Applying Biogeographic Principles to Resource Management: a Case Study Evaluating Holdridge's Life Zone Model

Great Basin Naturalist Memoirs

Volume 2 Intermountain Biogeography: A Symposium Article 16

3-1-1978

Applying biogeographic principles to resource management: a case study evaluating Holdridge's Life Zone model

James A. MacMahon Department of Biology and Ecology Center, Utah State University, Logan, Utah 84322

Thomas F. Wieboldt Department of Biology and Ecology Center, Utah State University, Logan, Utah 84322

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Recommended Citation MacMahon, James A. and Wieboldt, Thomas F. (1978) "Applying biogeographic principles to resource management: a case study evaluating Holdridge's Life Zone model," Great Basin Naturalist Memoirs: Vol. 2 , Article 16. Available at: https://scholarsarchive.byu.edu/gbnm/vol2/iss1/16

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 Memoirs by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. APPLYING BIOGEOGRAPHIC PRINCIPLES TO RESOURCE MANAGEMENT: A CASE STUDY EVALUATING HOLDRIDGE'S LIFE ZONE MODEL

1 1 2 James A. MacMahon and Thomas F. Wieboldt -

Abstract.— Conservation schemes require some portioning of the world into a discrete number of subunits which might benefit from similar management practices. The Holdridge Life Zone scheme, proposed for such

purposes previously, is applied to Utah as an initial test of its usefulness. A hypothetical life zone map was devel- oped entirely on the basis of weather station data and data derived from these values. This predictive map compared favorably to data on patterns of vegetation, mammal, reptile, and amphibian distribution in Utah.

Since the publication of MacArthur and (1977a) suggested a series of concrete steps Wilson's (1967) analytical approach to the one might opt to test the various hypoth- biogeography of islands, several authors eses. It was hoped that this would be appli- have attempted to apply island bio- cable on a world scale. geography theory to the problem of opti- In summary the suggestion was to deter- mum size and number of nature reserves. mine the most sensitive species to be pre-

Several aspects of theory have been in- served (i.e., rarest, largest, highest trophic- voked including species/ island area relations level, most vagile, etc.). This species deter- (Diamond 1975, Sullivan and Shaffer 1975, mines the minimum size of the reserve area. Wilson and Willis 1975) and extinction rates One might also, for a community, use the

(Terborgh 1974). Not all workers agree that species area relationship (MacArthur and this approach is correct or robust (Sim- Wilson 1967). That relationship is berloff and Abele 1976). [See also rebuttals S = CA Z to Simberloff and Abele, e.g., Diamond where S = number of species, A = island (1976)]. Simultaneously the theories of is- area, C = parameter characteristic of a land biogeography are being changed or re- ticular taxon and archipelago and z = pow- stated in verifiable formats (Simberloff er derived by assuming species abundances 1976). are distributed in a log normal manner Currently economics (Myers 1976) and (Preston 1962). The value of C is a commu- even international cooperation (Franklin nity coefficient and not known for most 1977) are being included as factors jn na- communities. One must also invoke consid- ture reserve establishment. Despite all of eration of extinction rates for determining the interest in the application of theory to the number of replicate areas necessary practical problems there are few attempts (Terborgh 1974). to provide a reasonable plan to test the effi- MacMahon pointed out that if the total cacy and appropriateness of the implied world variety of communities was reduced theory /practice merger. into some small grouping to determine Recently, without judging whether or not functions like C and determine whether or theory was adequate or correct, MacMahon not there is similar value of C for most ex-

'Department of Biology and Ecology Center, Utah State University, Logan, Utah 84322.

'WieDoldt reduced some data for this paper. He did not prepare the manuscript and should be held accountable for the content.

