Great Basin Desert
The Great Basin Desert is the largest desert biome in North America, spanning approximately 200,000 square miles across western North America, primarily within Nevada and parts of surrounding states such as Utah, Oregon, Idaho, and California. This semi-arid region is characterized by its unique elevation variations, ranging from 5,000 to 12,000 feet above sea level, and its lack of direct water outlet, earning it the designation of a "basin." The climate is defined by significant temperature fluctuations, with averages from minus 32°F in winter to 99°F in summer, and precipitation levels that vary widely based on elevation, from about 6 inches in lower areas to over 30 inches in the mountains.
Biodiversity is rich; the desert hosts various ecosystems, including salt-desert shrublands, sagebrush steppe, and pinyon-juniper woodlands, along with the ancient Great Basin bristlecone pines. Wildlife includes mammals like elk and bighorn sheep, a range of birds, and both native and nonnative fish species. Human impact has been significant since the arrival of settlers, with extensive livestock grazing, water diversion for urban areas, and the introduction of invasive species posing threats to the ecosystem. Climate change further exacerbates these challenges, leading to concerns over water sustainability and habitat integrity. The Great Basin Desert remains a complex and ecologically significant area, rich in natural history and biodiversity, yet increasingly vulnerable to human influence and environmental change.
Subject Terms
Great Basin Desert
- Category: Desert Biomes.
- Geographic Location: Western North America.
- Summary: The Great Basin, the largest desert biome in North America, is home to numerous unique species and subspecies of plants and animals.
The semi-arid and desert region referred to as the Great Basin Desert has been defined in at least five different ways, each affecting its reported size and location. The hydrographic definition will be used here; this refers to the low elevation areas west of the Wasatch Range, east of the Sierra Nevada mountains, south of the Columbia Plateau, and north of the Mojave Desert and Colorado Plateau. This great stretch of land covers roughly 200,000 square miles (518,000 square kilometers), with elevations ranging between 5,000 feet (1,500 meters) and up to 12,000 feet (3,700 meters) above sea level. There are also many cave systems in the basin.
Geography and Climate
Since this area has no outlet to the sea, the term basin is used in its most literal sense: a broad area of the earth, beneath which the strata dip usually from the sides toward the center. Land area in the Great Basin includes about 50 percent of the state of Utah, almost all of Nevada, and smaller areas of southeastern Oregon, southern Idaho, and eastern California. This makes it the largest of the four desert regions of North America and, generally, composes the northern portion of the basin and Range Province.
Water is scarce and consists mainly of shallow groundwater, large regional springs, and small creeks. Each of these sources depends on healthy groundwater flows supported by precipitation in mountain ranges, which receive more moisture than the valleys. The climate here is typical of mid-latitude semi-arid lands, where the evaporation potential exceeds precipitation throughout the year.
Since the basin suffers from lack of precipitation due to the rain shadow effect of the Sierra Nevada mountains, most annual moisture reaches the basin during the seasonal runoff of snowmelt. Average annual precipitation ranges from about 6 inches (15 centimeters) at the lowest elevations to more than 30 inches (75 centimeters) at the upper elevations. At lower elevations, about half of the precipitation falls as snow during the November 1 to May 1 winter season, increasing to more than three-quarters in high elevations. June and September are the driest months; summer thunderstorms are common.
Temperatures range from minus 32 degrees F (minus 36 degrees C) to 99 degrees F (37 degrees C). The mean January temperature is 18 degrees F (minus 8 degrees C); the mean July temperature is 55 degrees F (13 degrees C). The maximum and minimum daily temperature differences can range from 37 to 50 degrees F (3 to 10 degrees C) on any day, depending on elevation and site.
Flora and Fauna
Often referred to as the Cold Desert because of its high latitude and elevation, low seasonal temperatures, and the accumulation of surface snow in the winter, the basin is biologically diverse. The composition of the flora and fauna in the basin varies widely, based on available water, elevation, soil chemistry, and structure. The simplest plant systems are found in barren salt flats, starting usually below 5,500 feet (1,670 meters) in elevation. These plant communities make up what is called salt-desert shrub: greasewood (Sarcobates vermiculatus), shadscale (Atriplex confertifolia), and green molly (Kochia americana) appear in conjunction with creosote brush (Larrea tridentata), four-winged saltbush (Atriplex canescens), and rabbitbrush (Chrysothamnus viscidiflorus).
