Great Basin shrub steppe
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The Great Basin Desert is part of the Great Basin between the Sierra Nevada and the
Wasatch Range The Wasatch Range ( ) or Wasatch Mountains is a mountain range in the western United States that runs about from the Utah-Idaho border south to central Utah. It is the western edge of the greater Rocky Mountains, and the eastern edge of the G ...
. The desert is a geographical region that largely overlaps the Great Basin shrub steppe defined by the
World Wildlife Fund The World Wide Fund for Nature Inc. (WWF) is an international non-governmental organization founded in 1961 that works in the field of wilderness preservation and the reduction of human impact on the environment. It was formerly named the Wo ...
, and the Central Basin and Range ecoregion defined by the
U.S. Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
and
United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...
. It is a temperate desert with hot, dry summers and snowy winters. The desert spans large portions of
Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
and
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
, and extends into eastern
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
. The desert is one of the four biologically defined deserts in North America, in addition to the Mojave, Sonoran, and
Chihuahuan Desert The Chihuahuan Desert ( es, Desierto de Chihuahua, ) is a desert ecoregion designation covering parts of northern Mexico and the southwestern United States. It occupies much of far West Texas, the middle to lower Rio Grande Valley and the lo ...
s.
Basin and range topography Basin and range topography is characterized by alternating parallel mountain ranges and valleys. It is a result of crustal extension due to mantle upwelling, gravitational collapse, crustal thickening, or relaxation of confining stresses. The ex ...
characterizes the desert: wide valleys bordered by parallel mountain ranges generally oriented north–south. There are more than 33 peaks within the desert with summits higher than , but valleys in the region are also high, most with elevations above . The biological communities of the Great Basin Desert vary according to altitude: from low salty dry lakes, up through rolling sagebrush valleys, to pinyon- juniper forests. The significant variation between valleys and peaks has created a variety of habitat niches which has in turn led to many small, isolated populations of genetically unique plant and animal species throughout the region. According to Grayson, more than 600 species of
vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...
s live in the floristic Great Basin, which has a similar areal footprint to the ecoregion. Sixty-three of these species have been identified as species of conservation concern due to contracting natural habitats (for example, '' Centrocercus urophasianus'', ''
Vulpes macrotis The kit fox (''Vulpes macrotis'') is a fox species that inhabits arid and semi-arid regions of the southwestern United States and northern and central Mexico. These foxes are the smallest of the four species of ''Vulpes'' occurring in North Amer ...
'', '' Dipodomys ordii'', and '' Phrynosoma platyrhinos''). The ecology of the desert varies across geography also. The desert's high elevation and location between mountain ranges influences regional climate: the desert formed by the rain shadow of the Sierra Nevada that blocks moisture from the Pacific Ocean, while the
Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...
create a barrier effect that restricts moisture from the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...
. Different locations in the desert have different amounts of precipitation depending on the strength of these rain shadows. The environment is influenced by Pleistocene lakes that dried after the last ice age:
Lake Lahontan Lake Lahontan was a large endorheic Pleistocene lake of modern northwestern Nevada that extended into northeastern California and southern Oregon. The area of the former lake is a large portion of the Great Basin that borders the Sacramento Rive ...
and
Lake Bonneville Lake Bonneville was the largest Late Pleistocene paleolake in the Great Basin of western North America. It was a pluvial lake that formed in response to an increase in precipitation and a decrease in evaporation as a result of cooler temperature ...
. Each of these lakes left different amounts of salinity and alkalinity.


Definition and boundaries

The Great Basin Desert is defined by its animals and plants, yet the boundaries are unclear. Scientists have different definitions of the Great Basin Desert, which are often defined by negatives. J. Robert Macey defines the "Great Basin scrub desert as lacking
creosote bush ''Larrea tridentata'', called creosote bush and greasewood as a plant, chaparral as a medicinal herb, and ''gobernadora'' (Spanish for "governess") in Mexico, due to its ability to secure more water by inhibiting the growth of nearby plants. In S ...
." The Great Basin Desert includes several arid basins lacking ''
Larrea tridentata ''Larrea tridentata'', called creosote bush and greasewood as a plant, chaparral as a medicinal herb, and ''gobernadora'' (Spanish for "governess") in Mexico, due to its ability to secure more water by inhibiting the growth of nearby plants. In S ...
'' (chaparral) such as the " Chalfant, Hammil, Benton, and
Queen Queen or QUEEN may refer to: Monarchy * Queen regnant, a female monarch of a Kingdom ** List of queens regnant * Queen consort, the wife of a reigning king * Queen dowager, the widow of a king * Queen mother, a queen dowager who is the mother ...
valleys," as well as all but the southeast portion of the
Owens Valley Owens Valley ( Numic: ''Payahǖǖnadǖ'', meaning "place of flowing water") is an arid valley of the Owens River in eastern California in the United States. It is located to the east of the Sierra Nevada, west of the White Mountains and Iny ...
. Conversely, the " Panamint, Saline, and
Eureka Eureka (often abbreviated as E!, or Σ!) is an intergovernmental organisation for research and development funding and coordination. Eureka is an open platform for international cooperation in innovation. Organisations and companies applying th ...
valleys" have creosote bush, unlike the
Deep Springs Valley Deep Springs Valley is a high desert valley in the Inyo-White Mountains of Inyo County, California. It is east of the Owens Valley and the Sierra Nevada mountain range, and south of Fish Lake Valley, Nevada, near the California-Nevada state borde ...
which includes part of the Great Basin scrub desert. The study and definition of
ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of ...
s can also indicate the boundaries of the Great Basin Desert. In 1987 J.M. Omernik defined a desert ecoregion between the Sierra Nevada and Wasatch Range, naming it the "Northern Basin and Range" ecoregion. In 1999, the U.S. EPA renamed the "Northern Basin and Range" the "Central Basin and Range" and the "(Snake River) High Desert" the "Northern Basin and Range". The World Wildlife Fund adopted the Basin and Range ecoregions from Omernik, but excised a small region of high-altitude areas which contain
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
refugia, from the former "Northern Basin and Range" ecoregion and renamed it the "Great Basin Shrub Steppe". Although the EPA had refined the boundaries of the Central Basin and Range ecoregion by 2003, when USGS geographer Christopher Soulard wrote his reports on the region, his maps used the 1999 boundary for the "Central Basin and Range", which is essentially the same as the "Great Basin Shrub Steppe". He states that the Great Basin Desert is "encompassed within" that area. This article describes the general ecology of the region, including the high-elevation areas, and does not rely on minor differences in the definitions of the ecoregion or desert. See Great Basin montane forests for more specific details on the high-elevation ecoregion.


