Ecology of the Southwestern Deserts 

In order to better understand how human development and population growth in the Southwest is effecting desert ecosystems, we spent the first half of the semester learning about general desert biology.  Worldwide there are (depending on your definition of desert) approximately 23 deserts which cover almost 15% of the world's land surface. The largest desert of all is the Sahara, in Africa.  Another well known desert is the Gobi in Asia.  Of controversy is the supposition that certain areas of the Arctic are deserts because they receive little precipitation.   In North America there are generally considered to be four deserts.

Elf Owl peering out of a Saguaro Cactus
 


 

The Great Basin Desert is the largest desert within the United States and is considered a "cold desert" due to its higher latitude and altitude in relation to the other deserts.  The Great Basin Desert spans across states of Nevada, southern Utah and Idaho, and the southeastern corner of Oregon.  The Great Basin is vegetatively dominated by various species of Sagebrush.  The animals that are characteristic of the Great Basin are the pygmy rabbit and sage grouse.

The other three deserts are considered "hot" deserts due to the extremely high daily temperatures.  The Chihuahuan Desert is the largest desert in North America although the majority of it is in Mexico and only a small portion reaches into the states of Western Texas and Eastern New Mexico.  The Chihuahuan Desert is dominated by agave in the hills and creosote bushes in the lowland area.  There is a great diversity of birds in the Chihuahuan Desert (some 400 species).

The Sonoran Desert has perhaps been most impacted by human development and urban growth.  The rapidly expanding cities of Palm Springs, Phoenix and Tucson, among others, are all located in the Sonoran Desert.  The saguaro cactus is characteristic of the Sonoran Desert and provides a home for the common Gila Woodpecker and the Elf Owl (pictured above).

Finally, the Mojave is the smallest and hottest North American Desert and is located in South Nevada, Eastern California and Southwest Utah. The hot temperatures have resulted in the Mojave having a high level of endemism as plants have evolved to the heat. 25% of all Mojave plants are endemics. The Mojave Desert is characterized by low-growing shrubs, cacti and yuccas.

This part of the web page gives basic information on the following ecological topics related to the North American deserts:


1) What is a desert?

2) Desert biodiversity

3) Plant and animal adaptations to life in the desert

4) Community Structure and Energy Flow within the desert
 
 

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