245 246 GREAT BASIN NATURALIST MEMOIRS No. 2

amples of communities within one of these titudinal belt, the latitudinal region alone is groups, then the conservation process could used with the humidity province. An ex- proceed more rapidly and be applied more ample will illustrate this procedure. Logan,

broadly. Utah, lies at an elevation of 4,790 ft (1460 The suggestion was made that a possible m), has a mean annual biotemperature of system of classification, often used but sel- 10.0 C and a mean total annual precipi- dom tested, was that of Holdridge (1947, tation of 16.64 inches (423 mm). Using the 1967). Holdridge's scheme uses mean annual standard lapse rate of 6 C per thousand me- biotemperature (the sum of mean monthly ters, a mean annual sea level biotempera-

temperature above C divided by 12), ture of 18.76 C is calculated corresponding

mean annual precipitation and potential to the subtropical latitudinal region (Fig. 2). evapotranspiration to place localities on a The actual biotemperature of 10.0 C corre- chart divided into hexagons representing sponds to the montane altitudinal belt (Fig.

vegetation types (Fig. 1). Corrections are 2). The lines for a 10.0 C biotemperature made for altitudinal differences at similar and 423 millimeters precipitation intersect

latitudes (Holdridge 1967, Sawyer and Lind- within the steppe life zone (Fig. 1). The tri-

say 1963, Tosi 1964) (Fig. 2). nomial life zone designation of Logan, The hexagonal areas are termed life Utah, would be subtropical montane steppe.

zones. When a specific site is located on The question is, do all communities of the the Holdridge model, a trinomial designa- world falling into a particular life zone,

tion corresponding to its latitudinal position, e.g., subtropical montane steppe, have sim- altitudinal belt, and humidity province is ilar values of C and can they be treated in

applied. If the station lies in the basal al- the conservation sense in a similar way?

ALTITUDINAL BELTS LAT ITUDINAL REGIONS

:'. -* POLAR £ \ i a i

\ \ 64 00 32 00 \ \ \ \ SEMIPARCHED SUPERARID PERARID PERHUMID SUPERHUMID

HUMIDITY PROVINCES

(after Fig. 1. Graphical model to assign life zone designations to localities based on three abiotic measurements Holdridge 1967). 1978 INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM 247

Note that we are aware that the evolution (see review Holdridge et al. 1971) suggest of species, major taxa differences, and the its plausibility for vegetation (Lindsey and specific species-species interactions in the Sawyer 1970, Sawyer and Lindsey 1963, various examples of particular life zones 1971, Thompson 1966), tropical birds (Slud will all dictate detailed differences from 1960, 1976), and tropical reptiles and am- place to place. Despite this, the question re- phibians (Heyer 1967), a more detailed mains—is there a least common denominator faunal and vegetational test seems appropri- of similarity such that not every community ate. We report here on an attempt to an- in the world will have to be studied before swer the question whether life zones pre- it can be conserved? If ecological laws dicted on Holdridge's model do coincide really exist this least common denominator with the patterns of distribution of animals should be identifiable at some level of reso- and plants in nature to a significant degree. lution, albeit generalized. The first step in answering the specific Methods question at hand is to ascertain whether or not the Holdridge model is applicable si- Data from 68 weather stations, selected multaneously to plants and animals (commu- from throughout Utah and having long cli- nities), outside of the tropics and in an area matic records (i.e., a minimum of 30 year where sufficient climatic and distribution averages of monthly temperatures and an- data are available. nual precipitation based on 1931-1960 Since the few tests of the Holdridge mod- records) were the main data base to gener- el by people outside the Holdridge group ate the "theoretical life zones" of Utah. Re-

BASAL BELT POSITION

0" 1.5" 3

L A^O LAr|_ _BOR EAL_ _COO L TEMPE R_ATU R E_ _WA RM_T E MP ERAJ U R E SUB T R OjMCAL TR ICAL fO I _ _[ _ j_ _ _ _ °f

u LATITUDINAL REGIONS (MEAN ANNUAL BIOTEMPERATURE AT SEA LEVEL. O)

Fig. 2. Approximate guideline positions of latitudinal and altitudinal corrections to the Holdridge life zone system. Data based on an average adiabatic lapse rate of 6°C/1000 m (after Holdridge 1967). 248 GREAT BASIN NATURALIST MEMOIRS No. 2

cords of longer duration are available for Records of shorter duration are used wher- certain stations. In these cases averages ever climatological data gaps occurred in based on the total vears of record are used. critical geographic areas.