Climate

The climate of the Great Basin desert is characterized by extremes: hot, dry summers and cold, snowy winters; frigid alpine ridges and warm, windy valleys; days over followed by nights near . This is the climate of the high desert. The Great Basin desert climate begins with the Sierra Nevada in
eastern California Eastern California is a region defined as either the strip to the east of the crest of the Sierra Nevada or as the easternmost counties of California. Demographics According to the 2010 census, the population of the eastern border counties of Ca ...
. Rising above sea level, this mountain range casts a large rain shadow over the desert. Weather coming in from the Pacific Ocean quickly loses its moisture as rain and snow as it is forced up and over the steep mountains. By the time it reaches the east side of the mountains, little moisture is left to bring to the desert. The rain shadow effect is more pronounced closer to the Sierra Nevada, with yearly precipitation in the Great Basin desert averaging in the west and inches in the east. Moisture that manages to reach the ecoregion tends to precipitate as rain and snow in higher elevations, primarily over the region's long, parallel mountains. Ultimately, any precipitation that falls within the desert fails to drain either to the
Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
or to the Pacific Ocean (thus the term "basin"). Instead, precipitation drains to
ephemeral Ephemerality (from the Greek word , meaning 'lasting only one day') is the concept of things being transitory, existing only briefly. Academically, the term ephemeral constitutionally describes a diverse assortment of things and experiences, fr ...
or
saline lake A salt lake or saline lake is a landlocked body of water that has a concentration of salt (chemistry), salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of ...
s via streams, or disappears via evaporation or absorption into the soil. The desert is the coldest of the deserts in North America. On any given day, the weather across the Great Basin desert is variable. The region is extremely mountainous, and the temperatures vary depending on the elevation. In general, temperature decreases 3.6 degrees F for every 1000 feet gained in elevation. This translates to as much as a difference between mountaintops and valley floors on the same day at the same time. In the heat of summer this difference can be even more pronounced. With some exceptions wind generally increases with elevation or altitude and thus strong winds are often encountered on mountain tops and ridges. This dry climate and rugged topography proves too harsh for many plant and animal species; however, genetic adaptations to these conditions have led to reasonably high species richness within the ecoregion. The
Great Basin National Park Great Basin National Park is an American national park located in White Pine County in east-central Nevada, near the Utah border, established in 1986. The park is most commonly entered by way of Nevada State Route 488, which is connected to U ...
, located in a central part of the Great Basin desert, provides perhaps the best example of a typical climate for the region. Fallon's climate is typical of lower elevations in the western part of the Great Basin desert. Located in the
Forty Mile Desert The Lahontan Valley is a basin in Churchill County, Nevada, United States. The valley is a landform of the central portion of the prehistoric Lake Lahontan's lakebed of 20,000-9,000 years ago. The valley and the adjacent Carson Sink represent a ...
, precipitation is rare, and summers are hot, though temperatures are more moderate than those in deserts like the Mojave and Sonoran, due to the region's higher elevation and latitude. Winters in this section of the basin are still cold, however. The
Great Salt Lake Desert The Great Salt Lake Desert (colloquially referred to as the West Desert) is a large dry lake in northern Utah, United States, between the Great Salt Lake and the Nevada border. It is a subregion of the larger Great Basin Desert, and noted for wh ...
, located near the northeast corner of the Great Basin desert, is an excellent example of a
cold desert climate The desert climate or arid climate (in the Köppen climate classification ''BWh'' and ''BWk''), is a dry climate sub-type in which there is a severe excess of evaporation over precipitation. The typically bald, rocky, or sandy surfaces in desert ...
. Although still arid, it is worthy to note that this portion of the desert receives more precipitation than the similar playas and salt pans on the western edge of the Great Basin desert.


