin, pine of Quercus ruber and 9. coccinia. This problem seedlings, which deer do not eat, are encroaching is less pronounced in areas of lower deer density upon traditional oak habitat. Unless the elim- on East Mesa, as downed oaks typically stump ination of black oak seedlings by deer over- sprout. However, where large numbers of deer browsing is reduced substantially, the conversion occur, these sprouts are eaten 'back and even- of oak to pine habitat appears to be a strong tually die. possibility. 2 There was no significant difference (X = Finally, mule deer influence black oak re- 2.35, p>0.05, 1 df) between the mean DBH of cruitment by consuming large numbers of acorns. living black oaks (?=63.7 cm) and the mean DBH Longtime residents of the Cuyamaca Mountains for dead ones (x=70.5 cm) throughout oak habitat. recall that the 1978 acorn crop is the largest This suggests that many black oaks may be in in memory. The majority of black oak acorns was imminent danger of being lost from the population. dropped on October 2 and 3, 1978. The number of viable acorns produced during fall is esti- The impact of deer on black oak was further mated at 6,440/oak or 309,100/ha. Yet, wild- assessed by comparing seven areas of varying life consumed over 85 percent of this mast by deer densities with the corresponding DBH and October 20 (fig. 2). All acorns had been re- BLH measurements of black oak. Significant moved from -the 20 unprotected plots by the end positive correlations were found between deer of November (fig. 2). A corns remaining within density and both DBH and BLH (fig. 3). Moreover, the exclosure suggest deer consumed 94 percent the percentage of black oaks less than 150 cm in of the acorns removed by wildlife. Thus, an height in each area was negatively correlated average deer ingested approximately 315 acorns/ with deer density, tut not significantly (fig. 3). day during fall, which would total 1.21 kg (dry No 'black oaks less than 150 cm in height were wt)/deer/day. Indeed, acorns are preferred over found in areas where summer deer densities ex- all other forage, and all deer rumen samples ceeded a total of 2.4 deer/ha (fig. 3), which examined during fall contained a large percent- includes all oak habitat on East Mesa. age of acorns'%

^unpublished data, R. Terry Bowyer, School of ~ersonalcommunication from Joe Agozino , Re- Natural resources, The University of Michigan, source Ecologist, California Department of Parks Ann Arbor, Michigan. and Recreation, San Diego, California. Figure 4--Cattle overgrazing and range deterio- ration on East Mesa in December, 1955.

Simultaneously, other environmental per- mutations were further influencing East Mesa's Figure 3--Regressions of DBH (line A , triangles), plant communities. During the late 1940's and BLH (line B, circles) and percentage of trees early 19501s, wildfires burned vast areas of less than 150 cm in height (line C, squares) chaparral adjacent to East Mesa. These fires for California black oak on total deer days created large tracts of newly available and of use per hectare (DD/H~)during summer productive deer habitat, and likely resulted in months. Regression equations for lines A, B, a population irruption of these animals. We and C are Y=2.12x +35.66, Y=4.34x +90.75, and know of no other environmental changes which Y= - 0.66~+10.05, respectively. r=Spearman might explain this increase in the deer popula- rank correlation. tion. However, burned chaparral declines rapid- ly in nutrient value, and provides suitable deer habitat for only about five years iswe well 1961, DISCUSSION Biswell & al. 1952, Dasmann 1956, and Taber and Dasmann 19587. As the chaparral once again be- We hypothesize that the current relation- came dense and the shrubs less palatable, it no ships between southern mule deer and California longer would support this massive number of black oak are linked to environmental changes deer. Thus, we hypothesize an influx of large which occurred approximately 25 years ago. Thus, numbers of deer from the chaparral to East Mesa. we have attempted to reconstruct the range his- Residents of this area recall seeing groups of tory of East Mesa through discussions with long- several hundred deer on East Mesa during this time residents and Park personnel, and by exam- period. Yet, this was considerably more deer ining Park files. than East Mesa was capable of supporting. DBH measurements suggest that the last black oak Grazing pressure by cattle on East Mesa was seedlings in oak habitat were established some- relatively light during the first half of the time prior to this period of heavy use by deer 20th century. But, in the mid-19501s, the orig- and cattle. inal objective of running Cuyamaca Rancho State Park as a cattle ranch was used to secure a The removal of cattle from East Mesa allowed lease permitting the grazing of 300 cattle on the recovery of plant species which were not pre- Park land. The majority of this livestock was ferred by deer. Most spectacular was the re- pastured on East Mesa. The impact of cattle juvenation of stands of native deer grass which overgrazing on East Mesa's plant communities was the cattle had nearly eliminated. Unfortunately, catastrophic (fig. 4). A concerted effort by the browselines on many shrubs and trees, and the Park personnel finally resulted in the removal lack of black oak seedlingswent largely unno- of cattle from East Mesa, but not before over- ticed by Park personnel. Eventually, the deer grazing had wrought dramatic changes. It is population came to a new equlibrim at perhaps likely that this damage to the range contributed half its previous size. Today, groups of even to the replacement of native perennial grasses 40 deer are observed only infrequently on East by introduced annual forbs and grasses, as well Mesa. as leading to tremendous increases in the den- sities of ground squirrels (S ermo hilus The decrease in the deer population from and perhaps pocketgophersomomys levels attained in the 1950's is probably the major reason for deer damage going unnoticed for so many years. The general opinion was Cottam, G. and J.T. Curtis. that a decreasing deer population must be well 1956. The use of distance measures in phyto- below carrying capacity, and therefore unlikely sociological research. Ecology 37 :451-460. to cause further serious range problems. But, present deer densities are more than sufficient Dasmann, R.F. to prevent black oak regeneration for most areas 1956. Fluctuations in a deer population in of East Mesa. Furthermore, the current deer California chaparral. N. Am. Wild1. Conf . population is probably substantially larger than Trans. 21 :487-&99. under pristine conditions. Oak groves on East Mesa are hundreds of years old, and it is diffi- Dixon, J. cult to explain the existence of these multiple- 1934. A. study of the life history and food aged stands without postulating lower deer den- habits of mule deer in California. Cal- sities when they were established. Indeed, ifornia Fish and Game 20: 187-273, 315-39. Amaral (1978), Peterkin and Tubbs (1965) and Stoeckler et al. (1957) demonstrated that graz- Graves, W.C. ing mammals are capable of almost completely 1977. Oaks provide habitat for 86 species of preventing regeneration of other tree species. birds, 11 mammals. Outdoor California 38 (5) :I?-18, 33. The ramifications of this decline in the black oak population are enormous. Even if Leopold, A.S., T. Riney, R. McCain and L. Tevis, management practices designed to perpetuate Jr. 1951. The Jawbne deer herd. California black oaks were implemented immediately, the Dept. Fish and Game, Game Bull. &:I-139. proliferation of multiple-aged stands could take decades. Moreover, the adverse impact of Linsdale, J.M. and P.Q. Tomich. the loss of oak habitat on the myriad of wild- 1953. A herd. of mule deer. Univ. Calif. life species that rely on mast for food and/or Press, Berkeley. 567 p. oaks for nesting and cover raves 1977) may be immense. Longhurst, W.M., A.S. Leopold and R.F. Dasmann. 1952. A survey of California deer herds and their management problems. California Dept. Fish and Game, Game Bull. 6:l-136.

We are indebted to James Geary for grant- Mackie, R.J. ing permission to conduct research in the Park, 1970. Range ecology and relations of mule and for arranging for the collecting permits. deer, elk and cattle in the Missouri Breaks, Joe Agozino freely shared his substantial knowl- Montana. Wildl. Monogr. 20:l-79. edge of range ecology and was a source of con- stant support. Mike Cox, Mike Curto, Randy Rabb, Munz, P.A. Bobby Vaughan and Steve Wexler helped with most 1974. A flora of southern California. Univ. of the vegetation sampling. This study was sup- Calif. Press, Berkeley. 1086 p. ported by the California Department of Parks and Recreation, Mr. and Mrs. Darrell V. Bowyer, Mr. Peterkin, G.F. and C.R. Tubbs. and Mrs. Walter T. Johnson, Sigma Xi, John C. 1965. Woodland regeneration in the New Forest, May Memorial Fund, and Federal A.id in Wildlife Hampshire, since 1650. J. Appl. Ecol. 2: Restoration Project ~-26-~(~alifornia) , "Wild- 159-170. life Habitat Development." Staley, J.M. 1965. Decline and mortality of red and LITERA.TUEE CITED scarlet oaks. Forest Science 11:2-17.

Amaral, M. Stoeckler, J.H., R.O. Strothmann and L.W. 1978. Black-tailed deer (Odocoileus hemionus Krefting. 1957. Effects of deer browsing columbianus) and forest reproduction: Blake in northern hardwood-hemlock type in north- Island Marine State Park, Washington. eastern Wisconsin. J . Wildl. Manage. 21 (1) : Northwest Sci. 52(3) :233-235. 75-80.

Biswell, H.H. Taber, R.D. and R.F. Dasmann. 1961. Manipulation of chamise brush for deer 1958. The black-tailed deer of the chaparral, range improvement. California Fish and Game its life history and management in the North 47(2) :125-144. Coast Range of California. Calif. Fish and Game, Game Bull. 8:l-163. . R.D. Taber and D.W. Hedrick. 1952. Management of chamise brushlands for Wood, W.E., C .W. Zumwalt and W.P. Dasmann. game in the North Coast Region of California. 1960. Range Snalysis field guide. U.S.F.S. California Fish and Game 38(4) $453-484. Div. Range and Wildl. Manage. Calif. 184 p. Trends in Oak Utilization-Fuelwood, Mast Production, Animal Use1

John W. Menke-2 /and Michael E. Fry-3/

Abstract: Trends in oak harvest levels in California were shown to be increasing rapidly. The foods produced by oaks, including acorns, leaves, twigs, and lichens,were monitored for two years in blue oak, California black oak, and interior live oak. Oaks were shown to produce quite variable mast crops, whereas crops of leaves, twigs, and lichens were rather steady in quality.

Analyses of deer rumen content showed that deer rely heavily on oak foods in spring, summer, and fall, especially using acorns, when available, from July through October.

Acorns were shown to be an important dietary supplement for sheep, allowing them to maintain their weight when supple- mented at a 20% level in the diet or more.

INTRODUCTION

California's oaks (trees and shrubs and others). Total timber harvest increas- of the genus Quercus) are a valuable ed steadily between 1947 and 1953, after resource that is largely unmanaged. They which there began a long decline. In constitute a critical habitat component for contrast, the harvest of fuelwood has many wildlife species, and, as a source of generally increased since 1959, turning good quality fuelwood, they are currently sharply upward in 1973. The average of new commercial value in California. increase in fuelwood harvest reported between 1972 and 1975 was about 38% per Fuel From Oaks year. Reported fuelwood production declin- ed in 1976 and 1977. However, current Figure 1 compares trends in total production remains about 58% above the reported timber harvest in California with average annual production reported between trends in reported fuelwood harvest. These 1959 and 1973. data are from annual California Department of Forestry notes on harvest of California As fuelwood production increased, the timber operators, 1959 to the present. It cost of fuelwood also rose. From 1944 to is assumed that fuelwood consists primarily 1966 the average price per cord of oak of hardwood species (oak, tan oak, madrone, fuelwood was $18, slightly higher if delivered to the buyer's yard (Reveal 1944; Grah 1953, 1955; Gilden 1957, 1959; 'Presented at the Symposium on the Ecology, Dost and Bemis 1966). Today, oak fuelwood Management, and Utilization of California harvested in the north coast counties and Oaks, Claremont, California, June 26-28, brought by truck to the San Francisco Bay 1979. area is often sold for as much as $100 per cord. "~ssistant Professor of Range Ecology, Department of Agronomy and Range Science, In light of the increased demand Univ. of California, Davis, CA 95616. for fuelwood and other hardwood products, new emphasis must be placed on the many ^~ildlife Biologist, Pacific Gas and significant relations between oaks and Electric Company, San Ramon, California other forest and range resources. 94583. others (1976). Similar data on oak browse was reported by Makie (1903) and Gordon and Sampson (1939). In general, acorns are eported Harvest in California 1 0 shown to be high in carbohydrates and crude fiber, and low in protein and ash. Oak browse is relatively high in both protein and carbohydrates, although the presence of Timber w> tannin may reduce protein digestibility. Q- ? In California, acorns produced by oaks P Q 0 of the foothill woodlands ripen and fall to - I0 0 the ground from late August to November, u5 thereby becoming available to wildlife and 3 I I I O^ livestock at a time when other range forage 1955 1960 1965 1970 1975 has matured and lost much of its nutritive YEAR quality. The importance of acorns as forage for wildlife and livestock lies in Figure I--Total timber production as its ability to provide large quantities of compared with fuelwood production energy when other range forage may be low in California. in caloric value.

Utilization of Oaks From 1975 to 1977, studies were by Wildlife and Livestock conducted at the University of California's Hopland Field Station, Mendocino County, to Several of California's most import- define further the ecology of oaks on ant game species consume oak browse and foothill rangelands. This paper presents acorns to an appreciable extent (Barrett the following: 1) measurements of acorn and others 1976, Dixon 1934, Fry and Vaughn production in three oak species; 2) monthly 1977, Leach and Hiehle 1957, and Stienecker nitrogen and phosphorus levels in oak 1977). Here and elsewhere in the United leaves, twigs, and acorns, plus oak-associ- States the availability of acorns has been ated lichens; and 3) data on the use of oak correlated with success or failure of forage by deer and domestic sheep. reproduction in certain wildlife species (Barrett and others 1976, Burns and others STUDY AREA 1954, Korschgen 1955, Matschke 1964). The University of California's Hopland Van Dyne and Heady (1965) studied Field Station is in southeastern Mendocino the botanical composition of sheep and County on the west slope of the Mayacmas cattle diets on mature annual range in Mountains. Elevations range from 150 to Mendocino County, California. Leaves and 915 m (500-3000 feet). The dominant acorns of blue oak (2. douglasii), black vegetation types are oak savannah with oak (2. kelloggii), valley oak (Q. lobata) an understory of introduced annual grasses, and interior live oak (Q. wislizenii) were oak woodland, and chaparral. Average found in 60% or more of the diets and annual precipitation of 890 nun (35 inches) composed 4 to 12% of the dietary weight. falls primarily as rain, between October Longhurst and others (1979) studied the and March. interrelations of deer and domestic sheep in parts of Mendocino and Lake Counties, METHODS California, where sheep were found to consume oak leaves and/or acorns nine Acorn Production and Nutrient Analysis months out of the year. The production of acorns and oak Nutritive Quality of Acorns and Oak Browse litter was monitored over two years in three oak species (blue oak, California Gordon and Sampson (1939) discussed black oak, and interior live oak). Produc- the composition of blue oak acorns relative tion was assessed with a modification of to other California foothill range vegeta- the funnel-type acorn trap described by tion. Wolf (1945) reported the moisture, Easley and Chaiken (1951) and Gysel (1957). protein, carbohydrate, fiber, and ash The modified trap consisted of a woven- content of acorns of several California oak fence-wire barrel 0.6 m (2 feet) in diameter species. Protein, fat, and tannin values and 0.9 m (3 feet) high. Steel fence posts were reported by Dasmann (1971) for four were driven into the ground and wired to species of western oak. The results of the trap to prevent disturbance by wind or those studies are summarized by Barrett and livestock. The trap was then fitted with a heavy polyethylene liner. The top of the four treatment groups. Each treatment was trap was not screened. It was felt that replicated once. All animals were fed a the depth of the trap and the presence of base ration of maintenance quality (6.15% the liner would prevent pilferage by crude protein) consisting of barley straw wildlife. Weights were placed in the (74.4%), alfalfa (21.1%), and molasses (4.5%) bottom of the trap to keep the top open in a pelleted form. In addition to the during windstorms. Small drainage holes base ration, three treatment groups receiv- prevented rain water from accumulating. ed acorns at rates of 10, 20, and 30% by weight of total feed allowed per day. The Trees were selected on the basis fourth group, a control, received only the of: 1) the species of oak desired; 2) ease base ration. Each animal received three of access from main roads; and 3) conformity pounds of feed per day. AH feed not with typical growth patterns. Traps were consumed during a 24-hour period was placed one per tree beneath the canopy removed from the troughs and weighed before without regard to distance from the bole or additional feed was issued. All animals aspect (Burns and others 1954, Christisen were weighed every seven days, and blood and Korschgen 1955). Thirty-three traps samples taken. Blood was collected from were divided evenly among the three oak the jugular vein and separated with a species. centrifuge, and the serum was decanted and frozen. Blood-chemistry parameters studied During the first acorn season, traps were blood urea nitrogen (BUN) and blood were visited and their contents collected serum cholesterol (BSC). BUN was measured every one to two weeks. By the end of by the autoanalyzer method of Skeggs (1957) December of the first year (1975) the and Marsh and others (1957). BSC was interval between collections was extended measured by the colormetric method of to four weeks and remained so throughout Zlatkis and others (1953). The trial the remainder of the study. When collected, lasted 41 days. the contents of each trap were separated and oven-dried at 77 C to a constant RESULTS AND DISCUSSION weight. The contents of each bag were sorted and weighed into four categories (1) Acorn Production acorns; 2) leaves; 3) twigs; and 4) lichens) and finely ground (30-mesh) in a Wiley Figure 2 summarizes acorn production mill. Nitrogen levels were determined by in the three species studied. In the the Kjeldahl colorimetric method. Phosphor- first year of sampling, blue oak produced us levels were determined by atomic-absorp- many more acorns than either black oak or tion spectrophotometry. interior live oak. Sound acorns of all species began falling in late August, Use of Oak by Deer and Domestic Sheep but the majority of sound acorns fell in October and November. Seed fall in all The seasonal nature of oak forage cases was lowest in March. In the first use by black-tailed deer (Odocoileus year, total blue oak acorn production was hemionus columbianus) was determined by 4.80 times that of black oak and 2.75 times postmortem analysis of rumen contents of that of interior live oak. 61 adult deer collected over a period of two and one-half years between the summer In the second year, acorn production of 1975 and fall of 1977. Percent composi- declined in all species. Production was tion (volume basis) of all food items was greatest by interior live oak, but this based upon visual estimates (Korschgen species still produced only 57% of the crop 1962). Recorded values represent the mean of the previous year. Blue oak showed percent estimate for a given forage species the greatest decline in production, being during a given month. In the raw data, all only three percent of the previous year. estimates lower than five percent were Black oak remained the poorest producer in recorded as trace (TI. In computing the both years. monthly mean values, trace values were treated as zero percent. Immature acorns of black oak and live oak began falling in May. Seeds The use of oak forage by domestic mature over two growing seasons for these sheep was studied in a pen feeding trial. two species, and the early loss of immature The objective was to assess the effect of seeds in the second year was thought to be acorns as a late-season dietary supplement. due largely to mechanical disturbance of The trial was designed as a factorial the canopy by wind and rain. Immature and experiment. Thirty-two ewe lambs of the insect-damaged acorns of blue oak, which Targhee type were divided randomly among require a single season to mature, began ACORNS Black Oak Q. ^

1074 o-o-Â Interior Lf'v Oak

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OCT. JAN. APR. JULY OCT JAN. APR. 1975 1976 1977

Figure 2~Cumulative(April-March) annual JULY SEA NOV. JAN. MAR. MAY acorn production of blue oak, interior live oak, and black oak canopies (note 1976 1977 log scale). falling in July in the second year. In all Figure 3~Seasonal nitrogen levels in cases, as in the first year, the majority the twigs, leaves, and acorns, of of sound acorns fell in October and November. three oak species.

Acorn productions were largest in deer and domestic sheep during gestation 1975, when average blue oak acorn production and lactation, and therefore are well reached 2955 kg (6515.7 lb) per hectare above the level required for simple body (2.47 acres) of canopy. The values were maintenance (Church and Pond 1974, Dasmann lowest in 1976, when average black oak 1971). The nitrogen content of the leaves acorn production measured only 36 kg (79.3 of interior live oak, an evergreen species, lb) per hectare of canopy. varied little seasonally, lacking the high spring peaks found in the deciduous Nutrient Analysis species. The highest values were recorded from spring samples, but these did not Figure 3 shows the seasonal levels exceed the one percent level. The year- of nitrogen in oak twigs, leaves, and long crude protein content of live oak acorns. These data, derived from samples leaves remained below seven percent. The taken of material falling naturally from nitrogen content of twigs and acorns varied the canopies of trees, are therefore little and remained low throughout the year of significance more with respect to in all species. nutrient cycling than as a measure of forage quality. Nevertheless, with blue Figure 4 shows the seasonal phosphorus oak and black oak, both deciduous species, content of oak leaves, twigs, and acorns. the nitrogen content of leaves in spring Phosphorus levels showed two annual peaks, does suggest a significant source of crude one in spring and one (less pronounced) in protein for ruminant animals. Nitrogen late fall. This was true for all three values of two percent and above represent species but was most prominent in the crude protein values of more than 12% (% deciduous oaks. Blue oak and black oak nitrogen x 6.25 = % crude protein). leaves showed phosphorus levels exceeding Crude protein values of this magnitude 0.1 percent throughout most of the year. approach the dietary requirement of adult Phosphorus levels exceeding 0.2 percent - - (R (R I- -t- 2 2 0 Nitrogen k' k' Lichens Phosphorus 5 0 2.0 -\ - 0.2

Figure 5--Seasonal nitrogen and phosphorus levels in lichens falling from oak tree canopies.

Phosphorus levels in oak-associated lichens were similar to those in the leaves of deciduous oaks. Spring values reached 0.2 percent. Values fluctuated over the remainder of the year but did not fall below 0.1 percent. There was no late fall peak in the phosphorus content of lichen as observed in the leaves, twigs, and acorns of oak.

Deer Use of Oak Forage

Rumen content analyses showed the use Figure 4--Seasonal phosphorus levels in the made of oak browse (leaves and twigs) twigs, leaves, and acorns of three oak in all months of the year (table 1). species. Averagemonthlyconsumption of oak browse by deer ranged from 2.5 percent (in March) to were recorded in the spring. Phosphorus 50.2 percent (in August). Year-long levels of 0.16 percent are considered consumption of oak browse averaged 21.5% adequate to meet the gestation requirements per month. The frequency of occurrence of of domestic sheep and are probably adequate oak browse in deer diets expressed on a for deer as well. The phosphorus content seasonal basis is shown in Table 2. Oak of twigs and acorns was generally lower browse occurred most frequently in summer than that for leaves in all three species. diets (100%) but was also very prominent in Live oak phosphorus levels were generally fall diets (91.6%). Although 75% of spring lower than either blue oak or black oak in and winter diets contained oak browse, the all sample categories throughout the year. actual quantities consumed were lower than The spring and late-fall phosphorus peaks in summer and fall diets. Winter diets in live oak reached only slightly more than contained up to 10% oak browse, and spring 0.1 percent. diets had up to 30%. In contrast, summer diets contained up to 85% oak browse and Figure 5 shows monthly nitrogen and fall diets up to 60%. phosphorus values derived from a pooled seasonal sample of oak-associated lichens. Acorns in quantitites of 5 percent or Genera represented in the sample include more appeared first in samples collected Ramalina, Evernia, Parmelia, and Usnea. in July. Quantities consumed and frequency The seasonal nitrogen content of lichens of occurrence increased through October and remained very stable. No perceptible then dropped sharply (table 1). Trace spring nitrogen peaks were observed. amounts were recorded in December, January, Nitrogen levels remained at about 1.5 and March samples. Acorns were absent from percent throughout the year. Lichens spring diets. The greatest quantities of thus represent a potential crude protein acorns were present in samples collected in source of about nine percent for ruminant September. Of the six samples analyzed for animals. September three contained acorns in amounts 0 en

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H

H

in CM 1-1 Table 2--Frequency of occurrence of oak browse and acorns in the seasonal diet of black-tailed deer, southeastern Mendocino County, California.

Spring Summer Fall Winter Food Item (April-June) (July-Sept. ) (0ct.-Dec.) (Jan.-Mar.)

Oak browse 75% 100% 91.6% 75%

Acorns 0% 87.5% 75% 16.6%

No. of samples 13 24 12 12

of 85, 90, and 100% by volume. October weight gain, blood urea nitrogen and serum rumen samples also contained large quanti- cholesterol values observed in 32 ewe lambs ties of acorns. fed various levels of acorns during a 41-day feeding trial. The control group, Frequency of occurrence of acorns which received only the base ration with no in October diets was loo%, with quantities acorn supplement, lost weight at the rate ranging from 10 to 20% by volume. of nearly one pound per animal per week (-0.86 lb/wk). Treatment group one (10% Figure 6 shows the average seasonal acorn supplement) also lost weight, although composition of deer diets on the Hopland less than the control group (-0.18 lb/wk). Field Station as determined through rumen Treatment group two (20% acorn supplement) content analysis. In winter, deer relied showed no weight change, while treatment upon other forms of woody browse and grass group three (30% acorn supplement) gained and showed little use of oak. Small weight at 0.32 lb/wk. quantities (5% or less) of cured leaves from deciduous oaks (black oak, valley oak, Blood urea nitrogen (BUN) and serum and blue oak) were found in the diet at cholesterol are used as indicators of this time of year, and only trace amounts condition in ruminant animals. BUN reflects of acorns. Dixon (1934) also reports the generally the amount of digestible protein use of cured black oak leaves by deer in in the animal's diet, whereas serum choles- California.

The spring diet was very diverse, with forbs constituting the largest single BLACK-TAILED DEER DIETS forage category, and nearly equal amounts SPRING SUMMER of grass, oak browse, and other woody browse were consumed. The most prominent species of oak in spring diets were chapar- browse 23% ral oak species, scrub oak dumosa), and browse (4. lichens 40% shrub live oak (9. wislizenii var. frutes- cens). Acorns were entirely lacking. lichens grass 33% gross - 5% forbs 21% t2wse In the summer, deer showed a strong 12% preference for oak browse and acorns. These two forage items together constituted about FALL WINTER 60% of the diet. Woodland oak species constituted the majority of the oak forage browse other browse component. Seven species of oak forage were found in summer diets. browse F lichens. gross Fall diets contained less oak browse fungi 3% lichens, and fewer acorns than summer diets; however, 34% fungi these two forage items combined provided 11% 36% of the dietary volume.

