Hydrologic and Vegetal Responses to Prescribed Burning and Herbicidal Treatment of Broom Snakeweed on Blue Grama Rangeland in New Mexico
Broom snakeweed (Gutierrezia sorothrae Shinners) control results in conversion from shrub-dominated land to grassland. Changes in the hydrologic cycle including reduced runoff and erosion can be realized. These changes are most often considered to be beneficial to onsite production and downstream uses. Broom snakeweed numbers significantly decreased from both burning and spraying with herbicide. However, the broom snakeweed was not eradicated, and numbers increased significantly the first year after treatment, especially on burned plots. Runoff volume was highest during a wet year following burning and lowest in a drought year following all treatments. Only one runoff event in 1996 on the burned plots was considered to be flooding. Sediment concentrations were highest during a drought on all plots, but most prominent after plots had been burned. Runoff and sediment yield increased immediately after burning but those effects were not long lasting. Elevated sediment concentration levels only persisted the first year after both burns (1994 and 1996). Total sediment yield is a function of runoff volume and sediment concentration. Total sediment yield was highest during a wet year following burning.