Great Basin Naturalist
Volume 44 Number 4 Article 9
10-31-1984
Producer-consumer biomass in montane forests on the Arizona Mogollon Plateau
Warren P. Clary Shrub Sciences Laboratory, Intermountain Forest and Range Experiment Station, Provo, Utah
Peter F. Ffolliott University of Arizona, Tucson
Frederic R. Larson Forestry Sciences Laboratory, Anchorage, Alaska
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Recommended Citation Clary, Warren P.; Ffolliott, Peter F.; and Larson, Frederic R. (1984) "Producer-consumer biomass in montane forests on the Arizona Mogollon Plateau," Great Basin Naturalist: Vol. 44 : No. 4 , Article 9. Available at: https://scholarsarchive.byu.edu/gbn/vol44/iss4/9
This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. PRODUCER-CONSUMER BIOMASS IN MONTANE FORESTS ON THE ARIZONA MOGOLLON PLATEAU
Warren P. Clary', Peter F. Ffolliott-, and Frederic R. Larson'
.\bstract.— a substantially complete compilation of prodiicer-consmner biomass was achieved for two montane forest reference stands on the Arizona Mogollon Plateau. This compilation, containing published and previously unpublished data, shows these ponderosa-pine-dominated stands to be near the lower end of the biomass range of commercial forest types. The two stands averaged approximately 75 metric tons/ha of plant biomass. Consumers made up less than 0.01 percent of the forest biomass. About 9/10 of the measured consumer biomass consisted of domestic and native riuninants.
Knowledge of biomass quantity and distri- Description of Study Areas bution is useful for conceptualizing biological The study areas, part of the Colorado conditions of an ecosystem, and is necessary Plateau physiographic province (Fenneman for the study of primary and secondary pro- 1931 lie immediately north of the Mogol- duction, nutrient cycling, hydrology, and fire. ), lon Rim in central Arizona. The ponderosa Information on biomass is limited for many pine ecosystem occurs at elevations between vegetation types. Consumer data are particu- 1830 and 2590 m, although ponderosa pine is larly lacking in forested ecosystems where most strongly dominant between 2130 and mammalian herbivores are relatively less im- 2380 m (Schubert 1974). It spans the altitu- portant than in grassland ecosystems. Com- dinal range of Merriam's Tran.sition Zone paratively open forests, such as those of the (Merriam southwestern ponderosa pine (Finns pon- 1890, 1898). Most of the information presented was ob- derosa) ecosystem, represent an intermediate tained from the Beaver Creek watershed ecological position between dense humid for- south of Flagstaff, Arizona (Brown et al. ests and the more arid grasslands. Although 1974) and from Stermer Ridge near Heber, large herbivores are not as obvious here as in Arizona (Ffolliott and Baker 1977). A sum- the grasslands, their roles are significant. mary of their mean characteristics follows: Many different tree densities may occur within a forest ecosystem. Each density pro- vides a different combination of biological components. As information is accumulated from a variety of forested conditions, more accurate judgements can be made concerning the impact of vegetation management on the amount of plant and animal life likely to be supported.