Biological communities

The pattern of 'basin and range' with adjacent basins and ranges in this region results in incredible biological diversity. Climate, elevation, soil type, and many anthropogenic variables greatly influence the diversity and distribution of shrubland,
grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...
, and
woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ''plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (se ...
communities in the desert. Across the high desert there are numerous sub-climates correlating to the varied elevations. Heading from the valley bottoms to the mountain peaks one will encounter constantly changing combinations of plant and animal species making up some 200 distinct biological communities. These communities can be generally grouped into six general communities or “life zones”.


Shadscale zone

In the lower valley bottoms where mountain run off evaporates to create saline soils is the
shadscale ''Atriplex confertifolia'', the shadscale or spiny saltbush, is a species of evergreen shrub in the family Amaranthaceae, which is native to the western United States and northern Mexico Mexico (Spanish: México), officially the United Me ...
zone. Plants in this community are adapted to living with very little
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
, high heat, and saline conditions. The amount of water and the soil type in any one area will determine exactly which plants will live there. Certain areas of the valley floors may harbor no life. These parched areas that flood periodically are called playas. On the shores of the playas, shadscale is the dominant plant, but is kept company by iodine bush, saltgrass, spiny hopsage,
winterfat ''Krascheninnikovia'' is a genus of flowering plants in the subfamily Chenopodioideae of the family Amaranthaceae known as winterfat, so-called because it is a nutritious livestock forage. They are known from Eurasia and western North America. Th ...
, four-winged saltbrush, and green rabbitbrush. Trees are not found in this community. Big greasewood is the dominant shrub in more saline areas or where the
water table The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. T ...
is high. These shrubs and associated grasses typically produce abundant small seeds that are harvested by rodents and insects. The soil salinity and lack of moisture in this zone is not very conducive to most agriculture; however, livestock grazing and grain farming have historically contributed to a decline in the already scattered vegetation.


Sagebrush zone

The drop in soil salinity and increase in moisture as elevation increases leads to a transition to sagebrush ( Artemisia) and grasses just above the shadscale zone. This expanse, called the sagebrush zone, constitutes the largest amount of land in the desert (38.7 percent) and is dominated by big sagebrush (''
Artemisia tridentata ''Artemisia tridentata'', commonly called big sagebrush,MacKay, Pam (2013), ''Mojave Desert Wildflowers'', 2nd ed., , p. 264. Great Basin sagebrush or (locally) simply sagebrush, is an aromatic shrub from the family Asteraceae, which grows in ari ...
'') shrubland. The sagebrush zone occurs on the lower mountain slopes,
alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...
s, and bajadas. Areas in this zone that have wetter and less saline soils are dominated by big sagebrush. Low sagebrush or black sagebrush dominate areas with steep rocky slopes and shallow soils. Introduced annual grasses such as cheatgrass ('' Bromus tectorum'') and halogeton ('' Halogeton glomeratus'') also characterize this zone, although native bunchgrasses once thrived amongst sagebrush. Historical fire suppression, adjusted fire frequency following the introduction of annual grasses and widespread livestock grazing have contributed to contraction of the sagebrush zone. According to Noss, 99 percent of the sagebrush-grass zone has been damaged by livestock, with major damage in 30 percent of the zone. Other shrubs commonly found in the sagebrush zone are rabbitbrush, bitterbrush,
snowberry ''Symphoricarpos'', commonly known as the snowberry, waxberry, or ghostberry, is a small genus of about 15 species of deciduous shrubs in the honeysuckle family, Caprifoliaceae. With the exception of the Chinese coralberry, '' S. sinensis'', wh ...
, and Mormon tea (ephedra).


Pinyon-Juniper community

The pinyon-juniper community is adjacent and above the sagebrush zone. The main plants in this community are singleleaf pinyon pine and Utah juniper, often with a sagebrush and bitterbrush understory. Other species of junipers also occur in this zone, including ''
Juniperus communis ''Juniperus communis'', the common juniper, is a species of small tree or shrub in the cypress family Cupressaceae. An evergreen conifer, it has the largest geographical range of any woody plant, with a circumpolar distribution throughout the coo ...
'' and ''
Juniperus occidentalis ''Juniperus occidentalis'', known as the western juniper, is a shrub or tree native to the Western United States, growing in mountains at altitudes of and rarely down to . It is listed as Least Concern on the IUCN Red List because it is a widesp ...
''. The elevational range of this zone varies, but it is usually found between , with lower limits determined by lack of moisture and the upper limits determined by temperature. The pinyon-juniper community consists of short evergreen trees that rarely grow over 20 feet in height. This zone of dense vegetation, made possible by thermal inversions and increased precipitation, is important to a wide variety of isolated animals that rely on this vegetation interface for survival (for example, '' Eutamias palmeri''). The trees are widely spaced and have an understory of a mixture of shrubs and herbaceous plants, often with nearly bare ground. These characteristics have led this zone to be named the “pygmy forest” by many scientists. The lower end of this zone is dominated by juniper; the middle is a combination of both species, and the upper end is dominated by pinyon.


