Western North American Naturalist

Volume 65 Number 3 Article 1

7-28-2005

A comprehensive ecological land classification for Utah's West Desert

Neil E. West Utah State University

Frank L. Dougher Utah State University and Montana State University, Bozeman

Gerald S. Manis Utah State University

R. Douglas Ramsey Utah State University

Follow this and additional works at: https://scholarsarchive.byu.edu/wnan

Recommended Citation West, Neil E.; Dougher, Frank L.; Manis, Gerald S.; and Ramsey, R. Douglas (2005) "A comprehensive ecological land classification for Utah's West Desert," Western North American Naturalist: Vol. 65 : No. 3 , Article 1. Available at: https://scholarsarchive.byu.edu/wnan/vol65/iss3/1

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 Western North American Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Western North American Naturalist 65(3), © 2005, pp. 281–309

A COMPREHENSIVE ECOLOGICAL LAND CLASSIFICATION FOR UTAH’S WEST DESERT

Neil E. West1, Frank L. Dougher1,2, Gerald S. Manis1,3, and R. Douglas Ramsey1

ABSTRACT.—Land managers and scientists need context in which to interpolate between or extrapolate beyond discrete field points in space and time. Ecological classification of land (ECL) is one way by which these relationships can be made. Until regional issues emerged and calls were made for ecosystem management (EM), each land management institution chose its own ECLs. The need for economic efficiency and the increasing availability of geographic informa- tion systems (GIS) compel the creation of a national ECL so that communication across ownership boundaries can occur. ECOMAP, an 8-level, top-down, nested, hierarchical, multivariable approach designed to solve this problem has been endorsed by the Federal Geographic Data Committee. While the coarsest, upper 4 levels of ECOMAP have been produced for the entire U.S., the task of completing the 4 finer-grained levels has been left to local practitioners. We tried to apply the suggestions of ECOMAP for completing an ECL for a 4.5-million-hectare area centered in western Utah. Due to the lack of complete and consistent sets of spatial databases suggested as necessary by ECOMAP for com- pleting the ECL for this area, we developed alternatives to complete the ECL using extant information. We stressed 1 dominant landscape feature per hierarchical level, using repeatable protocols to identify landscape units. We added 2 additional levels below the 8 suggested by ECOMAP. Ecological sites (ESs), the 9th level, are designed to overcome the nestedness of ECOMAP that we found prevented us from using important data on ESs already available from the Nat- ural Resources Conservation Service. Vegetation stands (VSs), the 10th and finest-grain level, are subdivisions of indi- vidual polygons of ESs based on differences in disturbance histories that have led to differing current vegetation struc- ture and composition. The ECL we created should help federal, state, and private land managers in western Utah more easily communicate about issues that cross ownership boundaries.

Key words: Great Basin, desert, military, Air Force, Army, Bureau of Land Management, Natural Resources Conser- vation Service, climate, geological formations, land forms, watersheds, soils, vegetation, ecological sites, Lake Bonneville, Great Salt Lake.

It is logistically impossible and financially The traditional method for accomplishing unfeasible to make complete inventories of these extensions of information is through eco- and monitor changes in all biotic species, com- logical classifications of land (ECL) based on munities, or physical and chemical features of similarities within and dissimilarities between the environment across large land areas. While pieces of land, usually viewed at a variety of scientists can randomly or systematically sub- scales in space and time and organized into a sample and use statistical or geostatistical hierarchical structure (Carpenter et al. 1999). inference to estimate characteristics of bio- The history of land classification is extensive, physical resources over a large land area, the especially in forested or agriculturally impor- location of the usually point- or quadrat-based tant parts of the temperate zone. Geographers subsamples will only coincidentally match up and ecologists have tended to create synthetic with areas on the ground where managers multivariable classificatory approaches which have to make decisions or scientists consider are difficult to repeat. Specialists have usually possible generalities. Accordingly, there needs focused only on features of special interest to be a method of interpolating between and (e.g., soils). Before the development of geo- extrapolating beyond points in space and time graphic information systems (GIS) and the call where previous data were collected if manage- for ecosystem management (EM), each disci- ment or science is to be based on more than pline and each land management entity devel- limited sampling and personal experience and oped its own preferred or legislatively man- intuition. dated ways of classifying land. However, this

1Department of Forest, Range and Wildlife Sciences, Utah State University, Logan, UT 84322-5230. 2Present address: Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717-3120. 3Present address: HC64, Box 2915, Moab, UT 84532.

281 282 WESTERN NORTH AMERICAN NATURALIST [Volume 65

TABLE 1. Naming of the 8 proposed levels of the National Hierarchical Framework of Ecological Units (NHEU) our proxies at finer scales, and approximate size of an average mapped polygon at each level. NHEU is from ECOMAP (1993). Level ______Approximate size of an average NHEU Ours mapped polygon Domain 106 mi2 Division 105 mi2 Province 104 mi2 Section 103 mi2 Subsection Bolson segments 102 mi2 Landtype Association Macroterrain units 1000 ac Landtype Mesoterrain units 100 ac Landtype Phase Microterrain units 10 ac

has led to what Boulding (1980) called “special- however, the advent of progressively more ized deafness,” wherein different groups fail to workable GIS, budgetary restraints, and the use any information except that offered within possibility of sharing databases electronically their own discipline or institution. Because over the Internet that accelerated the debate ecosystem management (EM) requires consid- and eased the tendencies to always first pro- eration of broad issues, regardless of land tect institutional traditions. Creation of the ownership or preferred or mandated ways of Federal Geographic Data Committee (FGDC) collecting, analyzing, and labeling data, com- in 1990 provided focus to critical discussion promises in the approaches to land classifica- of nationally applied standards of measure- tion are necessary to make the collaboration ment and mapping. For a conceptual basis of required during EM possible. land classification, FGDC has accepted the The recent development of GIS has made National Hierarchy of Ecological Units (NHEU; much more feasible the attainment of a land ECOMAP 1993), begun by the U.S. Forest Ser- classification serving many users. Thus, if we vice (USFS). can agree on how to classify land, managers NHEU is an 8-level, hierarchical approach can more easily repeat successful actions on (Table 1) focused on climatic, geologic, geo- similar lands and avoid repeating mistakes by morphic, edaphic, and vegetational character- identifying dissimilar land elsewhere and not istics. The major demonstrations to date have overextending actions where they will not be employed top-down, nested hierarchicality, al- successful. Scientists will also find it easier to though alternate approaches are not conceptu- generalize if they can place their data in an ally forbidden by the NHEU design. Maps of ECL. We hope eventually to have inexpensive the first 4 coarsest levels of this nationwide and reliable landscape-level monitoring so as approach have already been published (Bailey to use each study and accidental and manage- et al. 1994, Bailey 1995, McNab and Bailey ment-induced action as a “quasi-experiment” 1994, McNab and Avers 1994). Delineation of from which we can learn and thus move toward the remaining, finer-grained subdivisions has more predictable responses in the future—a been left for local development with scant sug- process called adaptive resource management gestions about how that should be accom- (ARM; Szaro 1999, Thomas and Birchfield plished. Very little of this more detailed work 2000). has been completed, particularly for the drier, To make ARM and EM more feasible, a less productive parts of the nation where the broadly accepted land classification system is USFS is not a major land steward. required. This is because managers, scientists, and other stakeholders need to be able to de- STUDY AREA scribe and communicate, in commonly under- stood terminology, the ecological contexts of In 1995 the authors, as part of a larger Utah their concerns. Since the 1972 passage of the State University group, were funded by the Resources Planning Act, the executive branch U.S. Air Force (AF) to find already extant in- of the U.S. government has formally recog- formation and collect new data on the occur- nized these needs (Driscoll et al. 1984). It was, rence of threatened, endangered, and sensitive 2005] UTAH’S WEST DESERT ECL 283

