Effect of honey mesquite on the water balance of Texas Rolling Plains rangeland

Abstract

Understanding hydrologic processes on rangelands is essential to determine if water yield will increase through shrub management. Nine nonweighable lysimeters were monitored for 3 years to determine the water balance as referenced by vegetation. Cover types studied were honey mesquite (Prosopis glandulosa) plus herbaceous vegetation (M+H), mesquite removed leaving only herbaceous vegetation (H), and mesquite and herbaceous vegetation removed (BG). Throughout the study, BG lysimeters had greater soil water content than the vegetated sites but, regardless of cover type, only 0.5-1.4% of precipitation drained below 3 m. Runoff and interrill erosion were closely associated with rainfall amount, peak short-term storm intensity, and amount of bare ground. Evapotranspiration accounted for over 95% of water leaving the vegetated sites. Herbaceous vegetation on the H lysimeters increased following mesquite removal. This increase offset any water yield benefit that may have accrued through shrub management. Results indicate that there is essentially no net change in deep drainage, evapotranspiration, or runoff on sites where the herbaceous component increases in response to shrub removal.