Montane community

The taller ranges of the Great Basin desert have a montane community. Due to the great distances created by basins between these small forest habitats, various rock substrates, and local climates, montane forests are tremendously varied across the desert. Isolated from one mountain range to the next, montane communities in the region have long individual histories, each one affected differently by chance factors of migration over vast expanses of desert. Smaller communities are also vulnerable to adverse effects of climate change and to genetic drift.
White fir ''Abies concolor'', the white fir, is a coniferous tree in the pine family Pinaceae. This tree is native to the mountains of western North America, including the Cascade Range and southern Rocky Mountains, and into the isolated mountain ranges ...
, Douglas fir, and
ponderosa pine ''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is the ...
s are found in the middle elevations of some mountain ranges, while
limber pine ''Pinus flexilis'', the limber pine, is a species of pine tree-the family Pinaceae that occurs in the mountains of the Western United States, Mexico, and Canada. It is also called Rocky Mountain white pine. A limber pine in Eagle Cap Wildernes ...
,
subalpine fir ''Abies lasiocarpa'', the subalpine fir or Rocky Mountain fir, is a western North American fir tree. Description ''Abies lasiocarpa'' is a medium-sized evergreen conifer with a very narrow conic crown, growing to tall, exceptionally , with a t ...
,
Engelmann spruce ''Picea engelmannii'', with the common names Engelmann spruce, white spruce, mountain spruce, and silver spruce, is a species of spruce native to western North America. It is mostly a high-altitude mountain tree but also appears in watered canyon ...
, and
bristlecone pine The term bristlecone pine covers three species of pine tree (family Pinaceae, genus ''Pinus'', subsection ''Balfourianae''). All three species are long-lived and highly resilient to harsh weather and bad soils. One of the three species, ''Pinus ...
s occupy the higher elevations, continuing to the upper tree line.
Mountain mahogany ''Cercocarpus'', commonly known as mountain mahogany, is a small genus of at least nine species of nitrogen-fixing flowering plants in the rose family, Rosaceae. They are native to the western United States and northern Mexico, where they grow ...
often dominates drier, warmer south-facing slopes. Pure stands of
aspen Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the '' Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (Chin ...
are also common in this community. The bristlecone pine is an important species that is indicative of the Great Basin desert. Bristlecones live a long time, some for thousands of years. The harsh areas they occupy are often devoid of other plant life, so there is little competition and reduced risk of fire. The trees grow very slowly, producing very dense, disease-resistant wood. These factors contribute to the bristlecone's long life.


Alpine community

Some mountain ranges in the Great Basin desert are high enough to have an
alpine Alpine may refer to any mountainous region. It may also refer to: Places Europe * Alps, a European mountain range ** Alpine states, which overlap with the European range Australia * Alpine, New South Wales, a Northern Village * Alpine National Pa ...
community; a community of low growing plants above the
treeline The tree line is the edge of the habitat at which trees are capable of growing. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually cold temperatures, extreme snowp ...
. Treeline is generally found above in the Great Basin desert, moving downslope with higher latitudes. The plants that grow above treeline are separated from other such areas by miles of foothills and valleys. This “island” phenomenon produces many
endemic species Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
- species that have evolved while isolated on a particular mountain peak or range and are found only in that one place.
Grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...
es,
sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus '' Carex'' ...
s, low perennial herbs, and wildflowers grow above treeline.


Riparian community

The
riparian A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks a ...
communities of the Great Basin desert cut across all elevations and life zones. In the Great Basin desert surface water is rapidly lost by evaporation or infiltration. However, areas around streams where plant life is abundant constitute a riparian area. Water-loving plants like
willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...
, narrowleaf cottonwood,
choke cherry ''Prunus virginiana'', commonly called bitter-berry, chokecherry, Virginia bird cherry, and western chokecherry (also black chokecherry for ''P. virginiana'' var. ''demissa''), is a species of bird cherry (''Prunus'' subgenus ''Padus'') nat ...
, wild rose, and
aspen Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the '' Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (Chin ...
are found along these wet areas. The willow has a spreading root network that allows it to reach all around for water and it also helps streams by slowing erosion. These plants provide wood for beavers. In this community, silver buffaloberry often provides shelter for
North American porcupine The North American porcupine (''Erethizon dorsatum''), also known as the Canadian porcupine, is a large quill-covered rodent in the New World porcupine family. It is the second largest rodent in North America, after the North American beaver ('' ...
s.


Subregions

The U.S. Environmental Protection Agency defines its Central Basin and Range ecoregion as Level III: it is at the third level of a tree of ecoregions that cover North America. It further defines sub-ecoregions at Level IV, which describe differences in the ecoregion at different locations. The map shows the Level IV EPA ecoregions in Nevada. The low-elevation ecoregions lie in the Great Basin shrub steppe, while the high-elevation ones lie in the Great Basin montane forests (as defined by the WWF).