Sheep Feeding Trial Figure 6--Average seasonal dietary composi- tion of deer on the Hopland Field Table 3 summarizes average weekly Station. Table 3--Average weekly gain, blood urea canopy. Nutrient-content analyses showed nitrogen, and serum cholesterol values that oak leaves and twigs can supply the of sheep fed various levels of acorns dietary requirements of ruminants for during a 41-day feeding trial. protein and phosphorus in spring and fall and that oak-associated lichens supply a rather steady year-long 9% crude protein I Acorn supplement level (percent of diet) source. Response 0 10 20 30 Rumen-content analyses on 61 black- tailed deer showed that acorn quantities in Average weekly gain -0.86 -0.18 0.00 0.32 the diet of 5 percent or more appear- (lbs/wk) ed first in July, and quantities and Average blood urea frequency of occurrence increased through nitrogen (mg %) October and dropped sharply in November. Average serum cho- Oak-associated foods accounted for more lesterol (mgldl) than 60% of the deer's diet in summer and more than 36% in fall on the Hopland Field Station.

Thirty-two yearling ewe lambs were fed terol is a measure of the energy component 0, 10, 20, or 30% of their diet as acorns (lee., fats and carbohydrates). BUN values in a 41-day feeding trial simulating fall were highest in the control animals field conditions. Acorns were shown to be and declined with increasing acorn supple- a valuable dietary supplement since animals ment. Serum cholesterol values were lowest in the zero-level group lost 0.86 lb/week in the control animals and Increased while animals in the 30% acorn supplement as acorn supplement increased. The inverse group gained an average of 0.32 lb/week. relation of BUN and serum cholesterol The high-carbohydrate and solid-fat composi- was believed to be a function of the tion of the acorn, as well as high tannin low-protein, high-carbohydrate, and solid- level, was suggested as the reason for the fat composition of the acorn. In addition, inverse relation between blood urea nitro- the presence of tannin in acorns may reduce gen and serum cholesterol responses over protein digestibility. the range of acorn supplements fed.

Since acorns may make up 15-202 or ACKNOWLEDGMENTS more of the diet of black-tailed deer in summer and fall, this food resource is The authors thank Mr. Doug Updike, clearly an important one. An intake level University of California, Davis; Mr. of 20% or more in the diet appears to be William Grenfell, California Department of adequate for yearling sheep to maintain Fish and Game; and Ms. Audrey Goldsmith, their body weight while seasonal forage University of California, Berkeley, for conditions are poorest. The value of their help In deer food habits analyses; acorns in the diet is probably at least as the University of California, Davis, great in deer as it is in sheep. Department of Animal Science for BUN analysis; and special thanks to Mr. A1 SUMMARY AND CONCLUSIONS Murphy, Chuck Vaughn, and the entire staff of the Hopland Field Station for assistance Fuelwood harvest , including oaks, throughout the project- has generally increased since 1959, turning sharply upward in 1973. The average LITERATURE CITED increase in fuelwood harvest between 1972 and 1975 was about 38% per year, and with Barrett, R. He, J. W. Menke, M. E. Fry, increasing energy costs greater harvests and D. Mangold. 1976. A review of are probable. the values of hardwoods to wildlife in California with recommendations for Blue oak, California black oak, research. Final Report to USDA Forest and interior live oak production of acorns Service, Supplement No. 8, Part A, and litter (leaves, twigs, lichens) were Master Agreement No. 21-395. 45 p. monitored for two years. During a good mast year,blue oak, interior live oak, and Burns, P. Y., D. M. Christisen, and J. black oak respectively produced 2955, M. Nichols. 1954. Acorn production 1074, and 616 kg/ha of tree canopy; while in the Missouri Ozarks. Missouri during a poor year they respectively Agric. Exp. Station. Bull. 611. 8 p. produced 88, 614, and 36 kg/ha of tree Christisen, D. M., and L. J. Korschgen. Korschgen, L. J. 1962. Foods of Missouri 1955. Acorn yields and wildlife usage deer, with some management implica- in Missouri. Trans. N. Amer. Wildl. tions. J. Wildl. Manage. 62(2):164- Conf. 20:337-357. 172.

Church, D. C. and W. G. Pond. 1974. Leach, H- R., and J. L. Hiehle. 1957. Basic animal nutrition and feeding. Food habits of the Tehama deer herd. D. C. Church, Publisher. 300 p. Calif. Fish and Game 43(3):161-178.

Dasmann, W. 1971. If deer are to survive. Longhurst, W. M., G. E. Connolly, B. M. Stackpole Books. 128 p. Browning, and E. 0. Carton. 1979. Food interrelationships of deer and Dost, W. H., and W. P. Bemis. 1966. sheep in parts of Mendocino and Lake Markets for woodland products in Counties, California. Hilgardia (In California. Report No. 5, Univ. of press). Calif. Agric. Ext. Serv. Makie, W. W. 1903. The value of oak Dixon, J. S. 1934. A study of the life leaves for forage. Calif. Agric. Exp. history and food habits of mule deer Sta. Bull. 150. 21 p. in California. Calif. Fish and Game 20:181-282, 315-354. Marsh, W. He, B. Fingerhut, and E. Kirsch. 1957. Determination of urea nitrogen Easley, L. T., and L. E. Chaiken. 1951. with the diacetyl method and an An expendable seed trap. J. Forestry automatic dialyzing apparatus. Am. J. 49(9):652-653. Clin. Path. 28:681-688.

Fry, M. E., and C. E. Vaughn. 1977. Matschke, G. H. 1964. The influence of Acorn selection by band-tailed pigeons. oak mast on European wild hog reproduc- Calif. Fish and Game 63(1):59-60. tion. Proc. Ann. Conf. S. E. Assoc. Game and Fish Coma. 18:35-39. Gilden, E. E. 1957. Markets for woodland products in California. Univ. of Reveal, J. L. 1944. Markets for farm Calif. Agric. Ext. Serv. 22 p. forest products Sonoma County, Cali- fornia. Sonoma Farm Forestry Demon- Gilden, E. E. 1959. Markets for woodland stration Project, SCS/CDF. 11 p. products in California. Univ. of Calif. Agric. Ext. Serv. 30 p. Skeggs, Jr., L. T. 1957. An automatic method for colorimetric analsyis. Am. Gordon, A., and A. W. Sampson. 1939. J. Clin. Path. 28:311-322. Composition of common foothill plants as a factor in range management. Calif. Agr. Expt. Sta. Bull. 627. 95 p. Stienecker, W. E. 1977. Supplemental data on the food habits of the Western gray Grah, R. F. 1953. Markets for woodlands squirrel. Calif. Fish and Game products in the central Sierra region. 63(1):11-21. Univ. of Calif. Agric. Ext. Serv. 11 p. Van Dyne, G. M. and H. I?. Heady. 1965. Grah, R. F. 1955. Markets for woodlands Botanical composition of sheep and products in California. Univ. of cattle diets on a mature annual range. Calif. Agric. Ext. Serv. 29 p. Hilgardia 36(13):465-492.

Gysel, L. W. 1957. Acorn production on Wolf, C. B. 1945. California wild tree good, medium and poor oak sites in crops. Rancho Santa Ana Botanic southern Michigan. J. Forestry Garden, Santa Ana Canyon, Orange 55 (4) :570-574. County, Calif.

Korschgen, L. J. 1955. Fall foods of Zlatkis, A., B. Zak, and A.J. Boyle. waterfowl in Missouri. Missouri Cons. 1953. A new method for the direct Comm. R-R Ser. No. 14. determination of serum cholesterol. J. Lab. Clin. Path. 41:486-492. Livestock Utilization of California's Oak

2I 31 D. A. Duncan and W. J. Clawson- Quercus dougl asii Abstract: California's oak woodlands are important to the range livestock industry. Among interactions between oaks and livestock are effects of grazing on oak regeneration and the canopy effect of oaks on the herbaceous understory. Oak leaves and acorns vary in value according to species and other factors, as browse and food for livestock and wildlife. Key words: Oak woodlands, livestock utilization, browse, mast, range livestock

INTRODUCTION

The oak woodlands of California are an portion of the woodland zone between the important source of range forage for the treeless plains below and the higher brushy State's livestock industries, even though the and timbered belts" (Hutchison and Kotok oaks themselves play a minor role. It is 1942). It is "open and everywhere accessible estimated (Biswell 1956) that out of the to livestock...with scattered trees and 17.5 million acres which provided 80 percent bushes, and occasionally dense clumps of of the forage for domestic livestock raised shrubs. The lower ground cover, consisting on California wildland, 7.5 million acres chiefly of annual grasses and herbs...is made were woodland-grass. In addition, some up of a large number of different species." 3 million acres of woodlands are usually This description applies to much of the dominated by oaks. The total of more than California oak woodlands. 10 million acres of oak woodlands, a figure which corresponds to other estimates in the The oak woodlands have been historically literature (Wieslander and Jensen 1946), linked with California's vast livestock include the foothills, which have been industry. The early Spanish missions and referred to as "the most important range area rancheros were often located in the oak wood- within the State" (Bentley and Talbot 1951). lands of the Coast Range. After the discovery of gold in the western Sierra foothills, the The San Joaquin Experimental Range oak woodlands again supported an expanding (Madera County) includes areas typical of livestock industry to supply meat to the much of the California oak woodlands, which miners, as homesteads and ranch developments have been described as being "in the lower spread throughout the State.

REGIONAL DIFFERENCES Ñ1~resente at the Symposium on the Ecology, Management, and Utilization of California A recent treatment of California's oak Oaks, June 26-28, 1979, Claremont, California. woodlands by Griffin (1977) provides an excellent summary of knowledge of the area zl~angeScientist, Pacific Southwest Forest and its regional differences. Earlier, based and Range Experiment Station, Forest Service, on the "plant communities" of Munz and Keck U. S. Department of Agriculture, Berkeley, (1959), Griffin and Critchfield (1972) iden- Calif., stationed at Fresno, Calif. tify three oak woodland associations--foothill woodland, northern oak woodland, and southern ?'state Extension Range Specialist, Coopera- oak woodland. The northern oak woodland of tive Extension, University of California, the north Coast Ranges is characterized by Davis, Calif. the presence of the Oregon white oak (Quercus garryana), with an associated livestock industry comprised of both sheep and cattle producers operating the year around. At the herds more practical. Sheep, however, were other end of the State, the southern oak more numerous than cattle through the 1880's." woodland is characterized by the presence of Now wildhog hunting ranks second in popularity the Engelmann oak (Q. engelmannii) and coast among California's big game animals. Wild- live oak (9. agrifolia) and much of it is hog habitat is often associated with the oak not grazed. The relatively small livestock woodlands (Barrett 1978). Of a relatively industry is mainly beef cattle production small number of range goats in California including both year-round cow-calf and (Spurlock and others 1978), there are prob- seasonal stocker operations. ably more in the areas of heavy brush than in the oak woodlands. The foothill woodlands are more exten- sive and cover a vast area of the great Man's search for desirable places to Central Valley and lower elevations of the live is probably the greatest constraint on Coast Range. Blue oak (Q.douglasii) and use of the oak woodlands for livestock digger pine (Pinus sabiniana) characterize production. The climate and scenic beauty the community, with neither species ranging of the oak woodlands make them highly attrac- far beyond this particular type (Griffin and tive for human habitation. It is estimated Critchfield 1972). There are many other that Madera County has lost at least 10 per- species of oaks present, including the cent of its oak woodlands to subdivisions valley oak (Q. lobata) and interior live oak (McDougald 1979). As one travels the central (Q. wislizenii) in the north, coast live coast or the Sierra foothills, this settle- oak in the south coast, and California black ment pattern is seen repeating itself. Many oak (Q. kelloggii) at higher elevations. other land uses (military reservations, water The livestock industry in the south Coast storage, natural preserves, etc.) limit Ranges is centered around beef cattle produc- opportunities for grazing on the oak woodlands. tion involving both year-round, cow-calf, and seasonal stocker operations. The foothill Most quantitative information relating woodlands of the western Sierra foothills livestock production to the oak woodlands have historically been used on a seasonal comes from three experimental areas. The basis rather than for year-round operations. oldest is the San Joaquin Experimental Range These have been heavily used during the which was established in 1934 by the Forest winter and spring flush of growth; the cattle Service, U. S. Department of Agriculture. have been moved to the upper elevations, The University of California, Division of mostly on Federal grazing permits, or to Agricultural Sciences, operates the Hopland irrigated and dryland pastures down in the Field Station, established in 1951, and the Central Valley. Livestock production, again, Sierra Foothill Range Field Station, estab- is primarily beef cattle, with more stocker lished in 1964. Summaries of the livestock cattle present in the southern foothills research and a list of publications for the than in the north. Another distinctive type San Joaquin Experimental Range are found in of livestock operation occurs in the northern Wagnon and others (1959) and Duncan (1975), and northwestern foothills of the Sacramento and for Hopland in California Agriculture Valley. Both sheep and cattle are grazed in (Univ. Calif. Agric. Exp. Stn. 1976). this area during the winter and spring grow- ing season. The livestock are transported to southern Oregon or to the Sierra-Cascade OAKS AND LIVESTOCK mountain ranges during the summer and early fall. Oaks and livestock affect each other's welfare in many ways. For example, oaks Although cattle are now the most impor- serve as a source of shade for domestic tant, other species of livestock also use livestock during hot weather. The need for California's oak woodlands. Many of the shade is well known (McDaniel and Roark horses in California are in the oak woodlands 1956), but is difficult to quantify in terms area; they are used in livestock operations of animal production and will not be discussed and, increasingly for pleasure. In swine here. production, acorns were utilized until economic factors curtailed this type of extensive management. The Madera County Regeneration Historical Society (1968) notes, "At the time placer mining first penetrated the area, The browsing of young trees by livestock farming and ranching were already becoming has often been cited as the cause of poor or established. Hogs evidently were more impor- no oak regeneration. Exclusion of cattle in tant than cattle until barbed wire was avail- several instances for a rather long period able in the mid-18701s, making large cattle did not bring about any instant oak regeneration, however. A considerable increase herbaceous vegetation under the canopy of in digger pine and buck brush (Ceanothus oaks, especially blue oak, is readily cuneatus) was noted in the Natural Area at apparent even to the casual observer, the San Joaquin Experimental Range, which has especially in the winter and early spring. been protected from grazing and fire since The canopy effect of the various oaks of 1934, (Woolfolk and Reppert 1963), but no course varies regionally, and definitely is increase in oaks was reported. Photographs influenced by the density of the oak trees. indicated extremely little change in older A summary of work in northern California, blue oaks over periods of more than 20 years. noting that removal or reduction of blue oaks In another paper in this Symposium, Griffin increased forage production,is presented by noted exclusion of cattle on the U. C. Hastings Kay and Leonard in a paper in this Symposium. Natural History Reservation in Monterey A discussion of the effects of blue oak on County did not result in oak regeneration. forage production and nutritional quality in central California may be found in the In discussing lack of the blue oak seed- Symposium papers of Holland, and Holland and lings and young trees in Kern County, Norton, and the picture is quite different Twissleman (1967) reasoned that poor oak from areas studied by Kay and Leonard. In reproduction was probably a combination of earlier reports, Holland (1973, 1976), noted drought, livestock browsing, and the inabil- that in central California herbaceous vegeta- ity of young seedlings to compete with tion production was 40 to 100 percent greater introduced annual plants. He suggested under blue oaks than in open grasslands. prolonged drought might be the most signif- Many of the data in Holland's reports were icant of the above factors. collected on the San Joaquin Experimental Range in Madera County. In a severe drought The effect of combined sheep and deer year on the Experimental Range considerably use on oak regeneration at the Hopland more herbage was noted under the blue oak Station was discussed by Longhurst and others canopies than in open areas (Duncan and (1979). After only 5 years of protection Reppert 1960). This was confirmed over a 554 oak seedlings were counted per acre, period of seven years, and herbage growth was compared to none in the grazed area. The observed to begin earlier, and plants to stay authors conclude that "with virtually no green longer, underneath blue oaks (Duncan replacement of oak stands under the combined 1967). Also, observations and utilization weight of deer and sheep use, this important records showed that cattle preferred forage source of browse and mast will gradually be under blue oaks, both in green and dry reduced as trees mature and die." seasons. Discussion with ranchers indicate that in some other areas of the State, cattle There is no doubt that consumption of apparently do not show this preference. acorns by domestic livestock and many species of wildlife greatly reduces the number of acorns that might possibly become trees. In OAKS AS BROWSE AND MAST addition to acorn use by domestic animals, which will be discussed in more detail, acorns It is difficult to estimate the value are very important diet items for quail and of the oak species as browse. Sampson and ground squirrels (Glading and others 1940, Jespersen (1963) pointed to the difficulty Shields and Duncan 1966, Schitoskey and of identifying the oak species of primary Woodmansee 1978). browse importance because grazing animals in different situations vary in their choice of Observations of recent events on the San species. Interior live oak, California scrub Joaquin Range provide an example. A severe oak (g. dumosa), blue oak and California drought in 1977 resulted in scanty forage, black oak were seen as being the more palat- but blue oaks produced a good crop of acorns. able in most situations, however. Listed as Ground squirrels were repeatedly seen securing secondary are the Oregon white oak, canyon acorns up in the oaks in an ungrazed area; the live oak (3. chrysolepis) and huckleberry oak few acorns that reached the ground were (2. vaccinifolia). The food value of coast consumed by deer. Although the following year live oak and valley white oak is probably was wet, few seed were left for oak regenera- mainly in the acorns. Browse ratings of tion. several oak species are listed for domestic livestock and deer (table 1).

Canopy Effect on Forage An estimated 1 to 2 percent of the forage utilized by domestic livestock year after year In many foothill areas in central Calif- was obtained from all browse plants on the San ornia, the difference in amount and kind of Joaquin Experimental Range (Hutchison and Kotok I/ Table I--Summary of browse ratings of oak species for domestic livestock and deer- 21 Overall Browse Valuer"

Species (Quercus) Common Name Cattle Horses Sheep Goats Deer

-Q. agrifolia Coast live oak 5 5 4-5 4-5 3-4

-Q. chrysolepis Canyon live oak 5 5 5 5 3-4

-Q. douglasii Blue oak 4 4-5 3-4 3-4 1-2

--Q. dumosa California scrub oak 4-5 5 4 2-4 1-2

-Q. garryana Oregon white oak 4-5 5 4-5 4-5 2-3

-Q. kelloggii California black oak 2-4 4-5 3-4 3-4 1-2

--Q. lobata Valley white oak 4 5 4-5 4-5 3-4

-Q. vaccinifolia Huckleberry oak 4-5 5 4-5 4-5 3-4

Q. wislizenii var Scrub interior live oak 4 5 3-5 3-4 1-2 frutescens

Adapted from Sampson and Jespersen 1963.

2' Overall rating symbols are: 1 = excellent, 2 = good, 3 = fair, 4 = poor, 5 = useless.

1942). These species do provide some green the effect of the grazing animals on oak regen- material as a source of protein, phosphorus, eration. In general, they found deer consumed and possibly vitamin A during the summer when more acorns and relied more on browse than the herbaceous forage is mainly dry. The sheep. For a 5-year period, average acorn species most commonly browsed are the Calif- production from blue oak trees was about 13 ornia blue oak, interior live oak, and Calif- lblper treelper year, and the amount of ornia buckeye (), in that acorns by year varied from less than 2 lb to order. over 55 lblper tree. Similar wide variations in acorn production have been observed by Hopland Field Station sudies (Van Dyne workers at the San Joaquin Experimental Range. and Heady 1965) with sheep and cattle during More detailed treatments of mast production the months of July, August, and September and/or animal use are presented by Menke and indicated that more than 5 percent of the Fry, and by Graves in other Symposium papers. field-harvested forage in late summer was Barrett (1978) lists acorns as the most impor- fallen leaves and acorns of Quercus species, tant food item of feral hogs inhabiting oak which occurred in 60 percent or more of the woodland in the Sierra foothills. animal diets and composed 4 to 12 percent of the diet by weight. Sheep diets in the late On the San Joaquin Experimental Range, summer frequently contained newly-fallen acorns, cattle definitely do browse to some extent and field observations indicated that both on the oaks, and seem to prefer blue oak to cattle and sheep browsed on the low-hanging interior live oak. Observations by the senior branches and on fallen twigs and leaves. The author indicate the opposite preference is Hopland pastures had been grazed by sheep for shown by deer. Hutchison and Kotok (1942) and several years, so that there was a browse line Wagnon and others (1959) have surmised brows- at approximately 4 feet. Thus, it would appear ing of oaks and other woody vegetation results that more browse was available to cattle than in adequate provision of vitamin A even in to sheep, but on the average cattle and sheep periods when there is no green herbaceous selected about the same amount. material available.

Also reporting on work at the Hopland In the central part of the State's oak Station, Longhurst and others (1979) presented woodlands, both domestic livestock and many findings on the use of oak mast and leaves by species of wildlife consume acorns when the range herbivores, on mast production, and available. Considerable attention has been paid to acorn use by cattle because of an ab- policy of livestock management, with supple- normal congenital condition, described by Hart mental feeding that will enable the breeding and others (1932) which has existed in cattle cows to produce maximum percentage calf crops on the foothill ranges for many years. The and calves of optimum weaning weight, can be deformity is more common in the oak belt, and counted on practically to eliminate acorn usually occurs in poor feed years; the name calves. " "acorn calves" for deformed animals originated from the general impression that the deform- Reporting on early acorn-feeding trials at ities resulted from the dams' consuming excess- the San Joaquin Experimental Range, Wagnon and ive amounts of acorns during the gestation others (1942) noted marked differences in the period. In describing early acorn-feeding palatability of acorns from different live oak trials at the San Joaquin Experimental Range, trees in 1936. In August, consumption of acorns Wagnon and others (1942) stated their prelim- was 3 or 4 pounds per day, and by September, inary results indicated acorns were not the cows were eating 14 to 18 pounds per head daily. primary factor in causing "acorn calves". Consumption increased to as much as 37 pounds per day for one cow. In describing the reasons In a bulletin entitled "Acorn Calves", for a series of studies on acorns as cattle feed Hart and others (1947) reported on long-term Wagnon (1946) noted that of the various species studies and said the name was incorrect. They of trees on California rangelands oaks are concluded that examination of fifteen years of easily the most abundant, and the occasional data on acorn calves showed the condition is large crops of acorns are readily eaten by range nonhereditary, and that it is due to maternal cattle. These years of heavy mast have been of nutritional deficiency, probably occurring be- concern to many stockmen, and among the delete- tween the third and sixth month of gestation. rious effects attributed to heavy feeding on They also stated the specific deficiency or acorns are deformed calves, abortions, death deficiencies involved had not been ascertained. from impaction, and weight losses. Wagnon Since the acorn calves had occurred without the noted, however, that some cattlemen claim that dams' having access to acorns, it was evident the cattle gained weight. Usually the greatest that their ingestion was not the direct causa- weight losses occurred in cattle consuming tive agent. They concluded by stating, "Acorns acorns just prior to the onset of winter, when may be a contributing factor, however, when feed conditions were poor. He summarized the they are the main ingredient of the diet, by chemical content of acorns of several oaks preventing the formation or utilization of some (table 2), and his studies demonstrated that dietary essential. A consistent, constructive heavy ingestion of low-protein acorns when the 11 Table 2--Chemical analysis of acorns from five different species of oak-

Blue oak Live oak Black oak Valley oak Scrub oak Quercus Quercus Quercus Quercus Quercus douglasii wislizenii kelloggii lobata dumosa

Moisture

Crude Protein

Crude Fiber

Fat

Nitrogen-free Extract

Ash

Calcium

Phosphorus

Tannins

ÑIFro Wagnon 1946. forage was dry and also low in protein resulted The exclusion of grazing on many acres of in rapid weight loss. However, providing a the oak woodlands calls attention to one good protein supplement counteracted any ill effects effect of livestock utilization that is com- and promoted gains when the forage was poorest. monly overlooked. This is the reduction of When green forage was available, acorns gave the fuel build-up. Those of us who live in good results. He summed up his results as, the tinder-dry foothill areas every summer "Thus with adequate supplemental feeding, acorns shudder at the idea that the mass of herbage can become a very important feed resource instead that grows each year should not be used by of a decided liability." livestock. The problem of fuel build-up has become more noticeable in recent years as Wagnon (1960) described a series of studies increasing acreage in the oak woodlands has in which cattle were fed oak leaves in addition been sold, subdivided, or otherwise removed to acorns, to gain insight into the old question from grazing. More and more people are moving and differences of opinions among stockmen into areas where more and more fuel is avail- whether acorns were harmful or good cattle able to carry wildfires. feed. Results were not conclusive, but provid- ing a protein supplement to range cows grazing The effect of oak tree canopy has been on dry forage and eating blue oak acorns resulted treated briefly here. The decision to remove, in weight gains as he had reported earlier or thin, or leave oaks undisturbed depends on (Wagnon 1946) and cows receiving no supplement the objectives of the landowner or manager, lost weight. and the particular combination of climatic, edaphic, and vegetative features of each indi- Gordon and Sampson (1939) noted that the vidual area. Economic considerations usually crude protein content of blue oak leaves on the enter the picture. But, one thought should be San Joaquin Experimental Range varied from 30 kept in rnind~removalof an old oak tree, though percent for young leaves to 10 percent for mature perhaps not permanent, has long-lasting effects leaves. However, Sampson and Jespersen (1963) on the people and all other organisms in the assigned the blue oak a "poor" browse rating for immediate vicinity. cattle. No ill effects from feeding blue oak leaves were reported by Wagnon (1960), but he The sustained yields of the oaks themselves noted that the study animals would not eat the are covered only indirectly in this paper. Per- leaves from certain trees. Similarly, they ate haps the "whys" of little or no oak regenera- acorns from some trees readily, but not those tion in some areas have been brought into focus from others. by this Symposium. Hopefully the interchange of facts, ideas, and opinions will help us make In a comprehensive report on-the behavior better informed decisions leading to more rapid of beef cows, Wagnon (1963) noted they spent strides in gaining a realistic understanding about 18 percent of the feeding time beneath of the problem, what is causing it, and in canopies, as compared to 60 percent on open developing ways of obtaining oak regeneration slopes and 22 percent in swales. He determined where desired. that browsing was of practically no importance when green forage was abundant and of minor California's oak woodlands have been, are, importance as a source of feed the rest of the and probably will continue to be an important year. Animals spent less than 4 percent of the area in which the range livestock industry total feeding time browsing. can, under proper management, produce a consid- erable proportion of the food and fiber prod- MANAGEMENT IMPLICATIONS ucts needed to meet the demands of the popula- tion of the State. In addressing the question, Can California's oak woodlands be managed for sustained yield?, in this paper, we must look at the sustained LITERATURE CITED yield in terms of livestock utilization of the oak woodlands. There is seldom a simple answer Barrett, Reginald H. to a complex biological/sociological/economic 1978. The feral hog on the Dye Creek Ranch, question, and blanket statements can always be California. Hilgardia 46(9):283-355. picked apart. In general, however, livestock use of California oak woodlands can probably Bentley, J. R., and M. W. Talbot continue at today's levels without jeopardizing 1951. Efficient use of annual plants on the oak stands. And, with present technology, cattle ranges in the California foothills. livestock production could probably be increased. USDA Circ. 870. 52 p. Overall production of livestock in the area probably is, and will be, decreased more by loss Biswell, H. H. of grazing lands to other land uses than by over- 1956. Ecology of California grasslands. utilization by domestic livestock and wildlife. J. Range Manage. 9(1):19-24. Duncan, Don A. Hutchison, C. B., and E. I. Kotok 1967. Blue oak canopy effect on herbage 1942. The San Joaquin Experimental Range. yield on central California foothill Calif. Agric. Exp. Stn. Bull. 663. 145 p. rangeland. Abs. Papers 20th Annu. Meet. Amer. Soc. Range Manage., Seattle, Wash. Longhurst, William M., Guy E. Connolly, Bruce Feb. 14-17. p. 61-62. M. Browning, and Edward 0. Garton 1979. Food interrelationships of deer and Duncan, D. A. sheep in parts of Mendocino and Lake 1975. Comprehensive network site descrip- Counties, California. Hilgardia 47(6): tion San Joaquin. Grassl. Biome, USIIBP. 191-247. Tech. Rep. No. 296. 153 p. Natural Resource Ecol. Lab., Fort Collins, Colo. Madera County Historical Society (in coop. Madera Co. Diamond Jubilee Comm.) Duncan, D. A., and J. N. Reppert 1968. Madera: the rich, colorful and 1960. A record drought in the foothills. exciting historical heritage of that area USDA Forest Serv. Misc. Pap. 46, 6 p. now known as Madera County, California. Pacific Southwest Forest and Range Exp. Charles W. Clough (publ.). 96 p. Stn., Berkeley, Calif. McDaniel, A. H. and C. B. Roark Glading, Ben, H. H. Biswell, and C. F. Smith 1956. Performanace and grazing habits of 1940. Studies on the food of the California Hereford and Aberdeen-Angus cows and quail in 1937. J. Wildl. Manage. 4(2): calves on improved pastures as related to 128-144, illus. types of shade. J. him. Sci. 15(1):59-63.