The purpose of this paper is to synthesize the current published and unpublished infor- mation on producer-consumer biomass from several representative situations within the montane forest ecosystem on the Arizona Mogollon Plateau. These values are com- pared to situations where the forest stand has undergone severe changes. 628 Great Basin Naturalist Vol. 44, No. 4 present, and quaking aspen (Popiilns tremu- 1950s to the late 1970s. Some of the informa- loides) was occasionally found. The her- tion has not been reported previously, but baceous layer was dominated by such grami- much has been obtained from reports and noids as mutton bluegrass {Poa fendleriana), publications from the primary reference bottlebrush squirreltail (Sitanion hystrix), areas and supplemental study areas. The bio- blue grama {Bouteloua gracilis), black drop- mass estimates are most complete on the two seed {Sporobohis interruptiis), and dryland reference areas. Therefore, information from sedge (Carex geophila). In some areas Arizona these will be presented as base condition for fescue {Festuca arizonica) and mountain muh- forest stands on the Mogollon Plateau. Esti- ly {Muhlenbergia montana) were prevalent. mates of how the biomass quantity and com- Typical forbs and half-shmbs were showy as- position changes as tree density decreases ter {Aster commutatus), showy goldeneye {Vi- from either cutting or fire are based on infor- guiera midtiflora), western ragweed {Am- mation from supplemental areas. hrosio psilostachya), and broom snakeweed Assumptions for this synthesis include: (Gutierrezia sarothrae). The shrub layer was 1. The primary reference areas represent typical un- represented by Gambel oak sprouts and an even-aged cut-over ponderosa pine stands. occasional buckbrush ceanothus {Ceanothus 2. Typical forest grazing practices are followed on the fendleri) or New Mexico locust {Robinia cattle allotments. neomexicana). 3. A livestock animal-\mit represents 1121 kg/ha live weight. The vertebrate animal biomass was domi- 4. Native consumer populations have luiiform distribu- nated by Riminants. Cattle {Bos taunts), elk tion of sex and age classes. {Cervus canadensis), and deer {Odocoilens Information sources used to estimate bio- hemionns) were the primary species. Impor- mass are shown in Tables 1 and 2. Only tant smaller mammals included deer mouse aboveground living biomass near growing {Peromysciis maniculatns), brush mouse {P. boylei), Mexican woodrat {Neotoma mexi- cana), cliff chipmimk {Eutamias dorsalis), Table 1. Sources of producer biomass estimates for gray-collared chipmunk (£. cinereicollis), Beaver Creek and Stermer Ridge. golden-mantled ground squirrel {Spermo- Woody plants phihis lateralis), Mexican vole {Microtus mex- Ponderosa pine icanus), cottontail {Sylvdagus nuttallii), and — Individual stem equations from Gholz et al. Abert squirrel {Sciurus aberti). Reptiles in- (1979). (Data from Fort Valley Experimental For- cluded eastern fence lizard {Sceloporus iindu- est, Arizona). — Stand tables from Brown et al. (1974) and latits) and tree lizard {Urosarus ornatus). The Ffolliott and Baker (1977). more common birds included common flicker Gambel oak {Colaptes auratus), Steller's jay {Cyanocitta — Individual stem equations based on file data, stelleri), white-breasted nuthatch {Sitta caroli- Shrub Sciences Laboratory, Provo, Utah. — Stand tables from Brown et al. (1974) and nensis), pygmy nuthatch (S. pygmaea), Ffolliott and Baker (1977). Grace's warbler {Dendroica graciae), and Alligator juniper gray-headed junco {Junco caniceps). Insects —Individual stem biomass based on data from Bar- and other invertebrates were excluded from ger and Ffolliott (1972) and Miller et al. (1981), this study. and equations from Gholz et al. (1979). — Stand tables from Brown et al. and Supplemental information from other pon- (1974) Ffolliott and Baker (1977). derosa-pine-dominated montane forest stands Aspen was obtained from the Rattle Burn area —Individual stem equations from Peterson et al. southwest of Flagstaff (Campbell et al. 1977), (1970), -Stand table Brown et al. from several wildfire burns northwest of from (1974). Shrubs (including Gambel oak sprouts) Flagstaff (Lowe et al. 1978), and from an ear- —Field sample for current leaf and twig growth ad- lier informational synthesis (Clary 1978). justed to total biomass based on Whittaker and Woodwell (1969) and Brown (1976). Background and Procedures Herbaceous plants The information presented was synthesized —Data from Clary (1975) and Ffolliott and Baker (1977). from source data collected from the late October 1984 Clary et al.: Montane Forest Biomass 629 season end was calculated. Two trophic lev- Differences in biomass on the supplemen- els are presented— producers and consumers. tal study areas (with and without reductions Because no reliable carnivore information in overstory tree density) are expressed as was found, no attempt was made to estimate percent change because of some differences biomass of carnivores. Also, because of a lack among areas in manner of data collection. of insect information for the herbaceous lay- er, no insect biomass was estimated for modi- Results in Reference Areas fied forest conditions. Producer Table 2. Sources of consumer biomass estimates tor Beaver Creek and Stermer Ridge.' Plant biomass on the two reference areas, Beaver Creek and Stermer Ridge, totaled Domestic 83,459 and 67,943 kg/ha, respectively (Table Cattle —Biomass based on average animal-unit-month car- 3). Coniferous trees made up approximately rying capacities (Clary 1975) and from field sam- 89 percent and hardwood trees approx- pling of fecal dropping densities. imately 11 percent of the producer biomass, and shrubs and herbaceous plants contributed Native only trace amounts. conifer Elk The category — .\nimal-days from fecal group data of Neff (1972), consisted of 98 percent ponderosa pine and 2 Knise (1972), Clary and Larson (1971), Ffolliott and Baker (1977), and Neff (pers. comm.). T.\BLE 3. Producer-consimier biomass estimates. —Live weight per animal from Murie (1951) and Quimln and Johnson (1951). Deer — Animal-davs from fecal group data of Neff (1972), Kni.se (1972), Ffolliott and Baker (1977), and Neff (pers. comm.). —Live weight per animal adjusted from McCulloch (1962). Tree squirrels —Density estimates from David Patton (pers. comm.).
