• Van Dyke, Fred
  Department of Biology Wheaton College
  
• Darragh, Jeffrey A.
  Department of Biology Wheaton College
  

To better understand the role of herbivory and fire as potential disturbance processes in sagebrush communities, we examined responses of a grazing ungulate, elk (Cervus elaphus), following prescribed burning of sagebrush (Artemlsia tridentata ssp. vaseyana) in south-central Montana (USA.) with concurrent monitoring of changes in plant production, nutritional quality, and community diversity from 1989-1999. Burning transformed low-diversity, sagebrush-dominated communities into high-diversity, graminoid-forb communities that persisted for '10 years without significant reestablishment of sagebrush. Elk increased use of burned sites one year after burning, but elk use returned to pre-burn levels over the next two lo nine years. Forage biomass and nutritional quality declined after initial increases that coincided with increased elk use. increases in elk use appeared to be influenced by increases in combined graminoid and forb production and changes in structural vegetation characteristics that permitted greater foraging efficiency. Declines in use were associated with loss of nutritional enhancement and declines in combined graminoid and forb production. Managers may observe only short-term responses from grazing ungulates to prescribed fire in sagebrush communities, but can expect longer-term increases in plant diversity and establishment of qraminoid-forb communities.