(T,E&S) species in a 4.5-million-hectare (11.2- of the MOA representing the Deep Creek million-acre, 17,400-mi2) area centered in Mountains (Figs. 1, 2B). Utah’s West Desert (Fig. 1). In assembling both The MOA intersects 3 provinces (Fig. 2C): old and new information relevant to our main the Intermountain Desert and Semidesert Pro- objectives, we were faced with the task of ad- vince in the south and east, the Intermountain vising the AF on how well the inevitably in- Semidesert Province to the north, and Nevada– complete information could be either inter- Utah Mountains Semidesert Coniferous Forest– polated between the field-sampled points or Alpine Province centered on the Deep Creek extrapolated beyond. We undertook 2 alter- Mountains on the western edge of the MOA. nate approaches to fill this need—modeling The NHEU (ECOMAP 1993:4) states: and land classification. Examples of the species- by-species–oriented modeling approach can be Provinces (are) climatic subzones, controlled pri- found elsewhere (Scott et al. 1993, Edwards et marily by continental weather patterns such as length of dry season and duration of cold tempera- al. 1995). We deal here with the more general tures. Provinces are also characterized by similar approach through ECL. soil orders. The climatic subzones are evident as Our study area is called the Hill Air Force extensive areas of similar potential natural vegeta- Base Military Operations Area (MOA), where tion such as those mapped by Küchler (1964). training of pilots and related ground activities of the AF take place (Fig. 1). The proportion of Other criteria used in mapping provinces in- land within the MOA where ground access is clude gross patterns in physiography, such as controlled by the DOD, including the U.S. glaciated versus non-glaciated regions, prox- Army’s Dugway Proving Ground, is 15% of the imity to major bodies of water, and so forth. total land. The Bureau of Land Management Thus, provinces are mapped using multiple (BLM), U.S. Department of the Interior, con- biotic and abiotic factors that change at this trols 63% of the MOA. Included within the spatial scale. MOA are sovereign Indian lands (Goshute and The NHEU (ECOMAP 1993:4) states: Skull Valley Reservations) that make up about Sections [are] broad areas of similar sub-regional 1%, and 1 federal wildlife refuge (Fish Springs) climate, geomorphic process, stratigraphy, geologic that makes up about 0.4% of the area. The origin, topography, and drainage networks. Such State of Utah controls 8%, and private land- areas are often inferred by relating geologic maps holders control slightly over 12% of the land to potential natural vegetation “series” groupings within the MOA. Thus, if this landscape is such as those mapped by Küchler (1964). In recent years, numerical analyses of weather station and ever going to be managed without primary remotely sensed climatic information have assisted regard to land ownership (e.g., through EM in determining Section boundaries. and ARM), then communication and coordina- tion between these different owners and their Thus, sections are mapped using multiple biotic managers must be facilitated. We contend that and abiotic factors that change at this spatial an ECL applying to all of these lands, regard- scale. less of ownership, is a necessary 1st step. The Four different sections occur in the MOA AF provided the resources to make that attempt (McNab and Avers 1994; Fig. 2D). The one for the MOA over a 5-year period. occupying the greatest area is the Bonneville Basin Section. The others all involve much ECOMAP’s Legacy less area: Northeastern Great Basin, North- We began by applying the already pub- western Basin and Range, and Central Great lished NHEU products to our study area (Fig. Basin Mountain Sections. 2). Gross physiography and climate at conti- While the large polygons created by map- nental scales explain most of the delineation of ping the 4 upper levels in the NHEU hierarchy domains (Fig. 2A). The MOA is entirely within may be of interest to planners with national the Dry Domain. Divisions (Fig. 2B) are sub- and regional perspectives, they are of only divisions of domains based primarily on regional moderate interest to most local managers and climatic patterns. Most of the land area of the scientists. This is because there are too few MOA is within the Temperate Desert Divi- delineations subdividing the obviously hetero- sion. The Temperate Desert Regime Moun- geneous lands for which they are managerially tains Division occurs on the western boundary responsible or scientifically interested. Thus, 284 WESTERN NORTH AMERICAN NATURALIST [Volume 65 it is largely the remaining, lower levels and terminology for the finer-grained levels of finer subdivisions that local land managers the ECL we produced so that readers will and scientists can relate to in their day-to-day not be confused with the terms suggested in efforts. These lower, locally important levels, ECOMAP’s literature. Table 1 shows the cor- however, have generally not been delineated, respondences between approaches. Descrip- especially in desert regions. tions of our complete ECL can be found in Since the task of finishing the NHEU to its Table 2. finest grain has been passed on to local exper- Bolson Segments tise, we began by trying to do just that. Only rudimentary suggestions were available in the Bailey (1996) and Omernik (1997) warn that ECOMAP literature on how to accomplish watershed boundaries are not appropriate for this task. Furthermore, examples of how this all needs of land managers and scientists to has been done in other areas usually do not stratify their information. We assert that nei- involve arid landscapes, especially those that ther are the multivariable-derived boundaries do not drain surface waters to the sea (endo- of the NHEU. We have used watershed bound- rheic), the situation for most of the MOA. aries at the next level in the nested hierarchi- Some of the suggested information ECOMAP cal part of our ECL because watershed-based recommends as needed to develop the rest of concerns are paramount to people living in a the classification scheme (e.g., fine-grain and largely arid region. The watershed concept is high-resolution geologic and geomorphic maps, understood by most interested parties, and most potential and actual vegetation maps) was nei- management actions consider watersheds first ther available, consistently done, nor inexpen- and foremost in the Interior West. sive and easy to develop over the short run. In desert terrain the term “bolson” (Peterson Faced with these impediments to progress, we 1981, West 1995) applies well. A bolson is the turned to our own ingenuity to fill local needs. entire area, from surrounding mountaintops, where water and sediments are shed, through Our Modifications mountain-flanking slopes, diminishing with Having accepted the NHEU legacy of an distance from the ridgelines, to the center of already established classification with published either a river valley or, in case of nearly all the maps down through the section level, we thus MOA, terminal lake (endorrheic) basins now focused our efforts on producing finer-grained mostly dry (called playas). categories and smaller mapped polygons to Because the mountains surrounding our bol- approximate subsections, landtype associations, sons usually have highly variable elevations and landtypes, and landtype phases (Table 1). The especially differing exposure of geologic strata ECOMAP approach has been described as a (due to the horst and graben topography created top-down, qualitative, visual-pattern, weight- by the common extensional faulting of this of-evidence approach (McMahon et al. 2001). region; Fiero 1986), we decided to create our While that characterization oversimplifies what substitute for NHEU subsections from bolsons the NHEU recommends (ECOMAP 1993) and cleaved into approximate halves. We called is actually practiced in more densely invento- these half-bolsons “bolson segments.” Bolson ried and productive regions, we lacked most segments were defined first by the main ridge- of the information needed for such refinements. line of the many, usually north–south trending Instead, we chose to hierarchically build these mountain ranges in the region and all the land 4 next lower levels from dominant features, draining to the prevailing slopes, (generally preferably 1 per level. Furthermore, we opted east- or west-facing exposures), and a “wedge” for the simplest, most repeatable and transpar- of appended playa (in proportion to the area ent methods possible. This approach should and height [mass] of nearest mountain) where make it easier for others to understand, apply, sediments have been accumulating over eons. and improve upon our efforts in the future Our approach thus contrasts with that taken in when environmental and biotic data bases im- California where Goudey and Smith (1994) prove. McMahon et al. (2001) describe this as used the boundaries of the lower limits of fan a quantitative, data-driven approach. Because skirts surrounding entire mountain ranges to we deviated substantially from the NHEU demarcate subsections in the Mojave Desert. (ECOMAP 1993) approach, we introduce new The 60 bolson segments completely within 2005] UTAH’S WEST DESERT ECL 285 2,029,456 ha–402,799,860 ha 2,029,456 ha–110,158,058 ha 952,590 ha–75,399,068 ha 577,699 ha–22514,140 ha ed from coarsest to finest. 102,174 46 ha, 95 ∼ Number of polygons potential vegetation(NRCS’s county soil surveyplus ecological site descriptions overlain on Ecological Sites orthophoto quads) involving ~130 (NRCS 1997) 1.0 ha–3485 ha middle portion of the west slope of Grassy Mountains surface adjacent to middle portion of the west slope of Grassy Mountains tail shrubsteppe converted to cheatgrass polygon (orthophoto quads plus field inspection) 14 ha–167 ha segments connected bajadas and salt flats watersheds (DEMs) 18,400 ha–467,900 ha units depositional surface adjacent to (Geological Map of Utah) 38,020 ha–1870 ha ECOMAP Our alternate Dominant environmental intersecting or entirely sizes, standard Average Associations units west slope of Grassy Mountains and average slope (DEMs) 203 ha–240,006 ha Phases units erosional/depositional of mixed 2.0–52,214 ha cological Sites Desert gravelly loam Major soil family and about 800 268 ha, 454 2. Outline of hierarchical levels for the ecological classification scheme developed Hill AFB MOA. The listing is order Domains — Dry Domain Climate 1 259,207,650 ha, 223,227,599 Divisions — Lowlands Dry Temperature Climate 3 40,927,523 ha, 37,078,014 Provinces — Intermountain Semideserts Climate 3 22,836,520 ha, 19,672,139 Sections — Basins Bonneville and Adjacent Topography 4 4,770,693 ha, 4,079,581 SubsectionsLandtype Bolson Macroterrain slope of Grassy Mountains and West Alluvial fan adjacent to massif on Intermediate scale position Topographic 60 574 110,200 ha, 100,100 7896 ha, 24,976 Landtypes MesoterrainLandtype erosional/ Eolian sediments of mixed Microterrain Major soil parent material Loess terrace of aeolian sediments 4) Landforms (see Table 2460 1834 ha, 6501 44673 101 ha, 1270 ABLE T 1 2 3 4 5 6 7 8 9E Level name designation Example name character (database) within Hill AFB MOA deviation, and range 10 Stands Vegetation Recently burned shadscale/squirrel- vegetation Actual 286 WESTERN NORTH AMERICAN NATURALIST [Volume 65 or intersecting the MOA near its edges are process produces polygons that encompass all mapped in Figure 3. Names of all 60 bolson the area most likely affected by shedding of segments can be found in the Appendix. water and sediment from a given side of a The minimal mapping unit (MMU) size used mountain range. for bolson segments is 100 km2. The average As we moved down the ECL hierarchy and size of the bolson segments delineated is 1102 thus produced more map polygons per unit km2, with a standard deviation of 1001 km2 area, we were forced to deal sequentially with and a range of 184–4679 km2. Bolson segment only parts of the vast MOA because of the names were derived from the names of major need for decreasing map scale to illustrate the mountain ranges and lowlands (“true” valleys remainder of our discussion. Thus, we will ex- do not occur in endorheic basins and are thus emplify how we classified 1 corner of the MOA, designated with quotation marks) found on the part known as the North Unit of the Utah relevant USGS 7.5-minute topographic maps. Test and Training Range (UTTR), the north- Long, compound word names are necessary ernmost block of land indicated in yellow in to be explicit and reduce ambiguities in ECLs. Figure 3 and the smaller inset map in Figure 4. If this is bothersome, the frequent user could At this location, we encountered typical topog- replace the names with a “zip code”-like num- raphy of the MOA that was transected by a bering system where placement of the num- boundary fence separating AF- from BLM-con- bers in the sequence could indicate what clas- trolled property. An example of Bolson Seg- sification level was being referred to. Use of ments 32 and 33 on the eastern and western differing colors for the various portions of the slopes of the Grassy Mountains, respectively, numerical address would also ease use of such is presented in Figure 4. A 2-mile-wide strip numerical designations. A completed ECL must (dashed line) straddling the fenceline along be in place, however, before reliable replace- the AF-BLM property and extending over ment of names with numbers can be done. 30.15 miles (Fig. 4) was used to exemplify our The basic data needed to develop bolson ECL down to a finer grain. segments were 30-m-resolution Digital Eleva- tion Models (DEMs). By draping contour lines Macroterrain Units over a shaded relief model derived from DEMs, Macroterrain units are subsets of bolson seg- we identified the ridgeline along the water- ments delineated using ideas developed in shed divide separating 2 adjacent bolson seg- ments. We then defined the portion of the bol- hydrology, namely the nested hierarchicality son segment extending from the mountain of watersheds and their erosion cells in which massif, across the fan skirts, and into the river each has source, transfer, and sink components valley or terminal lake basin (playa). The low- at multiple scales (Pickup 1985). We recognized est-elevation “wedge” of bolson segment most that the highest, steepest, and wettest portions relevant to the adjoining mountains can be of each bolson segment would have the great- determined by computing the mass in an est weathering and gravitational gradients and imaginary slice of the mountain upslope from thus usually experience the most erosion by the farthest extension of adjoining playa or water and produce the most new sediment in valley up to the highest point on the ridgeline, each bolson segment. These major waterborne at relatively coarse scales, and then position- sediment source zones were called mountain ing the lowest point in proportion to the masses massif macroterrain units. The coalesced fan in adjoining bolson segment polygons (Fig. 3). skirts (bajadas), with gentler slopes usually This algorithm is necessary because the preci- fringing each mountain massif (Peterson 1981, sion of 30-m DEMs is usually insufficient to West 1995), are a mixed erosional and deposi- find distinct drainage lines in the generally flat tional, or transfer, zone which we called the terrain of the playas. While the precision of “mixed” macroterrain units. Finally, we identi- such DEMs in the intervening lower moun- fied the flattest, depositional-process-dominated, tain slopes and fan skirts (bajadas) is also low, but occasionally surface-water-connected, piece it is sufficient to connect the prevailing expo- of the bolson segment on the playas or salt sure of roughly half of the entire mountain flats (West 1995) as “sinks.” Wind erosion re- massif and intervening fanskirt to the appro- works the details of these depositional macro- priate adjoining “wedge” of valley or playa. This terrain units much more than those of the 2005] UTAH’S WEST DESERT ECL 287

