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5 . S i e r r a N e v a d a Ecoregion 5 is a mountainous, deeply dissected, and westerly tilting block. It is largely composed of granitic rocks that are Ecoregions of lithologically distinct from the sedimentary rocks of the Klamath (78) and the volcanic rocks of the Cascades (4). A Ecoregions denote areas of general similarity in and in the type, quality, Vegas, Reno, and Carson City areas. Most of the state is internally drained and lies Literature Cited: high fault scarp divides the (5) from the Northern Basin and Range (80) and Central Basin and Range (13) to the 2 2 . A r i z o n a / N e w M e x i c o P l a t e a u east. Near this eastern fault scarp, the Sierra Nevada (5) reaches its highest elevations. Here, , cirques, and small lakes and quantity of environmental resources. They are designed to serve as a spatial within the ; rivers in the southeast are part of the River system Bailey, R.G., Avers, P.E., King, T., and McNab, W.H., eds., 1994, Ecoregions and subregions of the Ecoregion 22 is a high dissected underlain by horizontal beds of limestone, sandstone, and shale, cut by canyons, and (map): Washington, D.C., USFS, scale 1:7,500,000. are especially common and are products of alpine glaciation. Large areas are above timberline, including Mt. Whitney framework for the research, assessment, management, and monitoring of ecosystems and those in the northeast drain to the . There are 5 level III ecoregions punctuated by mountains, , and . The / Plateau (22) is transitional between surrounding higher, Bryce, S.A., Omernik, J.M., and Larsen, D.P., 1999, Ecoregions—a geographic framework to guide risk in , the highest point in the conterminous United States at nearly 14,500 feet. The Sierra Nevada (5) casts a and components. By recognizing the spatial differences in the capacities and 43 level IV ecoregions in Nevada and many continue into ecologically similar forested, mountainous ecoregions and lower, more arid shrublands. Ecoregion 22 is similar to the Colorado (20) to the characterization and ecosystem management: Environmental Practice, v. 1, no. 3, p. 141-155. over Ecoregions 13 and 80 to the east. Higher elevation areas are mostly federally owned and include several national parks. In and potentials of ecosystems, ecoregions stratify the environment by its probable parts of adjacent states (McGrath and others, 2002; Woods and others, 2001). north in having abundant pinyon-juniper woodland and deep canyons (e.g. the ). However, the Arizona/New Mexico Commission for Environmental Cooperation Working Group, 1997, Ecological regions of North Nevada, vegetation grades from Jeffrey pine to fir and whitebark pine at higher elevations. Alpine conditions exist at the highest response to disturbance (Bryce and others, 1999). Ecoregions are general purpose Plateau (22) is higher than the Colorado Plateaus (20), and it has less physiographic diversity. Ecoregion 22 lacks the broad, hot regions that are critical for structuring and implementing ecosystem management The level III and IV ecoregion map on this poster was compiled at a scale of America—toward a common perspective: Montreal, Commission for Environmental Cooperation, 71 p. elevations. 1:250,000 and depicts revisions and subdivisions of earlier level III ecoregions that Gallant, A.L., Whittier, T.R., Larsen, D.P., Omernik, J.M., and Hughes, R.M., 1989, Regionalization as basins, such as Monument and the , that are found in the Colorado Plateaus (20). The Arizona/New Mexico strategies across federal agencies, state agencies, and nongovernmental organizations a tool for managing environmental resources: Corvallis, Oregon, U.S. Environmental Protection Within Nevada, the Mid-Elevation Sierra Nevada ecoregion begins abruptly in the foothills of the Carson Range at the Plateau (22) also contains more semiarid shrubland and subhumid grassland than Ecoregion 20, making it more suitable for that are responsible for different types of resources in the same geographical areas were originally compiled at a smaller scale (USEPA, 2002; Omernik, 1987). This 5a poster is part of a collaborative project primarily between USEPA Region 9, USEPA Agency, EPA/600/3-89/060, 152 p. western edge of the state. Physiographically, the Carson Range is a Great Basin range, but its grazing cattle. (Omernik and others, 2000). and forest type are more typical of the Sierra Nevada. The mid-elevation dry forest of Ecoregion 5a contains a diverse National Health and Environmental Effects Research Laboratory (Corvallis, Griffith, G.E., Omernik, J.M., Wilton, T.F., and Pierson, S.M., 1994, Ecoregions and subregions of The Middle Elevation Mountains ecoregion, represented in southeastern Nevada by the Virgin Mountains, is a small Iowa – a framework for water quality assessment and management: Journal of the Iowa Academy of mix of conifers, including Jeffrey pine, sugar pine, incense cedar, and California white fir. The understory includes sagebrush, The approach used to compile this map is based on the premise that ecological Oregon), Nevada Department of Conservation and Natural Resources–Division of 22d portion of the Arizona/New Mexico Plateau (22). Its woodland zone differs from the woodlands of other mountainous Science, v. 101, no. 1, p. 5-13. antelope bitterbrush, and a fire-maintained chaparral component of snowbrush and manzanita. The amount of pinyon–juniper regions can be identified through the analysis of the spatial patterns and the Environmental Protection, Nevada Department of Conservation and Natural areas in the Great Basin in the prevalence of interior chaparral species, such as Gambel oak, scrub oak, and canyon maple, J.A., Shelden, J., Crawford, R.C., Comstock, J.A., and Plocher, M.D., 2002, Ecoregions of Idaho: woodland in Ecoregion 5a is insignificant in contrast to other Nevada ecoregions in this elevation range. composition of biotic and abiotic phenomena that affect or reflect differences in Resources–Nevada Natural Heritage Program, United States Department of Reston, Virginia, U.S. Geological Survey (map scale 1:1,350,000). interspersed with the pinyon and juniper. On the lower slopes, juniper mixes with Joshua tree and Mojave yucca; here, woodland The High Elevation Sierra Nevada ecoregion includes subalpine forest and parkland between 7,500 and 9,500 feet ecosystem quality and integrity (Wiken, 1986; Omernik, 1987, 1995). These Agriculture–Forest Service (USFS), United States Department of McMahon, G., Gregonis, S.M., Waltman, S.W., Omernik, J.M., Thorson, T.D., Freeouf, J.A., Rorick, 5b starts at a lower elevation (about 4,000 feet) than in the or Great Basin. Broad areas of mountain brush grow on phenomena include geology, physiography, vegetation, climate, soils, land use, Agriculture–Natural Resources Conservation Service (NRCS), United States A.H., and Keys, J.E., 2001, Developing a spatial framework of common ecological regions for the elevation. The vegetation in this zone is adapted to extremes in heavy winter snowpack and summer drought. Sierra upland slopes above the woodland. Isolated pockets of Rocky Mountain white fir and Rocky Mountain Douglas-fir also occur. wildlife, and . The relative importance of each phenomenon varies from Department of the Interior–Bureau of Land Management (BLM), United States conterminous United States: Environmental Management, v. 28, no. 3, p. 293-316. In Nevada, the Sierra Nevada (5) contains the Carson Range and . Dense lodgepole pine, red fir, western white pine, mountain hemlock, and whitebark pine comprise the moist forest at these elevations. They are outliers of a higher montane zone that is not extensive enough to map in Nevada. one ecological region to another regardless of ecoregion hierarchical level. A Roman Department of the Interior–Fish and Wildlife Service, and United States Department Omernik, J.M., 1987, Ecoregions of the conterminous United States (map supplement): Annals of the forests, high precipitation levels, heavy snowpack, and a high stream density are Alpine tundra occurs on Mt. Rose, but it is too small an area to be mapped at this scale. The highest average annual precipitation The mountains, buttes, and canyons of the Arizona/New Mexico Plateau (22). Photo: NRCS numeral hierarchical scheme has been adopted for different levels of ecological of the Interior–Geological Survey (USGS)–Earth Resources Observation Systems Association of American Geographers, v. 77, p. 118-125, scale 1:7,500,000. characteristic and are in stark contrast to the drier conditions that are common in the rest of the state. amounts anywhere in Nevada occur in Ecoregion 5b. The east and west slopes of the Carson Range and the adjacent Lake Tahoe regions. Level I is the coarsest level, dividing North America into 15 ecological (EROS) Data Center. Omernik, J.M., 1995, Ecoregions-—a framework for environmental management in Davis, W.S. and basin serve as important watersheds supplying water to urban and agricultural areas in . Simon, T.P., editors, Biological assessment and criteria-tools for water resource planning and regions. Level II divides the continent into 52 regions (Commission for decision making: Boca Raton, Florida, Lewis Publishers, p. 49-62. Environmental Cooperation Working Group, 1997). At level III, the continental The Nevada ecoregion project is associated with an interagency effort to develop a common framework of ecological regions. Reaching that objective requires Omernik, J.M., Chapman, S.S., Lillie, R.A., and Dumke, R.T., 2000, Ecoregions of Wisconsin: United States contains 104 ecoregions and the conterminous United States has 84 Transactions of the Wisconsin Academy of Sciences, Arts, and Letters, v. 88, p. 77-103. ecoregions (U.S. Environmental Protection Agency [USEPA], 2002). Level IV is a recognition of the differences in the conceptual approaches and mapping methodologies applied to develop the most common ecoregion-type frameworks, U.S. Department of Agriculture–Soil Conservation Service, 1981, Land resource regions and major land further subdivision of level III ecoregions. Explanations of the methods used to resource areas of the United States: Agriculture Handbook 296, 156 p. 1 3 . C e n t r a l B a s i n a n d R a n g e define the USEPA’s ecoregions are given in Omernik (1995), Omernik and others including those developed by the USFS (Bailey and others, 1994), the USEPA Ecoregion 13 is composed of northerly trending fault-block ranges and intervening drier basins. Valleys, lower slopes, and alluvial fans are either shrub- and grass-covered, or shrub-covered. Higher elevation mountain slopes support woodland, mountain brush, and (Omernik, 1987, 1995), and the NRCS (U.S. Department of Agriculture–Soil U.S. Environmental Protection Agency, 2002, Level III ecoregions of the continental United States (2000), Griffith and others (1994), and Gallant and others (1989). (revision of Omernik, 1987): Corvallis, Oregon, USEPA–National Health and Environmental scattered forests. The Central Basin and Range (13) is internally drained by rivers flowing off the east slopes of the Sierra Nevada and by the , one of the longest internally drained river systems in North America. In western Nevada, Pleistocene Lake Conservation Service, 1981). As each of these frameworks is further refined, their Effects Research Laboratory, Map M-1, various scales. Lahontan inundated a large part of Ecoregion 13 below about 4,400 feet elevation. Today, evidence of exists as extensive, nearly flat playas covered by fine textured, alkaline or saline deposits. In general, Ecoregion 13 is drier than the Sierra Nevada (5), Nevada’s physiography is composed of a repeating pattern of fault block mountains differences are becoming less discernible. Regional collaborative projects, such as Wiken, E., 1986, Terrestrial ecozones of Canada: Ottawa, Environment Canada, Ecological Land cooler than the Mojave Basin and Range (14), and warmer and drier than the Northern Basin and Range (80). Soils grade upslope from Aridisols or Entisols to Mollisols. The land is primarily used for grazing and a greater percentage is used for livestock grazing than and intervening valleys. Valleys are shrub-covered or shrub- and grass-covered. this one in Nevada, where agreement has been reached among multiple resource Classification Series no. 19, 26 p. in Ecoregion 14. In addition, some irrigated cropland is found in valleys near mountain water sources. Military bases also occur in Ecoregion 13 and are of environmental significance because of their large area and their unique land use management practices. Mountains may be brush-, woodland-, or forest-covered. Land use is primarily management agencies, are a step toward attaining consensus and consistency in Woods, A.J., Lammers, D.A., Bryce, S.A., Omernik, J.M., Denton, R.L., Domeier, M., and Comstock, rangeland but many mines and large military reservations occur. Some valleys are ecoregion frameworks for the entire nation. J.A., 2001, Ecoregions of : Reston, Virginia, U.S. Geological Survey (map scale 1:1,175,000). The Salt ecoregion is composed of nearly level playas, salt flats, mud flats, and saline lakes. These features are The basins and semi-arid uplands of the Carbonate Sagebrush Valleys surround the carbonate ranges of eastern Nevada irrigated and farmed, and rapid urban and suburban growth is occurring in the Las 13a characteristic of those in the Bonneville Basin; they have a higher salt content than the Lahontan and Tonopah Playas 13p (Ecoregions 13e and 13q). Like the ranges, the Carbonate Sagebrush Valleys (13p) are also largely underlain by limestone 120° 119° 118° 117° 116° 115° 114° (13h). Water levels and salinity fluctuate from year to year; during dry periods salt encrustation and wind occur. Vegetation or dolomite. The combination of summer moisture and a limestone or dolomite substrate affects regional vegetation, particularly in 42° is mostly absent although scattered salt-tolerant plants, such as pickleweed, iodinebush, black greasewood, and inland saltgrass, terms of species dominance and elevational distribution. The substrate favors shrubs, such as black sagebrush and winterfat, that OREGON 80 42° Subsurface water that percolated through the The scarcity of water in the Central Basin G IDA HO 80d J occur. Soils are not arable, and there is very limited grazing potential. The salt deserts provide wildlife , and serve some can tolerate shallow soil. Even in alluvial soils, root growth may be limited by a hard pan or caliche layer formed by carbonates porous limestone and dolomite of the Ruby and Range (13) creates conflicts among 9 a o k r o e Denio b Jackpot s e recreational, military, and industrial uses. leaching through the soil and accumulating. As a result, shrub cover is sparse in contrast to other sagebrush-covered ecoregions in Mountains (in Ecoregions 13n and 13o) competing users. Lake Winnemucca (in S Owyhee i e r McDermitt d 80a 80l o B g u 80e ru C resurfaces to the east as seeps and springs. Ecoregions 13h and 13j) disappeared during t n e Nevada, including Ecoregions 13c, 13k, and 13r. The grass understory grades from a dominance of cool season grasses, such as h O e The Shadscale-Dominated Saline Basins ecoregion is arid, internally drained, and gently sloping to nearly flat. These 80g w a R Jarbidge The Ruby Marshes in Ecoregion 13g the last century when it no longer received F yh u 80j 80j e i 80a o v 13b bluebunch wheatgrass, in the north, to warm season grasses, such as blue grama (an indicator of summer rainfall) in the south. r e R e 80 basins are in, or characteristic of, the Bonneville Basin; they are higher in elevation and colder in winter than the Lahontan provide crucial nesting and feeding grounds water from due to increased k 80l 80j O i r w 80j v