—Live weight per animal from Patton et al. (1976). Rabbits —Density estimates from fecal count data of Costa
et al. (1976). —Live weights per animal from field sampling. Croimd-dwelling rodents —Beaver Creek biomass from Goodwin and Hun- gerford(1979). —Stermer Ridge density estimates by field trapping with calculations according to Schnabel method (Overton and Davis 1969), and home range areas estimated from wildlife literature. Birds —Beaver Creek breeding bird densities and live weights from Szaro (1976). — .\ge-class distribution from Wiens and Innis (1974). —Stermer Ridge bird densities determined bv strip
census. Live weights from Carothers et al. (1973). Reptiles — Densitv estimates from strip census and calcu- lation method of Hayne (1949). —Live weight per animal from Universitv of Ari- zona collection. Insects —Direct sampling of insect biomass (dry weight) per unit weight of conifer and hardwood foliage from Ronald Yoimg (pers. comm.).
Live weight multiplied by 0.3 gives dry weight (Davis and Golley 1965). 630 Great Basin Naturalist Vol. 44, No. 4 percent alligator juniper. The deciduous tree 1974, Ffolliott and Baker 1977) suggests that biomass was nearly all Gambel oak with only these stands, and indeed most cut-over south- a trace of aspen. Woody tissues dominated. western ponderosa pine stands (Pearson Tree boles constituted 69 percent and 1950), would have a much younger average branches made up 24 percent of the total age and much less accumulation of biomass producer biomass. Only 7 percent of the late than the stands of Whittaker and Niering growing-season standing crop biomass was fo- (1975). While the latter stands apparently liage, which is the primary food source for represented specific situations (sampled by most of the consumer component of the 0.1-ha plots), the reference stand data of this forest. study represented the average situation
These proportions vary in their com- across several hundred hectares of forest. It is parability to other forest types. Conifer likely, therefore, to be acceptably representa- stands are often 3-5 percent foliage, 12-17 tive of cutover forests. In comparison to sev- percent branches, and 78-85 percent boles eral forests in other areas, the reference (Grier et al. 1981, Whittaker and Niering stands contain biomass equivalent to 17 per- 1975). Balsam fir {Abies hahamea) may be 23 cent of a 180-year-old Pacific silver fir {Ahies percent foliage and only 59 percent boles amahiUs) stand in Oregon (Grier et al. 1981), (Post 1970). Hardwoods are generally 2-3 about 73 percent of several Wisconsin hard- percent foliage, 18-34 percent branches, and wood forests (Crow 1978), and about 185 63-79 percent boles (Crow 1978, Post 1970, percent of a 26-year-old mountain maple Ovington et al. 1963). Thus, the montane stand {Acer spicatum) in New Brunswick conifer-dominated Mogollan Plateau forests (Post 1970). are similar to other conifer forests in their proportion of foliage, but similar to many Consumer hardwood forests in the proportion of branches and boles. A possible reason is that The producer biomass supported a com- most southwestern ponderosa pine forests are paratively small amount of consumer biomass rather open. This open characteristic may en- (Fig. 1). The consumer biomass was approx- courage the production of large branches, a imately 3 to 7 kg/ha, or less than 0.01 per- trait typical of southwestern ponderosa pine cent of the total. Domestic herbivores, prin- (Pearson 1950). cipally cattle, made up 86 percent of The tree biomass in these reference stands consumer biomass. The remainder was con- averaged approximately 75 metric tons/ha. tributed by a variety of native species