Subtropical Lower ["""I Subtropical Montane Warm Temperate Montane Montane Desert Scrub Dry Scrub Moist Forest

Subtropical Lower Subtropical Montane Warm Temperate Montane Montane Steppe Steppe Wet Forest

Subtropical Montane Subtropical Montane Warm Temperate Subalpine Desert Moist Forest Moist Forest

F!^1 Subtropical Montane Subtropical Montane Warm Temperate Subalpine Li^J Desert Scrub Wet Forest Wet Forest

Fig. 3. Predicted potential life zone map of Utah. Assignment of localities to Holdridge life zones derived entirely from abiotic data based on United States Weather Bureau data corrected as described in the text. 1978 INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM 249

precipitation Temperature and data pro- drawn (Fig. 8) based on data in Stebbins vide only a rough approximation of the life (1966). These two groups of vertebrates zones because of topographic and phys- were used because they represent taxa of iognomic complexity. Maps of available relatively high habitat fidelity, relatively evapotranspiration, heat, potential and nor- low vagility (compared to birds), and well- mal annual precipitation from Jeppson et al. known distributions, and they represent a provided information to correct for (1968) range of physiologies (e.g., ectotherms vs. these irregularities. Additionally, we had ac- endotherms). cess to precipitation data from the United States Forest Service, Dixie National Forest, Results and Discussion snow survey data from the Soil Con- Service, reported in the servation and data The "hypothetical" life zone map derived literature (Price and Evans 1937). All of entirely from estimates of abiotic factors ac- these data were used to derive estimates of cording to the Holdridge (1967) scheme is values of the three factors necessary to de- presented in Fig. 3. fine the hypothetical life zones of a particu- A comparison of Fig. 3 to the Utah vege- lar locality. tation map (Fig. 4) reveals interesting sim- The development of certain regression ilarities and differences. The vegetation map relationships (Figs. us to 9, 10) permitted is more detailed in the Great Basin desert take point data and derive yearly values (western one-half of the state) area and the and thus estimate life zone boundaries Canyonlands floristic section (southeastern where few weather stations were available. one-fourth) than the hypothetical map. In This was particularly valuable because Utah mountainous regions (Montane Zone, Fig. 4) weather stations are generally in the valleys. the hypothetical map is more detailed. The station data or calculated points were These differences are merely matters of plotted on a life zone chart (Fig. 1). Names scale in some cases and map basis in others. were applied to life zones using the altitu- Much of the Great Basin desert mosaic is dinal and latitudinal corrections (Fig. 2). undoubtedly due to edaphic factors in the Life designations were then to zone used Cronquist et al. (1972) presentation. Since generate a theoretical life zone map (Fig. the vegetation map relies on species distri-

3). butions, shadscale (Atriplex confertifolia) vs. To determine whether or not the hypo- sagebrush (Artemisia tridentata) commu- thetical life zones coincided with existing or nities are differentiated even though they potential life zones, several maps were gen- may be in similar climate zones. erated or used. In the montane areas the Cronquist map, The recent vegetation map of Cronquist because of scale, recognizes one community et al. (1972), interpreted in light of while the hypothetical map includes topo- Kiichler's (1964) map, was used as the vege- graphically related climatic changes and tation standard (Fig. 4). Additionally maps predicts community differences. Similar rea-

were prepared of conifer (Fig. 5) and some soning explains the Canyonland area dis- semiarid shrub (Fig. 6) distributions. Conifer crepancies between the two maps. distributions are taken from Little (1971). An integrated interpretation of the maps Shrub distributions are based on field data, suggests a high degree of coincidence. The unpublished dissertations, and analysis of creosote bush vegetation zone clearly coin- herbarium specimens at Brigham Young cides with an isolated part of the Sub- University and Utah State University. tropical Lower Montane Desert Scrub. The Maps of mammal biotic provinces (Fig. 7) Subtropical Montane Desert Scrub plus Sub- were adapted from Durrant (1952), while a tropical Montane Steppe clearly coincides series of reptile and amphibian maps were with the sagebrush plus shadscale vegetation j