80a e K y R for wildlife. Photo: State of Nevada, Division of withdrawals for irrigation and urbanization. h r 80k Salt Shrub Basin (13j) to the west. Light-colored soils with high salt and alkali content occur and are dry for extended periods. The In the Carbonate Woodland Zone the pinyon–juniper woodland canopy overtops and spans the existing sagebrush and i e i 80j n v 80d g e Environmental Protection Photo: Jim Morefield, Nevada Natural Heritage e 13q s R r saltbush vegetation common to Ecoregion 13b has a higher tolerance for extremes in temperature, aridity, and salinity than big mountain brush communities. The pinyon–juniper woodland has a broader elevational range in the carbonate areas of R Program i

v i v e 80j e r Wild Horse sagebrush, which dominates Ecoregion 13c at somewhat higher elevations. The basins in Nevada, in contrast to those in Utah, are eastern Nevada than elsewhere in Ecoregion 13, even extending onto the floors of the higher basins, partially because of greater r 80j 80k Vya 80j Reservoir 80b 80d 80j more constricted in area and more influenced by nearby carbonate mountain ranges, which provide water by percolation through the summer precipitation. Both pinyon and juniper decline north of Ecoregion 13q; in Ecoregion 80, juniper grows alone and without M limestone substrate to valley springs. Isolated valley drainages support endemic fish, such as the Newark Valley tui chub. distinct elevational banding. Historically, miners cut pinyon and juniper for mine timbers. Since the beginning of fire suppression ar ys