TABLE 3. Summary of mean size, standard deviations, and range for the source, transfer, and sink macroterrain units. Type Mean size (ha) Standard deviation Range (ha) Source 2980 6023 203–32,116 Transfer 8683 17,699 203–104,199 Sink 13,189 39,980 208–240,006 Overall 7896 24,976 203–240,006

uplands, but that issue was deferred to lower, the erosional landscape on the west-facing finer levels of our ECL. slope of the Grassy Mountains (red in Fig. 6) Our algorithm to determine macroterrain where the macroterrain units intersecting the units employed elevation and relative change sampling strip are shown in more detail. in apparent elevation (slope) from adjacent 30- Average macroterrain unit size was 7896 ha m DEM cells and classifying cells upslope of with a standard deviation of 27,976 ha and a equal or higher slope position. Thus, most range of 203–240,006 ha. The MMU for these “mixed” macroterrain unit cells will have “ero- was 200 ha. Mean macroterrain unit size was sional” cells upslope and “depositional” cells least in source (erosional) macroterrain units, downslope from their position. This principle intermediate in mixed (transfer) macroterrain of “superposition” is enforced by the applica- units, and greatest in sink (depositional) macro- tion of macroterrain class by watershed func- terrain units (Table 3). tions, wherein all cells draining into a given Mesoterrain Units cell must have a similar or higher-elevation macroterrain slope position. It is possible that Since macroterrain units are still relatively macroterrain units may be found upslope of large, and thus too heterogeneous for some units of higher slope position (e.g., mini-playa needs, we further divided them into mesoter- lakes kept from moving downslope by remnant, rain units. It is at this level that the colluvial unbreached bay bars created by Lake Bonne- and eolian processes ignored within the macro- ville [Benson et al. 1990]), but these units rep- terrain units are considered. This was done by resent topographical sinks superposed upon focusing on the major geologic formations or predominately mixed or source units. Such ex- sediments that were exposed at the land sur- ceptions to the superposition rule are rare face within the various macroterrain units. In under the 200-ha MMU rule at this level of the Great Basin relatively narrow, generally the ECL. north–south trending mountains with exposed Figure 5 shows how the 60 bolson seg- bedrock rise like “islands in a sea” of uncon- ments were subdivided into 574 macroterrain solidated segments up to several thousands of units across the entire MOA. Ideally, there is a meters deep at the center of broader, individ- 3-fold subdivision of bolson segments into ual basins (Fiero 1986). macroterrain units because there is at least 1 Because the exposure of geologic forma- mountain massif, fan skirt, and playa or river tions in this largely horst- and graben-created valley within each bolson segment. However, landscape will usually be different along the heterogeneous terrain frequently results from longest axes of the mountain ranges, we sub- variable elevations, slopes, and exposures of divided the macroterrain units based on the mountain massifs and fan skirts which result dominant exposed bedrock in the case of moun- in a need to create more and smaller macro- tain massifs. We used a digitized map of Hintze terrain units than one would expect under ideal (1980) for exposure of geological formations at conditions. The 574 macroterrain units for the 1:500,000 scale. Hintze’s map shows 43 geo- MOA resulted in an approximate 9-fold sub- logic formations or complexes within the Utah division. The names for these macroterrain portion of the MOA. Some combinations of polygons can be constructed by taking the similar materials (e.g., limestones and dolo- names of the bolson segments and adding mites; Table 4) were necessary to obtain a rea- “erosional, mixed, or depositional” plus a poly- sonable (less than 10-fold) increase in number gon number to each (Table 2). Examples are of polygons from the macro- to the mesoter- the 4 polygons, oriented north to south, across rain level (Table 2). Since each mesoterrain 288 WESTERN NORTH AMERICAN NATURALIST [Volume 65

TABLE 4. Summary of geologic groups used to identify and map mesoterrain units of the Hill AFB MOA in Utah.

