Successional Trends in a Ponderosa Pine/Bitterbrush Community Related to Grazing by Livestock, Wildlife, and to Fire

Abstract

A ponderosa pine/bitterbrush community in the South Fork of the Salmon River, Idaho, was determined to be a seral stage of a Douglasfir/snowberry habitat type. An exclosure, erected in 1959 to evaluate effects of browsing on bitterbrush by big game, contained more kinnikinnik and less Idaho fescue than did the outside area. Bitterbrush density was similar outside and inside the exclosure, but twig production was 12 times greater outside. A combination of periodic natural fire prior to effective suppression starting in the 1940's, and livestock grazing were probably initially responsible for the secondary successional vegetation on the site. Subsequently, utilization by big game of this vegetation has served to maintain the productivity of the bitterbrush and retard succession to climax.