Wednesday, November 15, 2006

Grazing and Military Vehicle Effects on Grassland Soils and Vegetation.

John A. Guretzky, The Samuel Roberts Noble Foundation, Inc., 2510 Sam Noble Parkway, Ardmore, OK 73401, Jeffrey S. Fehmi, Univ of Arizona, PO Box 210043, Tucson, AZ 85721, and Alan B. Anderson, US Army Construction Eng Rsch Lab, 2902 Newmark Dr, Champaign, IL 61821.

Vehicle training, a common disturbance of military lands, is part of a suite of land uses that also can include cattle grazing.  Yet, no studies have examined their interaction.  Our objective was to review the effects of vehicle training and grazing on grassland soils and vegetation and develop a state-and-transition model that incorporates grazing and training for Fort Hood, Texas.  Both grazing and training can cause soil compaction and vegetation disturbance, altering hydrology and increasing erosion.  While grazing effects largely depend on stocking rate, vehicle training causes greater disturbance as the number of vehicle passes increase, when wet soils are driven on, and when vehicles are turned sharply.  Grazing and training are expected to maintain grasslands in secondary succession, though eroded sites dominated by annuals also could develop under frequent training.  The state-and-transition model may guide decision making for military land managers faced with training and grazing effects.