干旱区生态环境知识资源中心

A soil survey and rangeland resource inventory of the Santa Rita Experimental Range (SRER) was conducted by staff from the Tucson office of the Natural Resources Conservation Service (NRCS) during April and May of 1997. Thirty-two soils series and taxadjuncts were mapped on the SRER and delineated in 24 different mapping units. These soils all occur in an Aridic and Ustic moisture regime and span three precipitation zones, and all soils are in the thermic soil temperature regime. Soil series and mapping unit descriptions are provided. The rangeland inventory and the soil map correlate soils into ecological Sites and determine the present day status or condition of the sites by comparing present plant communities with potential plant communities as described by NRCS in their technical ecological site descriptions. Eighteen different ecological sites were identified in two Major Land Resource Areas (MLRA 40 and 41) on the SRER, and eight sites were mapped in the 10- to 13-inch precipitation zone of MLRA 40, the Upper Sonoran Desert. Eight sites were mapped in the 12- to 16-inch precipitation zone of MLRA 41, the Southern Arizona Grassland. Two ecological sites were mapped in the 16- to 20-inch precipitation zone of MLRA 41, the Mexican Oak Savanah.