Salt deserts

The Salt desert ecoregion is composed of nearly level playas,
salt flats Salt flats, Salt flat, Salt Flats, or Salt Flat may refer to: Geology *Salt pan (geology), a flat expanse of ground covered with salt and other minerals *Dry lake, an ephemeral lakebed that consists of fine-grained sediments infused with alkali salt ...
,
mud flat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal fl ...
s, and
saline lake A salt lake or saline lake is a landlocked body of water that has a concentration of salt (chemistry), salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of ...
s. These features are characteristic of the Bonneville Basin: they have a higher salt content than those of the Lahontan and Tonopah playas ecoregion, below. Water levels and salinity varies from year-to-year, during dry periods, salt encrustation and wind erosion occur. Vegetation is mostly absent, although scatted salt-tolerant plants, such as pickleweed, iodinebush, black greasewood, and inland saltgrass occur. Soils are not arable and there is very limited
grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
potential. The salt deserts provide wildlife habitat and serve some recreational, military, and industrial uses.


Shadscale-dominated saline basins

The Shadscale-dominated saline basins ecoregion is arid, internally drained and gently sloping to nearly flat. These basins are in, or are characteristic of, the Bonneville Basin: they are higher in elevation and colder in winter than the Lahontan salt shrub basin ecoregion to the west. Light-colored soils with high salt and alkali content occur and are dry for extended periods. The
saltbush Saltbush is a vernacular plant name that most often refers to '' Atriplex'', a genus of about 250 plants distributed worldwide from subtropical to subarctic regions. ''Atriplex'' species are native to Australia, North and South America, and Eurasia. ...
vegetation common to this ecoregion has a higher tolerance for extremes in temperature, aridity, and salinity than big sagebrush, which dominates ecoregion 13c at somewhat higher elevation. The basins in Nevada, in contrast to those in Utah, are more constricted in area and are more influenced by nearby mountain ranges with extensive
carbonate rock Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and dolomite rock (also known as dolosto ...
exposures, which provide water by
percolation Percolation (from Latin ''percolare'', "to filter" or "trickle through"), in physics, chemistry and materials science, refers to the movement and filtering of fluids through porous materials. It is described by Darcy's law. Broader applicatio ...
through the
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
substrate to surface as valley springs. Isolated valley drainages support
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
fish, such as the Newark Valley tui chub.


Lahontan and Tonopah playas

The nearly level and often barren Lahontan and Tonopah playas contain mudflats,
alkali flat A dry lake bed, also known as a playa, is a basin or depression that formerly contained a standing surface water body, which disappears when evaporation processes exceeds recharge. If the floor of a dry lake is covered by deposits of alkaline c ...
s, and intermittent
saline lake A salt lake or saline lake is a landlocked body of water that has a concentration of salt (chemistry), salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of ...
s, such as the
Black Rock Desert __NOTOC__ The Black Rock Desert is a semi-arid region (in the Great Basin shrub steppe eco-region) of lava beds and playa, or alkali flats, situated in the Black Rock Desert–High Rock Canyon Emigrant Trails National Conservation Area, a si ...
,
Carson Sink Carson Sink is a playa in the northeastern portion of the Carson Desert in present-day Nevada, United States of America, that was formerly the terminus of the Carson River. Today the sink is fed by drainage canals of the Truckee-Carson Irrigat ...
, and Sarcobatus Flat.
Marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found a ...
es, remnant lakes and playas are all that remain of
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...
Lake Lahontan Lake Lahontan was a large endorheic Pleistocene lake of modern northwestern Nevada that extended into northeastern California and southern Oregon. The area of the former lake is a large portion of the Great Basin that borders the Sacramento Rive ...
, which was once the size of
Lake Erie Lake Erie ( "eerie") is the fourth largest lake by surface area of the five Great Lakes in North America and the eleventh-largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also h ...
. Playas occur in the lowest elevation of the Lahontan Basin, and represent the terminus or sink of rivers running east of the Sierra Nevada. The playas fill with seasonal runoff from the surrounding mountains, providing habitat for migratory birds. Black greasewood or four-winged saltbush may grow around the perimeter in the transition to the salt shrub community, where they often stabilize areas of low sand dunes. This ecoregion has limited grazing potential. Windblown salt dust from exposed playas may affect upland soils and vegetation. The Lahontan and Tonopah playas are important as wildlife habitat, as well as for
recreational Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasur ...
and military uses.


Lahontan salt shrub basin

The Lahontan salt shrub basin is an expansive dry plain that was once below Pleistocene Lake Lahontan. The
Lahontan Basin Lake Lahontan was a large endorheic Pleistocene lake of modern northwestern Nevada that extended into northeastern California and southern Oregon. The area of the former lake is a large portion of the Great Basin that borders the Sacramento Rive ...
, compared to the Bonneville Basin to the east, is lower in elevation and warmer in winter. Although there is a direct connection to the south to the
Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily ...
, winters are cold enough in this ecoregion to discourage the northward dispersal of Mojavean species into the Lahontan Basin. In addition to
shadscale ''Atriplex confertifolia'', the shadscale or spiny saltbush, is a species of evergreen shrub in the family Amaranthaceae, which is native to the western United States and northern Mexico Mexico (Spanish: México), officially the United Me ...
, other salt-tolerant shrubs, such as Shockley's desert-thorn and Bailey greasewood, cover the lower basin slopes. These shrubs distinguish the Lahontan salt shrub basin and the Tonopah Basin from other Nevada salt shrub ecoregions. Sand dunes may occur where windblown sand accumulates against a barrier; dune complexes support a specialized plant community and diverse small mammal populations. The Carson and
Truckee River The Truckee River is a river in the U.S. states of California and Nevada. The river flows northeasterly and is long.U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed October 20, 2012 Th ...
s, originating in the Sierra Nevada, provide water for irrigated farming. Riparian corridors along these rivers support the only trees found in this ecoregion.