Orovada N early in the last century, juniper–pinyon woodland has increased in density and expanded into lower sagebrush zones. More 80j o R The Sagebrush Basins and Slopes ecoregion consists of semiarid valleys, alluvial fans, low hills, and mountain flanks r 80a

80j i t v

h e 13c recently, large areas of pinyon–juniper woodland have been cleared to increase forage for cattle. The woodland understory is

dominated by big sagebrush. The sagebrush areas are situated at higher elevations than the Shadscale-Dominated

r 80b

ive F R r 80g o diverse due to the influence of carbonate substrates and summer rainfall. There are more springs and live streams in Ecoregion 13q t 80a r Saline Basins (13b) where soils are not as saline, moisture levels are slightly higher, and winter temperatures are more moderate. k 13c er ld v o Tuscarora than in western non-carbonate woodlands (e.g. Central Nevada Mid-Slope Woodland and Brushland (13s)) because the carbonate i b R Y Associated cool season bunchgrasses increase to the north in Ecoregion 13c, but they are less abundant than in Ecoregions 80a and 80j m E mboldt n u Hu substrate is soluble and porous, allowing rapid infiltration. N n 13l L H R Montello 80g, which may be considered to be sagebrush steppe. Associated vegetation, substrate, and climate determine the differences O i 80j L iv 80b Y u 13k N 80g e A A Q r e between Ecoregion 13c and other sagebrush-dominated ecoregions in Nevada, such as Ecoregions 13p, 13r, and 13v. Several rodent The Central Nevada High Valleys ecoregion contains sagebrush-covered rolling valleys that are generally over 5,000 C V l L t 80b L t k 13c i 13r A T e and bird species and the pronghorn antelope depend on sagebrush for food and shelter. feet in elevation. Alluvial fans spilling from surrounding mountain ranges fill the valleys, often leaving little intervening W 13k L e R 13k r

E C The characteristic landscape of the Central Basin and Range (13) has an alternating 13b S flat ground. Wyoming big sagebrush and associated grasses are common on the flatter areas, and black sagebrush dominates on the T The occurs in the E The Woodland- and Shrub-Covered Low Mountains ecoregion includes low, rocky mountain ranges, mountain slopes, k pattern of fault block mountain ranges and intervening valleys. Precipitation increases R 13d 9 80j D 13z 13l c Wells 13d volcanic hills and alluvial fans. Ecoregion 13r tends to have a lower species diversity than many other sagebrush-dominated Truckee River-Pyramid Lake system of E o 13g and air temperature decreases with increasing elevation, and both influence the and foothills with enough available moisture to support open groves of juniper and pinyon. The region includes a zone of

R 13q S 13e Ecoregion 13j and in perennial streams ° 80j 13j 13z distribution of vegetation. ecoregions (including Ecoregions 13c, 13m, 13p, 13aa, 80a, and 80g) because of its aridity and its isolation from more species-rich 41 80d E 13m 13q 13p ° mountain brush that replaces woodland above the elevational limit of pinyon. In southeastern Nevada, Ecoregion 13d is transitional draining the Sierra Nevada in Ecoregions D 13k 13k Humb 41 o 13q areas. Saline playas may occur on available flats. Less shadscale and fewer associated shrubs surround these playas than in other C 13x and 13aa. Their numbers are declining 13h 13k ld between the , Great Basin, and Mojave Desert, with some characteristics of each region. There, Gambel oak, scrub t L Winnemucca due to loss of habitat, diversion of perennial K O lower, more arid ecoregions to the west, including the Lahontan Salt Shrub Basin (13j) and Tonopah Basin (13u). Valleys with oak, Joshua tree, and blue grama grass may be associated with pinyon–juniper woodland. Summer rainfall is a factor that

80 C V streams, and competition with introduced The value of streams and associated riparian

O E contributes to woodland diversity and productivity. Ecoregion 13d differs in climate, associated vegetation, and substrate from other permanent water support endemic fish species, such as the Monitor Valley speckled dace. game fish. Photo: Gary Vinyard, University of R R areas as critical habitat for wildlife far Rive 13o 13a 80j r Elko 13b 13a woodland ecoregions in Nevada at similar elevations, such as Ecoregions 13q and 13s. The Central Nevada Mid-Slope Woodland and Brushland ecoregion at 6,500 to 8,000 feet elevation is analogous in Nevada-Reno, Biological Resources Research outweighs their limited areal extent in the K 13l 13k 13l 13c C 13l 13n Center Central Basin and Range (13). 80j A West 13s L 13k 13a altitudinal range to other woodland areas in Nevada. However, continuous woodland is not as prevalent on the mountains Rye Patch The High Elevation Carbonate Mountains ecoregion includes a series of mountain ranges composed of limestone, B Sou Wendover Carlin t Reservoir h 13q V 13e of central Nevada as in other woodland ecoregions, such as Ecoregions 13d and 13q. Pinyon–juniper grows only sparsely through F A dolomite, quartzite, and conglomerate in east central Nevada. These mountains are in the zone of summer rain, although 13k o L 13a r the shrub layer due to the combined effects of past fire, logging, and local climate factors, including lack of summer rain and the 13k k L much of the precipitation percolates through the porous rock to reemerge at lower elevations as springs. Still, these carbonate- A Gerlach H E I 13q u Y pattern of winter cold air inversions. Where extensive woodlands do exist, understory diversity tends to be very low, especially in N Beowawe m b iver 13p dominated mountains support a wider variety of conifers, such as white fir, Douglas-fir, and Engelmann spruce, and a greater R 13l o R 13k Battle ldt 13o O closed canopy areas. Areas of black and Wyoming big sagebrush grade upward into mountain big sagebrush and curlleaf 13l Y diversity of understory species than other ranges in Nevada at similar elevations. Bristlecone pines have their widest distribution on F 13k Mountain 13q 13q 13a I E 13h

L mountain-mahogany, which straddles the transition between this mid-elevation brushland and the mountain brush zone of the L 13e carbonate substrates above 9,500 feet elevation. Conditions do not favor alpine tundra, however; alpine plants are more limited than H A 13q 13b L 13k 13k Crescent Valley u C 13b higher Central Nevada Bald Mountains (13t). n A 13b 13a on the nearby granitic High Elevation Ruby Mountains (13o). t V 13e 13h 13h i

13h n 13l 13l 1 g 3 The Central Nevada Bald Mountains are dry and mostly treeless. Although they rise only a hundred miles east of the

13s t 13t o The Wetlands ecoregion includes saline, brackish, or freshwater wetlands in flat to depressional terrain. Wetlands may dry 13a a

13l n 13t

13q 13g Sierra Nevada, they lack Sierra Nevada species because of the dry conditions. These barren-looking mountains are 13k C 13b

13g up seasonally or be maintained by springs and groundwater infusions. Many wetlands have disappeared with farmland

r q

13l e Y 13q 3

e covered instead by dense mountain brush that is dominated by mountain big sagebrush, western serviceberry, snowberry, and low