BEDROCK GROUPS Hard igneous and metamorphic rock; includes all Pre-Cambrian and Cambrian age rocks, including Cambrian limestone and Jurassic and Tertiary age intrusives Moderately hard sedimentary rocks; includes all Triassic through Ordovician age sediments Soft sedimentary and volcanic rocks; includes tuff and weakly consolidated sediments of Tertiary age Rhyolites and andesites; Quaternary through Tertiary age volcanics Basalt; Quaternary through Tertiary age volcanics SEDIMENT GROUPS Alluvium: Quaternary and Tertiary unconsolidated alluvium Lake Bonneville sediments; Quaternary lacustrine sediments Glacial sediments; Quaternary glacial till (very limited extent) Eolian sediments; Quaternary sand dunes

unit had to be nested within its appropriate cesses. Specifically, soils with high content of macroterrain unit, the shape and size of poly- coarse, rounded rock fragments (gravel and gons on Hintze’s original map will not be the larger) are highly likely to be alluvial. Another same as on our map of mountain massif meso- clue to alluvial origin is clear textural stratifi- terrain units. cation. Colluvial soils were grouped with allu- For the mixed and depositional mesoterrain vial soils at this level due to their limited units, we relied on the Soil Survey Geographic extent and the sometimes uncertain differentia (SSURGO) database (Natural Resources Con- in soils data. servation Service 1998). These data occur at a Soils lacking coarse fragments could still be 1:24,000 scale for most of the MOA (Loerch et alluvial; however, large deposits of uniformly al. 1997, Trickler et al. 2000). While SSURGO- fine-textured alluvium could not only be ex- derived maps fail to adequately differentiate pected in backwater areas of major floodplains, bedrock types in mountain massifs, they do a but are dominant on the playas/salt flats of the superior job of identifying different kinds of basin bottoms once covered by pluvial Lake sediment in fan skirts and playas. This infor- Bonneville (Benson et al. 1990). The elevation mation was crucial in delineating polygons of of the uppermost beachline of Lake Bonne- similar soil-forming potential and grossly simi- ville (about 1580 m, depending on degree of lar potential vegetation, particularly for the isostatic rebound) generally marked the upper mixed and deposition-dominated mesoterrain boundary of where lacustrine influences on units. Using the SSURGO coverage, it was pos- mixing of sediments occurred below and cre- sible to derive 5 sediment groups: glacial sedi- ated larger and more homogeneous polygons. ments, alluvium (degrading), eolian sediments Where the Pre-Wisconsinan soils are ex- (Quaternary sand dunes and loess), degrading posed, about 0.67 m of reddish clay is under- lake sediments, and aggrading lake sediments. lain by about a similar depth of lime-enriched Only 1 small polygon of glacial till was identi- weathered parent material. Wisconsinan de- fied in the highest elevations of the Deep Creek posits have had less time for their cobbles and Mountains. boulders to be weathered to clay than older SSURGO soil-mapping units were felt to materials (Hunt 1972). best match the units within the geologic groups DEM modeling was not functional for delin- of Table 4, by a rationale based on probability. eating landforms on the low-relief landscapes First, exposed bedrock units were identified of basin bottoms due to a lack of precision in by steeper slope classes, the presence of rock the 30-m-resolution DEM. It is possible that outcrop, and/or soils of <1 m depth to bedrock exposure, slope, and elevation modeling of land- as dominant components of mapped complexes. form units could provide further definition Eolian, lake, and alluvial sediments were when DEMs of greater resolution become differentiated by comparing soil textural fami- available. Small (<20 ha) polygons of bedrock lies, slope classes, and the presence or absence or detritus were ignored when found sur- of subsoil development with known relation- rounded by vast areas of playa. These island- ships of these properties to land-forming pro- like features are accounted for at lower levels 2005] UTAH’S WEST DESERT ECL 289

Fig. 1. Map of the Hill Air Force Base Military Operations Area (MOA) showing important natural and state (inset) boundaries. 290 WESTERN NORTH AMERICAN NATURALIST [Volume 65

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PHH H PHH RHH THH VHH IHHH B uilometers

Fig. 2A, Map of entire U.S. showing the Dry Domain within which the MOA is located. Outer MOA boundary is indi- cated by the red line. Great Salt Lake, in blue, occurs at its northeastern corner. B, Map of entire U.S. showing its divi- sion boundaries. The 2 divisions intersecting the MOA are in different colors. The outer boundary of the MOA is indi- cated by a red line. Great Salt Lake is in blue, at its northeastern corner. C, Map of entire U.S. showing its province 2005] UTAH’S WEST DESERT ECL 291

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boundaries. The 3 provinces intersecting the MOA are in different colors. The outer boundary of the MOA is indicated by the red line. Great Salt Lake, in blue, occurs at its northeastern corner. D, Map of entire U.S. showing section bound- aries. These 4 sections intersecting the MOA are in different colors. The outer boundary of the MOA is indicated by the red line. Great Salt Lake, in blue, is at its northeastern corner. 292 WESTERN NORTH AMERICAN NATURALIST [Volume 65

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Fig. 3. Map of entire MOA showing boundaries of all 60 bolson segments. See Appendix for names of each of the numbered bolson segments. 2005] UTAH’S WEST DESERT ECL 293

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Fig. 4. Map of the Utah Test and Training Range (UTTR) and Bolson Segments 32 and 33 intersecting the example transect. in our ECL. Extending this process across UTTR in the northern part of the MOA. Here state lines will require assembling similar geo- we focus on the southwesternmost spur of the logic and soils maps in the other states (Nevada Grassy Range called Finger Ridge. Mesoter- and Idaho) within the MOA. rain Polygon #4 is the most elevated erosional Figure 7, as an example, shows the meso- surface dominated by moderately hard, sedi- terrain units that straddle a portion of the mentary bedrock (Table 4). Degrading alluvium more intensively sampled strip along the is found at intermediate elevations, mainly in southern boundary of the North Unit of the the saddle between Finger Ridge and the 294 WESTERN NORTH AMERICAN NATURALIST [Volume 65

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Fig. 5. Map of macroterrain units over the entire MOA. 2005] UTAH’S WEST DESERT ECL 295

Fig. 6. Map of macroterrain units within Bolson Segments 32 and 33. 296 WESTERN NORTH AMERICAN NATURALIST [Volume 65

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Fig. 7. Map of mesoterrain units in Bolson Segment 33. largest, main mountain massif polygon (#3 in but further apart to the east or south because Fig. 6) along the westerly exposure of the main of the gentler topographic gradients in those axis of the Grassy Range. Because of the steep directions. topographic gradients on the westernmost At the level of detail used in delineating extent of Finger Ridge, depositional polygons mesoterrain-unit polygons, geographic descrip- are closer to each other to the north and west, tors are not always available on the 7.5-minute 2005] UTAH’S WEST DESERT ECL 297

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Fig. 8. Map of microterrain units over the entire UTTR North Unit and adjacent lands to the south administered by the Bureau of Land Management. 298 WESTERN NORTH AMERICAN NATURALIST [Volume 65

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Fig. 9. Map of microterrain units over 2 example mesoterrain unit polygons.

USGS topographic quadrangle maps; thus, we (see arrow in Fig. 7). If the entire MOA could resorted to numerical descriptors for mesoter- have been similarly mapped, we would expect rain units. An example of the naming of meso- 2460 mesoterrain polygons to be delineated, terrain units would be “Mesoterrain polygon with a 1834-ha mean size, 6501-ha standard #4, moderately hard sedimentary erosional unit deviation, and a range of 20.0 (the MMU) to on Middle West Slope of Grassy Mountains” 138,020 ha. 2005] UTAH’S WEST DESERT ECL 299

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Fig. 10. Map of the individual polygons associated with ecological sites (ESs) intersecting the sampling strip along the southern boundary of the UTTR, North Unit.