Gordon, A., and A. W. Sampson McDougald, Neil K. 1939. Composition of common California 1979. Walt Ellis Ranch coordinated resource foothill plants as a factor in range plan. Madera Co. Coop. Ext. Serv. mimeogr. management. Calif. Agric. Exp. Stn. Bull. pap. 7 P. 627. 95p. Munz, P. A., and D. D. Keck Griffin, James R. 1959. A California flora. Univ. Calif. 1977. Oak woodland. Michael G. Barbour Press, Berkeley. 1681 p. and Jack Major, eds. Terrestrial vegeta- tion of California. John Wiley and Sons, Sampson, Arthur W., and Beryl S. Jespersen New York. p. 383-415. 1963. California range brushlands and browse plants. U. C. Man. 33. 162 p. Griffin, James R., and William B. Critchfield 1972. The distribution of forest trees in Schitoskey, Frank, Jr., and Sarah R. Woodmansee California. USDA Forest Serv. Res. Pap. 1978. Energy requirements and diet of Calif- PSW-82, 114 p. Pacific Southwest Forest ornia ground squirrel. J. Wildl. Manage. and Range Exp. Stn., Berkeley, Calif. 42(2) :373-382.

Hart, G. H., H. R. Guilbert, and H. Goss Shields, Paul W., and Don A. Duncan 1932. Seasonal changes in the chemical 1966. Fall and winter food of California composition of range forage and their quail in dry years. Calif. Fish and Game relation to nutrition of animals. U. C. 52(4):275-282. Agric. Exp. Stn. Bull. 543. 62 p.

Hart, G. H., H. R. Gullbert, K. A. Wagnon, and Spurlock, G. M., R. E. Plaister, W. L. Graves, H. Goss T. E. Adams, and R. B. Bushnell 1947. "Acorn calves." A nonhereditary 1978. Goats for California brushland. congenital deformity due to maternal Univ. Calif. Agric. Ext. Serv. Leafl. nutritional deficiency. U. C. Agric. Exp. 21044. 30 p. Stn. Bull. 699. 24 p. Twisselmann, Ernest C. Holland, V. L. 1967. A flora of Kern County, California. 1973. A study of soil and vegetation under Wasmann J. Biol. 25(1 & 2):l-395. Quercus douglasii H. & A. compared to open grassland. Ph. D. dissertation. University of California Agricultural Experi- Univ. of Calif., Berkeley. 369 p. ment Station 1976. Special Issue, Hopland Field Station, Holland, V. L. 25 years of research. Calif. Agric. 30(7): 1976. In defense of blue oaks. Fremontia 1-31. 4 (I) :3-8. Van Dyne, G. M., and H. F. Heady Wagnon, K. A., H. R. Guilbert, and G. H. Hart 1965. Botanical composition of sheep and 1959. Beef cattle investigations on the cattle diets on a mature annual range. San Joaquin Experimental Range. Calif. Hilgardia 36(13):465-492. Agric. Exp. Stn. Bull. 765. 70 p.

Wagnon, K. A. Wieslander, A. E., and Herbert A. Jensen 1946. Acorns as feed for range cattle. 1946. Forest areas, timber volumes and West. Livest. J. 25(6):92-94. vegetation types in California. Calif. For. and Range Exp. Stn., For. Sum. Release Wagnon, Kenneth A. No. 4. 66 p. 1960. Cattle feeding trials with acorns and oak leaves indicate need for supple- Woolfolk, E. J., and J. N. Reppert menting dry range forage. Calif. Agric. 1963. Then and now: changes in California 14(11):10-11. annual-type vegetation. USDA Forest Serv. Res. Note PSV-24, 9 p. Pacific South- Wagnon, Kenneth A. west Forest and Range Exp. Stn., Berkeley, 1963. Behavior of beef cows on a California Calif. range. U. C. Agric. Exp. Stn. Bull. 799. 58 p.

Wagnon, K. A., H. R. Guilbert, and G. H. Hart 1942. Experimental herd management. In The San Joaquin Experimental Range (C. B. Hutchison and E. I. Kotok eds.). U. C. Agric. Exp. Stn. Bull. 663. p. 50-82. ~uercus Effect of Blue Oak on Rangeland Forage Production douglasii in Central California1

V. L. Holland -2/

Abstract: Evidence presented in this investigation indicates that the current practice of eliminating blue oaks to increase rangeland forage is not a beneficial management practice. Forage production under blue oaks is often double that of adjacent open grassland. Furthermore, after the trees die or are killed. forage-. yields decrease to levels comparable to the less productive open grassland. The increased forage-, yield under blue oaks indicate that in order to maintain current rangeland production, existing trees should be preserved. Finally, a management plan should be implemented to assure successful future reproduction of blue oaks.

INTRODUCTION

Blue oak (Quercus douglasii H. & A.) is a increasing livestock forage. The elimination deciduous white oak (subgenus Lepidubalamus) of blue oak has occurred over thousands of endemic to California. It is the main tree hectares of land by bulldozing, burning, species on several million hectares of land and girdling, cutting (and used as cord wood), or covers an estimated 6.5 percent of the land by chemical treatment with 2, 4-D and 2, 4, 5-T area of California (Murphy and Crampton 1964). applied in axe cuts or even by aircraft spraying Restricted to the rather dry foothill woodland (Leonard and Harvey 1956, Leonard 1956, Johnson regions of California, its distribution pattern et al. 1959, Murphy and Crampton 1965, Dal Porto forms a ring around the Central Valley (Griffin and Carlson 1965, Murphy and Berry 1973). and Critchfield 1972). In contrast to these previous studies, Some range managers consider blue oak observations in many areas of California undesirable in areas used for cattle or sheep indicate clearly that forage production is grazing. One of the main reasons is that blue greater under blue oaks than in open grassland. oak reportedly reduces the quality and quantity This paper reports the results of an investiga- of forage growing beneath the trees (Murphy tion carried out in the foothills of the central and Berry 1973, Murphy and Crampton 1964, Sierra Nevada and South Coast Ranges on the Johnson et al. 1959). As a result, these effects of blue oak on rangeland species compo- investigators have advocated eliminating blue sition and forage production. Also discussed oak from foothill rangelands as a means of is the change in forage production and compo- sition after a tree dies. Nutritional quality of the forage is discussed in a companion paper (Holland and Morton 1979). Lipresented at the Symposium on Ecology, Management, and Utilization of California Oaks, Claremont, California, June 26-28, 1979. STUDY AREAS

Li~ssociateProfessor, Department of Biological Forage production under blue oak trees Sciences, California Polytechnic State Univer- (both living and dead) and in adjacent open sity, San Luis Obispo, California. grassland was measured in detail at the U.S. Forest Service San Joaquin Experimental Range (Madera County) and the U.C. Hastings Natural History Reservation (Monterey County). Forage Ahwahnee sandy loam. At the Hastings Reserva- production of two other sites was measured in tion sampling was carried out both in Tierra San Luis Obispo and Kern Counties with essen- sandy loam and Crafton sandy loam and the tially the same results (Holland 1973) but are results combined. More detailed information on not discussed in this report. climate, microclimate, soils and specific loca- The San Joaquin Experimental Range (SJER) tions of study sites are available (Holland is located near the center of the state in the 1969, 1973). Sierra Nevada foothills, 45 kilometers north of Fresno at an elevation of about 360 meters. The specific study site within the SJER was located METHODS in the natural area, a 32-hectare parcel set aside in 1934 to remain in its natural state Forage production measurements were and to serve as a check against management conducted at the end of the growing season when treatments applied in other areas of the range. plant growth had terminated and the annuals were The 772-hectare Hastings Reservation is starting to dry (early May, 1971, and mid-April, located in the Carmel Valley of the central 1972). At both sites forage production was south coast ranges at an elevation of about measured under three randomly selected, living 525 meters. It was established in 1937 and, trees, a dead tree, and in adjacent open grass- except for a 40-hectare horse pasture, has been land. There were no cattle or sheep grazing. protected from grazing since that time. The Forage was sampled at two meter intervals along reservation lies some 32 kilometers inland from transects leading out from the trunks of the the coast, at the upper end of the Carmel trees in east, west, north, and south directions Valley, between the Santa Lucia Mountains and into the open grassland. Herbaceous vegetation the Sierra de Salinas Range. The specific was clipped in a 0.1 square meter area at ground sampling sites are all within 1.6 kilometers level. Clippings were sorted as to species, north-northwest of the headquarters. dried at 10S° for 24 hours, and weighed. Both study sites have a Mediterranean For the dead trees, quadrats within a 6- warm summer climate. The mean annual precipi- meter radius of the trunk were considered tation at the SJER is about 483 millimeters "under" the tree. This distance was chosen with known extremes from about 229 to more than because it appeared from the size of the tree 813 millimeters. Hast ings Reservation's average trunk and dead branches that the canopies of annual precipitation is about 508 millimeters these trees had extended for at least this with known extremes of about 304 to 1051 milli- distance. The dead tree at Hastings Reservation meters. Of the two years of this investigation, had died in 1945. It is not known when the tree 1970-71 was slightly below average at both sites at SJER had died, but it is believed that it had while the 1971-72 season was among the driest been dead for a minimum of 30 years. since records have been kept (since 1934 at the In two years, 96 quadrats were clipped SJER and 1939 at U.C. Hastings Reservation). under living blue oak trees, and 32 within Annual precipitation in millimeters for the two 6 meters of the trunk of dead trees at both years is listed below: sites. In open grassland 64 plots were sampled 1970-71 1971-72 at SJER and 76 at Hastings Reservation. All plots from their respective areas were combined SJER 401.3 242.0 and averaged (Tables 1 and 2). Species Hastings 450.2 304.2 accounting for 1 percent or more of the total The temperature regimes at the two sites forage production are listed, whereas those are also similar except that temperatures are contributing less than 1 percent are combined slightly more moderate at Hastings Reservation as "other species". due to its proximity to the ocean. Mean tem- peratures for the two study sites in degrees centigrade are as follows: RESULTS AND DISCUSSION Mean Minimum Jan. July Annual At both SJER and at Hastings Reservation, forage production was significantly higher under SJER 0.4 16.0 7.6 both living and dead trees compared to open Hastings 1.5 10.3 5.2 grassland. At the Hastings Reservation (Table I), production was about 60 percent higher under Mean Maximum living blue oaks and about 80 percent higher Jan, July Annual "under" the dead tree compared to open grassland. Under living trees, Bromus diandrus, Avena fatua, SJER 11.8 36.8 23.8 and --Bromus mollis comprised 86.8 percent of the Hastings 15.5 31.8 22.3 total production. "Under" the dead trees Bromus Soils at both sampling sites are noncalcic -- brown soils with a sandy loam texture. The 'r 78.8 percent of forage samples collected at SJER were on roduction. In open grassland, ------Erodium botrys, Bromus mollis, Avena fatua, holding capacity of the soil. As a result, and Bromus diandrus accounted for nearly 80 soil under blue oak is higher in nitrogen, percent of the total production. phosphorus, magnesium, calcium and potassium Results obtained at SJER were similar to as well as having a higher cation exchange those of Hastings Reservation (Table 2). Total capacity and electrical conductivity compared forage production under living trees was more to soils in adjacent open grassland (Holland than 100 percent higher than that of the open 1973). All of these soil features, along with grassland. However, total forage production the moderated soil temperatures which reduce "under" the dead tree, while still about 50 frost damage in the winter and drying in the percent greater than that of open grassland, late spring, result in a microhabitat more was reduced by 42 percent compared to that favorable for plant growth and forage production. under living trees (Table 2). Bromus diandrus, Murphy and Crampton (1964) and Johnson et --Bromus mollis and Bromus arenarius accounted for al. (1959) reported that forage production is over 90 percent of the total production under less under living blue oaks; however, after the both living trees and the dead tree. Bromus trees are killed with 2, 4-D or 2, 4, 5-T, diandrus was the dominant contributing 69-76 forage yield increased to about twice that of percent of the total production. In open the open grassland. In contrast, the data grassland Bromus mollis, Erodium botrys, Bromus presented above indicate that forage production diandrus, and Festuca megalura comprised 84 is significantly higher under both living and percent of the total production. dead blue oak trees. Furthermore, once the In comparing 1970-71 to 1971-72 (which was tree dies, although there may be a short term a very dry season), it was found that forage increase in forage production, forage yield in production at Hastings Reservation was reduced the long term gradually decreases. This can be from an average of 350.9 gms/m2 in 1971 to shown clearly by comparing forage production 243.6 gms/m2 in 1972 (a reduction of 30 percent) (in gms/m2) at varying distances (0, 2, 4 and under blue oak trees. Forage production in 6 meters) from the trunks of living and dead open grassland was also reduced by about 30 trees. At SJER the results are as follows: percent (219 gms/m2 in 1971 to 152.2 gms/m2 Live Dead Percent in 1972). In both years production was over 60 percent higher under blue oak trees compared Distance Tree Tree Difference to open grassland. Om 402.2 422.7 +5.1 At SJER forage production was also reduced 2m 371.9 291.3 -27.7 in the drier 1971-72 season but on1 by about 4m 348.8 183.0 -90.6 16 percent under trees (407.3 gms/m2 in 1971, 6m 380.1 164.4 -131.2 344.3 gms/m2 in 1972) and 21 percent in open Results at Hastings Reservation are similar: grassland (209.5 gms/m2 in 1971, 166.9 .gms/m2 in 1972). In both years forage production was Live Dead Percent more than 100 percent higher under the trees. Distance Tree Tree Difference No significant changes in species composition 0 176.4 460.5 +263.0 were noted in comparing the two years at either 2 362.4 327.0 -10.8 of the study sites. 4 350.6 226.9 -54.5 In contrast to previous studies (Murphy and 6 319.7 241.4 -32.4 Crampton 1964, Johnson et al. 1959, Murphy and Berry 1973), in which forage production was These data indicate that the increased reported to be less under blue oaks than in forage yield extends to the edge of the canopy open grassland, these data clearly indicate (6 meters) of living trees and then decreases that forage yield is significantly higher under significantly and abruptly outside the canopy both living and dead blue oak trees when compared in open grassland. Open grassland forage yields to that in open grassland. This higher produc- averaged 185.7 gms/m2 at Hastings Reservation tion, although affected by a complex of environ- and 179.7 gms/m2 at SJER. By comparison, forage mental factors, seems most significantly a result production "under" dead trees was higher than of more favorable physical and chemical soil under living trees only next to the trunk and properties and a more favorable, moderated soil decreased significantly 2 to 6 meters from the temperature range (Holland 1969, 1973). trunk. This indicates that the circle of Soil physical properties under blue oak are increased forage yield under blue oaks gradually altered by deposition and decomposition of litter decreases after the tree dies (in this case (as well as decay of roots) from both blue oak about 30 years). For example, at both the 4 and and herbaceous plants. This gives the soil a 6 meter distances forage production was 32 to higher humus content which results in a more 131 percent lower "underv dead trees than under distinct aggregate structure, greater water living trees at the same distances. In fact, it holding capacity, greater friability, and lower was reduced to the point that it was not signif- bulk density (Holland 1969). Chemical soil icantly different from that of the less properties are also altered by increased humus productive open grassland (Tables 1 and 2). in the soil which is a major source of nutrient Live Dead Trees Grassland Tree Species I I 2 Table I--Average seasonal gms/m 1 pet. 1 gms/m2 1 pet. 1 gms/m2 1 pet. yield of forage growing under living and dead Avena barbata blue oak trees compared Avena fatua to that in open grass- Amsinckia intermedia land on Tierra and Bromus arenarius Crafton sandy loam, Bromus diandrus Hastings Reservation Bromus mollis (1971, 1972). *Signifi- Erodium botrys cantly higher than open Festuca megalura grassland to 0.05 level, Galium aparine using one-way analysis Hordeum leporinum of variance. (Sample Hypochoeris glabra sizes and methods given Lolium temulentum in text.) Rumex acetosella Other species

TOTAL

Live Open Dead Trees Grassland Tree Species I I Table 2--Average seasonal gmm2 pet. gms/m2 pet. gms/m- pct. 1 1 1 1 1 yield of forage growing under living and dead ~msinckiaintermedia 0 0 0 0 12.2 4.6 blue oak trees compared Bromus arenarius 26.8 7.1 10.2 5.7 11.0 4.1 to that in open grass- Bromus diandrus 75.9 34.4 285.0 19.1 183.5 69.2 land on Ahwahnee sandy Broms mollis 31.2 8.3 57.1 31.8 45.5 17.1 loam, San Joaquin Erodium botrys 13.0 3.5 41.4 23.0 3.6 1.4 Experimental Range Festuca megalura 8.6 2.3 18.2 10.1 2.1 0.8 (1971, 1972). *Signifi- Hordeum leporinum 3.7 1.0 0 0 2.6 1.0 cantly higher than open Hypochoeris glabra 0.5 0.1 6.1 3.4 2.6 1.0 grassland to 0.05 level, Other species 1.9 6.9 12.3 6.9 2.1 0.8 using one-way analysis * * of variance. (Sample TOTAL 375.7 100.1 179.7 100.0 265.2 100.0 sizes and methods given in text .)

Previous investigators have also suggested contrast to previous reports, my data indicate that species that occur under blue oak trees that when compared in terms of dry weight are less desirable than those of open grassland (gms/m2), desirable forage grasses such as and by eliminating blue oak the quality of the Avena barbata, Avena fatua and Bromus arenarius forage would improve. My results indicate that produced significantly more forage under blue even after a tree has been dead for thirty years oaks than in open grassland (Tables 1 and 2). or more, little change in species composition It is also of significance that the less occurs (Tables 1 and 2). These same results desirable Hordeum leporinum had a greater were reported by Murphy and Crampton (1964) who production "under" the dead tree than under wrote, "There is no clear trend as to whether living trees at Hastings Reservation (Table 1). removal of oak favors desirable forage grasses, A detailed report of the effect of blue oak on soft chess and slender wild oats, nor completely forage nutritional quality is presented by removes the less desirable ripgut and mouse Holland and Morton (1979). barley". Further, Duncan and Clawson (1979) have found that cattle actually prefer the CONCLUSION forage under blue oak to that of the open grass- land, indicating that perhaps those species Data presented in this report indicate found under trees are desirable. Also, in that the current practice of eliminating blue oak to increase rangeland forage production is Holland, V. L. not a beneficial management practice in the 1973. A study of vegetation and soils under central California foothills. Forage produc- blue oak compared to adjacent open grass- tion under blue oaks is significantly higher land. Ph.D. dissertation, Dept. of Botany, than that of adjacent open grassland. In U.C. Berkeley. addition, annual range plants start growing earlier and continue to grow longer at the end Holland, V. L. and Jimmy Morton of the forage season under blue oaks. These 1979. Effect of blue oak on nutritional characteristics, along with the increased quality of rangeland forage in Central nutrient content of the forage (Holland and California. In Proc., Symp. on Ecology, Morton 19791, indicate that not only should Management andutilization of California the existing blue oaks be preserved, but a Oaks, Claremont, Calif,, June 26-28, 1979. management plan should be implemented to assure successful future reproduction of blue oaks on Johnson, Walter, C. M. McKell, R. A. Evans, rangelands to maintain the long term beneficial and L. J. Berry effects of blue oak on rangeland production. 1959. Yield and quality of annual range Without such a program, there will be a gradual forage following 2, 4-D application on decline in rangeland production, in rangeland blue oak trees. Jour. Range Mngmt. soil fertility, and in an essential wildlife 12: 18-20. habitat, all of which will create serious management problems for future generations. Leonard, 0. A. 1956. Effect on blue oak (Quercus douglasii) of 2, 4-D and 2, 4, 5-T concentrates LITERATURE CITED applied to cuts in trunks. Jour. Range Mngmt, 9:15-19. Dal Porto, N. and C. Carlson 1965. Blue Oak Cordwood from Foothill Leonard, 0. A. and W. A. Harvey. Rangeland. Calif. Div. of Forestry, 1956. Chemical Control of Woody Plants in Bulletin No. 15. Sacramento. California. Calif. Agri. Exper. Station Bull. 755. Sacramento. Duncan, Don and Jim Clawson 1979. Livestock production in California Murphy, A. H. and L. J. Berry. oak woodlandso In Proc., Symp. on Ecology, 1973. Range pasture benefits through tree Management, and Utilization of California removal. California Agriculture. Oaks, Claremont, Calif., June 26-28, 1979. 27(l) :8-10. Griffin, J. R. and W. Critchfield 1972. The distribution of forest trees in Murphy, A. H,, and B. Crampton California. U.S.D.A. Forest Service 1964. Quality and yield of forage as Research Paper PSW-82. affected by chemical removal of blue oak (Quercus douglasii). Jour. Range Mngmt. Holland, V. L. 17~142-144. 1968. Canopy effect of Quercus douglasii. Unpublished M.A. Thesis, Department of Biology, Fresno State College. Effect of Blue Oak on Nutritional Quality of Rangeland Forage in Central California1

V. L. Holland and Jimmy Morton-2/

Abstract: Forage quality in open grassland and under blue oak trees (Quercus douglasii H. & A.) in central California foothills were compared. The results show that herbaceous plants growing under blue oak trees yield significantly higher levels of total nitrogen, crude protein, phosphorus, potassium and biomass. After the trees die, forage nutrient levels decline to levels found in adjacent, open grassland. The data indicate that removal of blue oaks to "improve rangeland" may lead to long-term decreases in both nutritional quality and yield of foothill rangeland forage.

