Location: Northern Chihuahuan Desert 37 kilometers N of Las Cruces, New Mexico on the NMSU College Ranch and the USDA Jornada Exp. Range. Climate: Characterized by an abundance of sunshine, a wide range between day and night temperatures, low relative humidity, an evapotranspiration rate averaging 229 cm per year, and extremely variable precipitation. The average annual precipitation is 230 mm, with 52% occurring during the summer. Droughts are recurrent climatic phenomenon.
Vegetation: We are studying 5 vegetation communities that are dominant on the Jornada and are hypothesized to differ in their degree of desertification: 1) remnant black grama (Bouteloua eriopoda) grasslands; 2) playas or low-lying areas with heavy soils ( which are periodically flooded) and dominated by tobosa (Hilaria mutica) and burrograss (Scleropogon brevifolius); 3) tarbush stands (Flourencia cernua); 4) mesquite dunes (Prosopis glandulosa); 5) creosotebush-dominated bajadas (Larrea tridentata). For each community type, three permanent plots representing a range of primary productivity have been established to examine patterns of NPP, soil moisture, plant nutrients as a function of climatic variation.