13s B 13e 1 k 13e development, river channelization, and stream incision; others have been created as a result of reclamation projects and irrigation 13h 13l U 13h 13h 13r 13g R Y sagebrush. They contrast with the forested High Elevation Carbonate Mountains (13e) to the east, where the mountain brush zone 13k 13q E seepage. Bulrushes, Baltic rush, cattails, burreed, and reed grass are common marsh plants. Many migratory birds, particularly 13r L e Wild horses are protected in Nevada and Lack of precipitation and shallow, gravelly 13k eek 3 13q L waterfowl and shorebirds, depend on the wetlands and marshes of the Great Basin. is too narrow to be mapped as a separate ecoregion. Scattered groves of curlleaf mountain-mahogany and aspen in moister 1 13q r A 13h C their populations are monitored and soil complicates grazing management in the Lovelock V 13l e 13b 13q microsites grow above the shrub layer. A few scattered limber or bristlecone pines grow on ranges that exceed 10,000 feet. The in managed. Though wild horses compete with Central Basin and Range (13). The sparse P E The nearly level and often barren Lahontan and Tonopah Playas contain mud flats, alkali flats, and intermittent saline 13t e P Pyramid 13q 3 13h Toiyabe Range (west of Big Smoky Valley) is high enough to have an alpine zone, but it lacks a suitable substrate to retain livestock and wildlife for limited forage, vegetative cover is easily over-grazed as Humboldt O 1 lakes, such as the , , and Sarcobatus Flat. Marshes, remnant lakes, and playas are all that Lake 13k 13a L their presence is tolerated because many shown here in the Carbonate Sagebrush 13x Lake 13s E snowmelt moisture. The isolation of these “sky islands” has led to the development of many rare and endemic plant species. 40° T 13h 13t 13q N 40° remain of Pleistocene Lake Lahontan, which was once the size of Lake Erie. Playas occur at the lowest elevations in the Lahontan consider them part of our national heritage. Valleys (13p). Photo: Jim Morefield, Nevada 13 13k A 13g 13q 13b 13c Basin and represent the terminus or “sink” of rivers flowing east off the Sierra Nevada. They fill with seasonal runoff from Photo: State of Nevada, Commission for the Natural Heritage Program 13x 13u Preservation of Wild Horses 13a 13b surrounding mountain ranges during winter, providing habitat for migratory birds. Black greasewood or four-winged saltbush may The Tonopah Basin lies in the transition between the Great Basin and the more southerly Mojave Desert. The Tonopah 13j 13h 13h 13h 13s 13a 13e 13j grow around the perimeter in the transition to the salt shrub community, where they often stabilize areas of low sand dunes. Basin shows varying degrees of Great Basin and Mojave Desert characteristics. The west side of the Tonopah Basin is a CARSON 13l 13t Y Y E

L Cherry SINK E 13z 13q 13b Ecoregion 13h has very limited grazing potential. Windblown salt dust from exposed playas may affect upland soils and vegetation. continuation of the Lahontan Basin while the lower and hotter on the east side is more like the Mojave Desert. L L Creek 13q L 13s r 13s A The Lahontan and Tonopah Playas are important as wildlife habitat and for some recreational and military uses. Similar to basins farther north, shadscale and associated arid land shrubs cover broad rolling valleys, hills, and alluvial fans. A 13s e V 13b 13p 13p iv 13p V 13a 13aa 13s R 13p 13x However, unlike the Lahontan Salt Shrub Basin (13j) and Upper Lahontan Basin (13z), the shrubs often co-dominate in highly 13 13t The Lahontan Salt Shrub Basin is an expansive dry plain that was once beneath Pleistocene Lake Lahontan. The D 13e r Y 13g E e 13e 13q N

e L s 13j L Y diverse mosaics. The shrub understory includes warm season grasses, such as Indian rice grass and galleta grass. Valleys with

v e Lahontan Basin, compared to the Bonneville Basin to the east in Ecoregion 13b, is lower in elevation and warmer in winter. i A 13s O

R V e E

Fernley K Y

R 13e 13t L

M

5a E perennial water contain endemic fish species, including the Railroad Valley tui chub, Pahranagat roundtail chub, Railroad

E

E

Reno Tru R L Although there is a direct connection to the south through low elevation valleys to the Mojave Basin and Range (14), winters are ck A The lowest elevations of the intermontane basins, such as the Black Rock Desert in e ee e C 13h I 13e k A c C E u S L

Tr a 13z Y n I D 13t D V Valley springfish, and White River springfish. R 13a Ecoregion 13h, are too arid and alkaline to support vegetation. However, saline lakes a L

5 13t cold enough in Ecoregion 13j to discourage the northward dispersal of many Mojavean species into the Lahontan Basin. In addition A 1 E X l W 13z 3 Eureka 13p

13x I D s A 13v Sparks L collect the outflow of the Great Basin’s internally drained streams and rivers. They E K

D Austin 13b 13q V to shadscale, other salt-tolerant shrubs, such as Shockley desert thorn and Bailey greasewood, cover the lower basin slopes, and The Tonopah Sagebrush Foothills ecoregion includes the low mountains and hills rising from the floor of the flatter 1

Fallon R L 13b support brine shrimp that are the basis of a complex community of shorebirds, waders, A 3

13x L A A H Y e O E U N LL

Lahontan TAN VA 13s 13q W and waterfowl. Photo: Jim Morefield, Nevada Natural Heritage Program distinguish the Lahontan Salt Shrub Basin (13j) and Tonopah Basin (13u) from other Nevada salt shrub ecoregions. Sand dunes Tonopah Basin (13u). The substrate is rocky and lacks the fine sediments found at lower elevations in Ecoregion 13u. Great Basin V

13z T E

Washoe Reservoir 13t

A

13r N

may occur where windblown sand accumulates against a barrier; dune complexes support a specialized plant community and species are common in this ecoregion as they are further north in the Lahontan Sagebrush Slopes (13k). However, because

5a Lake H

Virginia City 13s 13z 13e

5b 13k 13k 13a

River diverse small mammal populations. The Carson and Truckee rivers, originating in the Sierra Nevada, provide water for irrigated Ecoregion 13v is in the rain shadow of the Sierra Nevada and is adjacent to the Mojave Desert, it is more arid than Ecoregion 13k.

13h 13p n 13h Carson

o 13t 13u 13e

rs 13h farming. Riparian corridors along these rivers support the only trees found in the ecoregion. As a result, black sagebrush is more prevalent in the shrub overstory of Ecoregion 13v, and the more mesic understory species that

a Lake 13h 13e

C 13g

13t 13z 13q 13b Ely are found farther north and east are largely absent. Mojave desert species, such as blackbrush, Joshua tree, and cholla cactus,

Lake 13k Hills, alluvial fans, and low mountains within the Lahontan Basin comprise the Lahontan Sagebrush Slopes ecoregion. The alpine zone of the Central Nevada Bald

Tahoe 13k 13s

13l 13r 13h 13k become more common in the east and south, where summer moisture is more prevalent. Streams are ephemeral and flow during Mountains (13t) is characterized by a bare,

These areas are rock controlled and their soils lack the fine lacustrine sediments that are found in the lower parts of the

Carson City W E

al Y 13e windblown, gravelly substrate and scattered ke and immediately after storms. Storm events can be of sufficient magnitude to move large quantities of sediment in Bristlecone pines are endemic to the Great r E O G 13q Lahontan Basin. Because moisture increases and alkalinity decreases with elevation, the shrub community grades from the 13k Y 13t 13e Basin and northern Mojave Desert. They alpine forbs. Photo: Jim Morefield, Nevada L T N Great 5b E streambeds. Because of the droughty conditions, Ecoregion 13v has a low carrying capacity for cattle. L I Yerington P greasewood–shadscale community on the basin floor to a shrub community dominated by Wyoming big sagebrush and the endemic occur in scattered groves near timberline, Natural Heritage Program L Basin NP A R 13x E 13w 39° R 13k 13t L 13t V 13q 13q where individuals have been found to ° P i T 13b 39 Lahontan sagebrush at higher elevations. Understory grasses increase in productivity toward the northeast, outside the rain shadow The Tonopah Uplands ecoregion includes woodland- or shrub-covered hills and mountains ranging from 6,000 to 9,500 v A S Minden e 13j S exceed 4,000 years of age. Photo: Jim

r V

Preston influence of the Sierra Nevada. The low hills and mountains within the Lahontan Basin experience frequent summer lightning and feet in elevation. As elsewhere in the Tonopah region, Great Basin and Mojave Desert elements blend together especially toward 13s 13e Morefield, Nevada Natural Heritage Program 13x 13e

