Mojave National Preserve
Desert Ecology

World Deserts North American Deserts Protecting Deserts Home

Deserts stir the human imagination. They occupy nearly one-seventh of the world's land surface area, but carry only four percent of the human population. The immense spaces of the desert have inspired the explorer, and breed a heartiness in the people who live there. Today, especially with new means of transportation, more people than ever are discovering this unique resource. What is a Desert? Water, or more accurately the lack of water, is what defines a desert. In general terms deserts are dry places. The standard definition is an area that receives less than 10 inches of rain a year, and whose yearly evaporation rate exceeds 10 inches. To gain some perspective the driest desert in the world is the Atacama of South America. It’s average yearly rainfall is only 0.4 inches a year, although it’s common for several years to go by without rain. Tropical rainforests, however, receive an average of 80 inches a year, and some are deluged by as much as 200 inches. Many factors usually combine to produce a desert, and there are definite patterns as to where they occur. To learn more follow the buttons to your left.