Microterrain Units am14_1.html) gave us slope position for ero- Since the detail needed to solve problems sional landscapes, classified as ridge, side slope, tends to escalate through time, we thought it toe slope, foot slope, and basin bottom. This wise to extend our ECL beyond the level classification is achieved by an iterative process where most current needs exist and thus show wherein the topographic position of each cell the abilities of this approach to apply into the is compared to that of its neighbors. These future. We thus divided mesoterrain units into attributes and landforms, outlined in Table 5, subdivisions called microterrain units. Micro- were combined with the attributes of the terrain units are further nested subdivisions of mesoterrain classification to produce microter- mesoterrain units which we largely based on rain units. Relationships of phases of the soil landforms for the erosion-dominated surfaces series with landscape processes, geologic and landforms plus soils for the mixed and groups, and landforms are summarized in deposition-dominated landscapes. Table 6. Landforms for the mountain massifs were Figure 8 shows microterrain units for the identified by modeling DEMs. Since the mixed entire UTTR North Unit, plus some BLM land and deposition-dominated portions of our land- outside its southern boundary. Because of the scapes lack striking relief, landforms and asso- differing topography, we identified 24 ⋅ km–2 ciated soils for these landscapes had to be (38 ⋅ mi–2) microterrain units on the mountain inferred from the SSURGO database (NRCS, massifs, 0.7 ⋅ km–2 (2 ⋅ mi–2) on the fan skirts, 1998). The attributes we utilized were textural and 0.07 ⋅ km–2 (0.2 ⋅ mi–2) on the playas. If family, degree of subsoil development, and this landscape is typical, then we would ex- slope. Toposcale AML software (see http://www pect to find 44,673 microterrain units over the .wsl.ch/staff.niklaus.zimmermann/programs/ entire MOA. The mean size of a microterrain 300 WESTERN NORTH AMERICAN NATURALIST [Volume 65

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Fig. 11. Map of Vegetation Stand (VS) polygons delineated in the demonstration strip.

unit polygon in our sample was 101 ha, with a Further Differentiations standard deviation of 1270 ha, and a range of While the above satisfied the objective of 2.0–52,214 ha. The MMU at this level was developing a “shortcut” means to complete 2.0 ha. the lower ecological units in a nested, top- Figure 9 shows an enlarged version of Fin- down, hierarchical way, somewhat analogous ger Ridge where mesoterrain polygons within mountain massif (erosional) units were subdi- to those suggested by ECOMAP for the vided into ridge, side slope, and foot slope NHEU (Table 1), it did not leave us with a microterrain units. For mixed mesoterrain units, sense that we had finished the ECL nor made divisions into either recent or reworked allu- it user-friendly for the local land manager. vial fans or loessial terraces were identified. Also, we had discovered some serious limita- Depositional units were either low lake plains tions of the ECOMAP approach, as so far or playas (salt flats). Since there usually were developed in the West, and decided that most no unique existing place names on 7.5-minute land managers would need more generalizable USGS quadrangles associated with areas as land classifications at local levels. small as most microterrain unit polygons, we ECOMAP is a top-down regionalization developed numerical designators. An example that is hierarchically nested and explicitly geo- is Microterrain Unit Polygon #13, a piece of graphic (Bailey 1995). While hierarchical struc- ridge on the moderately hard sedimentary ero- tures allow related land classification units to sional bedrock of the middle northwest side of be used at scales appropriate to various needs, Finger Ridge (see arrow in Fig. 9). from national to local, a consequence of the 2005] UTAH’S WEST DESERT ECL 301

Bolson Class Segments

Data

Slope Data Slope Model

Model

Geological Macroterrain Data Units

Mesoterrain Units

SSURGO Slope Elevation Data Position Data Model

Microterrain Units

Ecological Site Descriptions Ecological Site Polygons

Management Vegetation History Data

Vegetation Stand Polygons

Fig. 12. Flow diagram summarizing the major features of our Ecological Classification of Lands (ECL) process from Bolson Segments to Vegetation Stands. The bold line between Microterrain Units and Ecological Site Polygons is inserted to emphasize a switch from nested above to nonnested below. 302 WESTERN NORTH AMERICAN NATURALIST [Volume 65

TABLE 5. Summary of landforms used for defining microterrain units on the Hill AFB MOA. Erosion-dominated macroterrain units (source areas, mountain massifs) Ridges Side slopes Toe slopes Foot slopes Mixed erosional-deposition macroterrain units (bajadas, fan skirts) Recent alluvial fans Relict alluvial fans Older Lake Bonneville terraces Recent very fine sand and silt deposits Active dunes Vegetated dunes Inset flood plains Deposition-dominated macroterrain units (sinks) Valley bottoms Low lake plains Playas/salt flats top-down, nested hierarchicality that domi- than nested hierarchicality (O’Neill et al. 1986) nates the NHEU is that perimeters of outer could be employed, we propose a simpler, more polygons created at lower levels have to be straightforward solution. vertically integrated (congruent) with the delin- The Natural Resources Conservation Ser- eation of polygons occurring at upper levels. vice (NRCS) over the past 50 years has been One consequence of this “top-down” process building a vast set of information that applies is that if the lowest levels are produced inde- to the above need. For instance, the NRCS has pendently of higher levels, one should logi- identified 532 ecological sites (ESs) in Utah cally readjust (merge from the “bottom up”) (Natural Resources Conservation Service 1997). the congruent polygon boundaries involved in Each ES is a distinctive category of land with all affected polygons created at higher levels. the potential to produce and sustain similar Another consequence of the strictly top- kinds and amounts of vegetation under its par- down nested hierarchical design of ECOMAP ticular combination of environmental factors, is that progressively more, smaller and unique especially climate, soils, and associated native polygons are created for each level. While this biota (Shiflet 1973, Bedell 1998, Creque et al. tidiness may please scientists, it misserves man- 1999). Thus, all polygons that are similar in agers who need means to relate research and these respects, nested within NRCS’s Major personal experience between similar types of Land Resource Areas (McMahon et al. 2001) land regardless of how they fit in an ECL. In and somewhat similar to ECOMAP’s Sections, other words, the ECOMAP process applied so can be aggregated into these managerially useful far prevents one from easily relating features categories. Furthermore, NRCS site descriptions at one location to those within other microter- include information about vegetation fluctua- rain, mesoterrain, macroterrain units, or bolson tions expected under climatic variability and segments. For example, responses of vegeta- successional responses to various kinds of non- tion and animals to wildfires in 2 particular anthropogenic (e.g., wildfire) and anthropogenic microterrain unit polygons on the flanks of 2 (e.g., livestock grazing) disturbances (Grazing different mountain ranges occurring within Lands Technology Institute 1997). This impor- different bolson segments of the MOA are likely tant information is helpful to both managers to be similar, provided elevations, slopes, ex- and researchers (Creque et al. 1999). We there- posures, geological materials, and soil charac- fore devised a way to integrate these NRCS teristics are similar. If such comparisons were databases with our ECL of the MOA. facilitated, the manager could extrapolate Our actions do not violate the well-known knowledge from one polygon to others that are principle (Rowe 1961) that an entire hierarchi- highly similar, but relatively distant, if only the cal land classification cannot be built induc- nestedness of the ECL were modified to over- tively (from the bottom up). We have simply come this limitation. While networked rather pointed out that following a top-down nested 2005] UTAH’S WEST DESERT ECL 303

TABLE 6. Summary of the bases of classification of macroterrain, mesoterrain, and microterrain units for the Hill AFB MOA. Divisions/classes Classification bases

MACROTERRAIN Erosional landscapes Selection of all SSURGO units of shallow soils and/or slope of greater than 30% (high range) Mixed landscapes Selection of all SSURGO units of deep soils ranging from 1% (low range) to 30% (high range) slopes Depositional landscapes Selection of all SSURGO units of deep soils ranging from 0% (low range) to 2% slopes MESOTERRAIN Hard igneous/metamorphic rock Ti, Ji, C3, C2, C1, PCs, Pci, Pcm on geology layer Moderately hard sedimentary TR1, TR2, JTR, K3, K2, D, S, M3, M2, PNP, P2, P1, PN on geology layer Soft sedimentary/volcanic clastics T4, T3, T2, T1, Tvu, Tov, TK on geology layer Rhyolites/andesites Qr, Tmr, Tma, on geology layer Basalts Qb, Tmb, Tpb on geology layer Glacial deposits Qe on geology matched to soil unit from SSURGO layer Eolian deposits Dunes, Torripsamments, and coarse-loamy and fine- silty Torriorthents from SSURGO layer Alluvium (degrading) Very deep loamy-skeletal and sandy skeletal soils plus associated small floodplains from SSURGO layer Lake deposits (degrading) Very deep, fine-silty and fine-loamy developed soils, slopes 1%–8%, from SSURGO layer Lake deposits (aggrading) Very deep, fine-silty and fine-loamy developed soils, slopes 0%–2%, from SSURGO layer Ridges Identify from landform model MICROTERRAIN Side slope Identify from landform model Toe slope Identify from landform model Foot slope Identify from landform model Valley bottom Identify from landform model Ground moraine SSURGO unit correlated to geology layer Relict alluvial fans Loamy-skeletal and sandy-skeletal Torriorthents, from SSURGO layer Inset alluvial flood plain Identified from position and flooding frequency from SSURGO layer Lake Bonneville terraces Fine-silty and fine-loamy families with diagnostic surface and subsoil horizons, from SSURGO layer Low lake plain Fine-silty and families, natric and sodic subsoils, 0%–2%, from SSURGO layer Playa/salt flat SSURGO layer, “playa,” “salt flat”

hierarchy to its finest subdivisions counters land as plant succession is allowed to proceed common sense and practicality. or actively managed for. Delineation of ESs focuses on potential VSs are subdivisions of ESs where the rela- vegetation. Since late successional vegetation tive homogeneity of the vegetation has been is frequently not found on the land because of changed by relatively uniform kinds and inci- disturbances, soils information is utilized to dences of disturbance (Aber and Melillo 2001). crosswalk to expected potential vegetation. In other words, disturbance history dominates Managers and scientists, however, also fre- over site potential at the stand level. Thus, VSs quently need to know what the current vege- are where our classification system turns its tation is to deal with immediate problems. attention from potential to actual vegetation Accordingly, we added vegetational stands (VSs) created because of differing land use and dis- as the 10th and final level to our classification. turbance histories. It is also at this finest de- Managers are faced with dealing with both the gree of resolution that the influences of aspect current situation and what once was or could and slope and how they alter local effective eventually be found on particular pieces of environments can be accommodated. 304 WESTERN NORTH AMERICAN NATURALIST [Volume 65