13h

Rou nd 13e 13e fire. Introduced cheatgrass tends to replace the shrub community and provides fuel for recurrent fires. the south and east, where some mountain brush and interior chaparral components, including Gambel oak, become more common. 13h 13h Mo untain

Pinyon–juniper woodland is extensive between 6,000 and 8,000 feet elevation. The highest peaks support a few white fir, Walker 13h t The Lahontan Uplands ecoregion is restricted to the highest elevations of the mountain ranges within the Lahontan Salt 13s 3 13y 13r Lund Lake Gabbs 1 13b 13l limber pine, or bristlecone pine. 13t Shrub Basin (13j). Slopes vary in elevation from 6,400 to 8,800 feet and are covered by sagebrush, grasses, and scattered

13t 13x

13t 13 t Utah juniper. Pinyon grows with juniper on the Stillwater Range and on Fairview Peak in the southeast portion of the Lahontan The Sierra Nevada-Influenced Ranges are those wooded Great Basin mountains that have climatic and biotic affinities

13s 13q 1

Markleeville 3 Y R Basin, but it is otherwise absent from Ecoregion 13l. Low sagebrush and black sagebrush grow to the mountaintops above the to the Sierra Nevada. Overall, Ecoregion 13x receives greater precipitation than the mountain ranges of Central Nevada 13u e K O 13q 13e 13y 13w T O 13t Y woodland zone. Cool season grasses, including bluebunch wheatgrass, dominate the understory in the north, but are replaced by (Ecoregions 13s and 13t). However, in Ecoregion 13x, precipitation amounts vary from range to range in relation to the local I 13x 13q E M N L L warm season grasses, such as Indian ricegrass, in the south. strength of the Sierra Nevada rain shadow. Because of minimal summer rainfall, Ecoregion 13x contains pinyon–juniper S 13s O A 13s Hawthorne V 1

13y 3 M 13e 13q 13c Y

13v w N woodland, but lacks oak and Ceanothus species. The White, Sweetwater, Pine Nut, Wassuk, and Virginia ranges support varying

13h r I The Upper Humboldt Plains ecoregion is an area of rolling plains punctuated by occasional buttes and low mountains. It E

5 13y e L

L v 13b M

i 13m amounts of Sierra Nevada flora, including small stands of ponderosa, lodgepole, Jeffrey, and western white pine. Scattered L A is mostly underlain by volcanic ash, rhyolite, and tuffaceous rocks. Low sagebrush is common in extensive areas of R

A H 13v Lockes V e ephemeral pools perched over areas of flat, impermeable volcanic bedrock are similar to those in the High Lava Plains (80g) and t shallow, stony soil, as are cool season grasses, such as bluebunch wheatgrass, Idaho fescue, and Sandberg bluegrass. The Upper G 13q i

I h 13y 13aa 13v Mina B 13b support unique assemblages of flora and fauna. High ranges near the Sierra Nevada are more likely to have perennial W Humboldt Plains ecoregion (13m) is wetter and cooler than other Nevada ecoregions in its elevation range. Ecoregion 13m is 13w 13t 13b 13h 13s streams. Bighorn sheep, deer, and black bear inhabit these mountains. Halogeton is an introduced plant that grows Clark’s nutcracker has been given credit for 13y 13y 13s D transitional to the Northern Basin and Range (80) that spans the Nevada–Oregon border. However, as in the warmer Lahontan Basin in arid basins and along roadsides. It is toxic expanding the distribution of limber and 13h A 13y 13y O to the west, lightning fires are common and a post-fire monoculture of cheatgrass tends to replace the native grasses and shrubs. The Sierra Nevada-Influenced High Elevation Mountains occupy the elevational zone above the woodland-covered Bridgeport R to livestock. whitebark pine into the Great Basin through IL 13x 13h A 13p 13q Grazing is the major land use, though there is some agriculture near the Humboldt River. Sierra Nevada-Influenced Ranges (13x), and are affected in varying degrees by Sierra Nevada climate. Elevations range from its collection and caching of pine nuts. 13s Warm Springs R 13p Photo: John Mariani 13u The Mid-Elevation Ruby Mountains ecoregion covers the lower slopes of the Ruby Mountains in northeastern Nevada. 9,000 to nearly 14,000 feet. Ecoregion 13y is generally covered by shrubs (e.g. mountain big sagebrush, low sagebrush, and 13 13c 13e 13n Although its elevation range, 6,500 to 8,500 feet, is typical of the pinyon–juniper woodland zone, sagebrush and mesic mountain-mahogany), small aspen groves (on moist sites), scattered stands of high elevation conifers, and Sierra Nevada subalpine 13h 13h Tonopah and alpine forbs. Moisture amounts captured by the highest ranges in Ecoregion 13y result in substantial perennial stream 38° mountain shrub species are dominant here. Pinyon and juniper are uncommon on the western slopes of the Ruby Mountains, 13v 38° possibly because these foothills are in the direct path of winter weather fronts from the west and cold air masses from the flow in some areas. 13t 13q 13z 13v Pioche north. This phenomenon is in contrast to the wide elevational distribution of pinyon–juniper in the Carbonate Woodland Zone (13q) The Upper Lahontan Basin lies outside of the rain shadow cast by the Sierra Nevada and records somewhat higher 13aa 13v 13p 13q 13u 13r 13h 13b Mountain ranges above 8,000 feet have varying degrees of forest cover depending upon that receives more summer rain and less winter precipitation. At higher elevations within Ecoregion 13n, curlleaf mountain- rainfall and cooler temperatures than other portions of the Lahontan Basin. Although its shadscale–greasewood plant community is 5 Sierra Nevada 13p precipitation, substrate, soil type, aspect, and slope. The High Elevation Carbonate 13y 13h 13s 13s 13a mahogany and aspen groves form the transition to the High Elevation Ruby Mountains (13o). similar to that in the Lahontan Salt Shrub Basin (13j), some species differ due to climate gradations. For example, Bailey 5a Mid-Elevation Sierra Nevada 13h 13h Mountains (13e) are pictured here. Ecoregion 13e receives some summer precipitation, 13q Panaca and is characteristically underlain by limestone and dolomite. The High Elevation Ruby Mountains ecoregion represents those portions of the Ruby Mountains that are dominated by greasewood is less common and Thurber needlegrass is more common in the Upper Lahontan Basin (13z) than in the 5b High Elevation Sierra Nevada 13r 13c 13h 13v 13o granitic and types, and that were heavily glaciated during the Pleistocene. Extensive periglacial Lahontan Salt Shrub Basin (13j). Ecoregion 13z also has a shorter growing season than the rest of the Lahontan Basin. 13w 13v 13r 13q 13b 13aa 13w 13q Sierra Nevada-Influenced Semiarid Hills and Basins 13 Central Basin and Range Goldfield 13q 13a phenomena, such as solifluction fields, are still active at higher elevations. Since the end of Pleistocene glaciation, closed canopy The ecoregion includes the basins and lower mountain slopes 13h 13h Hiko conifer forests have not recolonized the Ruby Mountains, even though the Ruby Mountains receive more precipitation than the High immediately east of the Sierra Nevada that are affected by its climate or that have its characteristic granitic substrate. Ecoregion 13a Salt Deserts 13v The White Mountains, and other parts of the Desert peach has somewhat higher moisture P Elevation Carbonate Mountains (13e) to the east. The High Elevation Ruby Mountains ecoregion (13o) is the wettest ecoregion in 13aa differs from the Lahontan Sagebrush Slopes (13k) in that plants with slightly higher moisture requirements, such as antelope Sierra Nevada-Influenced Ranges (13x), requirements than other plants in the A Caliente 13d 13b Shadscale-Dominated Saline Basins 13v H Nevada outside of the High Elevation Sierra Nevada (5b). Some of the most extensive aspen groves in Nevada occur here. bitterbrush and desert peach, may be associated with the semiarid shrub community, especially near the Sierra Nevada front. Three receive enough rainfall to support various semiarid shrub community. It grows in 13h R 13w 13w 13w A 13v Sierra Nevada plant and animal species. western Nevada in the Sierra Nevada- 13c Sagebrush Basins and Slopes N Subalpine meadows and scattered white fir, limber pine, and whitebark pine mingle upwards to the jagged, exposed peaks at large river systems, the Truckee, Carson, and Walker, flow eastward through this region from the Sierra Nevada, providing water Photo: Jim Morefield, Nevada Natural Heritage Influenced Semiarid Hills and Basins (13aa) A 13v 13d Woodland- and Shrub-Covered Low 13w G elevations over 11,000 feet. Snowmelt moisture trapped by the impervious substrate supports extensive alpine meadows and alpine for agriculture and urban development. Their floodplains support some of the best remaining riparian cottonwood forest in the Program Photo: Jim Morefield, Nevada Natural Heritage 6 13v A T Program lakes are common. Wildlife includes mule deer, bighorn sheep, and mountain goats. state, which has been degraded in many areas by grazing, agriculture, and invasive weeds. The Truckee and Walker rivers and