INTRODUCTION and no significant differences in nutritional quality of the forage under trees treated with Removal of blue oak (Quercus douglasii 2, 4-D compared to forage under living trees H. & A.) and conversion to open grassland has (Johnson et al. 1959, and Crampton and Murphy been advocated as a method of increasing 1964). quality and quantity of forage for livestock In contrast, Holland (1973, 1979) and in foothill rangelands of California (Johnson Duncan and Clawson (1979), working in central et al. 1959, Murphy and Crampton 1964, Murphy California, found forage production to be 15 and Berry 1973). These investigators, working to over 100 percent higher under living blue in northern California, have reported that oaks than in open grassland. Herbaceous plants forage production is lower under blue oaks under blue oaks started growing earlier, than in open grassland and that cattle prefer continued to grow longer at the end of the forage of open grassland to that under blue growing season, and remained green after the oaks. Further, they report that after trees grasses and forbs in the adjacent, open grass- are killed with 2, 4-D, forage yields under land had completely dried. Further, Duncan treated trees increase to levels higher than and Clawson (1979) reported that cattle prefer those of open grassland. These same investi- the forage under blue oaks to that of open gators report increased palatability and grassland, even in the summer when forage in desirability of forage under 2, 4-D treated both areas is dry. Holland (1973, 1979) found trees just three weeks after treatment. The that death or removal of blue oak trees results reasons for this increased palatability and in a gradual decline in forage production. desirability of the forage are not clear. This decline led to forage levels comparable There was little change in species composition to those of the less productive open grassland. This study was initiated for three purposes: (1) to further examine the contra- dictory reports on the effect of blue oaks on -I/ Presented at the Symposium on the Ecology, Management, and Utilization of California Oaks, quality and quantity of foothill rangeland Claremont, California, June 26-28, 1979. forage, (2) to examine the nutritional quality of forage under blue oak compared to that of open grassland, and (3) to determine changes -2/ Associate Professor and former student, Department of Biological Sciences, California in nutritional quality of forage following Polytechnic State University, San Luis Obispo, tree death. California. METHODS

The study site selected was at U.C. calcium content (both percentage and total Hastings Reservation (Monterey County), the uptake) yielded comparable results under the same as that used by Holland (1973, 1979). trees and in open grassland. Percent total Forage from under three of the four trees nitrogen and percent crude protein yielded studied previously, including the dead tree similar results under the dead tree and open (which died in 1945), were used in this study. grassland, but much higher values under the The sites in the open grassland were also the living trees. Total uptake (gms/m2) of total same. This was done so that the species nitrogen, crude protein, and both percent and composition reported by Holland (1973, 1979) total uptake of potassium and phosphorus were could be used and compared to the forage all higher under living and dead trees than nutritional quality findings in this study. in the surrounding grassland. All forage samples were collected on Tierra These data indicate that the forage sand loam. More detailed information regarding production under blue oak trees is not only soils, climate, species composition, and site higher than in open grassland but is also location is available (Holland 1973). nutritionally superior. Similar results were Samples were collected toward the end of obtained in a recent study at the U.C. Sierra the growing season (April, 1974) when plant Foothill Range Field Station (Kay and Leonard growth had nearly terminated. Herbaceous 1979) . These investigators found forage under vegetation was clipped in 0.1 square meter living blue oak trees was higher in percent areas at ground level along a transect that nitrogen, phosphorus and sulfur than that of extended out from the base of each tree to open grassland or "underu trees killed with the open grassland. For the living trees, 2, 4-D. However, because they report lower forage was sampled at 2-meter intervals. For forage yields under living blue oak trees, the dead tree, 1-meter intervals were used. total nutrient uptake in the forage (gms/m2) This resulted in a total of nine samples from was lower than that of open grassland or under living trees, eight from the open grass- "under" dead trees. In contrast, our data land and six within five meters of the trunk show that nutrients were higher both in per- of the dead tree, which was considered "under" centage and uptake because of the higher yield the tree. The canopy of the dead tree appeared under living trees. to have at least a 5-meter radius when it was Data presented in this study indicate living. that nutrient levels in the forage decline Each bulk plant sample was dried at 60° following tree death. Note that percent for one week and then weighed to the nearest nitrogen and crude protein were lower in 0.01 gram. The samples were then ground to a forage from "under" the dead tree than in that fine powder and percentages of total ash, under the living trees but were not signifi- nitrogen, crude protein, calcium, phosphorus, cantly different from the levels of open grass- and potassium were measured. Ashing was done land. Both nutrients were significantly in a Blue-M Lab-Heat Muffle Furnace. Nitrogen higher in forage under living trees. Potassium was determined using the boric acid modifica- and phosphorus also show declines "under" the tion of the Kjeldahl procedure (Anon. 1955). dead tree (Table 1). Crude protein was calculated using the same Further evidence of decline in forage method as Johnson et al. (1959). Calcium and nutrient content following tree death can be phosphorus concentrations were determined using seen by comparing nutrient uptake at various a Norelco SP 90 atomic absorption spectro- distances from the trunks of living trees and photometer. Colorimetry was used to determine the dead tree. These data (Table 2) indicate the phosphorus concentration. Methods used that average nutrient content of forage within are based on those of Berry and Johnson (1966), two meters of dead and living tree trunks, Humphries (1956), and Johnson and Ulrich although higher next to the trunk of the dead (1959) and are described in detail by Morton tree, are comparable. However, at distances (1974). All data were analyzed statistically greater than two meters from the trunk, using one-way analysis of variance. nutrient levels in forage "under" the dead tree decrease abruptly to levels comparable to open grassland. In contrast, the higher RESULTS AND DISCUSSION nutrient content of forage under living trees remains consistently high to the edge of the Results indicate that forage growing canopy (6 meters) before declining abruptly under living or dead blue oak trees differs into open grassland. Forage growing more in several ways from forage growing in open than 2 meters from the trunk of living trees grassland (Table 1). Forage production was but still under the canopy is more than twice significantly higher under the tested trees as high in nitrogen, crude protein, phosphorus than in open grassland. Only percent ash and and potassium as that growing at comparable distances "under" the dead tree (Table 2). of increased nutrient uptake in forage under In fact, forage samples collected 4 and 5 blue oak trees gradually decreases after the meters from the dead tree trunk are about the tree dies (in this case the tree has been same in nutrient content as those of open dead for about 30 years). grassland. This indicates that the circle

LIVE TREES DEAD TREE OPEN GRASSLAND Table 1. Mean total yield, gms /m2 % ps/m2 % gps/mZ % nitrogen, crude protein, calcium, potassium and Yield phosphorus of forage Ash growing under living oak Nitrogen trees, a dead tree Crude Protein (within 5 meters of the Calcium trunk) and grassland at Potassium U.C. Hastings Reserva- Phosphorus tion, Monterey County, California. 1 -Significantly higher than open grassland (0.05 level). Not significantly different than open grassland.

NITROGEN CRUDE PROTEIN PHOSPHORUS POTASSIUM Table 2. Mean dry weight .. of total nitrogen, crude Distance Live Dead Live Dead Live Dead Live Dead protein, phosphorus and (Meters) Trees Tree Trees Tree Trees Tree Trees Tree potassium in gms/m2 found in forage at varying distances from the trunk of living and dead trees. The six- meter distance was under the tree canopy. Beyond six meters was open grassland.

The higher yield and nutrient content of nutrients into the soil. This results in a forage under blue oak is in response to a higher level of nutrients (including nitrogen, complex of microhabitat conditions created by phosphorus, and potassium), organic matter, and the trees. However, the most important feature cation exchange capacity in soil under trees involved is probably the increased level of compared to open grassland (Holland 1973). soil nutrients under trees (Holland 1973). Because soil nutrients are more readily avail- Nutrient uptake by plants is largely a function able under trees, forage production and forage of soil nutrients. As soil nutrient levels nutrient uptake are higher than those of open increase, so do the percentages of nutrients grassland. Other factors such as greater soil in the plant tissue, and consequently the total water holding capacity, moderated soil temper- uptake by the plants. Bentley et al. (1958), ature and more favorable physical soil features in a study conducted at the San Joaquin Experi- under blue oaks also play a role (Holland 1969, mental Range, reported that herbaceous plants 1979). growing in plots fertilized with a mixture of After the tree dies, the reservoir of superphosphate and sulfur were higher in crude nutrients created by blue oaks can apparently protein, calcium,and phosphorus than those be maintained for several years by the decay growing in unfertilized plots. of the dead tree and the nutrient cycles of Blue oak trees accumulate nutrients from the herbaceous plants which are higher in deep in the soil and redistribute them on the biomass and nutrients than those of open grass- surface largely beneath the canopy, primarily land. Nutrient content gradually decreases as through litter fall (although leaching of the nutrients from the dead tree are released nutrients through rainwater drip and stemflow and utilized by the forage. The loss of may be important). Litter from the trees (as continuous nutrient input from living trees well as the herbaceous plants) falls to the results in a decline of the nutrient content soil surface, is mixed into the mineral soil in the soil and forage, and a loss in via animal activity, decomposes and releases herbaceous production. Eventually this area will decline to levels comparable to the less Holland, V. L. productive open grassland. 1973. A study of vegetation and soils under In summary, forage under blue oaks has a blue oak compared to adjacent open grassland. higher productivity and is higher in nutrients Ph.D. dissertation, Dept. of Botany, than that of open grassland. Following tree U .C. Berkeley. death, nutrient content in the forage decreases and eventually reaches levels comparable to Holland, V. L. open grassland. This indicates that removal 1979. Effect of blue oak on rangeland of blue oaks to improve rangeland forage is forage production in central California. not a beneficial practice in the foothills of In Proc., Symp. on Ecology, Management, and central California. Blue oaks improve quality Utilization of California Oak, Claremont, and quantity of rangeland forage for livestock California, June 26-28, 1979. and wildlife. In addition, they provide needed shade (Duncan and Clawson 1979), moderate soil and air temperatures (Holland 1969), improve 1956. Mineral components and ash analysis. rangeland soils (Holland 1973), and provide essential wildlife habitat (Graves 1977, Shields and Duncan 1966, Schitoskey and Woodmansee 1978). Therefore, continued Johnson, C. M., and A. Ulrich removal of blue oaks from foothill rangelands 1959. Analytical methods for use in plant will have many detrimental effects. If the analysis. California Agricultural Experi- overall integrity of the foothill woodland mental Station Bulletin. 766:25-78. ecosystem is to be maintained, programs to properly manage blue oaks must be implemented. Johnson, Walter, C. M. McKell, R. A. Evans, and L. J. Berry 1959. Yield and quality of annual range LITERATURE CITED forage following 2, 4-D application on blue oak trees. Jour. Range Mngmt. 12:18-20 Anonymous 1955. Official procedure No. 2.33. Improved Kay, Burgess L. and 0. A. Leonard Kieldahl method for nitrate-free samples. 1979. Effect of blue oak removal on forage ~ssociationof Official ~~ricultural- production. In Proc., Symp. on Ecology, Chemists. 8th edition. Management and Utilization of California Oaks, Claremont, California, June 26-28, Bentley, J. R., L. R. Green and K. A. Wagnon 1979. 1958. Herbage production and grazing capa- city on annual plant range pastures fertil- Morton, Jimmy D. ized with sulfur. Jour. of Range Mngmt. 1974. Quantity and quality of herbaceous 11:133-140. vegetation under Quercus douglasii compared to open grassland. Senior Proiect.". Berry, W. L. and C. M. Johnson ~iolo~icalSciences Department, California 1966. Determination of calcium and Polytechnic State University, San Luis magnesium in plant material and culture Obispo, CA. solutions, using atomic absorption spectro- scopy. Allied Spectroscopy 20:209-211. Murphy, A. H. and L. J. Berry 1973. Range pasture benefits through tree Duncan, Don and Jim Clawson removal. California Agriculture. 1979. Livestock production in California 27(l) :8-10. Oak Woodlands. In Proc., Symp. on Ecology, Management, and Utilization of California Murphy, A. H. and B. Crampton Oaks, Claremont, California, June 26-28, 1964. Quality and yield of forage as 1979. affected by chemical removal of blue oak (Quercus douglasii). Jour. Range Mngmt. Graves, Walter C. 17:142-144. 1977. Diminishing habitat - oaks provide habitat for 86 species of birds, 11 mammals Schitoskey, Frank, Jr. and Sarah R. Woodmansee and food for some. Outdoor California 1978. Energy requirements and diet of 38: 17-18. California ground squirrel. Jour. Wildlife Mngmt. 42 (2) :373-382. Holland, V. L. 1969. Canopy effect of Quercus douglasii Shields, Paul W. and D. A. Duncan H. and A., M.A. Thesis, Department of 1966. Fall and winter food of California Biology, Fresno State College, Fresno, CA. quail in dry years. Calif. Fish and Game. 52 (4) :275-282. Effect of Blue Oak Removal on Herbaceous Foraae - Quercus Production in the North Sierra Foothills1 douglasii

2 Burgess L. Kay and 0. A. Leonard- 1

ABSTRACT: Herbaceous forage production beneath blue oak trees increased when the trees were killed. Forage yields were greater in 11 years of the 13 years following treatment,averaging 66 percent if the roots were killed and 45 percent if only the tops were killed. Percent increases were greatest in the driest years. Yields when trees and roots were killed > tops only removed > naturally occurring grassland > under live trees. When trees were killed the botanical composition improved and total ground cover increased. Uptakelacre of nitrogen, phosphorus, and sulfur increased. Bulk density of soil increased. Possible reasons for the changes are discussed.

INTRODUCTION

Studies in northern California have demonstrated that herbaceous forage production can be increased at least fourfold by removing the overstory of blue oak trees (Quercus douglasii H. & A.) (Johnson et al. 1959; Murphy and Crampton 1964). The improved forage yields have been shown to exceed those of adjacent grasslands (Murphy and Crampton 1964). The increases are explained as resulting from the improved availability of light, moisture, heat, and soil nutrients. Also suggested as increasing yields was the stimulatory effect of low concentrations of 2,4-D exuded from the tops of dying trees killed by the cut-surface method (Leonard et al. 1965). Recorded changes in species composi- tion following tree removal were listed as Figure I~Experimentalarea before trees improving forage quality (Murphy and were treated. Photographed May 15, Crampton 1964). 1964, at the peak of the herbaceous growing season. This progress report presents the first 14 years of measurements following tree PROCEDURE removal. The site chosen is a gentle north slope at the UC Sierra Foothill Range Lipresented at the Symposium on the Ecology Field Station, at an elevation of 1,750 Management, and Utilization of California ft. on the east side of the Sacramento Oaks, Claremont, California, June 26-28, Valley. Annual rainfall during the study 1979. averaged 27 inches and varied from 10 to 42 (table 1). Soil is mapped as an Auburn, 21Specialist in Range Science and Botanist Las Posas, Sobrante complex. All are red (deceased). Department of Agronomy and soils derived from greenstone with a clay- Range Science, University of California loam surface. Depth varies from shallow Davis. to moderate with some soils underlain by clay. All have stones independent of the green-stone parent material. To determine whether significant phosphorus was released by the decom- The 4-acre study area was fenced to position of roots and litter, soil phosphate exclude deer, sheep, and cows. All trees phosphorus was sampled in the top six were mapped and measured for stem diameter inches of treated and untreated areas both and canopy size. Calibration measurements 13 and 16 months after the treatments were of forage were made in May of 1963, seven applied. The bulk density of the soil was months before the tree-removal treatments sampled 14 years after treatment. were applied, to determine a logical sample size and experimental design. Forage yield Forage composition and ground cover was measured beneath 92 trees at the end of were measured by the step-point method and this growing season. Six hundred and combined to obtain ground cover by species eighty one-foot-square samples were (Evans and Love 1957). Forty points were clipped to ground level and oven-dried. taken in each treatment of each replication Samples were taken from transects on both on transects within the treatment. Measure- the north and south sides of each tree at ments began in the calibration year (1964) 1.5 ft from the stem and every 3 ft to the and continued through 1974. edge of the canopy. Two to seven samples (mean of three) were taken on each transect, Residues of 2,4-D were recovered from with two to four accounting for 88% the roots in the zone 1-2 ft from the stem of the transects. After the calibration 172 days after treatment by digging a stump period the study area was divided into from treatments A, C, D, and E. 2,4-D four replications of about one acre amounts were determined by the cotton each, and the three treatments and two bioassay method (Leonard et al. 1962) and controls (A-E listed below) were applied to compared with the amount of 2,4-D in blocks within each replication. Each rainfall previously collected beneath cut- treatment or control consisted of at least surface-treated trees (Leonard et al. 10 trees to be included as transects in the 1965). yield sampling plus all other trees within the one-fourth acre, so as to reduce Recognizing that the herbaceous cover the edge effect of the observations. of annual plants would die each season, and In addition to the live trees (untreated the accumulation of residue represents an areas left as a control) (A) and naturally unnatural condition, efforts were made to occurring openings or grasslands (B) which remove the current season's growth after it were generally less than 1000 ft2and may or had matured and the seed shattered. In the may not be influenced by the trees, there summer of 1966 the study area was pastured were three treatments applied in December by cows, and in 1970 through 1973 by sheep. 1964: sprouting stumps (C) trees sawed Animals were in the area for only a 30-day about 6 inches aboveground and removed; period in the early summer. Utilization of trees sawed and removed and the stump this dry forage was unreliable and so was painted with 2,4-D amine to prevent sprout- discontinued. In the years 1974 and later ing (D); and cut surface treatment (E) in the general area of the transect was mowed which 2,4-D amine was placed in continuous and the forage removed in September, horizontal cuts which penetrated the ensuring that an adequate seed source cambium layer (Leonard 1956). The trees in remained. (E) fell after rotting in three to five years and were removed from the site. Data were analyzed by analysis of variance each year for forage yield, Green-forage samples were taken near species and chemical composition, uptake of the end of each growing season for all N, P, and S, and soil bulk density. Mean years. The earliest harvest was on April data for all years were compared by a 22, 1970, and the latest on June 2, 1975. split-plot analysis with years as the main Sampling after the calibration year was plots. from a permanent transect on the north side of each of 10 trees or stumps in each RESULTS treatment of each replication. Square ft samples were taken 1.5 ft from the stem and Calibration every 3 ft thereafter to the edge of the canopy. The number of ft samples averaged Mapping the area showed there were 33/treatment, for a total of 533, plus 50 150 treeslacre averaging 11.1 inches in samples (10 or more/replication) used to diameter measured 24 inches aboveground. sample the grasslands (B). The samples The diameters varied from 4 to 36 inches, were oven-dried before weighing. with only one treelacre exceeding 22 inches. There were no trees smaller than four inches. Canopy radius averaged 9.2 ft (F), 65% for stumps plus 2,4-D (D), and on the south side of the trees, and 7.4 ft. 45% for the sprouting stump (C). The on the north, with the radius on the south grasslands (B) averaged 21% more than under side being equal to or greater than that on the live trees (A). Relative yields were the north for 78% of the trees. A < B < C < D or E (significant at the 0.01 level). Mean yields of D and E are Forage samplings showed no difference not different. in yield between the north and south sides or between samples closest to the stem and The relative yield difference between farthest from the stem. Therefore all live trees (A) and all tree-removal treat- future transects were located only on the ments (C-E) was greatest in the driest north side of the trees. Average yield was year, 1977, when rainfall was 63% below 1,480 lblacre. average. This indicates the importance of competition between trees and herbaceous Forage Yield forage for available moisture. Variation in yields between years was nearly twice as Tree-removal treatments were applied great under live trees (A) as on the early in the growing season (December 1964) cut-surface treatment (E). Variation was and did not result in significant changes from a minimum of 390 lblacre, in 1977, to in forage yield in the following spring a maximum of 2,170 Ib, in 1971, for the (1965). Forage yield was 1,420 lblacre) live-tree area (A), and 1,040 and 3,230 for under live trees (A) and 1,720 lblacre on the cut-surface treatment (E) in those same grasslands (B). Forage yields for all years. This is a 5.6-fold variation under subsequent years appear in Table 1. the live trees (A), compared with a 3.1- fold variation on the cut-surface treatment Yields were significantly increased in (E) and 4.2 on the grassland area (B). the first full growing season following Although the difference in yield between treatment (1966), from 960 lb under the years was highly significant, there live trees (A) to 2,170 lb under the was no significant interaction between cut-surface-treated trees (E). This 126% years and treatments. increase in forage exceeded the grassland yield (B) and was slightly higher than Botanical Composition the stump treatments (C or D), which appeared to be depressed by sawdust Total ground cover (all species) accumulated from tree removal. This for the 10-year period was greater on all depression lasted for only one year. cleared treatments (B-E) than the live trees (A), with the newly cleared areas Yield increases were significant in 11 (C-E) greater than the natural openings of the 13 years following treatment, (B), which, in turn, averaged greater than averaging 67% for the cut surface treatment the live-tree area (A) (table 2). Because

Table 1. Effect of tree treatments on forage yields for the 13 years following treatment. Precipitation data are shown at bottom of table

Year 66 67 68 69 70 71 72 73 74 75 76 77 78 Mean5S.E.

Tens of pounds/acre

A Live trees B Grassland C Sprouting stumps D Stumps + 2,4-D E Cut-surf ace

LSD -05 .O1 Table 2--Mean percent ground cover by species groups and total cover for period 1965-1974.

Grass Legume Other Total

Percent

A Live trees 22 4 9 35 B Grassland 27 4 12 43 C Sprouting stumps 31 6 15 52 D Stumps + 2,4-D 32 5 15 52 E Cut-surface 32 16 15 53

LSD 0.05 5 NS 4 6 0.01 7 NS 5 8 of the sawdust the ground cover was lower chess (Bromus mollis L.), with a small around trees removed by sawing (C and D) increase in ripgut brome (2. diandrus than on the grassland (B) (1965) and the Roth.). cut-surface (E) (1965 and 1966). In the cut-surface treatment (E) the trees were Legumes (mostly Trifolium sp.), removed as they fell in later years, so a small component of the ground cover, were there was never a reduction in ground not changed significantly by tree removal cover. (C-E). Other forbs were increased slightly. There was an fncrease in tarweed (Madia Grass cover (1965-1974) was greater gracilis Keck.) and a reduction in geranium on all clearing treatments (B-E) (average (Geranium molle L.). 32% cover) than on the live tree area (A) (22%). Most of the increase was in soft The difference between years in ground cover (total, grass, legume, and forbs) was Table 3. Percent nitrogen (N), phosphorus (P), and sulfur (S) in forage, and total uptake of these elements/acre 1966-1978ÃI /

Total Sulfate N P S

Percent in forage

A Live trees B Grassland C Sprouting stump D Stumps + 2,4-D E Cut-surface'

LSD 0.05 0.01

Average uptake (lb/acre/year)

A Live trees B Grassland C Sprouting stump D Stumps + 2,4-D E Cut-surface

LSD 0.05 0.01

'~xceptPO P, which is for 1967-1977 only. 4 highly significant (0.01 level), as was the ground cover under the trees was identical interaction between years and treatments. in this and the study by Johnson et al. (1959). Rainfall was intermediate, 27 Chemical Composition inches, compared with 20-25 and 37 inches. The elevation was much higher (1,750 ft vs. Percent in the forage of nitrogen, 500 and 900 ft). The growing season was phosphorus (total and phosphate), and probably longer in this study because of sulfur was greatest beneath live trees (A) the higher elevation and north slope. The (table 3). There was generally a maturity growing seasons would start at the same difference between open (B-E) and shade- time but maturity may be 15-20 days later grown plants at the time of harvest, than at 500-900 ft at this field station. which would account for the difference. In determining the potential of a Total uptakelacre of all elements tree-covered area for increased forage measured was significantly increased production from tree removal it may be best by all tree removal treatments (C-E), but to compare yields under the live trees with did not differ between live trees (A) and open areas. This and other studies in natural openings (B) . northern California indicate that the increased yield can be expected to equal There was a highly significant differ- or exceed yields in the grassland areas. ence between years in percent of all Murphy and Crampton (1964) indicate about a measured elements as well as a significant threefold difference between a tree and interaction between years and treatments grassland area before the treatment that for the percent nitrogen and sulfur. gave 400-650% increases when the trees were killed. By comparison, the study reported Soil Phosphorus here shows only a 17% difference between grasslands and tree-covered areas, and a Available phosphorus, extracted from 67% increase from removing trees. Not all the top 6 inches of soil by 0.5 molar areas will indicate increased yields. bicarbonate solution at pH 8.5 and expressed Holland (1973) found that production under as ppm phosphorus in the soil, ranged from blue oak trees in Madera Co., some 170 12.6 to 18.0 in January 1966 (13 months miles south of this study area, was 60 to after tree removal) and 5.9 to 9.4 in April over 100% higher than that of an adjacent 1966. There was no significant difference open grassland. between treatments (A-E) at either date. Shade (light intensity) cannot be Bulk Density of Soil completely ruled out as a factor in reduced forage production beneath trees. However, Measured 14 years after treatment, the shade of the dead trees in the early soil collected from beneath live trees years after cut-surface treatment (E) did (A) was significantly lower (0.05 level) not reduce yields below those from removing in density (1.074) than soil from natural the tree and treating the stump (C). openings (B) (1.183) or on cut-surface- Leonard et al. (1965) suggest that the treated areas (E) (1.179). Measurements leaves of blue oak do not develop until were made near field capacity, and there after most of the herbaceous growth has was no difference in water-holding capacity. occurred, thus eliminating shade as a The difference was noticeable in walking on factor. the area, with the tree-covered area being relatively spongy. Competition with the living tree, perhaps for moisture and nutrients, DISCUSSION AND CONCLUSIONS may be a factor, as evidenced by the difference in yield between treated Forage yield increases were consistent stumps (D) (roots killed) and allowing and long-lasting. Measurements will stumps to sprout (C) (Table 1). Also, continue in an effort to determine just how production was greater beneath standing long they will persist. The increases to dead trees (E in early years) than standing date are much less than previously reported, live trees (A). however (Johnston et al. 1959; Murphy and Crampton 1964). The trees in this study The increase in yield in excess of were larger than those in the above studies grassland areas (B) following tree treat- (11.1 in., compared with 7.5 and 8.0 in.). ment (C-E) may be due in part to nutrients The number per acre was intermediate--150, released by decomposing roots. Forage compared with 115 and 225. Herbaceous increases were greater where roots were killed (D or E) than where roots were not killed (C). as much value as the increase in total forage production that results from tree Total uptake of nutrients (nitrogen, removal. phosphorus, and sulfur) was greatest in all tree-removal treatments (C-E), possibly REFERENCES indicating greater availability. Soil phosphate measurements apparently were not Evans, R. A., and R. M. Love. precise enough to detect increases. 1957. The step-point method of However, these samples were only from the sampling--a practical tool in top six inches and may have failed to range research. Jour. Range measure the contribution of the tree roots, Manage. 10:208-212. which are abundant at 8-20 inches (Leonard et al., 1965). The lowest levels of soil Holland, V. L. phoshorus measured are suggestive of a 1973. A study of vegetation and possible deficiency. soils under blue oak compared to adjacent open grassland. Ph.D. The standing live trees contributed to dissertation, Dept. of Botany, reduced soil bulk density, and their UC Berkeley. removal resulted in increased density even with minimal livestock use. Animals were Johnson, Walter, C. M. McKell, R. A. present only a few times, and then only in Evans, and L. J. Berry. the dry summer months, so their influence 1959. Yield and quality of annual on bulk density should have been minimal. range forage following 2,4-D application on blue oak trees. A stimulatory effect of low concentra- Jour. Range Manage. 12:18-20. tions of 2,4-D seems unlikely. Leonard et al. (1965) measured 2,4-D in rainfall under Leonard, 0. A. cut-surface-treated trees and found small 1956. amounts in the first year after treatment, Effect on blue oak (Quercus but none after one year. Roots measured in douglasii) of 2,4-D and 2.4.5-T this study 1-2 ft from the stump contained concentrates applied to cuts 0.040 ppm and 0.011 ppm from the cut-surface in trunks. Jour. Range Manage. (E) and 2,4-D-treated stump treatments (D), 9 :15-19. respectively, measured 172 days after treatment. The 2,4-D may have increas- Leonard, 0. A., R. J. Weaver, and B. ed the rate of decomposition and resulting L. Kay. availability of plant nutrients. 1962. Bioassay method for determin- ing 2,4-D in plant tissues. The changes in botanical composition Weeds 10:20-22. following tree removal generally improved forage quality. Of greatest importance was Leonard, 0. A., C. E. Carlson, and D. the increase in soft chess. The composi- E. Bayer. tional changes might have been quite 1965. Studies on the cut-surface different if the area had been grazed in method. 11. Control of blue oak winter and spring, as is the common practice. and madrone. Weeds 13(4): An increase in legumes and other forbs 352-356. could be expected if grazed. Murphy, A. H., and B. Crampton. The lesser variation between years in 1964. Quality and yield of forage forage production on grassland or tree- as affected by chemical removal of removal treatments than on tree-covered blue oak (Quercus douglasii). areas is of great value to a livestock Jour. Range Manage. 17:142-144. operator. The reduced variation may be of Oak Trees and Livestock-Management Options1

Alfred H. Murphy-2/

Abstract: In California, approximately 10 million acres of woodland-grass type offer opportunities for modifi- cation of the tree cover to improve their use in livestock management. Research projects on oak-grasslands at the Hop- land Field Station, over the past decade, have provided in- formation for the improvement of quality and quantity of range forage on mixed oak-grass vegetation, impacts of tree removal on water productivity, and the expectation of soil movement on various geologic formations by removal of tree cover.

