Subtropical Deserts

Santa Rita Mountains
Larry Jones, USDA Forest Service
The Coronado National Forest in southeastern Arizona encompasses portions of 12 mountain ranges called the Sky Island Archipelago, including the Santa Rita Mountains, shown here. GSD biologists conducted an assessment of vulnerability of species to climate change that included animal species that occur in the Santa Rita Mountains.

The continental deserts of Arizona and New Mexico are characterized by high air and soil temperatures and low annual precipitation (less than 8in/year), most of which falls during the Monsoon season from about mid July through September. These deserts contain xerophytic plants, most commonly spiny shrub, cacti or hard grass species and an abundance of annual species following rainfall events. Many of the endemic animal species have behavioral (nocturnal) or physiological adaptations for dealing with the hot climate. Parts of this region can be variously described as scrub, torn scrub, savanna and steppe grasslands. Sand dune habitat and sterile salt flats are also present. As with most deserts, soils tend to have little organic matter. High evaporation rates commonly leads to localized salinization, which produces a salt crust and leads to halophytic plant communities. Calcification is also common in well drained areas.

Three major deserts are defined in this area: The Sonoran, the Chihuahua and Mojave. Each of these major deserts have differing flora communities typically defined by the amount and timing of precipitation.

Management within these systems focuses around fire and climate change effects on southwestern deserts and grasslands, invasive species, and projects focused on the riparian areas within this region.

Projects