This value is toward the lower end of the (Table 3). range of 50-300 tons/ha for Rocky Mountain Nearly three-quarters of the native verte- forests suggested by Weaver and Forcella brate consumer biomass was contributed by (1977). The value appears reasonable because the large mammalian herbivores— elk and the ponderosa pine vegetation type normally deer. The categories of "birds" and "ground occupies the lowest elevation and the lowest rodents and rabbits" each contributed about precipitation zone of the commercial forest one-tenth of the native vertebrate biomass, types in the Southwest. However, in climax although it should be noted that rabbits gen- or near-climax ponderosa pine stands on the erally have very low populations in south- Santa Catalina Mountains near Tucson, Ari- western ponderosa pine forests (Costa et al. zona, the total stand biomasses were 213-330 1976). The remaining vertebrate biomass val- percent greater than the reference stands of ues were contributed by "tree squirrels" and this study (Whittaker and Niering 1975). "reptiles." The insect biomass exceeded all These relatively mature climax stands had categories of native vertebrates except "elk double the basal area per hectare of the Mo- and deer." gollon Plateau reference stands, and their av- Examination of the consumer distribution erage stem age of 93-150 years was probably suggests that a majority of the native verte- much greater. Although the age structure of brate biomass and nearly all livestock bio- the reference stands was not determined, the mass were supported by herbaceous plants, large number of small stems (Brown et al. which contributed less than one-half percent October 1984 Clary et al.: Montane Forest Biomass 631
All trees CONSUMER ncreased 300% removed
PRODUCER reduced 99%
Reference forest stands CONSUMER 3 to 7 kg/ha
PRODUCER 67,943 to 83,459 kg/ha
Fin. 1. Simplified hioinass p\iaiiiid for reference stands, and the approximate proportional change following tree removal. of the total biomass. Ponderosa pine trees ap- The biomass values given represented late- peared to provide the most direct food growing season situations. Live biomass dur- source and foraging substrate benefits to tree ing midwinter would be lower. Nearly all of squirrels (Patton 1975), certain bird species the herbage, all of the deciduous tree foliage, (Szaro 1976), and certain insect species (Ron- approximately one-third of the coniferous ald Young, pers. comm.). Gambel oak foliage, tree foliage, and a great majority of the con- which constitutes only about 6 percent of the sumer biomass would be absent then. The woody plant foliage, apparently provides a large herbivores, many birds, and some of the substantial contribution to consumer nutri- carnivores migrate to warmer winter habi- tion. Oak leaves were a major component of tats, leaving a much reduced consumer mule deer summer diets on the Mogollon biomass. Plateau (Neff 1974), and Gambel oak foliage The authors know of no other compilation supported insect biomass at approximately of forest consumer biomass against which five times the rate per unit weight of foliage these reference stand estimates may be as did ponderosa pine (Young, pers. comm.). compared. Normal activities of forest insects may be more important in energy flow and nutrient Results in Areas after cycling than are other consumers. If con- Reductions in Tree Density sumption by insects approaches 7 percent of total forest foliage biomass (Whittaker and Several sources of information show what Woodwell 1969), insect consumption in these happened to the consumer biomass when reference stands would approximate 350 partial reductions in the timber stand oc- kg/ha. This amount would greatly exceed curred (Table 4). As the forest density was re- that taken by all other consumers combined duced, tree foliage and total biomass were re- because it would exceed the total biomass of duced, and the biomass of herbaceous and the shnib and herbage components. Insect some shrubby plants increased. A parallel re- consumption at only half this amount would sponse in vertebrates occurred, with ground- still likely equal the amount taken by all feeding consumers tending to increase, and other consumers. those species most directly dependent upon 632 Great Basin Naturalist Vol. 44, No. 4 the trees, such as tree squirrels, tending to de- (pronghorn replace elk and deer, for ex- crease as forest density was reduced. Some ample) (Clary 1978). reductions in tree density occurred without Tree squirrels and many birds were