INTRODUCTION by Murphy and Crampton (1964) indicated that the shade-tolerant forb species were elimin- Most rangeland livestock operations are ated by killing the oaks, while several of confronted with the economic fact of obtain- the better forage grasses increased. In a ing the best returns from grazing lands. watershed conversion study from oaks to her- While yield and composition of forage is in- baceous cover, Pitt (1975) reported both in- fluenced by weather, soil, water, exposure, creases and decreases in percentage composi- and plant cover, man can encourage those tion of both desirable and less desirable for- plants that best meet his production needs. age species. On many acres of California rangelands, oak Removal of trees and brush from range- trees have a major impact on the productivity lands significantly influenced the water of the forage system. yield pattern of treated areas. An exten- Of California's 68 million acres of wild- sive review of watershed management studies lands, Love (1967) estimates that 10 million by Burqy and Papazafiriou (1971) revealed acres are in the woodland-grass type; he in- a preponderance of evidence and virtually fers that 10 percent could be improved in unanimous conclusion that the reduction of value by 12 times, and 50 percent by three vegetation density ....will result in increased times, while the remaining 40 percent would total water yield. The replacement of deeply have limited improvement potential. In a rooted plants with shallow-rooted grasses and grazing study with sheep at the Hopland Field forbs make greater amounts of water available; Station, Murphy and Berry (1973) stated that Burqy (1967) attributes this to reduced trans- the removal of oak trees increased the value piration and smaller interception loss. of livestock products by five-fold. In the The aim of this paper is to point out foothills of the Sacramento Valley, Bell some of the facts of tree management devel- (1960) reported a five-fold increase in dry oped at the Hopland Field Station and their feed and a four-fold increase in forage pro- influence on vegetation, livestock, and water. tein production per acre where blue oaks were These facts can be useful in decision making killed by the cut-surface treatment. Plant for landowners and managers who use the land species composition study under treated oaks for livestock production and where oaks are part of the rangeland plant community. -I/ Presented at the Symposium on the Ecology, Management, and Utilization of California Oaks, Claremont, California, June 26-28, 1979. THE HOPLAMD FIELD STATION 2/ Superintendent, Hopland Field Station, Uni- - The Hopland research station of the Uni- versity of California, 4070 University Road, Hopland, California 95449. versity of California consists of 5,358 acres (2170 ha), located in Mendocino County's a reduction of 1,000 pounds (1120 kg) DW due central coastal mountains. The greater part to tree competition. Composition of vegeta- of the land area is represented by vegeta- tion in the two types were as follows: tional types that include oak trees. The woodland-grass type amounts to 36 percent of Vegetative Open Under Tree the area which is characterized by a scattered Type Ground Canopy overstory of blue oaks (~uULCJLLS~dolLgiCL&.ii H. & A. ), valley oaks (2. Lob&% ~ee),and in------percent cover------terior live oaks (2. ~hfiZHn^iA. DC. ) , and Annual grass 64 53 an understory of grasses and forbs. In con- Forbs 23 36 trast, dense woodland covers approximately Legumes 13 7 22 percent of the Station area and consists Perennial grass -- 4 of the aforementioned oaks plus black oaks - (2. k&oggG Newb. ) Oregon oaks (2. gOAAY- Under the tree canopy such grasses as ripgut am7 ~ougl.),and several other oaks of lim- (B^o~~A'UJQ-Ldm Roth. 1 and dogtail (Ct/fln~~ku~ ited abundance. In part of this dense wood- CC/U.~L. ) were dominant; they are con- land are two prominent hardwoods--madrone sidered as poor quality forage plants. (&Lbu^tlU mWZh.ii Pursh.) and California bay (UmboILSLuJLaAA'0.c~oknica H. & A. )--with very little herbaceous vegetation found beneath HYDROLOGIC STUDY their dense canopy. Other vegetative areas of the Station include 23 percent in open Perhaps in terms of major impact on land grass, 15 percent in brush, and the balance areas, the hydrologic study of watershed man- of 4 percent in minor categories (Heady 1961). agement at the Hopland Field Station gives Climate is characterized as cool, mean the most comprehensive view of the effect of temperature 43O F (6.1' C), and wet from No- tree removal. Over a 25-year period,inten- vember to April, with annual precipitation of sive management studies relating to vegeta- about 37 inches (940mm); the balance of the tion, grazing use, soil, and water have been year is usually warm, mean temperature 65.4' observed. F (18.6' C), and dry with limited rainfall. Two watershed areas--210 and 60 acres Soil varies in depth to 6 feet (1.8m), on (85 and 24 ha) --had water yield, runoff, benches but mostly are 1 to 3 feet (.3 to .9m) erosion,' forage, and livestock data collected on moderate to steep slopes and include 18 during three testing periods~pre-treatment, different series (Josephine, Laughlin, Los treatment, and post-treatment. The pre-treat- gates, and Sutherlin are most prevalent), lo- ment period represented the watershed con- cated in an elevation range of 500 (153m) to dition before any changes were applied. The 3,000 (915m) feet. Generally the soils decrease treatment period involved reduction of trees in depth with increased elevation and this and shrubs by cutting, chemical treatment, depth often determines the character of the and fire followed by seeding of grasses and woody plant population (Gowans 1958). legumes. The final phase was evaluation of Generally the herbaceous vegetation will treatments by the collection of hydrologic yield an average of 2,000 pounds per acre data, sheep grazing use, and forage production. (2240 kg/ha) dry weight (DW) but yearly fluc- The conversion process in the 60-acre nations vary from 1,300 to 3,600 pounds per Watershed I was rapid, by falling the trees, acre (1455 to 4032 kg) DW depending on cli- burning the debris, and seeding grasses and matic variable. Most all of the plants mak- clovers during the period of June to September, ing up the herbaceous cover are annual grasses, whereas in the 210-acre Watershed I1 the trees clovers, and other forbs, with perennial plants were killed by applying 2,4-D mine by the cut- having a minor role. surface method around the tree trunks. Five years after the tree treatment, a summer con- trolled burn was used to remove dead, woody STUDIES AT THE HOPLAND FIELD STATION debris followed by seeding with grasses and legumes. For a 20-year period (1958-1978), annual forage yield determinations have been collected from pastures with open ground and under tree Forage Production canopy. These pastures represent the low to mid-elevation areas, 600 to 1,200 feet (183m Sheep were used to measure the effect on to 366m), with soil depth of 1 to 3 feet (.3 forage,with animal unit months (AUM) as the to .9rn), slopes up to 50 percent, and mostly measure of production; before, during, and south to west exposure; yield averages of the after the tree treatments. In both watershed open ground were 2,400 pounds per acre (2688 treatment methods, the increases were similar; kg/ha) DW, whereas the yields under an oak before treatment the average grazing capacity tree canopy were 1,400 pounds (1568 kg) DW or was 50 AUM, following conversion from woody cover to herbaceous cover it increased to 300 It was also observed that if the soil was sat- AUM. The major increase in feed production urated, earth tremor shocks caused lique- occurred on areas where tree canopy was dense faction to occur (Burgy <^t al. 1971). These and little herbaceous cover was present; ap- erosion conditions did not develop in Water- proximately half of the acreage was classed shed I after tree removal, as sub-surface as dense. The improved forage condition was water drainage out of the area prevented soil not only achieved by reduction of tree com- saturation. petition but by substituting grasses and le- gumes that were capable of producing as well or better than the resident species. CONCLUSIONS

The removal of oak tree cover will modi- Water Yield fy the rangeland ecology; thus the new con- ditions must be assessed to determine the Benefits derived from tree removal also value of tree cover modification. In many included an increase of water yield either by situations forage quality and quantity will surface or sub-surface flow. Research by improve, springs and stream flow will in- Lewis and Burgy (1964) determined that oak crease, and an economic return can be obtained trees will extend roots through fractured if the tree material is harvested for firewood. rocks to depths in excess of 70 feet (21.4m). If a large percentage of the trees are killed, In tree covered areas, where the density of under some geologic situations, erosion will trees was 150 to 500 per acre, the removal of increase in terms of channel scouring as well trees increased water runoff per year from 2 as by land slips. The browse value of oaks to 13 inches (5.1 to 33cm) in an eight year within reach of grazing animals will be lost period (Burgy and Papazafiriou 1970). The and the Fall acorn crops will be reduced. It average increase of total runoff attributable is important that rangeland operators fully to tree removal management was found to be in assess the changes that will result from tree the order of 50 percent as compared to pre- removal to determine whether they will benefit treatment amounts. his future land use plans. Interception losses in shrubs and trees are higher than for grasses and forbs. Also, when plants with deep roots, that remain in LITERATURE CITED leaf during most of the year, are replaced by shallow-rooted plants with short growing sea- Bell, M. son, the reduction of evapotranspiration 1960. Grass or Oaks - A report on blue oak losses results in an increase in water yield control. Glenn County Agric. Ext. Serv. (Burgy and Papazafiriou 1971). This was demonstrated in Watershed 11, where an inter- Burgy, R. H. mittent stream became perennial after vegeta- 1967. Watershed values of vegetation in for- tive conversion from trees and brush to grasses est and rangelands: Mans' Effect on and forbs. This evapotranspiration reduction California Watersheds, Section 111. Sub- resulted in the increase and extention of base committee on Forest Practices and Water- flow through the dry season. shed Management, California State Legis- Variations in watershed response to tree lature, p. 393-412. removal is well illustrated in these two areas. Geophysical drilling revealed that Watershed I Burgy, R. H. and 2. G. Papazafiriou had extensive fracturing of rock structure 1970. Hydrologic studies and watershed allowing water drainage out of the area by sub- management on brushland. Dept. of Water surface flow whereas in Watershed I1 the clay Sci., Univ. of Calif. and rock underlying the surface were imper- vious, holding water near to the surface. In Burgy, R. H. and Z. G. Papazafiriou Watershed I1 the increase of available water 1971. Biological effects in the hydrologic due to tree removal was thus expressed as cycle. Proc. 3rd Int'l Seminar for stream flow. Previous to tree treatment the Hydrologic Professors, Purdue Univ. stream flow ceased by July, whereas following tree treatment the stream was characterized Gowans, K. D. by a perennial flow. In Watershed I, where 1958. Soil Survey of Hopland Field Station. sub-surface drainage was good, the increase in California Agric. Exp. Sta. available water was not expressed as visible stream flow. Increased water flow in Water- Heady, H. F. shed I1 resulted in greater channel erosion 1961. Ecological research findings on the and scouring. The higher soil moisture re- annual grass type at Hopland Field Station. sulted in many zones of soil saturation caus- California Forest and Forest Products, ing creep deformation in a number of sites. #24, 4p. Lewis, D. C. and R. H. Burgy Murphy, A. H. and B. Crampton 1964. The relationship between oak tree 1964. Quality and yield of forage as af- roots and groundwater in fractured rock fected by chemical removal of blue oaks. hs determined by tritium tracing. J. J. Range Manage., 17 (3) :142-144. of Geophysical Res. 60(12) :2579-2588. Pitt, M. D. Love, R. M. 1975. The effect of site, season, weather 1967. Grazing lands of California: Mans' patterns, grazing, and brush conversion effect on California Watersheds, Section on annual vegetation, Watershed 11, 111- Subcommittee on Forest Practices Hopland Field Station, Univ. of Calif., and Watershed Management. California unpublished Ph.D thesis, 281 pp. State Legislature, p. 219-256.

Murphy, A. H. and L. J. Berry 1973. Range pasture benefits through tree removal. California Agric. , 27 (1) :6. A1 Groncki 2/ ^1 Querous chrysolepis Abstract: California oaks are a significant part of natural biomass stands in California that are capable of producing up to 30 million tons of dry wood per year. Managing the commercial and non-commercial oak stands with consideration of environmental needs could produce positive management benefits with incidental direction of oak biomass into a variety of possible alternative energy production processes.

INTRODUCTION In California, preliminary estimates based on incomplete data indicate we are producing 30 million dry tons of unused There is an increasing awareness of the forest biomass each year. We do not know potential various forms of wood biomass how much of this is recoverable because of hold as a renewable energy resource (Howard unknown harvesting and transportation costs 1974, Alich 1976, Howlett 1977). New plants and environmental considerations. Manage- using wood energy for heat, steam, and ment regimes for California's oaks, as an electricity production are being considered example, have not been designed, and is one throughout the nation. Research for the reason for this symposium. conversion of wood to liquid or gaseous Thirty million tons represent 0.51 Quads fuels is being funded by Federal and State or 7.8 percent of California's annual energy governments and by private industry and budget (Craig, et. al. 1978) of 6.5 Quads educational institutions. (based on 1975 figures). Nationally we produce 1.25 ~uadss/of Where do California o,aks fall into this energy from wood. Preliminary estimates scheme? California hardwoods are expected indicate a potential of 8.3% Quads Of to yield 3.5 million dry tons of biomass energy from wood. The Forest Service pre- annually, or approximately 11.4% of the dicts that 5.2 of these Quads will be real- total 30 million tons of estimated biomass ized. This will amount to 7% of the production. The oaks are a significant part Nation's energy needs. Estimates, however, of the hardwood resource. The above figures have been made from resource information assume a hardwood culture dedicated to more that was collected for conventional conver- economically valuable product uses than tible wood products. Information collected energy. The 3.5 million tons consists of for total biomass production may change estimated logging residues from commercial these estimates. hardwood stands, and managed biomass har- vesting from non-commercial stands. Hopefully this Symposium and other re- search and inventory work will provide bet- -1/ Presented at the Symposium on the ter data in the near future in the following Ecology, Management, and Utilization of categories: California Oaks, Claremont, California, June 26-28, 1979. 1. Acreage of commercial oak stands. Acreage of non-commercial oak -2/ Leader, General Forestry Assistance, stands. Cooperative Forestry & Fire, U.S. Forest Delineation by species, volume and Service, Pacific Southwest Region, San size classes by conventional inven- Francisco, CA. tory standards and total above-and below-ground biomass standards. -3/ 1 Quad = 1 quadrillion BTU's or 1x1015 BTU'S. -4/ National Framework for Energy from Biomass, U.S. Forest Service, Wash- ington D.C., May 25, 1977, Unpublished draft. RELATIVE EFFICIENCY OF WOOD AS FUEL Table 1 - Densities and Heating Values for Some West Coast Species

Wood as fuel contains approximately 8,500 BTUfs per pound or 17,000,000 per ton. Higher These figures vary somewhat within species Density Heating because of contained extractives, but gen- Dry Value-Dry erally can be used. Bark is closer to an Species lb./cu. ft. BTU/lb BTU/cu .ft . average of 9,000 BTUfs per pound or à 18,000,000 per ton. Douglas Fir 38 These figures are for dry wood. Green Ponderosa Pine 24 wood unfortunately contains high percentages Lodgepole Pine 24 of water. Green wood generally contains as Red Alder 23 much water by weight as solid wood sub- Ore. White Oak 37 stance. The relative efficiency of wood as a fuel is complicated significantly by the presence of this water. It increases hand- The use of wood stoves for space heating, ling and transportation costs, and decreases cooking,and heating water has increased the efficiency of the combustion process. significantly in the last few years. Fire- If used in a green state, roughly 20-30% of wood permits in California from Forest the contained BTU's will be used to drive Service Ranger Stations totaled 78,304 cords off the water. Air drying and the use of in 1972, and 329,634 in 1977, a 420% in- waste stack heat can increase the relative crease. It is difficult for the homeowner efficiency of combustion. The combustion to evaluate the effectiveness of the various of dry wood in conventional boilers compares wood-burning stoves. Comparative efficiency favorably with oil and coal. Because more tests have not yet been published, although wood is required for equal heat outputs, some are being conducted by the Department there is some increase in storage, handling, of Mechanical Engineering at Auburn Univer- and size of combustion equipment requir,ed sity, Auburn, Alabama. for burning wood. Without this comparative information, Dry wood has a boiler efficiency of there are three things you should look for 80.08% (Curtis, 1978) wood at 15% Moisture in a good stove: Content has an efficiency of 78.08%. 1. It should be air tight. Wood at 30% Moisture Content has an 2. It should provide for secondary com- efficiency of 76.08. bustion of fuel gases. Wood at 60% Moisture Content has an 3. It should provide refractory brick efficiency of 72.07%. lining. Wood at 100% Moisture Content has an A good reference is the Woodburners efficiency of 66.72%. Encyclopedia (Shelton and Shapiro, 1976.) Oak is preferred firewood for home con- This reference discusses the pros and cons sumption because it is dense and therefore of most of the models presently on the mar- contains more BTU's per cubic foot than ket. It also gives good information on Ponderosa Pine, although Ponderosa Pine safety, which should be a primary concern of actually contains more BTUfs per pound. yours if you are going into home wood heat- Since wood is often purchased on a weight ing. Consult your local county building basis in industrial operations, pine is a inspector for installation specifications, better buy than oak. Since wood is bought and then follow a rigid maintenance program. on a volume basis for home use, oak is a better buy than pine, although price adjust- ments are generally made to accommodate these differences in BTU content. Table 1 TECHNOLOGY OF INDUSTRIAL WOOD COMBUSTION below illustrates some of these relation- ships for some of our Western species. The combustion of wood by industry has undergone many changes in recent years. Some modern combustion units are smokeless and operate unattended. A brief review of the various types of systems in use will illustrate the broad range available today. Dutch Oven They can vary greatly in size. The largest units will consume 250 tons of hog fuel per day. Although hogged fuel or chips are Many old furnaces and some new ones use desirable, solid wood may also be burned. this system in which the fuel is burned in Fluidized bed systems, though expensive, a pile. The rate and efficiency of combus- have several advantages. They can burn very tion is regulated by the design and use of wet fuels and they are very flexible. They over-and under-fire air. Too much primary may fire boilers directly, may provide air under the fire lowers the combustion direct heat for heating or drying systems, temperature and produces more unburned part- or may produce gas for turbines or subse- iculates. Not enough over-fire air prevents quent combustion. A disadvantage is they the secondary combustion of particulates are very expensive and usually only just- and gases. A properly designed furnace ified for very large operations. provides the proper amounts of each kind of air, and some means of collecting and burn- ing all particulates. If particulates are not burned, then Pyrolysis they must be collected in precipitators, wet scrubbers, or bag house collectors to meet air pollution standards. These same Pyrolysis, or destructive distillation, comments apply to many of the other systems is the combustion of material with a minimal described here. amount of oxygen. Low-temperature pyrolysis produces gas, charcoal, and pyrolytic oils. High-temperature pyrolysis or gassification produces low BTU gas, mostly carbon monox- Moving Grate Systems ide, but some methane and hydrogen also. The low temperature pyrolysis permits the production of a mixture of char and oil There is a wide variety of systems in that may be hauled to some other location which the fuel is burned on a grate that for combustion. It may be further gass- moves in some fashion. There are dumping ified, mixed with fuel oil for combustion, grates, reciprocating grates, and moving or processed chemically. grates. The intent is to spread the fire High-temperature pyrolytic gases can in a uniform manner and to dispose of ash not be transported any significant distance. efficiently. There is a wide range of com- They may be used to operate gas turbines, bustion efficiency depending on the design fire steam boilers, or to operate internal of the furnace and the use made of air to combustion engines, either for shaft horse- obtain complete combustion. power or to run electric generators. Products of both processes may be used to create other chemicals such as ammonia or methanol. Suspension Systems

These are systems that use currents of Chemical Systems air to suspend the fuel while it is being burned. There are simple suspension systems as well as more complex horizontal or ver- A variety of chemical systems exist to tical vortex or cyclonic systems. Some use convert wood to methanol, ethanol, furfural, a single combustion chamber and some use acetic acid, ammonia, oil, crude sugars and secondary chambers for combustion or to trap animal feeds. Some of these systems are: unburned particles and return them for acid hydrolysis, wet oxidative hydrolysis, additional combustion. fermentation, carboxylase and hydrogassifi- cation.

Fluidized Beds Hybrid Geothermal

These systems employ vertical air flow and a bed of sand or other material to keep This is a system designed to use the vast fuel in constant agitation or suspension. amounts of low-temperature geothermal fluids found in the Western U.S. in combination with a wood-fired steam system. which the highest value components are Geothermal fluids are used to dry hogged removed sequentially. Again we come up wood material and pre-heat boiler feedwater. against the idea that tree components are The boiler feedwater is then super-heated possibly too good to burn. in a wood-fired boiler and used to generate electricity.

EXISTING AND POTENTIAL ANNUAL WOOD BIOMASS SUPPLIES IN Pelletization CALIFORNIA

A number of pelletizing processes exist. The following data on biomass supplies Pellets range in size from animal feed to was developed in 1978 as testimony for the presto-logs. The pellets may be used in California Energy Commission (Table 2). any of the processes described above and in They requested it for consideration in themselves do not constitute a new technol- hearings on siting applications for fossil ogy, pelletizing having been used since fuel power plants in the State. 1923. They do decrease transportation costs This section covers oak as well as all because the wood in pellets must be reduced other sources of wood biomass. Although we to about 15% moisture content (dry basis). have been unable to segregate the oak The increase in density also reduces the resource from the other categories of com- size of necessary storage facilities, and mercial and non-commercial hardwoods, the provides a transportable product for home implications of managing the oaks forces us fireplaces and campground fires. The to the same management concerns. experts in this field do not anticipate much use for pelletizing in industrial applica- tions in the future because the advantages are not great enough to justify the expense Material Available With Existing Technology of pelletizing. Category 1 - Mill Residues The Forest Service projects a total primary mill residue of 7.7 million dry tons Chemical Derivatives (Howard 1974). Stanford Research Institute estimates 4.6 million dry tons (Alich 1976). The Mitre Corportion estimated 8.8 million In addition to destructive distillation tons (Howlett 1977). The amount of this processes for converting wood to chemicals, residue being used fluctuates with the pulp wood and foliage contain a great number of chip market. We presently estimate 3.0 valuable chemical extractives. A quote from million tons unutilized. With the increased J.E. Stone of the Canadian Forest Service interest in power generation by primary illustrates the potential that exists for mills, this surplus will soon decrease to chemical uses of wood and exemplifies about 1.0 million tons. another attitude toward utilizing wood for This mill residue is primary mill energy (Carlisle 1976). residue from sawmill and veneer mills. It "Using a complex organic substance does not include residues from secondary merely for its calorific value is one of processing facilities such as molding its crudest uses . . . It takes no cogni- plants, sash and door plants, cabinet and sance of the chlorophyll, carotene, vita- furniture plants and miscellaneous forest mins, protein, essential oils, etc. in the industries. Secondary mill residue is foliage. No cognisance of the beautiful reported as a portion of urban wood residue. fibre structure of wood. No cognisance of A number of sawmills in California are the polymeric properties of the cellulose cutting some oak. Cal-Oak in Oroville cuts molecule, of the fact that 60 percent or oak almost exclusively, and they are on more of the wood is carbohydrate, or that this progranto talk about their operation. lignin is an aromatic phenolic polymer with Kimberly Clark, Philo Timber Co., Simonson many interesting properties . . . It is a Timber Co., Schmidbauer Timber Inc. all treasure house of structural and chemical cut some incidental hardwoods including components which should be exploited to some of the oaks. their fullest extent." He further suggests Humboldt County and at least one that surplus trees and their components Company are actively studying the should be put into a process stream in establishment of a hardwood processing plant is not anticipated due to environmental con- in Humboldt County. straints. Most of this material is there- fore assumed to be available for energy Category 2 - Woods Residue purposes. This data applies to pre-commercial The Pacific Northwest Forest and Range thinning material only. Commercial thinning Experiment Station has published voluminous residue is aggregated with other forms of data on the volumes of logging slash logging slash. (Howard 19731, (Adams 1976) & (Grantham 1974). Data has not beewdeveloped, how- ever, to predict annual accumulations of Category 4 - Dead and Dying logging slash on a statewide basis. SRI Endemic mortality during an average year estimated 5.1 million tons per year; the approaches 1 billion board feet in Calif- Mitre Corporation estimated 4.3 million ornia. About 13% of this material has been tons per year. We believe both of these utilized in the past. Current Forest are low and estimate 6.5 million tons based Service efforts to increase utilization of on the following assumptions: this material will reduce availability in the long run. Forest Service and State of A. 5 billion bd. ft. harvested in California policy to retain certain levels an average year. of dead trees for cavity-nesting birds and B. 30 thousand bd. ft. per average animals will further reduce the long-term acre of harvest. availability. C. 159,000 acres harvested each During epidemic insect outbreaks, such year on an assumed clear cut basis. as the present one augmented by the drought D. An average residue volume of 40 of 1975-77, vastly increased amounts of dead tons per acre. A significant and dying material are available. An esti- portion of this logging slash is mated 24 million tons is presently avail- from understory hardwoods. able. Much of this will, however, be used Woods residue is any material from the for sawlogs due to the increased Forest severed tree (excluding the stump) that is Service and industry effort to salvage as not harvested or removed from the site. much of this material as possible. Woods residue is often categorized by size In the long term, this amount should classes. The minimum diameter size of mate- decrease as virgin old-growth stands disap- rial most often used in oomputlng woods pear and thinning regimes increase the vigor residue Is 4 inches. This for two reasons: of young stands. No estimates have been (1) the diseeonomy of handling smaller made of volumes of dead and dying hardwoods, material; (2) the need to leave smaller though a recent survey on the Six Rivers material to maintain nutrient balances. National ores st?^ indicates that 75 percent of a total volume of 1,130 MMBF of As stumpage prices increase, utilization California Black oak is either dead or live standards will become more exact and less cull. residue will be left in the woods. We estimate a decrease of 7% due to increased Category 5 - Urban Residue utilization standards in the woods in the Urban residues represent a virtually long term. Virtually none of this material untapped source of wood fiber. Collection is being used now except for firewood and costs have been absorbed and dumping costs incidental salvage by small portable saw- add a negative value that is readily mills. In the long term, most of this recovered. Cities are generators of wood material, down to a 4" diameter, will be residue as much as forests are. Represented utilized for energy, particle board9or pulp. in urban residues are the following categories of material: Category 3 - Conifer Thinnings Fuel loading data from conifer. Secondary Mill Residues Crating thinnings indicate a range from 7 tons to 48tons per acre (Maxwell 1976). Using an Demolition Waste Tree Maintenance average of 20 tons per acre, we arrive at a & Removal total of 6.3 million tons per year available*assuming thinning 2% of the Construction Waste Building Construction 15,863,000 acres of softwoods each year. This material is available short and long term. The pulpwood industry in California has never utilized roundwood supplies, and -5/ Six Rivers Timber Harvest Scheduling additional pulpwood capacity in California study, 1979, unpublished. Household waste is not considered. Only board feet of hardwoods in just those three those wastes delivered in separate, dis- counties. Since the better hardwood sites tinct loads to dumps were considered. occur on the private commercial forest The data we have comes from the Kelbro land, these figures are probably conserva- corporation^ which has produced 180,000 tive. Also, early harvesting on the private tons per year from an area bounded roughly commercial acreage without regeneration and by Sacramento, Yolo, and Placer Counties. stand improvement practices has resulted in These three counties contain 4.2% of the heavy regrowth to hardwoods. California metropolitan population. An extrapolation to the total metropolitan Category 8 - Noncommercial Hardwoods population in California produces an annual Fuel loading studies of material in figure of 4.3 million dry tons per year. this category conducted on the National Much of the residue in this category is ~orests!^ indicate a range from 40 tons hardwood, especially pallets, secondary to 110 tons per acre occurs in natural mill waste, and city tree maintenance stands. We have used a low average loading material. of 50 tons per acre and a rotation of ^0 years. Culminination of mean annual incre- Category 6 - Orchard Prunings ment of biomass will occur much sooner, Orchard prunings are a readily available somewhere near ten years. We have chosen resource with negative value. The Cali- the longer rotation due to unknown factors fornia Department of Agriculture estimated of nutrient cycling and reproductive 2.0 million tons available each year. Some potential to be discussed under Environ- people wish to categorize them with agricul- mental Constraints. Total biomass available on an annual tural residues, but they have the same COB- bustion attributes as other wood residues. basis under this regime would be 1.6 Some agricultural companies are already million dry tons. A published report that considering using their prunings as a source supports these figures was done for the of fuel for their drying operations, so some central coast hardwoods (Pillsbury, 1978). of these will disappear in the long term. Category 9 - Noncommercial Softwoods Category 7 - Commercial Hardwoods The 7.5 million acres of noncommercial We assume a developing industry softwoods is represented by such species as utilizing the commercial hardwood stands in juniper, pinon pine, digger pine, and very California. Species include Oregon White poor stands of the commercial species such Oak, Calif. Black Oak, Alder, Big Leaf as Ponderosa pine and Douglas fir. By Maple, Cottonwood, Sycamore, Calif, Laurel, definition, noncommercial softwood stands Calif. Valley or White Oak, Tanoak, are stands that are growing less than 20 Chinquapin and Madrone. Our hardwood cubic feet per acre per year. An average resources are too valuable to use growth would probably be closer to ten cubic exclusively as a wood energy resource. feet per acre per year. These figures are, Volumes of slash from commercial hardwood of course, based on sawboard inventory stands vary from 50-120 tons per acre based standards and not on biomass standards. on fuel loading studies done at PNW Assuming, however, that we will not be using (Maxwell 1976). whole tree harvesting because of nutrient Inventory data on commercial hardwoods cycling constraints, we have used a figure has been lacking, because the hardwoods of 10 cubic feet per acre per year. While have previously not been important. Recent this results in 1 million tons of biomass inventory work on the Six Rivers National per year, we feel the need to proceed Forest?/ reports 2.3 billion board feet cautiously in this type as so little is of live, sound, hardwoods, 1.1 billion of known of the possible consequences of which is Tanoak and 331 million board feet harvest regimes in low-volume, sensitive of which is Black and White Oak. They stands. Harvesting in the pinon juniper report another 2.2 billion board feet of type will probably occur to augment the dead or live cull, all of which would be grazing resource. available for energy purposes. Extrapolation of this data to the three counties of Mendocino, Humboldt and Del Norte counties results in 16-20 billion -6/ Unpublished data from KELBRO -7/ Unpublished data. Fuel loading studies Corporation, Sacramento, CA. on individual National Forests in Region 5. Category 10 - Chaparral fuel treatment on both National Forest and Fuel loading studies by the Riverside Fire private land. It would reduce the existing ~aborator~g/ indicate a range from 10-46 discrepancy in treatment standards by land tons per acre. They also estimate 20 years ownership. Benefits would include a for a burned-over site to reach optimum reduction in resource losses and fire loading again. We have used an average of 20 suppression costs as well as energy yields. tons per acre and an assumed rotation of 20 Harvest of biomass from chaparral and years. These assumptions produce an annual other noncommercial sources is another production of 7.6 million dry tons per year. matter. Management regimes have not been Since harvesting technology has not been established, and harvesting technology has developed for chaparral, no estimate has been not been evaluated. We believe that the made of the percentage of this material feasibility of energy projects with a short that will eventually be available. planning horizon should be based on material The figures for all categories project sources available under present technology annual total biomass production. Physical, and present management strategies. economic, or environmental availability are Long-range energy projections can, how- not considered, nor is the backlog of residue ever, include assumptions about technologi- from previous logging and milling activities cal development and management strategies and considered. should include chaparral as a potential energy source.

