This study in Colorado examined the effects of variation in population density of Rocky Mountain elk (Cervus elaphus canadensis) on the availability and use of forage resources by cattle in a randomized complete block experiment conducted in sagebrush grassland during four years. The objective of the work reported in this study was to test the hypothesis that winter grazing by elk does not influence forage resources for cattle during the spring. The hypothesis was rejected: elk grazing exerted enhancing as well as harmful effects on forage available to cattle. In particular, elk grazing enhanced the nutritional quality of forage available to cattle by increasing live to dead ratios of standing crops. However, these improvements were not sufficient to overcome the harmful effects of elk grazing on forage availability. Reductions in supplies of forage available to cattle appeared to cause declines in their daily intake of dry matter and digestible energy. In the system studied, harmful impacts of elk grazing on cattle dry matter and energy intake began to occur when herbaceous forage available to cattle after elk grazing fell below about 45 g/m2 of dry matter. When forage production is low and cattle density is high, competition is a much stronger force than facilitation.
Citations and enhanced abstracts for journals articles and documents focused on rangeland ecology and management. RSIS is a collaboration between Montana State University, University of Idaho, and University of Wyoming.