Mountains 13w V 13v 13v A their also provide habitat for the threatened Lahontan cutthroat trout. 13u L 13e High Elevation Carbonate Mountains 14g L E 13g 13v 13w Y 13g Wetlands 13h 13h 13w S A R 13h Lahontan and Tonopah Playas C 14b O B A T 14b 13j Lahontan Salt Shrub Basin U sh 1 4 . M o j a v e B a s i n a n d R a n g e S 14a 14b a

14b F 13w W L y Ecoregion 14 is composed of broad basins and scattered mountains that are generally lower, warmer, and drier than those of the Central Basin and Range (13). Its creosote bush-dominated shrub community is distinct from the saltbush–greasewood and sagebrush–grass ° 13k Lahontan Sagebrush Slopes 14b 37 A 14a e A l T l 14b 37° m a associations that occur to the north in the Central Basin and Range (13) and Northern Basin and Range (80); it is also distinct from the creosote bush–bur sage and the palo verde–cactus shrub that occur in the Sonoran Basin and Range (81) to the south. The basin soils V

14c a 13l Lahontan Uplands 14f

C r 14a

A g 14f w

L o 14b o are mostly Entisols and Aridisols that typically have a thermic temperature regime; they are warmer than those of Ecoregion 13. Heavy use of off-road vehicles and motorcycles in some areas has made the soils susceptible to wind and water erosion. Most of Ecoregion

s d 14c

13m Upper Humboldt Plains I a

F a 14b

O e

Beatty 14 is federally owned and there is relatively little grazing activity because of the lack of water and forage for livestock.

R

M

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13n Mid-Elevation Ruby Mountains I A R Mesquite Level III ecoregion i The Creosote Bush-Dominated Basins ecoregion includes the valleys lying between the scattered mountain ranges of the with groves of limber pine and bristlecone pine. The isolation and relatively mesic climate of these “sky islands” have led to the v r 13o High Elevation Ruby Mountains e ve 14a r Ri Mojave Desert at elevations ranging from 1,800 to 4,500 feet. Elevations are lower, soils are warmer, and development of numerous rare and endemic species, many of which extend downward in elevation into the Mojave Mountain Level IV ecoregion Death 14b Moapa n gi 13p Carbonate Sagebrush Valleys Valley NP ir evapotranspiration is higher than in the Central Basin and Range (13) to the north. Limestone- and gypsum-influenced soils occur, Woodland and Shrubland (14c). Recreational use is especially heavy in the Spring Mountains between and Pahrump. County boundary A 14g V 13q Carbonate Woodland Zone M d but overall, precipitation amount has a greater ecological significance than geology. Toward the south and east, as summer rainfall A 14b 4 14b Mu 22 Arid Valleys and Canyonlands ecoregion includes steep canyons and benchlands below 2,000 feet elevation near the State boundary R 1 dd G y increases, the Sonoran influence grows, and woody leguminous species, such as mesquite and acacia, become more common. 14e Shrubs growing in the extremely dry The numbers of have 13r Central Nevada High Valleys O R 22d . This is one of the hottest and driest ecoregions in Nevada, receiving only 2 to 7 inches of rainfall per S 14f 14c iv conditions of the Creosote Bush-Dominated declined due to loss of habitat, past over- A e Creosote bush, white bursage, and galleta grass characterize the plant community of Ecoregion 14a. Pocket mice, kangaroo rats, and 7 r 14b year. Rocky colluvial soils cover eroded slopes and deeper soils occur on benches. Vegetation is a sparse, but diverse, shrub cover 13s Central Nevada Mid-Slope Woodland D A E Basins (14a) compete for limited water and hunting, and disease carried by domestic S R desert tortoise are faunal indicators of the desert environment. Desert willow, coyote willow, and mesquite grow in riparian areas,

E I that includes creosote bush, white brittlebush, white bursage, and occasional elements, such as ocotillo. Along the may suppress the growth of other plants livestock. There has been some success in and Brushland R 14f Z T 14f O although the alien invasive tamarisk is rapidly replacing native desert riparian vegetation. through the secretion of toxins. maintaining their numbers in protected A 14b rivers, the introduced tamarisk is replacing native riparian vegetation, such as Fremont cottonwood and willow. The presence of S N H wilderness areas through reintroductions and 13t Central Nevada Bald Mountains A M E 14c the Colorado River and greatly influences the management and of this ecoregion. A 14b the exclusion of livestock. Photo: Glenn D 13u Tonopah Basin O 14b W 14c Vargas, California Academy of Sciences 14b S The Arid Footslopes ecoregion is composed of alluvial fans, flows, hills, and low mountains that rise above the The Mojave Playas are generally smaller in area than the Lahontan and Tonopah Playas (13h) and are not part of the 13v Tonopah Sagebrush Foothills 80 Northern Basin and Range 14b 14f 14d 14a 14e basin floors of the Mojave Desert to an average elevation of 6,200 feet. The sparsely vegetated soils are very erodible during storm broad Pleistocene pluvial basins that are found in the Central Basin and Range (13) to the north. Ecoregions 14f and 13h 13w Tonopah Uplands 80a Dissected High Lava Plateau events. In areas transitional to the Great Basin in the north, blackbrush dominates slopes just above the upper elevational limit for are both largely barren and only sparse saltbush vegetation is typically found on their margins. Greasewood, which is common 13x Sierra Nevada-Influenced Ranges 80b Semiarid Hills and Low Mountains Las Vegas Lake 14b creosote bush. Elsewhere, a mixture of more typical Mojave Desert forbs, shrubs, and succulent species occurs, including Joshua near Lahontan and Tonopah Playas (13h), is absent from the margins of the Mojave Playas (14f). Where moisture is sufficient, 14f Pahrump 14b Mead 14b 13y Sierra Nevada-Influenced High 80d Pluvial Lake Basins tree, other yucca species, and cacti on rocky sites. Ecoregion 14b has a diverse array of reptiles, including iguanas, , and cold-intolerant trees and woody legumes such as velvet ash and mesquite occur on the Mojave Playas (14f), particularly toward the Henderson leopard, collared, horned, and spiny lizards. Desert bighorn sheep may also be present on remote rocky outcrops in south. 36° Elevation Mountains 80e Wetlands 14b 36° Ecoregion 14b, particularly in the Desert National Wildlife Range, which was established to preserve bighorn habitat. The ecoregion is an arid, internally-drained basin. It has greater temperature extremes and less Sonoran 14g C 14c 13z Upper Lahontan Basin 80g High Lava Plains o 14g lo The Mojave Mountain Woodland and Shrubland ecoregion occurs between 6,000 and 8,000 feet elevation where mean influence than the Creosote Bush-Dominated Basins (14a). This is due in part to the Spring Mountains that border Boulder r 80j Semiarid Uplands a 13aa Sierra Nevada-Influenced Semiarid City d The alternating mountain-and-basin pattern of Ecoregion 14 is similar to the Central

o annual precipitation levels increase to between 10 and 16 inches per year. Vegetation includes pinyon, Utah juniper, Rocky Ecoregion 14g on the east and block summer rainfall. In the Amargosa Desert (14g), rainfall occurs mostly between October and

