Painted by prehistoric residents, their exact age and meaning are unknown. Protecting Deserts introduces the Southwest's population growth and the impact on deserts. National Park Service. Cheatgrass and Wildfires in the Intermountain West describes the influence of this invasive plant on the fire ecology of the Intermountain Desert. From California Exotic Pest Plant Council.
Desertification describes the degradation of semiarid grasslands at the desert's edge.
United States Geological Survey. Study Questions 1. Describe the thermal budget of a human. This may be answered in the form of a diagram. Describe the physiological mechanisms humans have to prevent hyperthermia.