As elevation is increased, vegetation transitions into sagebrush, and these “oceans” of sage are often referred to as sagebrush steppe. The plant communities that thrive at even higher elevations are pinyon-juniper woodlands. The very highest elevations include the oldest living organisms on Earth, the Great Basin bristlecone pines, which have been recorded as living more than 4,000 years. Other plant species that can be found at various elevations throughout the Great Basin Desert include prickly pear cactus, alpine wildflowers, and aspen.
Animal wildlife is abundant in the Great Basin Desert, despite diminishing sources of water. Some of the mammals that can be found here are: elk, mule deer, bighorn sheep, mountain lion, marmot, beaver, porcupine, jackrabbit, ring-tail cat, weasel, skunk, sagebrush vole, and water shrew. There are many reptiles and some amphibians; the Great Basin rattlesnake (Crotalus oreganus lutosus) is the only venomous snake found here, and the chuckwalla lizard is the largest lizard in the United States.
Birds commonly found in the basin include the sage grouse, quail, several species of hawks and falcons, and three owl species. Great Basin National Park is home to four native fish species: Bonneville cutthroat trout, mottled sculpin, redside shiner, and speckled dace. It also provides habitat for four nonnative species: Lahonton cutthroat, rainbow, brook, and brown trout. These fish may all be found in creeks or lakes in the basin.
Human Impact
Although the basin was home to many tribes of Indigenous Native Americans including, but not limited to, Paiute, Shoshone, Ute, and Panamint, they left no written records of their respective environments, cultures, or lifestyles—although a few oral histories have been recorded. These groups, with their diverse cultures and languages, lived off the land primarily as hunter-gathers and had little effect on the overall ecology of the basin. The pristine nature of this land and the existing flora and fauna that the first White explorers and settlers found in the late 1700s has been completely changed due, primarily, to explosive human population growth, irrigation-based agriculture, and high levels of grazing by domestic livestock, principally cattle and sheep.
The distribution of plants and animals within the basin was initially constrained by the amount of available water and geographic latitude. However, approximately 78 percent of the basin is now administered as public land, primarily by the Bureau of Land Management, the U.S. Department of Agriculture's Forest Service, the Fish and Wildlife Service, the Bureau of Reclamation, the National Park Service, the Department of Defense, and various tribal and state agencies. Almost all of the Great Basin Desert lands are subject to governmentally subsidized livestock grazing, including areas protected as national parks, such as the Great Basin National Park. Consequently, livestock grazing in the arid west is one major cause of species endangerment.
Another major concern in the desert is water distribution. Much of the valuable and scarce groundwater is already being pumped into urban areas (such as Las Vegas), and if the amounts increase, the loss in the basin will likely impact sustainability of the wildlife here. Climate change due to global warming is expected to have a significant effect on the basin over the next several decades. Warming trends, increases in precipitation, decline in snowpack, earlier springs, and extended fire seasons may all have grave implications for water resources, and therefore for native ecosystems and biodiversity. It is thought there will be a continued shift in species communities, as the number of shrinking habitats and local extirpations increase.
Further, threats from invasive species are increased by the changes in environment created by climate change. Cheatgrass (Bromus tectorum) is an invasive plant to the region which occupies over 25 million acres of public land. Cheatgrass competes with native species for the limited resources and can intensify any wildfires that break out. Scientists predict that the changes in the biome are more favorable to cheatgrass than to most native plants.
Bibliography
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Grayson, Donald K. The Great Basin: A Natural Prehistory. Berkeley: University of California Press, 2011.
“The Great Basin Desert.” National Park Services, 24 Apr. 2021, www.nps.gov/grba/learn/nature/deserts.htm. Accessed 12 Dec. 2024.
Natchlinger, J., K. Sochi, P. Comer, G. Kittel, and D. Dorfman. Great Basin: An Ecoregion-Based Conservation Blueprint. Reno, NV: The Nature Conservancy, 2001.
Pellant, Mike. “Environmental Threats to the Great Basin (2).” U.S Department of the Interior,
11 Oct. 2007, www.doi.gov/ocl/hearings/110/ThreatToTheGreatBasin‗101107Pellant. Accessed 12 Dec. 2024.
Spray, Aaron. "Great Basin Desert: Why See America's High and Cold Desert." The Travel, 9 June 2022, www.thetravel.com/why-the-high-great-basin-desert-is-worth-seeing/. Accessed 12 Dec. 2024.
Trimble, S. The Sagebrush Ocean: A Natural History of the Great Basin. Tenth Anniversary Edition. Reno: University of Nevada Press,1999.
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