Lahontan sagebrush slopes

Hills,
alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...
s, and low mountains comprise the Lahontan sagebrush slopes ecoregion. These areas are rock controlled and their soils lack the fine
lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...
sediments that are found in lower parts of the Lahontan Basin. Because moisture increases and alkalinity decreases with elevation, the shrub community grades from the greasewood-
shadscale ''Atriplex confertifolia'', the shadscale or spiny saltbush, is a species of evergreen shrub in the family Amaranthaceae, which is native to the western United States and northern Mexico Mexico (Spanish: México), officially the United Me ...
community on the basin floor, to a shrub community dominated by Wyoming big sagebrush and the endemic Lahontan sagebrush at higher elevations.
Understory In forestry and ecology, understory (American English), or understorey (Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the forest canopy without penetrating it to any great extent, but abo ...
grasses increase the
productivity Productivity is the efficiency of production of goods or services expressed by some measure. Measurements of productivity are often expressed as a ratio of an aggregate output to a single input or an aggregate input used in a production proces ...
towards the northeast, outside the rain shadow influence of the Sierra Nevada. The low hills and mountains of the Lahontan Basin experience frequent summer lightning and fire. The introduced
cheatgrass ''Bromus tectorum'', known as downy brome, drooping brome or cheatgrass, is a winter annual grass native to Europe, southwestern Asia, and northern Africa, but has become invasive in many other areas. It now is present in most of Europe, southe ...
tends to replace the shrub community and provides fuel for recurrent fires.


Lahontan uplands

The Lahontan uplands are restricted to the highest elevations of the mountains ranges within the Lahontan salt shrub basin. Slopes vary in elevation from and are covered in sagebrush, grasses, and scattered Utah juniper. Pinyon grows with juniper on the Stillwater Range and on Fairview Peak in the southeast portion of the Lahontan Basin, but it is otherwise absent from this ecoregion. Low sagebrush and black sagebrush grow to the mountaintops above the woodland zone. Cool-season grasses, including
bluebunch wheatgrass ''Pseudoroegneria spicata'' is a species of grass known by the common name bluebunch wheatgrass. This native western North American perennial bunchgrass is also known by the scientific synonyms ''Elymus spicatus'' and ''Agropyron spicatum''. The g ...
, dominate the understory in the north, but are replaced by warm-season grasses, such as Indian ricegrass, in the south.


Upper Humboldt Plain

The Upper Humboldt Plains ecoregion is an area of rolling plains punctuated by occasional
butte __NOTOC__ In geomorphology, a butte () is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and tablelands. The word ''butte'' comes from a French word me ...
s and low mountains. It is mostly underlain by
volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...
, rhyolite, and tuffaceous rocks. Low sagebrush is common in extensive areas of shallow, stony soil, as are cool season grasses, such as
bluebunch wheatgrass ''Pseudoroegneria spicata'' is a species of grass known by the common name bluebunch wheatgrass. This native western North American perennial bunchgrass is also known by the scientific synonyms ''Elymus spicatus'' and ''Agropyron spicatum''. The g ...
, Idaho fescue, and Sandberg bluegrass. The ecoregion is wetter and cooler than other Nevada ecoregions in its elevation range. The ecoregion is transitional to the
Northern Basin and Range ecoregion The Northern Basin and Range ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Oregon, Idaho, Nevada, Utah, and California. It contains dissected lava plains, rolling ...
that spans the Nevada-Oregon border. However, as in the warmer Lahontan Basin to the west, lightning fires are common and a post-fire
monoculture In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monoculture is widely used in intensive farming and in organic farming: both a 1,000-hectare/acre cornfield and a 10-ha/acre field of organic kale are ...
of
cheatgrass ''Bromus tectorum'', known as downy brome, drooping brome or cheatgrass, is a winter annual grass native to Europe, southwestern Asia, and northern Africa, but has become invasive in many other areas. It now is present in most of Europe, southe ...
tends to replace the native grasses and shrubs.
Grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
is the major land use, though there is some agriculture near the
Humboldt River The Humboldt River is an extensive river drainage system located in north-central Nevada. It extends in a general east-to-west direction from its headwaters in the Jarbidge, Independence, and Ruby Mountains in Elko County, to its terminus in th ...
.