R Basin and Range (13) to the north. However, Ecoregion 14 is warmer and drier and has

Hills and Basins 80k Partly Forested Mountains i Mountain juniper, curlleaf mountain-mahogany, and cliffrose. In many areas, a denser and more diverse mixture of large interior April. Creosote bush and bursage predominate as they do in Ecoregion 14a, but the diversity of associated shrub species is lower.

v 14b e milder winters and a different vegetation mosaic than Ecoregion 13. Mojavean flora, 80l Salt Shrub Valleys r chaparral shrubs occurs, including oaks, ceanothus, silktassel, and Apache plume. A sagebrush zone is largely absent, but some Irrigated farms in the produce alfalfa, sorghum, dairy products, and pistachio nuts. As in the Pahranagat Valley Desert tortoise numbers have declined Ash Meadows is a system of springs, seeps, including creosote bush, Joshua trees and other yucca species, are pictured here in the precipitously in the last 20 years. The desert and ponds in the Amargosa Desert (14g). 14 Mojave Basin and Range foreground. 14f Wyoming big sagebrush may be found in the understory of the woodland along with blackbrush. The riparian zones along the few to the northeast in Ecoregion 13u, the Amargosa Valley is a discharge point for an underground water system. Where the tortoise is easy prey to hunters, off-road Maintaining the water levels of the ponds is 14a Creosote Bush-Dominated Basins 14b perennial streams in the Spring Mountains have willow, mountain brush, black cottonwood, and Gambel oak, and provide surfaces, it creates wetland oases that can be extensive, including near Beatty. A larger, but isolated, vehicles, and urban development. Ravens necessary for the survival of the endangered 14b Arid Footslopes 14 rare habitat for bird life in the desert. system of seeps and springs at Ash Meadows National Wildlife Refuge provides habitats for a large number of endemic plants and are also a major predator of young tortoises. Ash Meadows Amargosa pupfish and other Photo: Glenn Clemmer, Nevada Natural Heritage inhabitants of its springs and pools. Photo: 14c 14b 14e 14d 14c Mojave Mountain Woodland and 14 The Mojave High Elevation Mountains ecoregion is mostly underlain by limestone and other sedimentary rocks. The animals. Program State of Nevada, Division of Environmental 14b Shrubland Searchlight 14d Mojave High Elevation Mountains Lake SCALE 1:1 350 000 Mohave 14b 14e Arid Valleys and Canyonlands 15 10 5 0 30 60 mi 14f Mojave Playas 14b 8 0 . N o r t h e r n B a s i n a n d R a n g e 14g Amargosa Desert 30 20 10 0 60 120 km Kingman The Northern Basin and Range consists of dissected lava plains, rocky uplands, valleys, alluvial fans, and scattered mountain ranges. Overall, it is cooler and has more available moisture than the Central Basin and Range (13). Ecoregion 80 is higher and cooler than the 22 Arizona/New Mexico Plateau Albers equal area projection Laughlin Snake River Plain (12) to the northeast in Idaho. Valleys support sagebrush steppe or saltbush vegetation. Mollisols are more common than in the hotter and drier basins of the Central Basin and Range (13) where Aridisols support sagebrush, shadscale, and greasewood. Juniper woodlands occur on rugged, stony uplands. Ranges are covered by mountain brush, grasses (e.g. Idaho fescue), aspen groves, or forest dominated by subalpine fir. Elevational banding of mountain vegetation is not as apparent as in Ecoregion 13. 22d Middle Elevation Mountains Standard parallels 37° N and 41° N 14a Most of Ecoregion 80 is used as rangeland. The western part of the ecoregion is internally drained; its eastern stream network drains to the Snake River system. ° 35 35° The Dissected High Lava Plateau ecoregion is a broad to gently rolling basalt plateau cut by deep, sheer-walled canyons anadromous component. Bluebunch wheatgrass is generally associated with Wyoming big sagebrush, except where bunchgrasses 6 7 6 8 80a INTERIOR—GEOLOGICAL SURVEY, RESTON, VIRGINIA—2003 and covered with vast expanses of sagebrush. Ecoregion 80a differs from other sagebrush-dominated ecoregions in Nevada, have been depleted by grazing and replaced by cheatgrass. Scattered ephemeral pools on impermeable volcanic bedrock are ° ° ° ° ° ° 119 118 117 116 115 114 such as Ecoregions 13c, 13p, 13k, and 13v, in having higher precipitation and colder winters. Cool season grasses, such as characteristic of Ecoregion 80g in Nevada; they harbor unique flora and fauna as do those in the Sierra Nevada-Influenced Ranges PRINCIPAL AUTHORS: Sandra A. Bryce (Dynamac Corporation), bluebunch wheatgrass and Idaho fescue, are associated with the sagebrush. Understory species are denser and biological soil crusts (13x) of the Central Basin and Range (13). Alan J. Woods (Dynamac Corporation), James D. Morefield (Nevada tend to be more extensive and in better condition than in other ecoregions at similar elevations farther south in Nevada. Ecoregion Sheep graze the flanks of the Bull Run Biological soil crusts are composed of Level III Ecoregions of the Conterminous United States Natural Heritage Program), James M. Omernik (USEPA), Thomas R. The Semiarid Uplands ecoregion covers disjunct areas across northern Nevada. It includes hills, low mountains, volcanic Mountains in Ecoregions 80j and 80k. Here cyanobacteria, mosses, and lichens. They 80a drains externally to the Snake River, unlike the similar High Lava Plains (80g) that are internally drained. 80j cones, and buttes that rise out of the drier Dissected High Lava Plateau (80a) and High Lava Plains (80g). Elevational the juniper woodland zone is replaced by cover the dry desert floor and protect it from 1 Coast Range 29 Central Oklahoma/Texas Plains 57 Huron/Erie Lake Plains McKay (NRCS), Gary K. Brackley (NRCS), Robert K. Hall (USEPA), 77 mountain brush and scattered groves of erosion. Photo: Eric Peterson, Nevada Natural 1 2 2 Puget Lowland 30 Edwards Plateau 58 Northeastern Highlands Damian K. Higgins (U.S. Fish and Wildlife Service), David C. The Semiarid Hills and Low Mountains ecoregion is higher and more rugged than the sagebrush plains and basins of banding is much less apparent on the mountains of Ecoregion 80j than in Ecoregion 13q to the south. Mountain big sagebrush and aspen. Heritage Program 15 41 42 3 Willamette Valley 31 Southern Texas Plains 59 Northeastern Coastal Zone McMorran (USFS), Karen E. Vargas (Nevada Division of 80b 10 neighboring Ecoregions 80a and 13p. It is covered by mountain big sagebrush, low sagebrush, associated grasses, and on grasses, such as Idaho fescue, are common. The density and extent of juniper woodland varies with long-term climate fluctuations, 49 4 Cascades 32 Texas Blackland Prairies 60 Northern Appalachian Plateau 48 82 Environmental Protection), Eric B. Petersen (Nevada Natural Heritage shallow and rocky soils, scattered juniper woodland. These hills represent the northern limit for both pinyon and Utah juniper; grazing pressure, and fire frequency. Juniper woodland is absent in the Jarbidge and Santa Rosa mountains, where mountain brush 1 3 5 Sierra Nevada 33 East Central Texas Plains and Uplands Program), Desiderio C. Zamudio (USFS), and Jeffrey A. Comstock 4 11 42 6 Southern and Central California 34 Western Gulf Coastal Plain 61 Erie Drift Plain western juniper replaces them to the west and north. Groves of aspen grow on alluvial fans and along stream networks. and scattered aspen groves occupy the woodland zone. 16 17 43 50 58 (Indus Corporation). 