TABLE 7. Relationships of ecological sites to soil series and polygons shown in Figure 10. Ecological site name Soil series Polygon numbers Semidesert Shallow Loam (Utah Juniper–Salina Wildrye) Amtoft 1, 8, 11, 13, 25, 28, 41, 58 Desert Gravelly Loam (Shadscale) Cliffdown 2, 7, 10, 17, 18, 26, 27, 29, 40, 44 Gravel Pit (vegetation absent) soil removed 3 Desert Loam (Shadscale) Tooele 4, 6, 9, 12, 20, 30, 45, 51 Desert Loam (Shadscale) Timpie 5, 16, 21, 43, 46 Semidesert Shallow Loam (Utah Juniper–Bluebunch Wheatgrass) Amtoft 14, 15, 37, 48, 50, 52 Desert Gravelly Sandy Loam (Indian Ricegrass) Izamatch 19, 24, 42 Alkali Flat (Black Greasewood) Skumpah 22 Desert Flat (Shadscale) Skumpah 23, 47 Desert Flat (Black Greasewood) Timpie 31, 33 Desert Alkali Bench (Bud Sagebrush) Cliffdown 32, 49 Desert Salty Silt (Pickleweed) Saltair 34, 38, 39, 57 Desert Oolithic Dunes (Black Greasewood) Dynal 35, 36, 53, 56

We focus our demonstrations here on how to senting an ES. We expected to see vegetation delineate ESs and VSs in only a small portion recovery following livestock removal on the of the MOA, the southeastern corner of the AF side, whereas the successional status of North Unit of the UTTR (Fig. 4). Within the 2- VSs on the opposite side of the fence (BLM), mile-wide by 30.15-mile-long (60.3-mile2) area but still in the same ES, should be earlier seral straddling (1-mile wide on the AF side, 1-mile because livestock grazing continues (Mayne wide on the BLM side) the southeastern and West 2001). boundary fence, we identified ESs and VSs to We had a prepublication version of the soils illustrate our procedures. We did this because map that became more recently available to generally many more and smaller polygons the public in Trickler et al. (2000). We ignored occur at these lowest levels, requiring larger potential polygons <1 ha that may involve map- map scales for illustration. Another reason is ping errors, but still found soil mapping units that the identity and boundaries of ES and VS that either occurred totally within (15 polygons) polygons can be verified in the field. If field- or that partially intercepted (43 polygons) the based procedures are used to check the sampling strip (Fig. 10). In Table 5 of Trickler boundaries for ES and VS polygons, the process et al. (2000), the correspondences of all ES becomes much more expensive, but also more polygons to soil series and their potential nat- reliable. We could afford to field check ESs ural vegetation are found. Using the names of and VSs in only 1 area under the temporal and relevant ESs and consulting condition and monetary constraints of the project. trend guides available from the State Office of We chose the demonstration area to map the NRCS, we have summarized in Table 7 ESs and VSs because it had landscapes with a these correspondences and the identification combination of mountain massif, bajada, and numbers of the individual ES polygons we playa macroterrain units typical of the entire found in the sampling strip (Fig. 10). MOA. The relatively low elevation of Grassy Modern “county” soil surveys like Trickler Mountains and Greyback Hills had fringing et al. (2000) have no unique polygons smaller bajadas, as well as playas, in the intervening than about 2 ha (MMU) separately delineated. Puddle and Ripple “Valleys.” Secondly, because Mapping units with a single named compo- the AF constructed a fence in 1968 along the nent are expected to contain at least 85% of boundary of the land they control, livestock that and similar soils. The remaining 15% have been excluded from the AF land where could be dissimilar soils, if discussed in the they had grazed previously. Livestock grazing, description of that mapping unit in the report. however, continues on the BLM side of the Soil mapping units may have up to 49% of the fence. Where ES polygons straddled the AF- total area within it actually occupied by up to BLM boundary, we saw this as an opportunity 3 other soil series besides the major series to pair up VSs within the same polygon repre- (Soil Survey Staff 1993). 2005] UTAH’S WEST DESERT ECL 305

Another potential problem (involving about VS polygons were drawn in the field on 15% of our study area) is that of mapped soil mylar overlays of the aerial photographs used complexes. These are situations where 2 or for the soil surveys. For practical reasons, we more kinds of soils occur in such small and ignored small unique areas <1 ha (MMU) intricate patterns that it is impractical to map and considered them inclusions. Furthermore, them separately (Soil Survey Staff 1993). These where a lobe or protrusion of a polygon nar- complexities can pose problems to inadequately rowed to <100 m in width, we drew the trained and inexperienced managers or re- boundary short of these narrow “tongues.” searchers, especially if field checking is fore- Thus, long, slim features such as linear rock gone. We have found that it is usually feasible outcrops and drainage lines with possibly dif- to have managers or investigators who know ferent landforms, soils, and vegetation were how soil maps are made, can read soil reports, not separately delineated, but included as part and can identify plants; they are thus able to of the dominant situation within the polygon. sort out these issues with minor amounts of If we had done otherwise, the cost of adding fieldwork. information at this level would have greatly Field validation during July 1996 was per- escalated. The user should realize, however, formed to check boundaries of the ES poly- that a few phenomena will be missed by such gons, note the degree of patterning of soil compromises (e.g., connection of some rare or series within these polygons, and subdivide T,E&S animals and plants to narrow rock out- them into VSs. Using the prepublication copies crops or riparian zones). of maps now found in Trickler et al. (2000), We found 75 VS polygons entirely within or plus both conventional aerial photography intersecting the sampled strip (Fig. 11). The (from the 1970s) and digital orthophotographic sampling strip VS polygons had a mean size of quadrangle photo-maps (DOQs) from 1995, 46 ha but varied between 14 ha and 167 ha we focused on differences in image brightness with a standard deviation of 95 ha. Where the and texture to delineate polygon boundaries. ES polygons straddled the ownership bound- The boundaries of most ES polygons were ary, at least 2 VSs were automatically created confirmed in the field, but a few minor modifi- because of differences in livestock grazing his- cations were made in the delinations of some tories created by the boundary fence (Mayne of these boundaries (Fig. 10). Please note that and West 2001). If there were obvious recent a conservative view of ESs was taken; where fires and mechanical disturbances within a VS there were differences in either the dominant polygon occurring totally on one side of the plants or soil series, distinctive ESs were used fence or the other, additional VS polygon (e.g., Desert Loam [Shadscale] on either Tooele boundaries were drawn. For instance, VS poly- or Timpie Series soils; Table 7). We did this in- gon 13C (hachured polygon in the upper right asmuch as differing approaches to management of Fig. 11) had significantly lower condition actions such as reseeding need to be taken on vegetation and soils than the other 2 larger these 2 ESs because of the soil differences. 13A and B polygons because it is closer to a The mean size of an ES polygon was 268 livestock watering point. Another example in- ha, with a standard deviation of 454 ha and a volves VS polygons 23C and D, which had evi- range between 1.0 ha and 3485 ha. Smaller dence of bombing craters and vehicle tracks polygons were located on mountain massifs, (probably created before 1968 when the AF- the largest on the depositional surfaces of the controlled property boundary extended much playas, and intermediate-sized ES polygons further southward), more introduced annuals, occurred on the mixed (transfer) zone of the and fewer native perennial plants on the ground fan skirts. We estimate that about 130 kinds of than VS polygons 23A or B. VS Polygons 23B ESs (in the NRCS sense) and about 800 ES and D are outside the fence and continue to polygons will be found on the entire MOA, if experience livestock grazing that adds to the the process we started is completed. This is a higher proportion of exotic to native plants than much more practical number of differing kinds the otherwise comparable VS polygons within of land for either the manager or scientists to the AF fence. deal with than the nearly 45,000 unique micro- If this sample is representative, 102,174 VS terrain units produced by following the strict polygons could be expected to be found over interpretations of ECOMAP. the entire MOA. The largest VS polygons were 306 WESTERN NORTH AMERICAN NATURALIST [Volume 65 found on depositional surfaces of the playa, tracked through GIS and other information- the smallest on erosional surfaces of the moun- retrieval systems. As we gained more experi- tain massifs. VS size was intermediate on the ence, the speed and ease of building this land mixed locations on the foothills and fan skirts. classification increased. Future expansions or The name of each VS polygon combines the refinements of the classification should there- common name of the dominant plant in the fore be more economical to produce. Demon- canopy layer, separated by a slash for under- stration of the utility of the classification awaits story strata, plus a unique number for each its application by land use planners and man- polygon (Table 2). agers in charge of lands under various owner- ships. Our efforts, however, should make EM CONCLUSIONS and ARM more feasible in the “West Desert.”