Carbonate Sagebrush Valleys

The basins and semi-arid uplands of the Carbonate Sagebrush Valleys surround the carbonate ranges of eastern Nevada. These valleys are underlain by
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
or dolomite. The combination of summer moisture and a limestone or dolomite substrate affects regional vegetation, particularly in terms of species dominance and elevational distribution. The substrate favors shrubs, such as black sagebrush and
winterfat ''Krascheninnikovia'' is a genus of flowering plants in the subfamily Chenopodioideae of the family Amaranthaceae known as winterfat, so-called because it is a nutritious livestock forage. They are known from Eurasia and western North America. Th ...
, that can tolerate shallow soil. Even in alluvial soils, root growth may be limited by a
hardpan In soil science, agriculture and gardening, hardpan or soil pan is a dense layer of soil, usually found below the uppermost topsoil layer. There are different types of hardpan, all sharing the general characteristic of being a distinct soil layer ...
or
caliche Caliche () is a sedimentary rock, a hardened natural cement of calcium carbonate that binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions ...
layer formed by carbonates leaching through the soil and accumulating. As a result, shrub cover is sparse in contrast to other sagebrush-covered ecoregions in Nevada. The grass understory grades from a dominance of cool season grasses, such as
bluebunch wheatgrass ''Pseudoroegneria spicata'' is a species of grass known by the common name bluebunch wheatgrass. This native western North American perennial bunchgrass is also known by the scientific synonyms ''Elymus spicatus'' and ''Agropyron spicatum''. The g ...
, in the north, to warm season grasses, such as
blue grama ''Bouteloua gracilis'', the blue grama, is a long-lived, warm-season ( C4) perennial grass, native to North America. It is most commonly found from Alberta, Canada, east to Manitoba and south across the Rocky Mountains, Great Plains, and U.S ...
(an indicator of summer rainfall) in the south.


Central Nevada high valleys

The Central Nevada high valleys ecoregion contains sagebrush-covered rolling valleys that are generally over in elevation.
Alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...
s spilling from the surrounding mountain ranges fill the valleys, often leaving little intervening flat ground. Wyoming big sagebrush and associated grasses are common on the flatter areas, and black sagebrush dominates on the volcanic hills and alluvial fans. This ecoregion tends to have lower species diversity than other sagebrush ecoregions, because of its aridity and isolation from more species-rich areas. Saline playas may occur on available flats. Less
shadscale ''Atriplex confertifolia'', the shadscale or spiny saltbush, is a species of evergreen shrub in the family Amaranthaceae, which is native to the western United States and northern Mexico Mexico (Spanish: México), officially the United Me ...
and fewer associated shrubs surround these playas than in other, lower more arid ecoregions in the west, including the Lahontan salt shrub ecoregion and the Tonopah Basin ecoregion. Valleys with permanent water support endemic fish populations, such as the Monitor Valley speckled dace.


Central Nevada mid-slope woodland and brushland

The Central Nevada mid-slope woodland and brushland ecoregion at of elevation is analogous in altitudinal range to other woodland areas in Nevada. However, continuous woodland is not as prevalent on the mountains of central Nevada as in other woodland ecoregions, such as ecoregions 13d and 13q. Pinyon- juniper grows only sparsely through the shrub layer due to combined effects of past fire, logging, and local climate factors, including lack of summer rain and the pattern of winter cold air inversions. Where extensive woodlands do exist, understory diversity tends to be very low, especially in closed canopy areas. Areas of
black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ...
and Wyoming big sagebrush grade upward into mountain big sagebrush and curlleaf mountain-mahogany, which straddles the transition between this mid-elevation brushland and the mountain brush zone of the higher Central Nevada Bald Mountains.


Central Nevada Bald Mountains

The Central Nevada Bald Mountains are dry and mostly treeless. Although they rise only east of the Sierra Nevada, they lack Sierra species due to the dry conditions. These barren-looking mountains are covered instead by dense mountain brush that is dominated by mountain big sagebrush, serviceberry,
snowberry ''Symphoricarpos'', commonly known as the snowberry, waxberry, or ghostberry, is a small genus of about 15 species of deciduous shrubs in the honeysuckle family, Caprifoliaceae. With the exception of the Chinese coralberry, '' S. sinensis'', wh ...
, and low sagebrush. They contrast with the High-elevation Carbonate Mountains to the east, where the mountain brush zone is too narrow to be mapped as a separate ecoregion. Scattered groves of curlleaf mountain-mahogany and
aspen Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the '' Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (Chin ...
in moister microsites grow above the shrub layer. A few scattered limber or
bristlecone pine The term bristlecone pine covers three species of pine tree (family Pinaceae, genus ''Pinus'', subsection ''Balfourianae''). All three species are long-lived and highly resilient to harsh weather and bad soils. One of the three species, ''Pinus ...
s grow on ranges that exceed . The
Toiyabe Range The Toiyabe Range is a mountain range in Lander and Nye counties, Nevada, United States. Most of the range is included within the Humboldt-Toiyabe National Forest. The highest point in the range, near its southern end, is Arc Dome (11,788 f ...
(west of Big Smoky Valley) is high enough to have an alpine zone, but lacks a suitable substrate to retain snowmelt moisture. The isolation of these "sky islands" has led to the development of many rare and endemic plant species.