usually reductions in bird life (Szaro 1976). If reduc- supported in higher biomasses in the forest tions in tree density result in accumulations than in the openings (Patton 1975, Szaro of slash, large proportional increases can oc- 1976). However, total bird biomass some- cur in small mammal populations (Goodwin times actually increases following tree re- and Hungerford 1979). moval when smaller tree-foraging birds are Total removal of trees resulted in much sufficiently replaced by larger ground-forag- less foliage per hectare. Nevertheless, the in- ing species (Lowe et al. 1978). Different re- creased herbaceous foliage supported a sever- sponses by birds to areas with trees removed al hundred percent increase in vertebrate were probably due to differing residual habi- consumer biomass (Table 4). This increase tats. Little habitat variety remained after was primarily a reflection of the difference in complete logging, whereas wildfire left a carrying capacity for livestock, although bio- large number of standing dead trees that pro- masses of many species of wildlife also in- vided specialized habits for certain bird and creased when herbaceous plants increased. small mammal species. Because the productivity of herbaceous vege- tation was higher, many ground-dwelling Conclusions wildlife species maintained higher biomasses in the absence of trees, particularly when The ponderosa-pine-dominated reference cover was present (Goodwin and Hungerford stands on the Mogollon Plateau averaged ap- 1979, Campbell et al. 1977, Reynolds 1962). proximately 75 metric tons/ha of plant bio- However, considerable variation in the den- mass. Consumers made up less than 0.01 per- sities of both small and large herbivores oc- cent of the total forest biomass, but increased curred, apparently because of cover require- in stands where tree densities were reduced. ments. Variations in the size of the opening, However, even the loss of all trees resulted in topography, presence of woody plants, and a gain of only 20 to 30 kg /ha of consumer the presence of slash and other low cover biomass. will result in differences in native herbivore These montane forests are near the lower densities. Available information suggests vari- end of the biomass range for commercial for- ations of ± 60 percent to 80 percent will oc- est types, but we know of no forested situa- cur. Animal species shifts also occur as open- tion for which equivalent estimates of con- ings become large if little cover is present sumer biomass are available. Therefore, no
Table 4. Percentage estimates of several biomass responses to reduction in forest stand densities.
Percentages
Several ages of Recent wildfire Recent wildfire Several ages of Several ages of thinning' burn- burn- wildfire burn' logging'
Woody plants 29 decrease 44 decrease"' 94 decrease' 99 decrease 100 decrease Herbaceous plants 57 increase 128 increase 195 increase 270 increase 451 increase Domestic animals Cattle 51 increase 14 increase 145 increase 375 increase Native animals Elk and deer' 67 increase 125 increase 90 increase 105 increase 200 increase Ground dwelling rodents 100 increase 109 increase 65 increase 40 increase 200 increase Tree squirrels 50 decrease 100 decrease Birds no change 73 increase 90 decrease Insects —
'Clary 1978
-Campbell et al. 1977.
'Lowe et al. 1978. 'Ba.sal area chanj;e. 'Conimercial volume change.
"Biomass of these larger animals is not supported on a continuous basis in forest openings because of their movements in and out. The biomass value given is proportional to the amount of use received. October 1984 Clary et al.: Montane Forest Biomass 633 comparisons are possible for the ability of the Ffolliott, P. F., and M. B. Baker, Jr. 1977. Character- istics of .\rizona ponderosa pine stands on sand- Mogollon Plateau forests to support con- stone soils. L'SD.A For. Serv. C.en. Tech. Rep. sumer biomass in relation to other forest RM-44. 7 pp. of the types. We do know that, because most Gholz, H. L., C. C. CIrier, A. G. Campbell, and A. T. vertebrate consumer biomass consisted of Brown. 