Sandy loam range sites dominate the La Copita and are uniformly distributed over the area.  They occur on nearly level to gently sloping (mostly  <3%) uplands.  Soils are deep with non-calcareous fine sandy loam surfaces and sandy clay loam subsoil.  The fine sandy loam surface ranges from 25 to 50 cm deep and average about 40 cm.

The potential natural vegetation of this region has been classified as Prosopis-b Acacia - Andropogon  - Setaria savanna.  The contemporary vegetation is subtropical thorn woodland.  The shrubs and small trees at the study site are characteristic of dry tropical and subtropical zones in Mexico, Central America, South America, Africa, Australia, India and Southeast Asia.  Current vegetation at the La Copita site, which has been grazed by domestic livestock since the late 1800s, consists of savanna parklands in sandy loam uplands that grade into closed-canopy woodlands in clay loam lowland drainages.  All wooded landscape elements are typically dominated by the leguminous tree Prosopis glandulosa in the overstory, with an understory mixture of evergreen, winter-deciduous, and summer-deciduous shrubs.