Great Basin National Park, Nevada, USA Photograph by John Morrison   Western North America: Southwestern United States Deserts and Xeric Shrublands   129,700 square miles (335,900 square kilometers) -- slightly larger than New Mexico Relatively Stable/Intact

· What’s So Great About This Basin?
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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What’s So Great About This Basin?

This ecoregion is bounded on the east by the Colorado Plateau and central Rocky Mountains, on the north by the Columbia Plateau, and on the west by the Cascade-Sierra ranges. It has a true "basin and range" topography, with about 100 smaller basins found within the overall Great Basin ecoregion. A basin is a valley or depression in the land that all the streams and rivers from the surrounding mountains flow into, rather than going to the sea. The small lakes that form in the basins are home to endemic shrimp and other species.

Special Features

The Great Basin is the northernmost of the four American deserts, and it receives less than 10 inches (250 mm) of precipitation per year. It is the largest arid area in the United States. The region supports several threatened and endangered species. Basins and ranges alternate throughout the ecoregion.

	The famous Painted Desert of Arizona, which was named because of its bright, multi-colored rock formations, is found in this ecoregion. The desert's shades of color change with the sun's position in the sky throughout the day.

Wild Side

Sagebrush, saltbrush, winterfat, rabbit brush, blackbrush, hopsage, horsebrush, and shadscale are some of the plants that have adapted to the dry conditions here. Unlike other deserts, this ecoregion has few cacti. Threatened and endangered species that live here include a species of greasewood and kangaroo mouse.

Cause for Concern

Virtually the entire basin has been heavily grazed by livestock, making this the biggest threat to the ecoregion. Less than 10 percent of the area remains intact. Introduced plants, such as the highly flammable cheatgrass brome, often take over grazed areas once inhabited by native plants. Loss of riparian vegetation to overgrazing and wetlands to water diversions for agriculture are also major problems. As water used for irrigation evaporates, it concentrates salts from within the soil on the soil surface, a condition called salinization. Mining has led to air and water pollution by heavy metals. Growth of urban areas, particularly those of Las Vegas, Reno, and Salt Lake City, is an additional threat to remaining habitat.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.