Our objective, to develop an ECL for the ACKNOWLEDGMENTS 4.5-million-hectare MOA, was accomplished. We did not modify the NHEU approach for This work was funded by the U.S. Air Force the upper 4 levels (in order of increasing grain: as part of a task order to the Bureau of Land domains, divisions, provinces, and sections). Management’s Landscape Ecology, Modeling However, because the information recom- and Analysis Unit located at Utah State Uni- mended to complete the lower levels of the versity. Terry Sharik was the principal investi- NHEUs for our area was too coarse and in- gator and strongly supported our efforts from consistent and not easy in either time or bud- beginning to end. Marcus Blood, environmental get to create, we largely developed from already officer at Hill Air Force Base, coordinated our extant information (Fig. 12) the next 4 lower activities on military lands. Many employees levels (bolson segments, macroterrain units, of the U.S. Departments of Interior and Agri- mesoterrain units, microterrain units) to com- culture and state resource agencies, too num- plete the NHEU and 2 additional levels (eco- erous to mention individually, provided infor- logical sites and vegetation stands). We stressed, mation crucial to our synthesis. wherever possible, a single dominant feature at each of these lower levels and repeatable, LITERATURE CITED transparent protocols. This contrasts with the ABER, J.D., AND J.M. MELILLO. 2001. Terrestrial ecosys- multivariable, difficult-to-repeat approach used tems. 2nd edition. Harcourt Academic Press, New by ECOMAP. Our 2 lowest levels go beyond York. what NHEU proposed but allow the constraints BAILEY, R.G. 1995. Description of the ecoregions of the of regionalization and “top-down” nested hier- United States. U.S. Department of Agriculture, For- est Service, Miscellaneous Publication 1391 (map archicality to be overcome without invoking scale 1:7,500,000). the complexities of networked hierarchies. ______. 1996. Ecosystem geography. Springer-Verlag, New Our approach to an ECL should make it York. easier for local managers to use the vast infor- BAILEY, R.G., P.E. AVERS, T. KING, AND W.H. MCNAB. 1994. mational databases already assembled by the Ecoregions and subregions of the United States (map scale 1:7,500,000). U.S. Department of Agricul- NRCS. These more detailed levels should also ture, Forest Service, Washington, DC. make the classification less abstract and there- BEDELL, T.E., CHAIRMAN. 1998. Glossary of terms used in fore more appealing to most managers and sci- range management. Society for Range Management, entists with only local interests. Furthermore, Denver, CO. 32 pp. BENSON, L.V., D.R. CURREY, R.I. DORN, K.R. LAJORE, C.G. these finest-grained units could be validated OVIATT, S.W. ROBINSON, G.I. SMITH, AND S. STINE. through some fieldwork. While these additions 1990. Chronology of expansion and contraction of four make the entire classification more expensive Great Basin Lake systems during the past 35,000 to produce, considerable error is corrected years. Paleogeography, Paleoclimatology, Paleoecol- and confidence gained to support it. Those with ogy 78:241–286. BOULDING, K.E. 1980. Science: our common heritage. interests only at coarser levels can simply ignore Science 207:831–836. these local distinctions if they wish. CARPENTER, C.A., W.N. BUSCH, D.T. CLELAND, J. GALLEGOS, We have produced maps with example poly- R. HARRIS, R. HOLM, C. TOPIK, AND A. WILLIAMSON. gons at all levels in the classification. We have 1999. Use of ecological classification in manage- ment. Pages 395–430 in R.C. Szaro et al., editors, also developed a hierarchical nomenclature Ecological stewardship. Volume II. Elsevier Science such that all existing and new data can be Publishers, Amsterdam, The Netherlands. 2005] UTAH’S WEST DESERT ECL 307

CREQUE, J.A., S.D. BASSETT, AND N.E. WEST. 1999. View- U.S. Department of Agriculture, Forest Service, point: delineating ecological sites. Journal of Range Washington, DC. Management 52:546–549. NATURAL RESOURCES CONSERVATION SERVICE. 1997. DRISCOLL, R.S., D.L. MERKEL, D.L. RADLOFF, D.E. SNYDER, Guides to ecological sites of Utah. NRCS, State Office, AND J.S. HAGIHARA. 1984. An ecological classification Salt Lake City, UT. framework for the United States. U.S. Forest Service, ______. 1998. SSURGO database for military lands in west- Miscellaneous Publication 1439. Washington, DC. ern Utah. Natural Resources Conservation Service, ECOMAP. 1993. National hierarchial framework of eco- Salt Lake City, UT. logical units. U.S. Department of Agriculture, Forest OMERNIK, J.M., AND R.G. BAILEY. 1997. Distinguishing be- Service, Washington, DC. tween watersheds and ecoregions. Journal of the EDWARDS, T.C., JR., C.G. HOMER, S.D. BASSETT, A. FAL- American Water Resources Association 33:935–949. CONER, R.D. RAMSEY, AND D.W. WIGHT. 1995. Utah O’NEILL, R.V., D.L. DEANGELIS, J.B. WAIDE, AND T.F.H. Gap analyses: an environmental information system. ALLEN. 1986. A hierarchical concept of ecosystems. U.S. Department of the Interior, National Biological Princeton University Press, Princeton, NJ. Service. PETERSON, F.F. 1981. Landforms of the Basin and Range FIERO, B. 1986. Geology of the Great Basin. University of Province defined for soil survey. Technical Bulletin Nevada Press, Reno. 28, Nevada Agricultural Experiment Station, Uni- GOUDEY, C.B., AND D.W. SMITH, EDITORS. 1994. Ecologi- versity of Nevada, Reno. 52 pp. cal units of California: subsections. U.S. Department PICKUP, G. 1985. The erosion cell—a geomorphic approach of Agriculture, Forest Service, Region 5, San Fran- to landscape classification in range assessment. Aus- cisco. Map 1:100,000 scale colored. tralian Rangeland Journal 11:114–121. GRAZING LANDS TECHNOLOGY INSTITUTE. 1997. National ROWE, J.S. 1961. The level of integration concept and ecol- range and pasture handbook. U.S. Department of ogy. Ecology 42:420–427. Agriculture, Natural Resources Conservation Service, SCOTT, J.M., F. DAVIS, B. CSUTI, R. NOSS, B. BUTTERFIELD, Washington, DC. H.A.C. GROVES, S. CAICCO, ET AL. 1993. Gap analy- HINTZE, L.F. 1980. Geologic map of Utah 1:500,000 scale, sis: a geographic approach to protection of biological colored with cross sections and stratigraphic columns. diversity. Wildlife Monographs 123:1–41 Privately published. SHIFLET, T.N. 1973. Range sites and soils in the United HUNT, C.B. 1972. Geology of soils: their evolution, classifi- States. Pages 26–33 in H.F. Heady, editor, Arid shrub- cation and uses. W.H. Freeman, San Francisco, CA. lands: proceedings of the Third Worship of the United LOERCH, J.C., K.D. ADAMS, AND V.L. PARSLOW. 1997. Soil States/Australia Rangelands Panel, Tucson, AZ, 26 survey of Box Elder County, Utah, western part. U.S. March–5 April 1973. Department of Agriculture, Natural Resources Con- SOIL SURVEY STAFF. 1993. National soil survey handbook. servation Service, Salt Lake City, UT. Title 430-IV, Soil Conservation Service, U.S. Depart- MAYNE, S., AND N.E. WEST. 2001. A field test of a new ment of Agriculture, U.S. Government Printing Office, Australian method of rangeland monitoring. Pages Washington, DC. 315–317 in E.D. McArthur and D.J. Fairbanks, com- SZARO, R. 1999. Monitoring and evaluation. Pages 223– pilers, Proceedings: shrubland ecosystem genetics 230 in N.C. Johnson et al., editors, Ecological stew- and biodiversity. General Technical Report RMRS- ardship. Volume I. Elsevier Science Publishers, P-21, U.S. Department of Agriculture, Forest Ser- Amsterdam, The Netherlands. vice, Rocky Mountain Research Station, Ogden, UT. THOMAS, J.W., AND J. BIRCHFIELD. 2000. Science, politics MCMAHON, G., S.M. GREGONIS, S.W. WALTMAN, J.M. OMER- and land management. Rangelands 22(4):45–51. NIK, T.D. THORSON, J.A. FREEOUF, A.H. FORICK, AND TRICKLER, D.L., D.T. HALL, C.D. FRANKS, S.K. FERGUSON, J.E. KEYS. 2001. Developing a spatial framework of L.D. CAMPBELL, P.J. SAVAGE, AND J.E. BREWER.2000. common ecological regions for the conterminous Soil survey of Tooele area, Utah. U.S. Department of United States. Environmental Management 28: Agriculture, Natural Resources Conservation Ser- 293–316. vice, Salt Lake City, UT. MCNAB, W.H., AND P.E. AVERS. 1994. Ecological subre- WEST, N.E. 1995. Deserts. Pages 475–492 in W.A. Niren- gions of the United States: section descriptions. U.S. berg, editor, Encyclopedia of environmental biology. Department of Agriculture, Forest Service, WO- Academic Press, Orlando, FL. WSA-5. MCNAB, W.H., AND R.G. BAILEY. 1994. Map unit descrip- Received 22 September 2003 tions of subregions (sections) of the United States. Accepted 6 December 2004