1979. Equations for estimating biomass ruminant grazers, the secondary production and leaf area of plants in the Pacific Northwest. Forest Research Laboratorv, Oregon State Uni- in tliis forest is easily channeled into meat versitv, Corvallis. Res. Pap. 41. 37 supplies for people. pp. Goodwin, G., Jr., and C. R. Hlnoerford. 1979. Ro- We feel there should be more thorough in- J. dent population densities and food habits in .\ri- of vestigations of biomass components most zona ponderosa pine forests. USDA For. Serv. biological systems. This would provide an im- Res. Pap. RM-214. 12 pp. proved basis for the understanding of the ba- Grier, C. C, K. a. Vogt, M. R. Keyes, and R. L. above- sic structure and fimctioning of natural and Edmonds. 1981. Biomass distribution and and below-ground production in young and ma- modified ecosystems. ture Abies amabilis zone eco.systems of the Wash- ington Cascades. Canadian For. Res. Literature Cited J. 11:1.55-167. Bai«;kh, R. L., and P. F. Ffolliott. 1972. The physical Havne, D. W. 1949. An examination of the strip census characteristics and utilization of major woodland populations. method for estimating animal J. bee species in Arizona. USDA For. Serv. Res. Wildl. Manage. 13:145-157. 80 Pap. RM-8.3. pp. Kbuse, W. H. 1972. Effects of wildfire on elk and deer Bhown, H. E., M. B. Baker, Rogers, \V. P. Jr., J. J. use of a ponderosa pine forest. USDA For. Serv. Clary, L. Kov.ner, F. R. Larson, C. C. Avery, J. Res. Note RM-226. 4 pp. AND R. E. Campbell. 1974. Opportunities for in- Lowe, P. O., P. F. Ffolliott, H. Dieterich, and D. creasing water yields and other multiple use val- J. R. Patton. 1978. Determining potential wildlife ues in ponderosa pine forest lands. USD.\ For. benefits from wildfire in Arizona ponderosa pine Serv. Res. Pap. RM-129. .36 pp. forests. USDA For. Serv. Gen. Tech. Rep. RM-52. Brow N, |. K. 1976. Estimating shrub biomass from basal 12 For. Res. 6:153-158. pp. stem diameters. Canadian J. McCulloch, C. Y. 1962. Influence on carrying capacity Campbell, R. E., M. B. Baker, Jr., P. F. Ffolliott, F. of experimental water conservation measures. R. Larson, and C. C. Avery. 1977. Wildfire ef- Ariz. R-6; WP5, Ariz. Game and fects on a ponderosa pine ecosystem: an Arizona FAP W78 J7. case studv. USDA For. Serv. Res. Pap. RM-191. Fish Dept., Phoeniz, Arizona. 19 pp. C. H. 1890. Results of a biological .survey of 12 pp. Merriam, desert of S. \\'., R. and R. P. Balda. the San Francisco Mountain region and Carothers, J. Haldeman, 1973. Breeding birds of the San Francisco Moun- the Little Colorado in Arizona. USDA, Div. of tain area and the White Mountains, Arizona. Ornithology and Mammalogy, North American Museum of Northern Arizona Tech. Ser. 12. Fauna 3. 136 pp. Northern .\rizona Society of Science and .\rt. 1898. Life zones and crop zones of the United Flagstaff. 54 pp. States. USDA, Div. of Biological Survey Bull. 10. Clary, W. P. 1975. Range management and its ecologi- 79 pp. cal basis in the ponderosa pine type of Arizona: D. 1981. Miller, E. L., R. O. Meeuwk;, and J. Bcdy. the status of our knowledge. USDA For. Serv. Biomass of singleleaf pinyon and Utah juniper. Res. Pap. RM-158. .35 pp. USDA Forest Serv. Res. Pap. INT-273. 18 pp. 1978. Producer-consumer biomass in .Arizona 1951. elk of North America. Stockpole MuRiE, O. J. The ponderosa pine. USDA For. Serv. Gen. Tech. and Co., Harrisburg, Pennsylvania, and the Rep. RM-56. 4 pp. Wildl. .Manage. Inst., Washington, D.C. 376 pp. deer use Clary, W. P., and F. R. Larson. 1971. Elk and D. 1972. Responses of deer and elk to Beaver Neff, J. to food sources in Arizona ponderosa are related Creek watershed treatments, .^nnu. .\riz. Water- For. Serv. Res. Note RM-202. 4 pine. USDA pp. shed Symp. Proc. 16:18-24. Costa, R., P. F. Ffolliott, and D. R. Patton. 1976. 1974. Forage preferences of trained mule deer on Cottontail responses to forest management in the Beaver Creek watersheds. Ariz. Game and southwestern ponderosa pine. USD.\ For. Serv. Fish Dept. Spec. Rep. 4. 61 pp. Res. Note R.\l-.3.30. 4 pp. Overton, W. S., and D. E. Davis. 1969. Estimating the
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