Proceedings of the Symposium on the Ecology, Management, And

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 today. The Agrifoliae, Lobatae, and Quercus chrysolepis 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 genus, 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 plant 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 evolution of oaks. secondary teeth on the lobes. This lineage includes leaves 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- Colorado (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 fossils 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 Quercus tomentella 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 northern California. 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 Castanopsis. 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 rain, 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 deciduous, and broadleaved ever- chrysolepis. green plants, 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 20Â°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 oak woodland 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 assemblages 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), Oregon, in press. The Miocene Seldovia Point USA. Am. Jour. Botany, 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 Sacramento Valley 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.

Ã‘'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, (Quercus garryana, 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 identify as typically Californian. Attention naturally 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 savannas, having a parklike appearance. 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 clearing 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 Savanna 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 (Chestnut 1902; Baumhoff 1963). ing range land, channelizing streams, 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 animals 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 throughout 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 Salinas Valley. 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 requirements 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 Santa Clara Valley, 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 particular 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 Ã‘'~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 fungus 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 soil". 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 individual 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 gophers 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 Tehachapi Mountains, "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 (Pinus sabiniana) 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 treatment 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, Ã‘~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 cutting 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 therefore 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 centuries 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 savannas, 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. 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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 Quercus douglasii 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 production 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 identification, but on hybridization between species, which sometimes complicates identification. Three hybrid complexes are discussed: 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 inflorescences. often in the same To the casual observer the tanoak looks inflorescence -- 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 catkin. 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 Shrubs", 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 (depending 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 shrub, 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 Quercus turbinella, 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 populations,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 northern Baja California. 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 preceding 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 Arizona, 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 principles. 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 establishment 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 computerized 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. Ã 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-jÃ‘Ãrom 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 pollination 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 Ã‘ 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 intermediates 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 (Fagaceae). 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 morphology 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%), transferred 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. Ã‘~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 Epidermis 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 promising 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 significance 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 photosynthesis ^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 availability, 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 evergreen 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 reproductive 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 mediterranean 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 replacement 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 measurements 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 Juglans californica 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 foothill zone of Sequoia National Park, California, during the very dry winter of 1977 and the subsequent moist winter of 1978 allow an interpretation 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 conditions 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 rains 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 Insect 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 -2SÂ° (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, tannin 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 tannins, 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 moth 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 Transverse Ranges 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 contiguous 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 Ã‘1~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 apparently 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 confined 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) Ã‘~retally data; see 3/ above. Ã‘~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 Ã‘'~ 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 increasing slope class- from 37 percent on slopes less than 20Â 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 comparison 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 Â±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 containing 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 woodlands (Dodge 1975). This paper presents some evidence that the differential response of these 2 species to fire during establishment may be an additional 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 7SÂ° to well over 220Â° temperature of 175'~ and 20 seconds above 6SÂ°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 protected 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 mechanism 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" woodlands 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), Ã‘1~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)Ã‘hint 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 identification 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 resourcesÃ‘a 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 chestnuts 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 Ã‘j~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, New Mexico 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 rhizomes 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 sexual reproduction 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 declining 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 Ã‘1~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 vertical 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 STREAM 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 reproduction 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 individuals 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 Â all 42-year periods in the future; that is, E v if they are held constant, the matrix may be 0.2r AÂ 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 decline 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 Stanislaus River region to south has less precipitation, 40+ inches (1100 mm) and lacks many of the Mixed Evergreen constituents. 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** Melica 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 Sanicula bipinnata Calocedrus decurrens* Stipa 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, rely 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 distributions, 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 hardwood 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 distribution 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 variables 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 correlation 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. Ã‘'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 Ã‘l~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+ Ã‘27 -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 Klamath Mountains 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 ...... Â¥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 ArmÂ¥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 - Â¤. 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 establishment 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)