Runoff and erosion from a mosaic tobosagrass and burrograss community in the northern Chihuahuan Desert grassland

A mosaic plant community pattern was studied in the northern Chihuahuan Desert grassland region of sourthern New Mexico. The principal plant species of the mosaic were tobosagrass (Hilaria mutica(Buckl.) Benth.) and burrograss (Scleropogon brevifoliusPhil.). Water runoff, sediment concentration, incremental sediment, and plant and soil properties of both species aggregations were measured. The study site was a large aggregation of burrograss plants in a tobosagrass matrix. Water runoff was three times greater from the burrograss aggregation than from the tobosagrass aggregation both before and after the growing season. Sediment concentration and cumulative sediment loss were also greater from the burrograss than the tobosagrass, except under wet conditions in the early autumn when sediment concentrations were similar. Differences are attributed to greater cover, phytomass, and surface roughness in the tobosagrass aggregation.