MANAGEMENT EFFECTS OF HARVESTING FOR BIOMASS Insect and Disease Management

Managing the forest resource for biomass production as well as higher valued products Forest sites can support an optimum will involve the areas of fire control, growth of trees without danger of insect insect and disease management, stand activity. When the volume of biomass on an improvement, wildlife management, range, and area exceeds this optimum state, stress in esthetics. trees will develop. Stressed trees will be removed by insect and disease activity if man does not do it first. Site capability is Fire Control affected by soil depth, parent soil material, amount of rainfall and other factors. Stands adequately managed through periodic thinning3 Substantial resource losses have occurred will optimize growth and be immune to insect in California because of wildfire in activity. commercial timber stands. Suppression of Management of noncommercial stands may these fires has been aggravated by result in unexpected problems including accumulations of slash in timber harvested insect and disease activity. More infor- areas. More complete utilization for energy mation on the management of such stands needs or other products will help reduce these to be generated by research and experience. losses and will also reduce fire suppression The off-site burning of forest residue costs. instead of on-site burning will be more From a fire management standpoint, the attractive from the standpoint of better air use of slash, dead and dying trees, and quality and reduced forest fuels. Less thinning waste for fuel can only be bene- injury to remaining trees will also be a ficial. Backlog slash from inadequately benefit. treated harvest areas of the past is still a substantial problem as there are an estimated 200,000 acres of this material on National Forest land. Current National Forest timber Stand Improvement sales are not a problem as more complete fuel treatment is performed. Utilization of timber sale residue for Practical forestry includes the practice energy will provide an economic incentive for of thinning stands periodically to decrease competition and soil nutrient drain, espec- ially from less vigorous trees of the stand, and to optimize growth in dominant or crop trees. Thinning as a normal practice in -5 / Personal communication - unpublished data. California stands has been discouraged by the TABLE 2 TEN CATEGORIES OF WOOD RESIDUE IN CALIFORNIA

ANNUAL AVAILABLE CATEGORY ACREAGE* VOLUME ROTATION DRY TONS IN MILLIONS~ SHORT TERM LONG TERM 5 ~r 5 yr + 1. - SRI 4.6 MM Tons Mill Residue MITRE 8.8 MM Tons F.S. 7.7 MM Tons 2. SRI 5.1 MM Tons Woods Residue 158,630 MITRE 4.3 MM Tons F.S. 6.5 MM Tons 3. 60- 120 Conifer 2% Thinning Thinnings Regime 4. Dead & Dying 15.8 MM 1 Billion B.Ft. 5. 500 Tons/Day Urban Residues - (~ellbroCorp . Sacramento, Yolo) 6. 14,000,000 Orchard 1973 Data 1.5 Tons/Acre Prunings (calif. State ~bstracts)

SUB-TOTAL (MATERIAL AVAILABLE WITH EXISTING TECHNOLOGY) . . . . . 24.5 18.6 (22.22) (16.87)

7. Commercial 2,837,000 50-120 Tons/Acre 90 0 1.9 Hardwoods Average 60 (1.72) 8. Noncommercial 1.319,000 40-110 Tons/Acre 40 0 1.6 Hardwoods Average 50 (1.45) 9. Noncommercial 7,532,000 20 Cu.Ft./Acre/Yr. Harvest An- Softwoods Assume 10 Cu.Ft./ nual Growth 0 1 .O Acre/Year 140 (0.907) 10. Chaparral 7,554,000 10-46 Tons/Acre Average 20 Tons/ 20 0 7.6 Acre (6.89)

SUB-TOTAL (MATERIAL DEPENDENT UPON DEVELOPMENT OF TECHNOLOGY) . . 0 12.1 (10.97) TOTAL ...... 24.5 30.7 (22.22) (27.64) *Acreage figures from U.S. Forest Service forest survey. -91 Metric tons in parentheses. 1 English ton = 0.907 metric tonnes. 1 metric tonne = 2,204.62 POUNDS. lack of a market for the products of D. Minimum road systems to decrease thinning. Leaving these products on the harassment of animals, but also to ground to slowly decay has been prohibitive provide quality hunting experiences. because of insect and fire threats. The E. Entry of equipment will need to utilization of this material for fuel will be restricted during certain times of have a twofold effect: it will provide fuel the year to protect animals during from the thinning operations and create reproductive activities. faster growth rates in residual stands that will also produce a residue component for fuel purposes. Research studies have indicated a possible doubling of sawlog Range volume on better sites through planned thinning operations. A generally more intensive management The range resource can be significantly strategy in commercial timber types will also increased through management of chaparral and permit the use of genetically superior stock brush systems. Our experience with burned- that will further increase productive over chaparral is that about 10 years of good capability. grazing follows the fires. Additional forage can be provided by thinning operations that permit more light to enter stands to produce more grasses and forbs. Wildlife Management Some oak types, such as the Blue and Valley Oaks, will be protected where thev form important shade and mast-producing The effects of managing for biomass can components in oak-grassland ranges. have profound effects on wildlife, both good Range and Wildlife management practices and bad. Knowledge of wildlife requirements need to be coordinated to provide for both will permit us to plan judiciously to uses. minimize negative impacts while taking advantage of the positive impacts, as illustrated below: Commercial forest stands in California Esthetics still contain many acres of virgin timber that are not prime wildlife habitat. Many chaparral and noncommercial hardwoods stands An additional benefit to forest manage- form impenetrable canopies of low value to ment will be the improved esthetic qualities wildlife. Management of both these types can of the forest. Dense and chaotic arrange- increase wildlife populations by: ments of slash and brush under commercial A. Increasing diversity of habitat stands will be eliminated. A greater and creating greater amounts of edge. diversity of habitat will also increase the B. Penetration of light in all non-game species of wildlife that will add to stands to permit greater production public enjoyment. Young stands will be of grasses, forbes, and brush. passable and attractive instead of being C. Creating access in dense impenetrable thickets. Greater control of chaparral and brush to make new wildfire and insect epidemics will also add forage, cover and water available. to the esthetic appreciation of the forests. Precautions need to be taken to provide The use of landscape managment tech- the following: niques as a tool in the managementof the A. An adequate number of dead trees visual resource can do much to make harvest to provide for animal dens and cavity- operations blend in with the natural land- nesting birds. An average of three scape. dead trees per acre in varying degrees of decay will normally support optimum numbers of cavity- nesting birds. ENVIRONMENTAL EFFECTS OF PROPOSED PROJECTS B. Thickets to provide thermal cover in cold weather and fawning grounds in the spring and summer. Harvesting for biomass will have both C. Adequate downed logs and ground good and bad effects on the environment. cover for certain species. Two to Man's intrusion into wildland systems four logs per acre about 12" in usually has a negative effect. We have diameter for 40 cubic feet of volume learned and still are learning to minimize is considered necessary. those effects on lands we now consider Nutrient recycling may be a commercial. Harvesting vegetation as an problem on short rotation schedules. energy resource will extend our definition of On long rotations, adequate mineral commercial wild land. There are no and organic nutrients are returned to management prescriptions that can be the soil through leaves, twigs, prescribed carte blanche for all wild lands. branches and needles (Zinke 1972). Management requirements are site specific and Most of the mineral nutrients found utilization must be tied to the needs of the in plants occur in this smaller land. material. Normal harvest operations also leave this smaller material in Some of the obvious effects which need to the final harvest cut. About three be planned for and monitored are: percent of the minerals in the tree A. Soil compaction will lead to a are removed in the bole or stem of decrease in infiltration rate of the tree. This amount is more than water and a loss of permeability. adequately replaced from parent soil Compaction will increase runoff, material. Nitrogen falling with rain erosion and downstream sedimen- and fixed biologically more than tation. Compaction decreases adequately replaces the amount survival of germinated vegetative removed in long-rotation forestry seeds. (Carlish 1976). Harvesting activities need to be Short rotations are, however, controlled during wet weather to another problem and are the reason minimize compaction. for the extended rotations suggested Selection of equipment with light for noncommercial categories of bio- load-bearing tracks will help limit mass. Further research is needed on compaction to acceptable levels. nutrient recycling problems in short- B. Reduced vegetative cover will rotation management regimes. promote both wind and water erosion. Whole-tree harvesting likewise Strategic management of cover to poses similar problems of nutrient provide protection from wind and the loss. Thinning operations in long effects of running water will be rotation conifer stands do not seem necessary. to be a threat but more information Increased siltation from road is needed on clearcut harvesting of construction activity is the largest brush and chaparral stands. erosion threat. All the experience The regeneration of chaparral gained in harvest operations on stands without fire poses questions timber land will have to be applied that need answering (Philpot 1977): to protect downstream water values. Downed logs and other vegetation left 1. Critical impact on nutrient for wildlife can also serve as budgets and productivity. physical obstructions to control 2. Allelopathic compounds may erosion. build up and be maintained leading to C. Certain micro-ecosystems may be lower productivity. threatened by permitting harvesting Wood has a low sulfur content. areas to become too large. Burning it in any of the latest tech- Harvesting prescriptions need to be nologically designed furnaces can be site specific. Smaller harvest areas done without polluting the surround- will be less economic but will add to ing air. Burning it alone or in vegetative diversity for wildlife and mixture with coal will reduce the be more attractive. amount of sulfur dioxide, fluorides, Certain sites requiring constant and other synergistically formed vegetative cover will need to be chemicals that are injurious to man, protected from all manipulative plants, and animals. Burned alone, activity. it does not require expensive D. Decreased vegetative cover on filtration and scrubbing equipment. some sites will result in increased Burned in conjuction with coal, temperatures, drier sites, and it also increases the life of furnace reduced vegetative reproduction. linings and produces a finer, more Adequate reproductive knowlege easily handled ash. (Morford, 1978). will be necessary to plan for these The addition of bark, however, usually sites. Nonsprouting species results in excessive particulate matter especially will be vulnerable. because of included soil particles. Table 3 below illustrates the relative merits of wood to natural gas and oil (Sassenrath 1979). TABLE 3 Air Contaminant Emission Rates The dangers are those we can envision (Pounds per million BTU heat input) with a rapidly escalating value for wood fuel that could result in unmanaged and unregulated cutting of natural biomass with consequent soil erosion, loss of wildlife habitat, and other deleterious effects that are unacceptable to the public. As managers, researchers, teachers, and Particulate 0.1 -12/ 0.01 0.07 administrators we all have the obligation Matter to see that we maximize the positive effects Sulfur Oxides Nil 0.0006 1.05 of management opportunities while protecting Carbon Monoxide 0.6 0.017 0.03 the environment. The vision we should hold Nitrogen Oxides 0.1 0.7 1 .O before usts ofbeautiful forests and wild Hydrocarbons 0.001 0.007 lands, virtualafree of fire, contributing I Oe2 in their many ways to a perhaps changed but still good life. Burning fuels with dirty bark included necessitates the addition of wet scrubbers, baghouse collectors or electrostatic precipi- tators, with wet scrubbers being considered Literature Cited the cheapest and most efficient. Even though new wood-fired boilers posess environmental and financial advan- Adams, Thomas C. tages to fossil fuel boilers, regulatory 1976. Economic Availability of Logging requirements are not limited to air Residue in the Douglas Fir Region. pollution requirements. U S D A Forest Service Res . Bul . Proponents of wood-fired systems must PNW-64, 9 p. Pacific Northwest Forest consider planning regulations, building and Range Experiment Station, Portland, codes, water quality approval, solid waste OR. disposal requirements, California Environ- mental Quality Act review and possibly Alich, J.A., Jr. etal. Coastal Commission approval before 1976. Program Definition for Fuels from construction may proceed. Biomass. SRI Project 5527 l6p. Stanford Research Institute, Menlo Park, CA.

CONCLUSIONS Carlish, A. 1976. The Utilization of Forest Biomass and Forest Industry Wastes for the Harvesting oaks and other natural Production and Conservation of Energy. biomass for energy purposes presents both 54 p. Petawa Forest Experiment Station, opportunities and some very real dangers. Canadian Forest Service, Chalk River, The management opportunities are those Ontario. we have always associated with ideal forest management as seen perhaps in parts of Graig, P. Europe: an esthetically attractive forest, 1978. Distributed Energy Systems in free of fire and insect problems, with Calif. Future, Interm Report Vol I and optimum growth. 11, Contract No. W-7405-ENG-48, 287 p. and 359 p. U.S. Department of Energy, Washington D.C. -10/ Values determined by HCAPCD Source Curtis, A.B. Jr. Tests. 1978. Fuel Value Calculator, U S D A Forest Service, Southeastern Area, -11/ Values from U.S.-E.P.A. publication State & Private Forestry, Atlanta, GA. AP-42. Grantham, John B. -12/ Equivalent to 0.04 Grains per cubic 1974. Energy and Raw Material Potentials foot. of Wood Residue in the Pacific Coast States. U S D A Forest Service. Gen. Tech. Rep. PNW-51, 37 p., Pacific Northwest Forest and Range Exp. Station, Portland, OR. Howard, James 0. Philpot, Charles W. 1974. California Forest Industry - Wood 1977. The Potential Environmental Consumption and Characteristics. Impacts of Harvesting Chaparral, U S D A Forest Service Resource Bul. Proceedings of Chaparral for Energy PNW-52, glp., Pacific Northwest Forest Information Exchange, 170 p. Sponsored and Range Exp. Station, Portland, OR. by Pacific Southwest Forest and Range Exp. Station, Riverside, California and Howard, James 0. Angeles National Forest, Pasadena, CA. 1973. Logging Residue - Volume and characteristics, In Washington, Oregon, Pillsbury, Norman A. and California, U S D A Forest Service 1978. Hardwood Stand Density Resource Bul. PNW-44, 26 p. Pacific Characteristicsfor Central Coast Northwest Forest & Range Exp. Station, Counties in California., 32 p. Natural Portland, OR. Resources Management Dept., Calif. Polytechnic State Univ., San Luis Howlett, K. and Gamache, A. Obispo, CA. 1977. Forest and Mill Residues as Potential Sources of Biomass, MITRE Sassenrath, Charles Technical Report No. 7347, Volume VI, 1979. Choosing a Wood Waste Boiler, 124 p. Mitre Corp./Metrek Division Proceedings of Conference on Wood Washington, D.C. Biomass for Energy, California Energy Commision, Claremont, Calif, April Maxwell, Wayne G. and Ward, Franklin R. 9-10, 6 p. Solar Energy Research 1976. Photo series for Quantifying Forest Institute, Golden, Colorado. Residues in the: Coastal Douglas-Fir- Hemlock Type; Coastal Douglas-Fir- Shelton, J. and Shapiro, A.B. Hardwood Type: U S D A Forest Service 1976. The Woodburners Encyclopedia, 155 Gen. Tech. Rep. PNW-51, 103 p. Pacific p. Vermont Crossroads Press, Northwest For. and Range Exp. Station, Waitsfield, Vermont Portland, OR. Wall, Brian R. and Oswald, Daniel S. Maxwell, Wayne G. and Ward, Franklin R. 1975. A Technique and Relationships for 1976. Photo series for Quantifying Forest Projections of Employment in the Residues in the Ponderosa Pine Type, Pacific Coast Forest Products Industry, Ponderosa Pine and Ass. Species Type, U S D A Forest Service Res. Paper Lodgepole Pine type, U S D A Forest PNW-189, 49 p. Pacific Northwest Service Gen. Tech. Rep. PNW-52, 71 p. Forest Range Exp. Station, Portland, OR. Pacific Northwest For. and Range Exp. Station, Portland, OR. Zinke, P.J. and Colwell, W.L. 1972. Nutrient Cycling in Forests, Morford , James V. proceedings First Annual Calif. Plant 1978. Supplemental Wood Fuel Experiment, and Soil Conf., 1 p. Sacramento, Board of Light and Power, Interim California. Report, 24 p. City of Grand Haven, Michigan. Economics of Utilizing Oak for Energy1

Raymond stin&'

Abstract: Utilizing oak as fuel for home heating, as well as commercial energy production, can be shown to be a viable alternative to the use of traditional fuels. An examination of the specific costs involved indicates while the use of oak for commercial energy production is approximately at the break-even point, the production of fuelwood for home consumption is a pro- fitable venture.

INTRODUCTION product to an urban woodlot for sale. The average selling price is assumed to be $90.00 Oaks comprise about 80 percent of Cali- per cord (Table 1). We will assume that the fornia's hardwood resource .?/ It can be shown production per day for a two-man operation is that oak is an economical source of fuel for approximately 6 cords, a haul distance of 100 energy production, not only for individual miles round-trip, and a payload of 16 cords consumers, but also for commercial energy per trip. To ease handling and to decrease generation. This paper describes the eco- hauling costs, the cut wood will be air dried nomics of using oakwood for fuel in two hypo- prior to transporting. thetical situations: 1. currently for in- dividual homeheating and cooking, and 2. Table I--Average cost for producing one potentially for commercial energy generation. cord of oak fuelwood *

OAK FUELWOOD FOR HOME CONSUMPTION I~estSierra & 1 Eastside Coast Range 1 Sierra Today, more and more people are realizing Cost Factor Tractor 1 Cable 1 Tractor the current benefits of using woodstoves and fireplaces in their homes for direct heating Stumpage $10.00 $10.00 and cooking, thereby offsetting to some degree - their rising energy bills. Thus a growing I- Harvesting Activities market exists for oak as a fuelwood for home use. Fall This economic analysis of fuelwood pro- Limb duction describes the typical California Buck foothill firewood operation where the operator LOP cuts, splits, loads and hauls his fuelwood Skid

Processing A Lipresented at the Symposium on the Ecology, Management, and Utilization of California Cut Oaks, Claremont, California, June 26-28, 1979. Split Load "wood Energy Forester, California Department of Forestry, 1416 Ninth Street, Sacramento, Trucking California 95814. General ÑBolsinger Charles L., Oaks in California's Overhead Commercial Forests ...Volume, Stand Structure, and Defect Characteristics. (Included in this Total Costs, Proceedings. ) Woodlot $72.38 $78.79 $70.02 P - * See text j r cost assumptions. Average selling price Sacramento area working days per year (wholesale 1-12-79) = $90.00/cord. Using aver- = 6 cords/day x 240 days = 1,440 cords/year cost per cord = $1,180.26 age selling price, profit equals $11.21/cord = s.82/cord for cable and $18.80/cord (average) for tractor 1,440 sales. 2. Labor As before, labor at $7.80/hr.x 8 hrs-/ day x 240 days/year gives a total Stumpage Costs costs = $14,976 and $14,976 - It is assumed that the stumpage price is $10.40 per cord $20.00 per thousand boardfeet (MBF). It is also assumed that 1 cord equals 500 Bf Scribner Total splitting costs = Rule. Stumpage will then cost $10.00 per cord. $.82/cord for equipment $10.40/cord for labor = $11.22/cord Harvesting Activities Loading - At loading production of 20 Costs were adapted from the U.S. Forest seasoned cords (stacked in semi-trailer) per Service Timber Appraisal Handbook 1977. These day (2 persons), costs equal. costsinclude all depreciation on equipmentand $7,80/hr. x 8 hrs./day x 2 persons labor but do not include costs for road con- = $124.80/day or struction. To adapt hardwood logging costs $6.24 per cord from softwood tables, it was decided that the total cost on the average should remain con- The total processing costs for cutting, stant although item costs vary. i.e., compared splitting, and loading = $27.86/cord. to logging softwoods there is more limbing and lopping during hardwood logging but less buck- ing prior to skidding. We assumed in this case Trucking Costs all additional costs of hardwood logging were cancelled by generally equal cost savings. Trucking costs for different road condi- tions are given in Table 2.

Processing Activities Table 2--Trucking costs - Average cost per cord mile L/ Cutting - For this analysis it was assumed that a person could buck into firewood length 6 cords of wood in an 8-hour day. Using the Total Haul Over Private USFS wage rates of $4.75-$7.30/hr. plus 32.60 or USFS Roads percent benefits, the average labor cost Cost Haul up to 10 to 30 to equals $7.80/hr. Class 10 mi.. 30 mi. 60 mi.

Splitting - Assuming the average cost of a commercial wood splitter of $2,500 at 10 per- cent interest plus maintenance costs of15 per- cent of the original purchase cost, the split- .420 .292 .189 ting costs are: -630 -441 .285 1. Commercial wood splitter-(5-year VI .947 ------life) original cost = $2,500 or Partial or Total Haul Over State $500/year. or County Roads + Cost Haul up to 10 to 30 to over Interest at 10 percent over depre- Class 10mi. 30mi. 60mi. 60mi. ciation period of 5 years = $1,526.28 + Maintenance - (includes maintenance, labor, oil, gasoline, lubrication, and hydraulic fluids ) = 15 percent of the original purchase price, price per year = $375/year

Total cost per year = $1,180.26 v~da~ted from U. S. Forest Service Timber Appraisal Handbook (1977)using 1 cord = 500 Bf Production - For this analysis we can Scribner. assume 6 cords per day as an average and 240 Cost per cord mile average haul includes Cost Haul Class VI: compensation insurance, social security, other insurance and taxes and depreciation, but not Poor, steep, crooked roads nearly impassable road construction, road maintenance or reload- for logging trucks, single track roads for one ing. way loaded traffic should be considered as two- lane roads.