250 GREAT BASIN NATURALIST MEMOIRS No. 2

- Montane I " Shadscale Zone Zone L I Absolute desert

Zone D Water Sagebrush

Creosote Pinyon-Juniper Bush Zone Zone

with reference to et al. (1972) and modified slightly Fig. 4. Vegetation map of Utah redrawn from Cronquist held notes and the map of Kuchler (1964). 1978 INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM 251

zones. The Canyonlands floristic section Finally there is high overlap of the aggre-

coincides well with large sections of the gated montane hypothetical life zones and Subtropical Lower Montane Desert Scrub. the Montane vegetation zone.

The Absolute Desert vegetation zone Analysis of conifer distributions (Fig. 5), coincides with Subtropical Montane Desert. mainly montane forms, in conjunction with

Fig. 5. Distribution outlines of 10 conifers in Utah (adapted from Little 1971). Species include Abies concolor, A. lasiocarpa, Juniperus communis, J. scopulorum, Picea engelmannii, P. pungens, Pinus contorta, P. flexilis, P. ponderosa, Pseudotsuga menziesii. 252 GREAT BASIN NATURALIST MEMOIRS No. 2

the hypothetical map (Fig. 3) shows surpris- ognition of a single montane vegetation for ingly close fits of species boundaries and the purpose of predicting management hypothetical life zone boundaries. This fit is practices. It is well known that steep topo- biologically more meaningful than the rec- graphic gradients cause community bound-

Fig. 6. The distribution limits of 13, mainly semiarid woody plants with limits in southern Utah. Data derived from unpublished theses, dissertations, and analysis of herbarium specimens and field notes. Species include: Ber- beris fremontii, Encelia frutescens, Fraxinus anomala, Yucca augustissima, Yucca baccata, Lycium pallidum, L. torreyi, Coleogyne ramosissima, Quercus undulata, Dalea fremontii, D. lanata, D. polyadenia, and D. thompsonae. 1978 INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM 253

aries to become discrete when they other- Montane Steppe plus Subtropical Lower wise form continua (Beals 1969). The Montane Desert Scrub hypothetical life vegetation is map generalized beyond man- zones. The Mojave desert section of Utah agement usefulness in the area of moun- (extreme southwestern corner) is not differ- tains. entiated in the hypothetical map from the The non-Great Basin desert semiarid larger Canyonlands area of Subtropical woody plants mapped (Fig. 6) approximate Lower Montane Desert Scrub. the distribution of the Subtropical Lower Interestingly, the woody plant, mammal,

Middle Rocky Colorado Plateau Great Basin Mtn.

Southern Rocky Columbia Plateau Northern Great Mtn. Plains

Fig. 7. Faunal areas of Utah based on distributions. mammal (Durrant 1952). Lines within a faunal area are boundaries of one of Durrant's provinces or subcenters. 254 GREAT BASIN NATURALIST MEMOIRS No. 2

reptile, and amphibian data (Figs. 6, 7, 8) of animal and plant species distributions suggest no absolute differences, but rather a cannot be used to delimit the Mojave gradual diminution of species numbers in desert. MacMahon (1977b) defines bound- the case of animals and replacement of aries of all North American deserts based on shrub species. This is not to say that the use exactly such data.