Tonopah Basin

The Tonopah Basin lies in the transition between the Great Basin Desert and the more southerly
Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily ...
. The basin shows varying characteristics of both deserts. The west side of the Tonopah Basin is a continuation of the
Lahontan Basin Lake Lahontan was a large endorheic Pleistocene lake of modern northwestern Nevada that extended into northeastern California and southern Oregon. The area of the former lake is a large portion of the Great Basin that borders the Sacramento Rive ...
, while the lower and hotter Pahranagat Valley on the east side is more like the Mojave Desert. Similar to basins further north,
shadscale ''Atriplex confertifolia'', the shadscale or spiny saltbush, is a species of evergreen shrub in the family Amaranthaceae, which is native to the western United States and northern Mexico Mexico (Spanish: México), officially the United Me ...
and associated arid land shrubs cover broad rolling valleys, hills, and alluvial fans. However, unlike the Lahontan salt shrub basin and Upper Lahontan basin, the shrubs often co-dominate in highly diverse mosaics. The shrub understory includes warm-season grasses, such as Indian ricegrass and
galleta grass ''Hilaria'' is a genus of North American plants in the grass family. Members of the genus are commonly known as curly mesquite. They are found in the Southwestern United States, Mexico, and Guatemala. The generic name honors French naturalist Au ...
. Endemic fish species, including the Railroad Valley tui chub, Pahranagat roundtail chub,
Railroad Valley springfish The Railroad Valley springfish ''Crenichthys nevadae'', is a rare goodeid fish of the Great Basin of western United States, occurring naturally in just seven thermal springs of Railroad Valley in Nye County, Nevada. The body gives a somewhat hea ...
, and the White River springfish are found in valleys with perennial water.


Endangered species

The topography of the Great Basin desert (“island” mountain tops separated from one another by vast expanses of desert valleys) renders it vulnerable to extinctions. Populations that occupy the high peaks are isolated from one another; therefore, they cannot interbreed. Small populations are more vulnerable to the forces of extinction - generally small populations have less genetic diversity and therefore a lesser ability to adapt to changing conditions. Groundwater pumping, road and home construction, grazing, and mining are all activities that alter habitat; as more habitat is affected, the threat of extinction increases. The Great Basin desert is home to many threatened and endangered species: *Birds **
Least tern The least tern (''Sternula antillarum'') is a species of tern that breeds in North America and locally in northern South America. It is closely related to, and was formerly often considered conspecific with, the little tern of the Old World. Ot ...
(''Sterna antillarum athalassos'') *Plants ** Sodaville milkvetch (''Astragalas lentiginosus var. sesquimetralis'') ** Ute lady's tresses (''Spiranthes diluvialis'') *Fish **
Lahontan cutthroat trout Lahontan cutthroat trout (''Oncorhynchus clarkii henshawi'') is the largest subspecies of cutthroat trout, and the state fish of Nevada. It is one of three subspecies of cutthroat trout that are listed as federally threatened. Natural history ...
(''Oncorhynchus clarki henshawi'') ** Desert dace (''Eremichthys acros'') ** White River spinedace (''Lepidomeda albivallis'') *Mammals **
Utah prairie dog The Utah prairie dog (''Cynomys parvidens'') is the smallest species of prairie dog endemic to the south-central steppes of the American state of Utah. The species is listed in the IUCN Red List of Threatened Species with a status of Endangered. ...
(''Cynomys parvidens'')


See also

* Becky Peak Wilderness (BLM) * Bristlecone Wilderness (BLM) * Goshute Canyon Wilderness (BLM) * Government Peak Wilderness (BLM) * Great Basin *
Great Basin National Park Great Basin National Park is an American national park located in White Pine County in east-central Nevada, near the Utah border, established in 1986. The park is most commonly entered by way of Nevada State Route 488, which is connected to U ...
* Highland Ridge Wilderness (BLM) * Humboldt-Toiyabe National Forest **
Bald Mountain Wilderness The Bald Mountain Wilderness is a wilderness area in White Pine County, in the U.S. state of Nevada. The Wilderness lies within the Humboldt-Toiyabe National Forest and is administered by the U.S. Forest Service. Located in the heart of the ...
(Humboldt NF) ** Currant Mountain Wilderness (Humboldt NF) ** East Humboldt Wilderness (Humboldt NF) **
High Schells Wilderness The High Schells Wilderness is a wilderness area in the Schell Creek Range of White Pine County, in the U.S. state of Nevada. The Wilderness lies within the Humboldt-Toiyabe National Forest and is therefore administered by the U.S. Forest Serv ...
(Humboldt NF) ** Jarbidge Wilderness (Humboldt NF) ** Quinn Canyon Wilderness (Humboldt NF) **
Red Mountain Wilderness The Red Mountain Wilderness is a wilderness area in southwestern White Pine County and northeastern Nye County, within the White Pine Range in the U.S. state of Nevada. The Wilderness lies within the Humboldt-Toiyabe National Forest, administ ...
(Humboldt NF) ** Shellback Wilderness (Humboldt NF) ** White Pine Range Wilderness (Humboldt NF) * Mount Grafton Wilderness (BLM) * Mount Moriah Wilderness (Humboldt NF / BLM) * South Egan Range Wilderness (BLM) * Fish Springs National Wildlife Refuge * Ruby Lake National Wildlife Refuge * Fallon National Wildlife Refuge *
Stillwater National Wildlife Refuge Stillwater National Wildlife Refuge is a National Wildlife Refuge of the United States in Nevada. It is located in the Lahontan Valley, near the community of Fallon, sixty miles east of Reno. It was established in 1949 and encompasses . The Stil ...


Notes


References


External links

* {{Deserts Deserts of Nevada Deserts of California Deserts of Utah Central Basin and Range ecoregion Ecoregions of the United States Ecology of the Great Basin Basin and Range Province