Windblown dust, an environmental problem in many disturbed arid lands, has the potential to affect the physiological performance of desert shrubs. Physiological parameters of gas exchange for three species (Larrea tridentata, Hymenoclea salsola and A triplex canescens) were measured at a Mojave Desert site, at which both undisturbed and heavily dusted individual shrubs occurred.
The geographic distributions of organisms are not static, but dynamic. Over time the ranges of species shift, expand, and contract. The distributions of higher taxonomic groups such as genera, families, orders, and classes also change because their geographic ranges simply reflect the cumulative distributions of all the included species.