Ecosystem

Mojave Desert

Location

The Mojave Desert stretches from the wedge-shaped Antelope Valley eastward across the Colorado River. Bordering the Sonoran Colorado Desert and running north to the majestic Sierra Nevada mountain range, the land in between is anything but what we first imagine a desert to be, flat and featureless

Climate

The Mojave Desert is the driest desert in North America

Temperature (highs/lows)/humidity

The Mojave Desert is found at elevations of 2,000 to 5,000 feet, and is considered a "high desert". Temperatures have been as low as 8°F in January and as high as 119°F in August. The night temperatures in July and August can at times be in the low to mid 90s. In late winter and early spring the wind is a prominent feature, with dry winds blowing in the afternoon and evening. Winds in excess of 25 mph, with gusts of 75 mph or more are not uncommon. Although it is windy during all months, November, December and January are the calmest. The humidity is below 40% most of the year. During most winter nights, and during and after summer rains the humidity can get above 50%.

Precipitation

The Mojave's desert climate is characterized by extreme variation in daily temperature and an average annual precipitation of less than 5 inches. Almost all the precipitation arrives in winter. Freezing temperatures occur in winter, while summers are hot, dry and windy. Most of the rain falls between November and April. There is, however, a summer thunderstorm season from July to September with violent and heavy rainstorms possible. In 1986 only 1.5 inches of rain fell on the Eastern Mojave Desert, while in 1983 6.5 inches came down. May and June are usually the driest months. The Mojave Desert experienced very heavy rains in the 1950s, when surface runoff resulted in severe erosion of gullies and washes and heavy silt deposits. A long dry period followed, ending with the present wet period.  

Soil & Land Description

Soil-forming processes including accumulation and vertical redistribution of clay minerals and calcium carbonate in different soil horizons lead to increasing soil profile development over time. The degree of soil development has a deep impact on soil water balance. The Mojave Dessert consists of a landscape of sand dunes, Joshua tree forests, and mile-high mountains in the heart of the desert. Wind action plays a major role in shaping the landforms in the Mojave Desert. Because vegetation is sparse in arid regions such as the Mojave, wind can move sand and fine gravel in suspension. Sand is carried much higher than gravel and for longer distances, sometimes for thousands of feet into the air while it makes its long journeys.

Land Uses/ Problems/ Solutions

The Mojave has been selected for study because it represents a wide variety of land uses within a relatively homogeneous natural landscape. Much of the Mojave Desert is designated wilderness that is owned and managed by the federal government, particularly the Bureau of Land Management (BLM Wilderness Areas, 1995), but a large proportion of the desert belongs to Army and Navy training facilities. Recently the National Park Service has gained land ownership surrounding Death Valley National Park and Joshua Tree National Park after enactment of the California Desert Protection Act of 1992. Private lands are held primarily by ranchers, and some mining interests yet exist throughout the desert. Overall, the diversity of land use and the factors that force change within the Mojave Desert make this region a natural choice to study the effects of anthropogenic disturbance on flora and fauna in a desert environment.

Major Weather Events Commonly Experienced

The Mojave Dessert regularly has a summer thunderstorm season; from July to September, during which the Soda Springs area has experiences violent and heavy rainfall, up to 2 inches in 2 hours.

Other Factors

The Mojave Desert is dominated by low, widely spaced shrubs, including the creosote bush (Larrea tridentata) and Mojave sage (Salvia mohavensis). The Mojave flora includes few trees other than the signature Joshua tree (Yucca brevifolia), but features a number of cacti, several parasitic plants, and a vast variety of wildflowers. Groundwater and the Mojave and Colorado Rivers are the primary water sources for the Mojave Desert's plants and animals, and for the booming populations of desert cities.

Plants and other producers

1. Creosote bush
2. Desert Christmas cactus
3. Joshua tree
4. Saguaro Cactus
5. Mojave aster
6. Barrel cactus

Animals

1. Red tailed hawk
2. Coyote
3. Long-nosed leopard lizard
4. Roadrunner
5. Whiptail
6. Red Racer
7. Horned lizard
8. Giant desert hairy scorpions
9. Mojave rattlesnake
10. Mojave patch-nose snake
11. Desert iguana
12. Chuckwalla
13. Zebra-tailed lizard
14. Fire Ants
15. Desert WoodRats

Additional Notes

-         human impacts

-         interesting facts

-         connections

Much of the less spectacular desert land in the southern USA and northern Mexico has been converted to agricultural use, supported by irrigation canals that draw water from the major rivers such as the Colorado River. The crop yields can be very high because of the warm growing conditions in these regions. The high-value market crops grown in these conditions include onions, peppers, tomatoes, alfalfa, citrus crops, grapes and nuts such as pecans and walnuts. Some examples are shown in the images below.

However, the ecological impacts of this are raising concerns, for at least two reasons.

·         Many of these intensively farmed crops rely on the use of insecticides and herbicides, which can seriously affect the populations of native pollinator species (moths and bees). The insecticides can kill these organisms, and the herbicides destroy the native "weed" plants that provide pollen and nectar for insects.

·         The widespread conversion to agricultural use causes fragmentation of the desert habitat, which can seriously disrupt the migration of pollinators and other migratory species (e.g. hummingbirds, bats, hawkmoths, monarch butterflies). These animals need "corridors" of wild vegetation on which they can feed during their annual migrations.