Evaluating post-fire cattle grazing strategies for sagebrush steppe rangelands

Authors: Clark, Pat; Hardegree, Stuart; Pierson Jr, Frederick

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/13/2007
Publication Date: 1/26/2008
Citation: Clark, P., Hardegree, S.P., and Pierson Jr, F.B. 2008. Evaluating post-fire cattle grazing strategies for sagebrush steppe rangelands. IN: Abstracts of teh 61st Annual Meeting of the Society for Range Management. January 26 - 31, 2008. Louisville, KY. Society for Range Management. Lukewood, CO. Abstract.

Interpretive Summary: Current agency guidelines and requirements for post-fire livestock grazing management lack a scientific basis. We evaluated how sagebrush steppe vegetation responds to the combined effects of fall prescribed fire and post-fire cattle grazing to determine if grazing rest following fire is necessary to maintain or improve the vigor and diversity of native plants on mountain big sagebrush rangelands and if so, how much rest was need. Preliminary results indicate rest is unnecessary if post-fire grazing is applied in late July-early August. These results have high potential impact for both, livestock producers and natural resource managers because agency post-fire rest requirements often force managers to tell producers to find alternative forage during the typical 2 growing seasons of rest.

Technical Abstract: Remnants of the sagebrush steppe ecosystem currently occupy about 10 million ha of the western U.S. Prescribed fire is used to manage the ecological condition of these rangelands. The interactive effects of prescribed fire and post-fire cattle grazing on sagebrush steppe vegetation, however, are not well understood. The efficacy of post-fire grazing management strategies requiring short-term grazing exclusion (e.g., 2-year rest) from burned areas has not been rigorously evaluated. Objectives of this study were to evaluate how sagebrush steppe vegetation responds to the combined effects of fall prescribed fire and post-fire cattle grazing; determine if grazing rest following fire is necessary to maintain or improve the vigor and diversity of native plants on mountain big sagebrush rangelands; and if post-fire rest is necessary, determine whether 1, 2, or 3 years of rest are adequate. Livestock exclosure sets were constructed on areas burned by the Breaks Fire, a prescribed burn applied during September 2002 within the Reynolds Creek Experimental Watershed (RCEW) in southwestern Idaho. These exclosure sets were located on sites representing low (3 sets) and moderate (3 sets) fire severity. Each exclosure set contained 4 adjoining exclosures (0.1 ha each) and 1 unfenced area (0.1 ha) nearby. Moderate cattle stocking (0.57 AUM/ha) was applied outside the exclosure sets during late July-early August 2003 and every year thereafter through 2007. At each exclosure set, sequential removal of exclosure fences allowed comparison of 4 post-fire grazing treatments including: 1) no rest (grazed 2003), 2) 1-year rest, 3) 2-year rest, and 4) 3-year rest. The remaining exclosure per set was retained as an ungrazed control. Plant species diversity, abundance, and basal cover were measured inside and outside each exclosure both before and after cattle grazing was applied each year. Preliminary analysis of these data indicated post-fire grazing rest was unnecessary to maintain diversity and vigor of native perennial plants on this study area if, grazing was applied in late July-early August. Additional analyses are required to confirm these early findings. A similar project was initiated on the RCEW during fall 2004 to evaluate post-fire grazing applied in the spring (May).