Appendix follows on pages 308–309. 308 WESTERN NORTH AMERICAN NATURALIST [Volume 65

APPENDIX. Names of numbered bolson segments in Figure 3. Number Name 1 East slope of Dove Creek–Grouse Creek Mountains and adjoining bajadas. 2West slope of Cedar Hills–Albion Mountains and east side of Junction Creek. 3 East slope of Middle and Goose Creek Mountains and west side of upper Junction Creek Valley. 4West slope of Middle and Goose Creek Mountains and eastern-valley portion of upper Goose Creek. 5 North slope of Raft River Mountains and adjoining bajadas. 6West slope of Cedar Mountains and eastern portion of Rock Spring Creek Valley. 7 South and west slopes of Grouse Creek Mountains and eastern portion of adjoining Grouse Creek Valley. 8 South slope of Raft River Mountains and adjoining Park and Curlew Valleys. 9 East slope of White Rock–China Jim Hills and adjoining Grouse Creek Valley. 10 East slope of Matlin Mountains and adjoining pediments. 11 East slope of Delano Peak and adjoining western portion of Crittenden Creek Valley. 12 West slope of White Rock–China Jim Hills and eastern portion of valley draining Crittenden Creek. 13 West slope of Matlin Mountains and adjoining pediments. 14 West slope of Delano Peak and adjoining eastern portion of valley where 1000 Springs and Rock Spring Creeks meet. 15 East slope of Hogup Mountains, adjoining bajadas, and salt flats of northwestern Great Salt Lake Desert. 16 West slope of Hogup Mountains and adjoining bajadas of northern Great Salt Lake Desert. 17 South slopes of Ninemile Mountain and Ninemile Ridge and western portion of 21-Mile Draw Valley. 18 East slope of Mineral Mountain and adjoining eastern side of 21-Mile Draw Valley. 19 West slope of Toana Mountains and adjoining eastern side of northern Goshute Valley. 20 East slope of Toana Mountains, adjoining bajadas, and western side of Pilot Creek Valley. 21 West slope of Pilot Mountain Range, adjoining bajadas, and eastern side of Pilot Creek Valley. 22 East slope of Pilot Mountain Range, adjoining bajadas, and salt flats of northern Great Salt Lake Desert. 23 West slope of Newfoundland Mountains, adjoining bajadas, and salt flats of northern Great Salt Lake Desert. 24 West slope of Goshute Mountains, adjoining bajadas, and salt flats on eastern side of northern Great Salt Lake Desert. 25 East slope of Newfoundland Mountains, adjoining bajadas, and salt flats of northern Great Salt Lake Desert. 26 East slope of Goshute Mountains, adjoining bajadas, and salt flats of western Great Salt Lake Desert. 27 East slope of Pequop Mountains, adjoining bajadas, and salt flats on eastern side of Goshute Valley. 28 West slope of Lakeside Mountains, adjoining bajadas, and salt flats of eastern Puddle Valley. 29 West slope of Lakeside Mountains, adjoining bajadas, and salt flats of northern Great Salt Lake Desert. 30 East slope of Lakeside Mountains, adjoining bajadas, and salt flats on west side of northern Great Salt Lake Desert. 31 West slope of Silver Island Mountains, adjoining bajadas, and salt flats of Great Salt Lake Desert. 32 East slope of Grassy Mountains, adjoining bajadas, and salt flats of west side of Puddle Valley. 33 West slope of Grassy Mountains, adjoining bajadas, and salt flats of eastern Great Salt Lake Desert. 34 West slope of Silver Island Mountains, adjoining bajadas, and salt flats of Great Salt Lake Desert. 35 East slope of Cedar Mountains, adjoining bajadas, and salt flats of western Skull Valley. 2005] UTAH’S WEST DESERT ECL 309

36 East slope of Stansbury Mountains, adjoining bajadas, and salt flats of western portions of Rush and Tooele Valleys. 37 West slope of Stansbury Mountains, adjoining bajadas, and salt flats on the eastern side of Antelope Valley. 38 East slope of the Antelope Range, adjoining bajadas, and salt flats of eastern side of Skull Valley. 39 West slope of the Antelope Range and adjoining bajadas on eastern side of Spring Valley. 40 West slope of Deep Creek, Kern, Moriah, and Snake Mountains, adjoining bajadas, and salt flats of western Antelope and Spring Valleys. 41 East slope of Deep Creek, Kern, Moriah, and Snake Mountains and adjoining salt flats of southern Great Salt Lake Desert and Snake and Hamblin Valleys. 42 West slope of Granite Dugway and Thomas Mountain Ranges, adjoining bajadas, and salt flats of southern Great Salt Lake Desert and Dugway Valley. 43 East slope of Granite Dugway and Thomas Mountain Ranges, adjoining bajadas, and salt flats of southern Great Salt Lake Desert and eastern Fish Springs. 44 West slope of Simpson and Desert Mountain Ranges and adjoining bajadas of eastern riverbed area. 45 East slope of Simpson and Desert Mountain Ranges and adjoining bajadas. 46 West and north slopes of Keg Mountain and adjoining bajadas in eastern Dugway Valley. 47 East slope of Schell Creek and Fortification Ranges, adjoining bajadas, and salt flats of eastern side of Spring Valley. 48 West slope of Fish Spring Mountain Range, adjoining bajadas, and salt flats of northeastern Snake Valley. 49 East slope of Fish Spring Mountain Range and adjoining bajada and salt flats of western Fish Springs Valley. 50 West slope of Confusion, Wah Wah, and Conger Mountain Ranges and adjoining bajadas of eastern side of Snake, Ferguson, and Pine Valleys. 51 East and south slopes of Keg Mountain and adjoining bajadas in Sevier Desert. 52 East slope of Confusion and Wah Wah Mountain Ranges and adjoining bajadas of eastern side of Tule and Wah Wah Valleys. 53 East slope of House and Swasey Mountain Ranges, adjoining bajadas, and salt flats on eastern side of Whirlwind and Sevier Lake Valleys. 54 West slope of House and Swasey Mountain Ranges, adjoining bajadas, and salt flats on eastern side of Tule Valley. 55 West slope of Cricket and San Francisco Mountain Ranges, adjoining bajadas, and salt flats on eastern sides of Sevier Lake and Tule Valley. 56 East slope of Cricket and San Francisco Mountain Ranges, adjoining bajadas, and salt flats of western Clear Lake Valley and western Beaver River bottoms. 57 North and west slopes of Burbank Hills and Tunnel Spring Mountain and adjoining bajadas in Ferguson Desert. 58 South and west slopes of Burbank Hills–Tunnel Springs Mountain and adjoining bajadas in Antelope and northern Pine Valleys. 59 East slope of Mountain Home–Needle Mountain Ranges, adjoining bajadas, and valley plains on western side of Pine Valley. 60 East slope of Cedar Hills and adjoining upper Raft River Valley.