Fig. 8. Distribution limits of reptiles and amphibians in Utah based on Stebbins (1966). A-boundaries of amphibians. B-boundaries of lizards. C-boundaries of snakes. D-analysis of the percentage of the entire Utah her- petofauna occurring in any one area. Analysis based on a grid of 10 x 10 mi (16 x 16 km) cells. 1978 INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM 255

The point is that one must pick certain scheme effectively predicts plant- and species as indicators to rigidly define the animal-based life zone boundaries, if one Mojave desert, but an analysis of the distri- can ignore a few "indicator" species. These butions of all species in the desert commu- data reinforce the general findings of others nities shows gradual loss or replacement mentioned previously that the Holdridge over a broader area. The same is true for scheme shows promise, but are more per- the Great Basin desert. The gradual species suasive in that they use plants and animals shifts and assignment of indicators is de- in a topographically complex area where tailed in MacMahon (1977b). distributions are well known. The Holdridge scheme separates the An interesting offshoot of these analyses

Great Basin desert from the other semiarid are shown in Figures 9 and 10. It is usually areas of the state by segregating western assumed that long-term weather records Utah into Subtropical Montane Desert would be necessary to derive Holdridge's Scrub plus Subtropical Montane Steppe. We climatic variables. Our data suggest, for believe this differentiation is probably im- Utah, that mean annual biotemperature can portant, because western Utah communities be predicted from mean annual temperature subjectively appear to us to be quite differ- (Fig. 9). This is not surprising, but it means ent from those of the southeast corner de- that one can take mean annual temperature spite floral overlap. Thus the vegetation data from a weather station in a valley cor- map implies a higher degree of similarity rected for altitude, etc., to get a corrected than we believe exists, particularly for man- mean annual temperature for a place dis- agement purposes. Again, animal boundaries tant from that station. Mean biotemperature

(Figs. 7, 8) are strongly coincident with sep- may be read directly from the curve or cal- aration of the Canyonlands area from the culated from the formulae. Additionally, for western deserts. Utah sites, a single measurement of snow

All data suggest that the Holdridge accumulation on one day a year (1 April, Snow Water Equivalents) predicts annual

precipitation (Fig. 10). For Utah this high

8186 - 5058X » 0578 >

D 5685 - 1 .0496 X <

Fig. 10. Relationship between the 1 April snow water equivalent (SWE) and the annual precipitation for

Fig. 9. Relationship between mean annual biotem- localities in the Manti-LaSal National Forest having perature and mean annual temperature for Utah snow courses studied by the United States Soil Con- weather stations. servation Service. 256 GREAT BASIN NATURALIST MEMOIRS No. 2

is part the high per- correlation due in to Diamond, J. M. 1975. The island dilemma: lessons centage of precipitation (60 percent or of modern biogeographic studies for the design of natural reserves. Biol. Conserv. 7: 129-146. more) that comes as snowfall. A similar 1976. Island biogeography and conservation: relationship may be of no value in other strategy and limitations. Science 193: 1027-1029. areas, but these results suggest that a person Durrant, S. D. 1952. Mammals of Utah. Univ. Kan- might be able to develop various other cor- sas Publ. Mus. Natl. Hist. 6: 1-549. Franklin, F. 1977. The biosphere reserve pro- rections specific to particular geographic J. gram in the United States. Science 195: 262- areas. The prospect of using simple data ex- 267. tends the potential use of the Holdridge Heyer, W. R. 1967. A herpetofaunal study of an scheme. Additionally, since one only needs ecological transect through the Cordillera de values for two variables to assign an area to Tilaran, Costa Rica. Copeia 1967: 259-271. a life zone hexagon, one may actually read Holdridge, L. R. 1947. Determination of world plant formations from simple climatic data. Sci- the approximate value of the unknown third ence 105: 367-368. parameter off of the life zone model 1967. Life zone ecology. Rev. ed. Tropical

(Thompson 1966). Science Center, San Jose, Costa Rica. The Holdridge life zone model does pre- Holdridge, L. R., W. C. Grenke, W. H. Hatheway, T. Liang, A. Tosi. 1971. Forest envi- dict plant and animal aggregations for Utah and J. ronments in tropical life zones—a pilot study. with reasonable accuracy. The next step to Pergamon, New York. reach the final goal of using this scheme to Jeppson, R. W., G. L. Ashcroft, A. L. Hurer, G. V. portion the earth into a reasonable number Skogerboe, and J. M. Bagley. 1968. of subsections for management purposes is Hydrologic atlas of Utah. Utah Water Research to apply the scheme to another area con- Laboratory, Utah State University, Logan. Kuchler, A. W. 1964. Manual to accompany the taining organisms not closely related to map. Potential natural vegetation of the those of Utah and then to determine wheth- counterminous United States. Amer. Geogr. Soc. er or not a similar value of C obtains for Spec. Publ. 36: 1-116. into life Lindsey, A. A., the unrelated areas falling the same and J. O. Sawyer. 1970. zone. That analysis must be left for another Vegetation-climate relationship in the eastern United States. Proc. Indiana Acad. Sci. 210- place and time. 80: 214.

