We head up the road this week to discover the California desert. Spring is an ideal time to go, especially in a year of drenching rainfall—which in these parts measures in the single digits—because well-timed rain brings the shocking exuberance of wildflowers.
California’s 25 million acres of desert stretch east from Los Angeles and San Diego and their edge cities into Nevada and Arizona, south into Mexico, and north to the southern Sierra Nevada foothills. Yet the south state’s desert is actually two distinct deserts: the low Colorado, which is the California extension of the vast Sonoran Desert, and the Mojave or high desert. Travelers heading north along the eastern Sierra Nevada traipse from the Mojave into the far western fringe of California’s third desert—the Great Basin, the endless “sagebrush desert” of the West, which dominates Nevada and extends also into Washington, Wyoming, Colorado, and New Mexico.
The Colorado Desert is desert as most people imagine it: a low-lying landscape of sand, undulating dunes, and stark mountains. It is hot in summer—an average of 120°F during the day—and mild and frost free in winter. The Colorado is also very dry, with just a few inches of rain in an average year. For all its typical modesty, a secret flamboyance bursts into bloom after winters of above-average rainfall—almost embarrassing botanical excess. Yet the Colorado’s plant and animal life is plentiful and quite diverse even during hard times. All three California deserts share plant species, and all have unique ones. Primary Sonoran Desert “indicators” are trees of the legume (pea) family, such as the smoke tree and green-barked palo verde, both found in California, and giant cacti, such as the saguaro, that are not, because of insufficient summer rain. Unlike Great Basin flora, which has an evolutionary connection to arctic climates, plants of the Colorado Desert are tropical descendants—jungle plants that learned to live
Most of the Mojave Desert, spreading north from the Colorado, ranges in elevation from 2,000 to 4,000 feet. Its one characteristic “indicator” is the striking Joshua tree, a giant yucca named by Mormon pioneers after the biblical Joshua, since, in their view, its “arms” turned upward in supplication to heaven. The presence or absence of Joshua trees helps determine the vague Colorado-Mojave boundary, an imaginary line that shimmers like a mirage between Indio near Palm Springs and Needles near the Nevada border. The transitional zone between the Colorado and Great Basin Deserts, the Mojave borrows seasonal extremes from each—being quite cold (sometimes snow-covered) in the winter, like the Great Basin, and hot in summer, like the Colorado.
For all their differences, the Colorado and Mojave Deserts share a fundamental ecological fragility—a fact that strikes many visitors as odd or unbelievable, given the landscape’s raw and rugged appearance and the well-honed survival skills of both animals and plants. Yet in such a dry climate with sparse, slow-growing vegetation, both major and seemingly minor disruptions leave lasting scars on the landscape—be they mining pits, off-road vehicle tracks, or old roads (some still marked by wagon-wheel ruts). And desert plants and animals, with so many specialized survival adaptations or requirements and sometimes vast territory needs, can suddenly face extinction with the loss of what might otherwise seem a minimal amount of habitat to housing and mall developments, golf courses, agriculture, and freeways.