Cost Haul Class I: For illustrative purposes we shall assume:

Main highways, two or more lanes wide, cement 1. Haul distance = 100 miles round trip. or bituminous concrete surface, excellent 2. Payload = 50,000 lbs. or 16 cords. alignment and grades not to exceed six percent. 3. Predominantly haul Class I11 roads Average truck speed approximately 35 miles per on State and county roads. hour. Reduce classification to I1 for sections of adverse grade over four percent. Trucking costs using USFS tablewould equal:

10 mi. @ $.426 x 16 cords = $ 68.16 Cost Haul Class 11: 20 mi. @ S.268 x 16 cords = $ 85.76 30 mi. @ $.I73 x 16 cords = $ 83.04 Secondary highways, 2 lane - combined effect 40 mi. @ $.099 x 16 cords = $ 63.36 of width surface, alignment and grade not so $ 300.32/trip favorable as in I for high speeds. Average or $ 18.77/cord truck speed approximately 30 miles per hour. Reduce classification to I11 for sections of adverse grade four percent to six percent and General Overhead to IV for sections over six percent adverse. General overhead figures include scaling but not road construction costs. Adapted from Cost Haul Class 111: U.S.F.S. Timber Appraisal Handbook (1977).

County roads and Forest Service high-standard utilization *-road - -* well-maintained oiled Total Cost gravel or earth surface - two lane or wide single lane with intervisible turnouts - good Total cost figures include equipment de- altomnpnt (80 feet radius curves) - grades not preciation and labor, but do not include costs exceeding eiqht percent. Truck speed approx- for road construction and maintenance. imately 20 miles per hour. Reduce classifi- cation to IV for sections of adverse grade six percent to eiqht percent and to V for over OAK FUELWOOD FOR COMMERCIAL eight percent. ENERGY PRODUCTION

Anticipating rapidly increasing prices, Cost Haul Class IV: many sawmills have begun to use more wood chips as boiler fuel to offset higher energy costs Forest Service medium-standard truck trails, and uncertain and interruptable supplies of single lanes with turnouts not always inter- energy. In fact, currently in California there visible - fair gravel or earth surface - broken are 58 lumber mills in 24 counties using wood grades up to 10 percent. Truck speed approx- for on-site production of process steam for imately 15 miles per hour. Reduce classifi- operating lumber dry kilns. In addition, the cation to V for sections of adverse grade over generating capacity of these mills amounts to eight percent. about 120 megawatts, with an additional 160 megawatts being planned or constructed (See appendix 1). The economic analysis in this Cost Haul Class V: example takes the same oak stumpage and working location as in the first example and IOOKS at Forest Service low-standard truck trails, utilizing it as boiler fuel at an adjacent mill. single lane with inadequate turnouts, unmain- tained earth surface - sharp curvature (40 for illustrative purposes we let feet radius) - numerous grades up to 12 percent. the haul distance be 75 miles round-trip with Truck speed approximately 10 miles per hour. a 25 ton payload. Interestingly, from actual in-woods chipping performed by the California Department of Forestry, it was determined that possibly the most effective and efficient means of reducing the logs to boiler fuel was to It is also assumed that there are approxi- transport this material in log form to the mill mately 5.26 green tons per thousand board where it is put through existing hogging equip- feet resulting in a stumpage cost of $3.80/ ment. By processing the logs in this way, the green ton. large cost and raw size constraints inherent in using an in-woods chipper, are eliminated. This analysis uses green tons or 50 percent Harvesting Activities moisture content on a wet basis. Seasoning of wood prior to combustion, reducing moisture Costs were adapted from the U. S. Forest content and thus increasing boiler efficiency, Service Timber Appraisal Handbook (1977) using may be desirable in this case. Finally, as cord weight of 5,270 pounds (green wt.) and compared to the first example, this case in- 1 cord equaling 500 board feet Scribner Scale. volves more mechanization and incurs greater All costs are included except road construct- capital investment. ion.

Table 3--Average costs per ton of producing heat for steam and/or electricity.* Trucking Costs

Trucking costs, adapted from the U. S. 1 West Sierra & 1 Eastside Forest Service Timber Appraisal Handbook Coast Range 1 Sierra (1977), are given in Table 4. Cost Factor Tractor 1 Cable 1 Tractor Table 4--Trucking cost per ton mile.^/ Stumpage 1 $ 3.80 I Harvesting Activities Total Haul Over Private or USE'S Roads Fall Cost Haul up to 10 to 30 to Limb Class 10 mi. 30 mi. 60 mi. Buck LOP Skid i!i i;; Load I11; 1:;: .12 .16 .ll Trucking -24 .17 .ll VI .36 -- -- Unloading & Partial or Total Haul Over State Handling or County Roads Cost Haul up to 10 to 30 to over Hogging Class 10mi. 30mi. 60mi. 60mi.

Conversion to Btu's

General Overhead

Total Costs Ll~da~ted from U. S. Forest Service Timber Appraisal Handbook (1977). Equivalent Heat Value = $21.21/ton. Cost per ton mile average haul, includes See text for cost assumptions. compensation insurance, social security, other insurance and taxes and depreciation, but do Using Equivalent Heat Value of $21.21/ not include road construction, road mainten- ton, net economic benefits equal= $2.97/ton ance or reloading. for cable and $.35/ton (average) for tractor sales. For illustrative purposes we assumed:

1. 75 mile haul distance - round trip. Stumpage 2. 25 ton payload 3. Haul class I11 on State and county Again it is assumed that the stumpage roads. price is $20.00 per thousand board feet (MBF). In this case - trucking costs would equal: lator using actual September 1978 #6 Fuel Oil Value of $20.01 and assuming a six percent 10 mi. x 25 tons x $.16/tm = $40.00 increase to April, 1979 equaling $21.21. 20 mi. x 25 tons x $.lO/tm = $50.00 30 mi. x 25 tons x $.07/tm = $52.50 15 mi. x 25 tons x $.04/tm = $15.00 CONCLUSION Total $157.50

The economic analysis of utilizing California oak for private consumption as well as commercial energy production indicates that Unloading and Handling Costs in each case the value of each product produced either meets or exceeds its production cost. Actual cost of unloading logging trucks and transporting material to hogging equip- ment at Michigan-California Lumber Company, LITERATURE CITED Camino, California.

U.S.D.A. Forest Service, Timber Sale Preparation Hogging of Boiler Fuel and Appraisal Handbook - FSH2 - 2425 - R5, (1977). Actual cost of hogging woody material at Michigan-California Lumber Company, Camino, U.S.D.A. Forest Service, Fuel Value Calculator, California. Includes costs of hogging and Developed by A.B. Curtis, Jr. Revised February, transportation of hog fuel to boiler. 1978.

Conversion Costs APPENDIX Conversion to Btu's - using actual cost of conversion of $0.217/million Btu @ 50 per- Present Wood Derived Power Capacity cent moisture content (Michigan-California Lumber Co., Camino, California) - and assum- A significant amount of energy is already ing 4,250 Btdlb. @ 50 percent moisture content being generated from industrial wood waste. and boiler efficiency of 70 percent. Net use- Fifty-eight mills in 24 counties are using ful energy = 4.250 Btu/lb. x .70 = 2,975 wood for power generation in one form or another. Btu/lb. or 5.95 mm Btu/ton. Cost per ton = Most of the 2,606,700 tons of wood waste being 5.95 nun Btu/ton x $0.217/m Btu = $1.29/ton used each year is used for generating steam, at 50 percent moisture content. either to operate lumber dry kilns or for other process steam uses.

Overhead Costs ~lectricitygeneration capacity amounts to 123.5 megawatts, with an additional 160 General overhead figures include scaling megawatts being constructed or planned. An but not road construction costs. Adapted from additional 3 million tons of wood waste is U.S.F.S. Timber Appraisal Handbook (1977). presently being disposed of by incineration or by burial in landfills. Much of this additional residue volume had previously been Total Cost directed into the pulp market. That market is presently oversupplied and depressed. Total cost figures include equipment depreciation and labor but do not include costs A detailed tabulation of wood industries for road construction and maintenance. Adapted creating and/or using wood waste for power has from U.S.F.S. Timber Appraisal Handbook (1977). been compiled by the Solid Waste Management Board, California Department of Forestry, and the California Energy Commission. It is Equivalent Heat Value reprinted here. It is reprinted here as Appendix 1. The equivalent Heat Value was calculated from the USDA Forest Service Fuel Value Calcu- WOOD FUELED BOILER LOCATIONS COMPILED BY STATE SOLID WASTE MANAGEMENT BOARD

Company Name Lum. Prod. WW Fuel Ind. Boiler Total Steam Total WW Max. Fuel Elec. Gen. (MW) County & Plant Type Location (1061~~1976) (W)ood Capacities Prod. Cap. Used Boiler Inpt. (P)roposed (B)ark (106 Btu/HR) (103 TIYR) (103 TIYR) (TIHR) (E)xisting

AMADOR Pm. Forest Prod. Martel 1 SAW PAR

BUTTE Cal Oak Lumber (SAW) Orovil le Diamond Int'l (SAW) Oroville Louisiana-Pac Oroville 5.6 30-40 (P) SAW HAR Wickes Forest Ind. (BAR) Oroville Diamond Int'l (RMN) Chico 1.I

CALAVERAS Snider Lumber (SAW) Wallace Brunswick Timber (SAW) San Andreas

CONTRA COSTA Fibreboard Antioch

DEL NORTE Simonson Lumber (SAW) Smith River McNamra & Peepe Lum.(SAW)Crescent City Mi 11er Redwood Crescent City SAW SVM Northcrest (SAW) Crescent City Simpson Timber Klamth Hambro Forest Prod. (PAR) Crescent City Westbrook (PLY) Crescent City

EL DORADO Golden State Bldg. Prod. Shingle Springs SAW SVM

SAW BAR

FRESNO Wickes Forest Ind. (SAW) Auberry Pm. Forest Prod. (SAW) Oinkey Creek Wickes Forest Ind. (SAW) Fresno

GLENN Louisiana-Pac (SAW) Elk Creek

HUMBOLDT Arcata Redwood (SAW) Orick Cal-Pacific (SAW) Orick Cal-Pacific (SAW) Hoopa Masoni te Hoopa SAW SVM Cal-Pacific Blue Lake McIntosh Lumber (SAW) Blue Lake Simpson Timber (SAW) Korbel McNamara & Peepe Lum. (SAW)Arcata Sierra-Pac Arcata SAW SPL Simpson Timber (PLY) Arcata Trend Lumber (SAW) Arcata Louisiana-Pac Samoa SAW SPL Schidbauer Lumber (SAW) Eureka Crown-Simpson Fairhaven Humboldt County Eureka Samills (SAW) Fortuna Pacific Lumber (SAW) Fortuna Halvorsen Lumber (RMN) A1 ton Carlotta Lumber (SAW) Carlotta Louisiana-Pac SAW Carlotta Louisiana-Pac [SAW] Dinsmore Pacific Lumber Scotia 22.5 (E) SAW SP\ Eel River Samills (SAW) Redcrest Georgia-Pac (SAW) Myers Flat Company Name Lum. Prod. WW Fuel Ind. Boiler Total Steam Total WW Max. Fuel Elec. Gen. County & Plant Type Location (1061YR 1976) (W)ood Capacities Prod. Cap. Used Boiler Inpt. (P)roposed (B)ark (106 BtulHR) (103 TIYR) (103 TIYR) (TIHR) (E)xisting

Louisiana-Pac [SAW) Alderpoint 35 bt Blue Ox Lumber (SAW) Eureka 0.8 bf Louisiana-Pac (SAW) Big Lagoon 33 bf Simpson Timber (SPL) Fairhaven Louisiana-Pac (PAR) Arcata 184e ft2 Twin Harbor (HAR) ' Dinsmore 25 ft2 Twin Parks (SAW) Arcata 7.8 bf Dimick Forest (BAR) Garberville -

KERN Louisiana-Pac (SAW) Inyokern 50 bf

LASSEh Main Ind. (SAW) Bei ber 21 bf Trin-CO Forest (SAW) Little Valley 6 bf Coin Lumber Susanville SAW 39.6 bf BAR Sierra-Pac Susanville SAW 96 bf BAR

LOS ANGELES Birchwood of LA (HPL) Los Angeles 4f ft2 Sunset Plywood (HPL) Los Angeles Plywood Prod. (HPL) Santa Fe Springs General Veneer Mfg. South Gate SPL

Torrance 5OOa ft2 6.5 ftz

MADERA AM. Forest Prod. (SAW) Oakhurst 30 bf Yancey Lumber (SAW) Madera 22 bf Am. Forest Prod. (SAW) North Fork 36.5 bf Norby Lumber (SAW) North Fork 9.4 bf Carney & Co. (BAR) Madera

MARIPOSA Carter's Sawmill (SAW) Mariposa .004 bf

MENDOCINO Louisiana-Pac (SAW) Cove10 35 bf Philo Lumber (SAW) Laytonville 26 bf Hardwood Products (SAW Branscomb 48 bf Hat-dwood Products (SAW1 Willits 29.4 bf Louisiana-PAC (SAW) Willits 40 bf Little Lake Ind. (RN) Willits Georgia-Pac (SAW) Louisiana-Pac SAW ~ouisiana-pac [SAW{ Hamson Lumber SAW) Louisiana-Pac (SAW) Masonite (SAW) Louisiana-Pac SAW PAR Phi10 Lumber (SAW) Phi10 23 bf Masonite Ukiah

-MODOC Suprise Valley Lumber(SAW) Cedarville 6 bf Calandor Pine (SAW) A1 turas 22 bf Edgerton Lumber (SAW) Adin 8 bf

NEVADA Sierra Mr. Mills (SAW) N. San Juan 34 bf Erickson Lumber (SAW) N. San Juan 5.3 bf Bear River Lumber Grass Valley SAW 32.7 bf RAR ~uby'~iverLumber (SAW) Grass Valley (;a) bf Douglas Lumber (SAW) Truckee 44.2 bf (Fibreboard)

Shelburne Ind. (HPL) Santa Ana 0.2a ft2

PLACER Am. Forest Prod. (SAW) Foresthill 38 bf h. Forest Prod. (SAW) Foresthill 32 bf Fi breboard (PAR) Rocklin 60e ftz Mountain Millinq (SAW) Rocklin 162),--, hf Lausmann Lum. &-hld (SAW) Loomis 28 if Brunswick Timber (RMN) Auburn Cmpany Name Lum. Prod. W Fuel Ind. Boiler Total Steam Total WW Max. Fuel Elec. Gen. County & Plant Type Location (IO~/YR 1976) (W)ood Capacities Prod. Cap. Used Boiler Inpt. (P)roposed (B)ark (106 BtuIHR) (103 TIYR) (103 TIYR) (TIHR) (E)xisting

Chester 75.6 bf 2se ft2 Greenville 25 bf Crescent Mills 60 bf Quincy 36.9 bf Quincy (25) bf Sloat 34.4 bf

SACMENTO Black Diamnd (SAW) Sacramento 47.2 bf

--SAN BERNAROINO Golden Bear Forest Prod. Redlands SAW 18 bf BAR Twin Peaks Timber Prod. Twin Peaks 20 bf (SAW

SAN DIEGO Solana Lumber (SAW) Solana Beach (6.2) bf

SAN JOAQUIN Cal Cedar Pmd. (RMN) Stockton Pacific Paperboard Stockton

SANTA CRUZ Big Creek Lumber Davenport SAW 16 bf BAR Holms Lumber fSAU) Scotts Valley 8 bf

SHASTA Fibreboard Burney SAW 40 bf HPL 72f ft2 Pub1 isher's Forest (SAW) Burney 98.5 bf Calavaras Cement (CEM) Pro.iect Citv - Cham~ionInt'l ~ndirson - SVM 120a ft2 SAW 69 bf Sierra-Pac (SAW) Central Val :ey 30 bf Coll ier Lumber (SAW) Reddi ng 12 bf Hudson Lumber (SAW) Anderson 30 bf Kimberly-Clark Anderson SAW 65 bf BAR Paul Bunyan Lumber Anderson SAW 40.4 bf. BAR

SIERRA Hol strom Lumber (SAW) Sattley 8.2 bf Sierra-Pac (SAW) ? Loyal ton 50 bfc

SISKIYOU SWF Plywood Haw Camp SVM 1 .oaft2 SAW 60.7 bf Hi-Ridge Lumber (SAW) Yreka 30,s bf Pine Mountain (SAW) Yreka 28 bf Int'l Paper Weed SAW 79 bf SVM 46b ft2 Cooper's Mi 11 Mt. Shasta SAW 27 bf BAR Kimberly-Clark (SAW) Mt. Shasta U.S. Plywood (Champion)SAW McCloud

Preston Lumber (SAW) Cloverdale G & R Lumber (SAW) Cloverdale Masonite (SAW) Cloverdale Berry's Samill Cazadero SAW BAR Calico Hardwoods (SAW) Windsor Chenoweth Lumber (SAW) Bodega Sonma Pacific (SAW) Schellville Louisiana-Pac (RMN) Cloverdale Cloverdale Prod. Cloverdale SVM SPL Company Name Lum. Prod. W Fuel Ind. Boiler Total Steam Total W Max. Fuel Elec. Gen. (KW) County & Plant Type Location (106IYR 1976) (W)ood Capacities Prod. Cap. Used Boiler Inpt. (P)roposed (B)ark (106 BtuIHR) (103 TIYR) (103 TIYR; (TIHR) (E)xisting

Diamond Int'l Red Bluff SAW SPL Louisiana-Pac (SAW) Red Bluff Crane Mills Paskenta -.a ... w BAR ~arris-crestline(SAW) Corning

TRINITY SWF Plywood (SAW) Burnt Ranch SWF Plywood Salver SAW ~VM Cal-Pacific (SAW) Weaverville Hyampom Lumber (SAW) Hyampom Sierra-Pacific (SAW) Hayfork Kimberly Clark (SAW) Wildwood Brooking's Plywood (PLY) Salyer

TULARE Wickes Forest Prod. Dinuba SAW BAR h. Forest Prod. (SAW) Johnsondale Sierra Pacific Terra Bella SAW BAR

TUOLDMNE Halter & Co. (SAW) Sonora (15.5) bf Snider Lumber Prod Chinese Camp SAW 16.5 bf BAR Fibreboard Fibreboard SAW SPL SVM BAR Whitt Mfg. Sonora (7.B)bf

YUBA Diamond Int'l (SAW) Marysville 40 bf W Erickson Lumber (SAW) Marysville 39 bf W Sierra Mt. Mills (SAW) Comptonville 15 bf

TOTAL

Assumptions: a 318'' basis ( ) Calculated value based upon: Plant Types: SAW samill b 118" basis 1. 1 LB wood produces 5 LB steam PAR particleboard plant PLYBAR plywoodbark plant plant c 1975 2. Boiler operation of 365 dayslyear SpL Softwood plywood plant RMN remanufacturing d Jeffrey's data 24 hourslday HAR hardwood plant e 314" basis 3. Actual steam production is approx. SVM softwood veneer mill HPLCEM cementhardwood plant plywood plak f 114" basis 75% of capacity 4, Plant production for 310 dayslyear Observations on Wildlife Abundance in Several Quercus California Black Oak Habitats in Northern kellogqii

Steven J. Kerns-21

Abstract: To determine the value of oaks to wildlife, five California black oak habitats and two "edge" areas were evaluated from April to June 1977 on the Shasta-Trinity National Forest. In each, sampling techniques included: a 3-acre bird transect, a 16-acre small mammal trapping area utilizing 9 Havahart traps, a small-rodent trapline with 20 Havahart traps, one 660 foot-long deer-elk transecty and one bait station designed to obtain fur samples. Mature oaks with scattered conifers and a moderately heavy understory of shrubs and grasses ranked highest for number of species and abundance of birds, rodents, deery and elk. Next in import- ance was the edge between the above type and young oak stands, followed by the edge between mature oaks and conifers.

My first involvement with oaks came in areas utilized by wildlife.-31 1977 when a forester asked, "How valuable are California black oaks to wildlife?" A moment later he stated, "sixty thousand acres of THE STUDY black oak on the Shasta-Trinity National Forest are currently categorized as under- This area is located on the east fork stocked backlog, and thus are subject to con- of Squaw Creek, which is a major tributary of version to conifers." Because much of this the Sacramento River. Elevations range from land was suspected of being prime wildlife 2y000 to 2,700 feet. Aspect is basically area, he got my immediate attention. southwest with an average slope of 25 percent. One main draw and several smaller draws make Soon after his pronouncement, this up the drainage- Three permanent water seeps forester requested input from wildlife . are located within one draw,with the others biologists to the potential conversion pro- having only intermittent flows. Although not gram. The biologists1 response was to evaluate quantified, some acorns were produced by which California black oak habitats were most California black oak in the fall of 1976. At beneficial to a wide range of wildlife species. the time of sampling in the study area, all Between April and June 1977 a 267-acre site but inviable acorns had disappeared. Newly representing a typical conversion area became dug holes and recently broken acorn shells on a wildlife observation area. Within it, the ground indicated, however, that viable National Forest and California Department of acorns remained, either buried or hidden under Fish and Game Wildlife Biologists identified leaves. five oak habitats and two transition or "edge" Temperatures in the area range from 105 degrees F. in the summers to 15 degrees F. in L1 Presented at the Symposium on Ecologyy the winters. Precipitation ranges between 35 Management and Utilization of California Oaks, and 60 inches each year. June 26-28, 1979, Claremont, California. -31 James Gordon, USFS, Modoc National Forest, Alturas, California,and Charles Graves, Cali- Wildlife Biologist, Shasta-Trinity National fornia Department of Fish and Game, Chico, Forest, Forest Servicey U.S. Department of California, aided in this portion of the study. Agriculture, Redding, California. Vegetation is highly variable in the Mature Oak area. Large pure stands of any single species are rare. Most of the area is composed of This area was located on a south aspect small stands or groups of conifers and oaks. with slopes of 10 to 90 percent. The over- Within each black oak group, age generally is story was mature California black oak (SO- to constant. This is because nearly all stands 200-years old) which comprised 90 percent of are of sprout origin (McDonald 1969). A major the crown canopy. A few scattered Douglas- disturbance in the past killed the trees to firs and ponderosa pines and several snags added groundline from where they sprouted to form variability to the overstory. Understory the trees of today. As disturbance tends to vegetation consisted of deerbrush* perennial be frequent in this elevation zone, the grasses* and a few herbaceous species (fig. 1). vegetation is made up of a mosaic of species and age classes.5' Of ten this pattern is in- dicative of difference~in soils, old fire patterns, or local snow storms which cause severe breakage.

An inventory of the observation (study) area was:

Category --Acres Percent Unproductive forest land 69 26 Stocked commercial forest land 62 23 Land with commercial size black oak 44 17 Non-stocked commercial forest land -92 -34 267 100

Overall, California black oak com- prises about 48 percent of the overstory canopy, with the remainder occupied by conifers, other hardwoods, woody shrubs* and rock outcrops. In addition to the even-aged trees, California black oak stands often con- tain seedlings and seedling-sprouts and occasionally an old monarch 250 to 350 years Figure 1--Heavy understory vegetation, well old. developed crowns and good mast production typify a mature oak stand. Defining and recognizing groups of vegetation proved to be difficult, but eventually vegetational groups of specific Mature Conifer-Decandent Oak stand structure and species composition were identified. These were characterized further In this habitat, the overstory was 80 by understory plant species. Further refine- percent with a few remnant overmature oaks ment of the groupings led to five broad but (fig. 2). The understory consisted of SO recognizably different habitats and two major percent duff and litter* and 20 percent shade- transition or "edge1' areas. These were then tolerant shrubs such as poison oak, California keyed to specific locations on the ground and hazelnut, and California storax. described as mature oak, mature conifer- decandent oak, mixed oak-conifer, young oak, mature oak-conifer, mature oak-conifer edge, and mature oak-young oak edge.

McDonald, Philip M. California black oak. -In Forest Cover Types of North America. Society of American Foresters. Revised des- cription 1979. Young Oak

Here Califomia black oak, 80- to 100- years old, comprised 90 percent of the over- story. A few small poison oaks and other lesser vegetation were scattered in the under- story (fig. 4). The study area consisted of a 16-acre block located on a north-south bearing.

Figure 2--Only a few decadent oaks remain in the mature conifer stand.

Mixed Oak-Conifer

Twenty percent of this area was rock outcrops and scattered patches of brush and grass. Cover on the remaining 80 percent con- sisted of small stands of canyon like oak, Califomia black oak, ponderosa pine, and shrub Oregon white oak. In places the under- Figure 4--Young oak stands are characterized story was extremely heavy with several grasses, by a relatively closed canopy with little deerbrush, shrub Oregon white oak, bigleaf understory vegetation. maple, poison oak, and other shrubs being present (fig. 3). Mature Oak-Conifer

This area was located on a north-south ridge with a south aspect. It consisted of about 25 acres of ponderosa pine and California black oak. Each of these species contributed about equally to canopy cover (fig. 5). The sparse understory of shrubs and grasses, how- ever, was more typical of that found under pines.

Mature Oak-Conifer Edge

California black oak and conifers some- times occupy different but predictable portions of the landscape. The oak is found on hotter west and south aspects and where the site is of lower quality. Consequently, California black oak will occupy upper slopes and ridge- tops with conifers below. Where the mature oaks and conifers meet, a narrow edge habitat is created which often is only 50- to 100-feet Figure 3--A variable blend of tree and shrub wide. Less common, but wider edge occurs when groups of conifers and oaks intermingle, or hardwoods, other woody shrubs, and conifers when they gradually blend together. In this make up the mixed oak-conifer habitat. habitat, grasses, Califomia hazelnut, bigleaf Department of Fish and Game biologist maple, and various other shrubs and herbaceous as being sufficient to obtain needed plants grow under an overstory of mature oaks information. Nine wire-mesh Havahart and conifers. traps were systematically located in each. They were baited with walnuts for two weeks before actual trapping to give the squirrels sufficient time to become accustomed to the traps and attracted to the bait. Sampling was done 4 days per week during the study

Rodent Trap Lines - Each of these lines consisted of 20 Sherman live traps placed at 40-foot intervals. Each line was located in the middle of each bird transect. Peanut butter and oatmeal was the bait. Animals caught, includ- ing deer mice, California meadow mice, wood rats, and voles, were recorded, toe clipped, and released.