Little, E. L. 1971. Atlas of United States trees.

Acknowledgments Vol. 1, conifers and important hardwoods. USDA Forest Service Misc. Publ. 1146. This work was made possible by the MacArthur, R. H., and E. O. Wilson. 1967. The US/IBP Desert Biome funded by the Na- theory of island biogeography. Princeton Monogr. Popul. Biol. 1: 1-203. tional Science Foundation (Grant GB32139). MacMahon, A. In press-a. Thoughts on the opti- Donna Baranowski and Bette Peitersen J. mum size of natural reserves based on ecologi- aided in manuscript preparation, and Linda Franklin (ed.), Biospher- cal principles. In: J. F. Finchum typed the manuscript. The United ic reserves. USDA. MacMahon, A. In press-b. North American States Forest Service, Dixie National Forest, J. deserts. In: R. Perry (ed.), Deserts of the world. and Soil Conservation Service, Manti-LaSal Cambridge University Press, Cambridge. Snow Course Project, kindly permitted use Myers, N. 1976. An expanded approach to the of their data. problem of disappearing species. Science 193: 198-202.

Preston, F. W. 1962. The canonical distribution of Literature Cited commonness and rarity. Ecology 43: 185-215. Price, R., and R. B. Evans. 1937. Climate of the Reals, E. W. 1969. Vegetational change along al- west front of the Wasatch Plateau in central titndinal gradients. 165: 981-985. Science Utah. Monthly Weather Rev. 65: 291-301. Cronquist, A., A. H. Holmgren, N. H. Holmgren, Sawyer, A. A. Lindsey. 1963. The Hold- J. O., and L. Reveal. 1972. Intermountain and J. ridge bioclimatic formations of the eastern and

Flora: Vascular plants of the Intermountain central United States. Proc. Indiana Acad. Sci. West. Vol. 1 Hafner Publ. Co., New York. 73: 105-112. 1978 INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM 257

1971. Vegetation of the life zones in Costa Stebbins, R. L. 1966. A field guide to western rep- Rica. Indiana Acad. Sci. Monogr. 2: 1-214. tiles and amphibians. Houghton-Mifflin, Boston. Simberloff, D. S. 1976. Species turnover and equi- Terborgh, J. 1974. Preservation of natural diversity: librium island biogeography. Science 194: 572- the problem of extinction prone species. Bio- 578. Science 24: 715-722. Simberloff, D. S., and L. G. Abele. 1976. Island Thompson, P. T. 1966. A test of the Holdridge biogeography theory and conservation practice. model in midlatitude mountains. Prof. Geogr. Science 194: 285-286. 18: 286-292.

Slud, P. 1960. The birds of finca "La Selva", Tosi, A., Costa J. Jr. 1964. Climatic control of terrestrial Rica: a tropical wet forest locality. Bull. Amer. ecosystems: a report on the Holdridge model. Mus. Natl. Hist. 121: 51-148. Econ. Geogr. 40: 173-181. 1976. Geographic and climatic relationships Wilson, E. O., and E. O. Willis. 1975. Applied of avifaunas with special references to com- biogeography, pp. 522-534. In: M. L. Cody, and parative distribution in the Neotropics. Smithso- J. M. Diamond (eds.), Ecology and evolution of nian Contr. Zool. 212: 1-149. communities. Harvard University Press, Cam- Sullivan, A. L., and M. L. Shaffer. 1975. bridge. Biogeography of the megazoo. Science 189: 12-

17.