58 Chaparral and Oak Woodlands 35 South Central Plains 62 North Central Appalachians 51 The Pluvial Lake Basins of northwestern Nevada were last filled with water during the Pleistocene Epoch. Presently, some In northern Nevada, the Partly Forested Mountains ecoregion covers the high elevation portions of the Jarbidge and 9 46 50 7 Central California Valley 36 Ouachita Mountains 63 Middle Atlantic Coastal Plain 17 59 COLLABORATORS AND CONTRIBUTORS: Bill Brooks (BLM), 80d 80k 78 83 8 Southern California Mountains 37 Arkansas Valley 64 Northern Piedmont basin floor playas collect and evaporate water seasonally. Ecoregion 80d has cooler mean annual temperatures than the Independence mountains. These mountain ranges support limber pine, subalpine fir, low juniper, whitebark pine, 80 12 17 57 60 58 52 53 Robin Tausch (USFS–Rocky Mountain Research Station), and Bill W. 56 62 9 Eastern Cascades Slopes and 38 Boston Mountains 65 Southeastern Plains basins of Lahontan Salt Shrub Basin (13j), and lacks its arid shadscale shrub community. Greasewood, inland saltgrass, and mountain brush, and, at highest elevations on poorly drained soils, small areas of tundra and alpine meadows. Alpine tundra 18 62 66 Blue Ridge Daily (NRCS). 44 47 Foothills 39 Ozark Highlands 57 61 67 67 Ridge and Valley seepweed grow in more alkaline soil, and Wyoming big sagebrush, basin big sagebrush, and associated grasses dominate better development is more limited in the Jarbidge Mountains than in the High Elevation Ruby Mountains (13o) because the 5 19 64 84 10 Columbia Plateau 40 Central Irregular Plains 13 54 11 Blue Mountains 41 Canadian Rockies 68 Southwestern Appalachians REVIEWERS: Edgar F. Kleiner (Emeritus Professor, University of drained, less alkaline soils. Alfalfa is grown on a limited basis in irrigated areas. metamorphic substrate of the Jarbidge Mountains is not conducive to soil building or water retention. Streams draining the 55 70 21 40 63 69 Central Appalachians Nevada-Reno), Frederick F. Peterson (Emeritus Professor, University 1 7 20 25 12 Snake River Plain 42 Northwestern Glaciated Plains Jarbidge and Independence mountains provide habitat for eastern populations of the threatened Lahontan cutthroat trout. 70 Western Allegheny Plateau Fewer mountain ranges occur in the Northern Basin and Range (80) than in the Central The High Desert Wetlands hold water more consistently than the Pluvial Lake Basins (80d). Although water levels 27 66 13 Central Basin and Range 43 Northwestern Great Plains of Nevada-Reno), Harold Klieforth (Emeritus, Associate Research 80e 6 72 69 14 Mojave Basin and Range 44 Nebraska Sand Hills 71 Interior Plateau Basin and Range (13). Broad plains covered in sagebrush steppe, rimrock, and rocky fluctuate from year to year, lakes and wetlands provide critical habitat for nesting and migratory birds as well as associated The Salt Shrub Valleys ecoregion is composed of arid basins once inundated by Pleistocene lakes. Climate, soil, and 28 40 71 Meteorologist, Desert Research Institute), David Charlet (Professor, 15 Northern Rockies 45 Piedmont 72 Interior River Valleys and Hills uplands are typical of Ecoregion 80. Photo: Jim Morefield, Nevada Natural Heritage Program 80l 14 39 Community College of ), David A. Mouat (Associate upland birds and mammals. Sedges, rushes, tufted hairgrass, meadow barley, and creeping wildrye grow in wetter areas. vegetation are similar and transitional to the Lahontan Salt Shrub Basin (13j). Nearly flat basin floors and barren playas This Humboldt beaver in the Jarbidge Open pit mines are common in the 8 16 Idaho Batholith 46 Northern Glaciated Plains 73 Mississippi Alluvial Plain 22 68 65 Research Professor, Earth and Ecosystems Sciences, Desert Research are poorly drained, have a high water table, and retain water seasonally. Strongly alkaline soils are characteristic. Vegetation is Mountains of northern Nevada is a relic of a Independence Range (80j). Photo: Jim 66 17 Middle Rockies 47 Western Corn Belt Plains 74 Mississippi Valley Loess Plains The High Lava Plains of Nevada are part of a vast sagebrush steppe that extends northward to the Blue Mountains of 6 26 38 time when beaver were more widespread. Morefield, Nevada Natural Heritage Program 45 18 Wyoming Basin 48 Lake Agassiz Plain 75 Southern Coastal Plain Institute), Glenn Gentry (Supervisor, Water Quality Monitoring, 80g dominated by black greasewood, spiny hopsage, bud sagebrush, Wyoming big sagebrush, inland saltgrass, alkali sacaton, and 37 67 Oregon. Ecoregion 80g is similar to the Dissected High Lava Plateau (80a) in its physiography, climate, and vegetation, Photo: David A. Charlet, 1993, Community 81 23 36 73 63 76 Southern Florida Coastal Plain Nevada Division of Environmental Protection), and Mark Warren 19 Wasatch and 49 Northern Minnesota Wetlands but, unlike Ecoregion 80a, it is internally drained. As a result, the fish assemblage of Ecoregion 80g lacks an basin wildrye. College of Southern Nevada 25 20 Colorado Plateaus 50 Northern Lakes and Forests 77 North Cascades 79 23 29 (Staff Biologist, Nevada Division of Wildlife). 21 Southern Rockies 51 North Central Hardwood 78 Klamath Mountains 74 27 32 35 65 22 Arizona/New Mexico Plateau 79 Madrean Archipelago 24 Forests CITING THIS POSTER: Bryce, S.A., Woods, A.J., Morefield, J.D., 33 80 Northern Basin and Range 75 23 Arizona/New Mexico Mountains 52 Driftless Area Omernik, J.M., McKay, T.R., Brackley, G.K., Hall, R.K., Higgins, U.S. DEPARTMENT OF THE INTERIOR 30 73 24 Chihuahuan Deserts 53 Southeastern Wisconsin Till 81 Sonoran Basin and Range D.K., McMorran, D.C., Vargas, K.E., Petersen, E.B., Zamudio, D.C., BUREAU OF LAND MANAGEMENT Nevada 25 Western High Plains Plains 82 Laurentian Plains and Hills 34 75 and Comstock, J.A., 2003, Ecoregions of Nevada (color poster with 26 54 Central Corn Belt Plains 83 Eastern Great Lakes and Hudson Natural Heritage 31 map, descriptive text, summary tables, and photographs): Reston, 27 Central Great Plains 55 Eastern Corn Belt Plains Lowlands Program 76 28 Flint Hills 56 Southern Michigan/Northern 84 Atlantic Coastal Pine Barrens Virginia, U.S. Geological Survey (map scale 1:1,350,000). Indiana Drift Plains This project was partially supported by funds from the USEPA– Office of Map Source: USEPA, 2002 Research and Development’s Environmental Monitoring and Assessment Program through contract 68-C6-005 to Dynamac Corporation.