Deer-Elk Transects - These transects followed that recommended in the U.S. Forest Service Range Analysis Handbook. Ten sampling points were installed along transects at 66-foot intervals and monitored weekly. At each, all elk Figure 5--A 50-50 blend of mature California and deer pellet groups were counted, black oaks and conifers is common along the and all vegetation according to con- Sacramento River north of Lake Shasta. dition, trend, and composition was noted within a 70.5 inch radius. This radius equals 11400 acre, and with ten plots Mature Oak-Young Oak Edge amounts to 1/40 acre sampled. Collected data gave number of plants and animal- This edge, although narrow, also creates days of use in each acre of sampled a specific habitat for wildlife. Under the habitat. more open stand of mature oaks, the understory is well developed; under the dense young stand, Fur (Bait) Stations - Six bait stations it becomes sparse. Many species of plants are were hung from tree branches randomly found in this habitat, including a few unique located in different cover types. Each to it. station consisted of salmon wrapped in a burlap sack suspended from a tree Within each habitat type, wildlife limb by wire. Barbed wire was wrapped biologists employed five sampling techniques: around the branch on which the bait was hung. Thus fur-bearing "raiders" had Bird Transects - Each consisted of to go across the barbed wire to reach three acres and 21 monitoring stations. the bait. The transect was "read" by spending three minutes at each station and noting the species and location of all birds Because of the preliminary nature of seen or heard. Transects were visited the study and because of budgetary limitations, several times each week from April replications of study areas were not possible. through June. Birds seen were tallied The findings that follow are based on a com- and plotted on a scaled diagram of the bination of data from the sampling techniques transect. If a bird was consistently as well as visual observations. observed in a given area, that area was considered as a breeding territory. Next, locations also were noted if they RESULTS were within the transect boundaries. In this study mature California black Squirrel Traps - Each trapping site oak stands proved to be the most valuable consisted of a 16-acre area. This size habitat for wildlife. The large, tall trees was recommended by a Califomia with well-developed crowns frequently yield large numbers of acorns which are a prime food observed. The reason seems to be that the source for many species of wildlife. The combination of oaks and conifers provide associated understory vegetation also seems excellent aerial pathways, as well as good to be an important element contributing to the opportunities for denning, feeding, and loafing. value of the habitat. Where the understory High use also was observed by avian species as is abundant, there is a large number of wild- well. life species. Another reason is vertical edge (that created by the stratification of The fourth most important habitat is vegetation between the forest floor and the found where young oaks are the dominant cover. forest canopy). Such edge creates additional Here, the entire stand typically is quite niches especially for birds and squirrels dense, often with a closed canopy. Little (Leopold 1933). This, coupled with a variety sunlight reaches the forest floor, and under- of understory plant species and their differ- story vegetation is limited to scattered ent berries, seeds, Stems, and leaves, com- plants. This habitat is utilized heavily by bined to create desirable wildlife habitat. birds but very little by small rodents, Shelter from predators and storms, and suit- squirrels, deer, or elk. able microhabitat for resting and breeding are additional reasons. The mature California The mature oak-mature conifer habitat in black oak habitat had the highest use by deer, which the oak grows as single trees, clumps, elk, birds, and small mammals. or or groves generally is quite dense. Seed production from both conifers and oaks is high The second most important oak habitat and tree seed, rather than seed from under- for wildlife is the edge between mature oak story species, influences the kind and amount stands and young oak stands. Here it is the of wildlife. Bird and gray squirrel utilization variety in environment and foodstuffs that is is good within this area. In locales where important. Mature oaks give openness and sunlight penetrates to the forest floor, a few hence warmer temperatures, longer visual brush and grass species become established and distances, more plentiful acorns, and a large are utilized by deer and small rodents. variety of fruits and greenery from the abundant understory vegetation. Younger oaks tend to The remainder of the habitats studj-ed form more dense stands and have tight narrow are used marginally by wildlife as a whole. crowns with little space between them. Only The mixed oak-conifer assemb1,~eis extremely a small amount of sunlight is able to penetrate variable. Large variation in site quality due into these dense stands and the environment so to strong dissection of the land and a wide formed is cooler and darker than that of the variety of slopes and aspects influence the mature oaks. The lower vegetation on the amount and patterning of the vegetation. Shrub forest floor tends to be sparse and poorly Oregon white oak provides a unique cover as it developed. Few acorns or fruits are formed in forms an almost impenetrable "jungle" to man this environment. In intermediate environments, or large animals. Acorn production of this foodstuffs from the more open and more closed shrub in the study area is unknown, but thought environments are available, although to a to be poor and infrequent. Most, but not all, lesser degree, as well as foodstuffs from of the oak trees are young in this area, and . different numbers and perhaps different species thus acorn production overall is low. Species unique to the intermediate environment. Bird of nearly all the wildlife evaluated in this utilization within the mature oak-young oak study utilized this area to some degree. None, edge was nearly the same as in mature stands, however, found it to be preferred habitat. In but rodent, squirrel, deer, and elk abundance spite of the large diversity of environments, declined. lack of overstory and understory foodstuffs could have been limiting. The third most important habitat is the edge between mature oaks and conifers. This As conifers mature and increasingly edge can be very sharp with a stand of oaks occupy the site, the oaks begin to fade from abruptly ending and a stand of conifers the landscape. In the mature conifer-decadent beginning. Often it can be an intermingling oak habitat, an abundance of dead wood is of groups, and sometimes even a gentle blending found along with a high amount of woodpecker of conifers and hardwoods. activity. Because the understory tends to be sparse with little food available for wildlife, Where the transition is abrupt, the ground-dwelling creatures are infrequently edge effect is found within a very narrow zone observed. but it receives heavy usage as animals move between conifers and oaks. The intermingling Diversity in environment within a given of groups, or mosaic edge, is much wider, and habitat seems to increase use by wildlife. within it the highest squirrel populations were Thus overstory-understory combinations appear beneficial. A much more important factor, LITERATURE CITED however, appears to govern wildlife abundance and use. And that is acorns. Large California black oaks with well developed crowns are Leopold, Aldo consistently part of the three habitats in 1933. Game management. Charles Scribner's which the largest number and the most species Sons, New York. p. 131. of wildlife are observed. Indeed, the thought that "acorn production reigns supreme as the McDonald, Philip M. greatest contributor to the welfare of forest 1969. Silvical characteristics of California wildlife" (Shaw 1971) seems to be supported black oak. U.S. Dep. Agric. Forest Serv. by this study. Res. Paper PSW-53, 20 p. Pacific Southwest Forest and Range Exp. Stn., Findings from this study, although Berkeley, Calif. preliminary, are the best available for the specific area, and have proved valuable for Shaw, Samuel P. showing relative wildlife abundance in 1971. Wildlife and oak management. different oak-related habitats. They currently White, D. E. and B. A. Roach-Oak are being used to assess wildlife values on Symposium Proc., p. 84-89. Northeastern other possible conversion areas. Forest Exp. Stn,,Broomall, PA. Acorns-Food for Modern Man1

Jeanine A. ~erb~z'

Abstract: Acorns, fruit of the oak, offer a nutritional potential which has long been overlooked. In bountiful years surplus acorns remain after wildlife needs are met and seed crops are accounted for. The surplus could serve as a supple- ment to human diets. Through sharing my own experiences with acorns as a food source, I hope to entice others to experiment.

We have learned at this symposium that acorns will not be processed immediately, the acorn is of nutritional value to wildlife. store them in a freezer. Cold storage halts We also know that acorns provided the staple the work of tiny larvae which are a natural diet for indigenous cultures in California part of the acorn ecosystem. Removing the (Balls 1972, Bean and Saubel 1972). Therefore, outer leathery shell is the most tedious part we can assume a food value to modern man, even of processing. Apply pressure with pliers, though precise nutritional data is meager. cracking only the outer shell, and then peel Acorns are reported to be high in magnesium, it away. Remove the brown skin from the nut calcium and phosphorus (Crowhurst 1972). if possible. If the skin clings tightly, When compared to barley and wheat, acorns are submerge the shucked nuts in water for several slightly lower in carbohydrate and protein hours, rolling them between the palms frequently. content but higher in fat and fiber content The skins will loosen and float to the surface. (Bean and Saubel 1972), and therefore have a This skin is likely to be high in tannin con- higher caloric content per unit weight than tent and the nuts will leach more rapidly if grains. Acorns contain one disagreeable and most of it is remwed. The acorn nuts are potentially harmful ingredient, tannin, which next ground in a blender to desired fineness. has a bitter and astringent taste. Tannin, Add nuts to the blender one cup at a time, however, is easily leached out of the acorn. with a few tablespoons of water. When several cups of acorn meal have accumulated, proceed Native Indian methods of grinding, leach- with the leaching process. ing and drying acorn meal are well documented (Balls 1972, Bean and Saubel 1972). The tra- Indians worked in bedrock mortars, ideally ditional food product was an acorn pudding or near a running stream. Acorns were submerged mush, quite tasteless to modern palates. The for leaching or water was poured through a preparation of acorns can be adapted to modern finely woven basket containing the acorn meal. technology and the product, acorn meal, is Searching through my house for the equivalent quite versatile. To demonstrate, there are of a flowing stream, I turned to the plumbing acorn cookies for you to sample after the pro- system. A cloth bag of acorn meal was sub- gram. merged in the toilet where each flushing renewed the fresh water flow and no water was When acorns begin to fall, (usually in - wasted. Expect brown-colored water in the October), gather them as they drop from the toilet bowl for a few days while the leaching trees. Float the acorns in water, discarding progresses. When the water is clear, acorns the floaters and keeping the sinkers. If the can be remwed from the tank and drained. The leaching process can be accelerated by pouring hot water frequently through acorns in a cloth 'presented at the Symposium on the Ecology, lined colander. The key to any leaching method Management, and Utilization of California Oaks, is to continue until water passing through the Claremont, California, June 26-28, 1979. acorn meal is perfectly clear. The time will vary depending upon the year and the kind of "Forest Botanist , San Bernardino National acorns used. Forest, Forest Service, U. S. Department of Agriculture, San Bernardino, California. After leaching, the aoorn meal must be ACORN COOKIES drained well. It can be used immediately or dried and stored. Dry acorn meal on trays in 1 cup brow* sugar 2 cups flour a low wen (12S0 F) or leave them for a day or 213 cup shortening 112 tsp nutmeg two in a gas wen with no heat other than the 2 eggs 1 tsp cinnamon pilot light. Stir occasionally to hasten dry- 1 cup buttermilk 1 tsp baking powder ing. Acorn meal can be sun dried but must be 1 tsp. vanilla 1 tsp soda protected from birds and insects. After the 112 tsp salt meal is thoroughly dry, store it under refriger- ation or in a freezer. stir in last: 1 cup "quick" oatmeal 1 cup acorn meal I have used several kinds of acorns suc- cessfully, including non-nat ives. Quercus Cream sugar, shortening and eggs. Stir in -ilex and 9. suber seem to have a higher tannin vanilla, add buttermilk alternately with dry content than the native live oaks that I have ingredients. Mix well. Stir in oatmeal and tried. Quercus agrifolia, 9. chrysolepis and acorn meal. Drop teaspoonfuls onto greased Q. kelloggii all seem equally good to my baking sheet. Bake 12 minutes at 375' F. indiscriminate taste. Many sources report Q. kelloggii (California black oak) as a favored species among Southern California Indians. LITERATURE CITED

I have substituted acorn meal for portions Balls, Edward K. of the dry ingredients in breads, crackers and 1972. Early Uses of California Plants. cookies. I find that substitution of acorn meal University of California Press, Berkeley, for up to one third of the flour called for in California, 103 p. most recipes will not change the texture of the final product. Oatmeal cookie or muffin recipes Bean, Low11 John and K. S. Saubel are ideal for use with acorn meal. Just substi- 1972. Temalpakh - Cahuilla Indian Knowledge tute acorns for one half of the oatmeal called and Usage of Plants. Malki Museum Press, for in the recipe. With a little experimenta- Morongo Indian Reservation, Banning, tion, you too will find satisfaction arid good California, 225 p. nutrition from using acorns as a supplementary food source. Try it during years of plentiful Crowhurst , Adrienne harvest. 1972. The Weed Cookbook. Lancer Books, Inc., New York, N. Y., 190 p. Wood Products from California Oaks, Cal Oak Lumber Company Style1

Guy Hall and Richard Allerr21

Abstract: In 1965. Cal Oak Lumber Company,- -. with $7.400 capitalization, began utilizing native California oaks as its basic raw material. The then-conventional sawmilling machinery and techniques proved inefficient, wasteful, and only moderately successful. This led to development of the mini-log and mini-mill concept which enabled the processing of a wide variety of hardwood logs, including those of small diameter and excessive crook. Higher utilization in woods and mill, and production of more high-grade material proved the efficacy of the concept. Wood products presently produced are high-grade lumber and pallets plus industrial timbers, sawdust for mulching, and bulk and prepackaged firewood. Cal Oak, as the largest hardwood manufacturer in California, has milled an estimated 70MM board feet of hardwood logs. This paper will primarily deal with the products manufactured from oak logs. Subjects deserving separate attention include hardwood lumber harvesting techniques and species character- istics.

Several California oaks recently have Cal Oak has learned to deal with the relatively become new and important wood product resources. high susceptibility of western hardwoods to Development of this resource has been continuous various types of deterioration during process- since 1965, largely through the cooperative ing. Some of the categories of deterioration efforts of Cal Oak Lumber Company, the include: (a) fungi attacks which cause stain University of California Forest Products and discoloration of the finished product, Laboratory, the U.S. Forest Service, and (b) collapse and honeycomb during drying, others. As is true with most pioneering (c) damage by insects (wood borers), (d) end efforts, the path is seldom smooth. Many and surface checking of boards, and (e) dis- companies, large and small, have previously tortion and warping during drying. This is attempted the development and marketing of not to imply that Cal Oak has solved all the western hardwood lumber products. These various problems of producing and marketing authors know of no long-term survivors of western hardwood products. Indeed, Cal Oak these numerous attempts except Cal Oak Lumber is in a state of continuous research and Company, which unlike the others, depends development, seeking new and better methods entirely upon western hardwoods, chiefly oaks, and products . for its raw material base. Over the years, California black oak (Quercus kelloggii) , and valley oak (Quercus lobata) are two major western hardwoods which have Ñ Presented at the Symposium on Ecology, Management, and Utilization of California Oaks. been developed to commercial sawtimber significance by Cal Oak Lumber Company,with Claremont, California. June 26-28, 1979. California black oak comprising the bulk of production (fig. 1). Although this paper deals 21 President and Chief Forester, Cal Oak Lumber with California oaks, it should be noted that Company, Oroville, California. Both are Cal Oak utilizes many other western hardwoods forestry graduates from U.C., Berkeley. Mr. as well. Some of these include: tanoak Allen is presently employed by Siller Bros. (Lithocarpus densiflorus), Pacific madrone of Yuba City, CA. (Arbutus menziesii), California sycamore in diameter and 10 feet long. It soon became apparent that conventional mill equipment was wasteful and inefficient. Cal Oak simply was not able to utilize many otherwise sound trees due to crook and/or small diameters, nor was it able to utilize sound limbs and branches. An estimated 37 percent by weight of each tree was being left in the woods.

During 1972-74, Cal Oak designed and constructed an innovative new sawmill. In many respects it is like a conventional mill except that it is miniaturized to handle short logs from 315 to 8 feet in length. Unlike a conventional bolt mill which also handles short lengths of small-diameter logs, Cal Oak's new mill is not limited to one or two dimensions Figure I--A typical deck of California black all cut in one plane, nor is it limited to oak sawlogs at Cal Oak's mini-mill. small diameters. By using a carriage and band- saw headrig, it is capable of sawing logs from 7 to 48 inches in diameter. The headrig also gives the capability of turning each log 360 (), Fremont cottonwood degrees around its longitudinal axis. Thus (Populus fremontii), bigleaf maple (& the new mill can cut many dimensions selectively macrophyllum), northern California walnut for grade and produce lumber of better quality. (Juglans hindsii) , willow (Salix spp.) , and Logs are sawn specifically to maximize the out- others. put of higher grade lumber, and by utilizing short logs, with defects cut out, to produce The commercial development of black oak an abundance of 4 foot "clears". Although much has reversed previous thinking~thespecies shorter than the conventional 10 to 16 foot is now viewed as a valuable resource. Not so board lengths, these have been well accepted by long ago it was considered a "weed" and many many consumer$. The innovation of this system thousands of dollars and millions of board of milling has, of course, created some dis- feet were wasted through poisoning and gird- advantages.' Most notable is the restriction of ling. Now it is regarded as an asset, creating lumber length with its associated higher pro- jobs and incomes for primary industries duction and handling costs, and a traditional (harvesting and sawmilling), and raw materials buyer resistance. Nevertheless, advantages for many secondary manufacturing concerns overly compensate for the disadvantages. (pallet manufacturers, cabinet and furniture manufacturers, etc.). An interesting project The capability of cutting shorter than for an economist would be to quantify the conventional logs also allows utilization of dollar multiplier effect of this raw material. material which by normal sawlog standards would Conservatively, it is at least 10=1, which be culled due to crook. Thus more wood is means that for every dollar spent by.Cal Oak, utilized and less is left in the woods. Because ten dollars are generated into the nation's the short logs produced are not exactly "bolts" economy. and not really "sawlogs", Cal Oak coined the term "mini-log" to describe them, and the term Cal Oak Lumber Company depends largely "mini-mill" to refer to the new mill. on California black oak for its raw material base. The wood structure characteristics of The mini-mill allows Cal Oak to utilize this oak are very similar to the Appalachian many trees which formerly would not have been red oaks. One major difference is growth form. harvested, especially those having small While many commercial eastern oaks produce diameters and crooked boles (fig. 2). The much of their volume in relatively straight, mini-mill also allows the utilization of limbs main stems, a portion of older California and branches, previously left in the woods as black oak volume is found in limbs and branches. waste. Before the mini-mill, Cal Oak utilized Tree trunks are not always straight either. only 50 percent by weight of a given tree. Now, it is utilizing about 87 percent by weight of In its early years, Cal Oak operated a the same type of tree. By combining the 37 sawmilling operation using conventional mill percent additional utilization with another 25 equipment capable of utilizing only the branch- to 50 percent additional volume (by weight) free straight main stems and occasionally some from a given stand of previously unmerchantable of the limb material which was of sufficient trees, the mini-mill has increased total diameter and length to make a log 10 inches utilization of hardwoods by 62 to 87 percent. Vol. by % Wt.

Conventional Sawlog Additional Lumber Utilization by Mini-Mill Left in Woods, or Recovered as Firewood

From the 87% of the tree taken to the mini-mill, product recovery is approximately divided as follows:

60% Lumber & Shook, 33% is pallets of which

22% is cabinet, furniture, & paneling stock

is industrial timbers

Slabs & Edgings, is boxed as market firewood of which is sold as bulk firewood

is wasted - 207s

20% Sawdust & Shavings 17% is sold as mulch, etc. of which 3% is wasted - 20%

TOTAL 100%

Figure 2--Western hardwood utilization, mini-mill style 1978, by Cal Oak Lumber Co., Oroville, California. Figure %Pallet shook produced at Cal Oaks mini-mill stacked and waiting for manufacture into pallets. Figure 4--Upper grade oak lumber air drying in preparation for kiln curing. Most important is that the mini-mill can now produce a significant "overrun" from very difficult logs.

Logs for the mill are purchased on a weight basis with the price per ton varying with grade. The conversion from ton to board feet is about 6.5 to 1. The logs are trimmed, conveyed to the mill and there reduced to short lengths. About 300 to 400 such short logs are sawn in each 8-hour shift, with two shifts usually operating. The total for two shifts is about 25,000 board feet per day, plus 15 to 20 cords of firewood. Yearly production from the mill is about 6 million board feet plus the firewood.

By producing short pieces of precise length, width, and presurfaced thickness, the mini-mill produces pallet shook ready for assembly into pallets (fig. 3). This process alone has eliminated the need for a planing and cut-up process whereby certain desired grades are sized and precision-trimmed from longer lumber. Thus the mini-mill has eliminated the Figure 5--Cabinet door panels made of upper cut-up process, which wasted 20 to 25 percent grade oak are used in high quality kitchen of the limbs, and now produces graded pallet cabinets. shook ready for assembly into highgrade pallets. Of course, the high cost of machining associated with the cut-up process also was eliminated. Seven workers are required to operate the "floor" About 60 percent by weight of Cal Oak's of the mill. Additional personnel for the mill production is lumber. Of this 60 percent, second shift, for yard, shipping, remanufacture, slightly over one third is recovered as "upper sales, forestry and overhead bring total em- grade" material. After sawing, the boards are ployment to about sixty workers. carefully piled to permit good air circulation As shown in figure 2, most of an oak (fig. 4). Boards are air dried for three to tree is utilized. On a weight basis, Cal Oak's eight months, depending on weather, to bring products can be divided into three major the moisture content down to 24% or less. Ends categories: of the boards have been waxed to avoid checking. They are then placed in a dry kiln for further Lumber and shook 60 percent seasoning. This upper grade material is sold Slabs and edgings 20 percent primarily for use in cabinets (fig. 5), paneling Sawdust and shavings 20 percent and moulding (fig. 6), and furniture (fig. 7). Figure 6--Upper grade oak is used for molding stock, picture frames and other specialty items.

Figure 8--A finished oak pallet ready for ship- ment.

able to stand up to heavy loadings and last for about 4 years. Or, stated differently, oak pallets have a life expectancy of 70 uses as compared to a single use for some pallets. At Cal oak, the pallet line includes an automatic stacker and other sophisticated machinery to facilitate pallet assembly. A pallet line costs about $150,000. Four workers will put up 1200 pallets in an %hour shift. Each pallet presently sells for about $10.00, and most go to grocery chains.

Slightly over 10 percent of the lower Figure 7--Two typical oak products, a solid oak grade is produced as short industrial timbers table and oak panelling on the wall behind it. and blocking (fig. 9). Examples of their uses

The short "clears" mentioned earlier fit well into the manufacture of most of these products. The remaining two thirds of the lumber pro- duced is lower grade. Most of this balance is utilized at Cal Oak's pallet plant, or sold as pallet shook to other assembly plants. The pallet operation works in conjunction with the mini-mill.

Most people do not realize the importance of pallets in our society. Of all the uses of wood, pallets rank second in the United States. Fully 15 percent of all wood goes into pallets. Pallets from oak are considered the "Cadillac" Figure 9--Lower grade oak is cut Into short of such structures (fig. 8). They have to be 4 x 6 x 48 inch industrial timbers. Figure 10--Oak slab firewood (dried, fumigated, Figure ll--Twenty percent by weight of the Cal and shrink-wrapped in plastic) is packed in Oak mill production is in sawdust and shavings. 1 cubic foot boxes for retail sale in food markets.

have been in the construction of dock facilities overseas and tunnels of the Bay Area Rapid Transit System.

Merchandising oak firewood has taken some effort. Consumers want a clean, dry, insect- free product with high heat energy. Wood borers often infest dry oak and it is discon- certing to consumers to have the larvae, which resemble small worms, come out of the firewood and crawl around the room. The homeowner's next thought is that the borers will soon be boring in the walls of his house. At Cal Oak the wood is dried, dust and dirt blown off, fumigated, shrink-wrapped in plastic, and "stacked in cubic-foot boxes (fig. 10).

About half of the firewood produced by Cal Oak is sold in these boxes to large Figure 12--Oak burls can be made into attractive grocery concerns for retail sale. Naturally, wall clocks. the boxes are shipped on Cal Oak pallets. About 35 percent of the firewood is sold at the even for the mini-mill. Some of it can be used mill directly to local consumers, usually in for firewood. Cal Oak logging crews work pickup-load quantities. Some $75,000 of such closely with firewood cutters. The cutters wood is sold annually. About 15 percent of take the wood and Cal Oak has less slash to the firewood ends up as waste, but this per- clean up. Burls and twisted-grain slabs of oak centage is decreasing as home heating costs are utilized for clocks, tables, plaques, and increase. novelties. Oak burls can be truly beautiful (fig. 12) and good ones are expensive. The remaining 29 percent by weight of mill production is in sawdust and shavings (fig. 11). Over 85 percent of this is either California black oak, being a vigorous sold or given away as mulch, livestock bedding, stump-sprouter and periodically a prolific or other uses. About 15 percent is waste. acorn producer, regenerates naturally especially in areas of commercial harvest. This Other wood products from California natural regeneration, in addition to the large oaks include split and round firewood produced volume of smaller, not-yet harvestable stems, from forest log residue and reject logs at the which will reach commercial size over the next mill (as opposed to that produced from mill one or more decades, and a significant volume residue). After logging, parts of each tree of currently merchantable oak (supplemented by remain which are too small, rotten, or crooked other hardwoods), gives futurity to Cal Oak's operations. It also warrants Cal Oak's con- It is not enough that Cal Oak alone has tinued sophistication of its product line. successfully established a short, multi-diameter Remanufacturing technology and more and better log milling facility; precision-sized shook by-product utilization show particular promise. production direct from the sawmill; short- This means that Cal Oak (and any others who length upper-grade lumber acceptance; and the enter the western hardwood business) will have first waste-derived grocery shelf oak firewood to continue to meet the unique challenges product acceptable in volume material handling. presented by California hardwoods. These To continue its success at manufacturing and challenges occur in such areas as stem form, marketing native California hardwoods, Cal Oak light stand density, environmental consider- must continue to research and Implement new ations, harvesting, transportation, market and better ideas to successfully compete in peculiarities and limitations, and by-product tomorrows markets. utilization.

GPO 792-915/49 Plumb, Timothy R., technical coordinator. 1980. Proceedings of the symposium on the ecology, management, and utilization of California oaks, June 26-28, 1979, Claremont, California. Gen. Tech. Rep. PSW-44, 368 p. Pacific Southwest Forest and Range Exp. Stn., Forest Sew., U.S. Dep. Agric., Berkeley, Calif.

The symposium, held at Scripps College in Southern California, addressed most aspects of California's vast oak resource. Papers represented four major subject categories: ecologi- cal relationships, silviculture and management, damage factors, and products. Both scien- tific and applied information was presented, including original material not published previously. Individual topics ranged from taxonomy and historical relationships to man- agement of insects and diseases. and various oak products. In California. oaks' value for wildlife, recreation, watershed protection, and esthetics exceeds their value for traditional lumber and wood products.

Retrieval Terms: Quercus spp., California, ecology, silviculture, forest management, 1 1 forest protection I I I L ------d

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