Fire And Vegetative Trends In The Northern Rockies

An approach for synthesizing the results of ecological research pertinent to land management is the analysis of the historic range of variability (HRV) for key ecosystem variables that are affected by management activities. This report provides an HRV analysis for the upland vegetation of the Bighorn National Forest in northcentral Wyoming. The variables include live tree density, dead tree (snag) density, canopy cover, abundance of coarse woody debris, species diversity, fire return intervals, the abundance of various diseases, the proportion of the landscape in different land cover types, and the degree of patchiness in the landscape. The variables were examined at the stand and landscape scales, using information available in the literature and USFS databases. High-elevation landscapes were considered separately from low-elevation landscapes. Much of the report pertains to forests dominated by lodge-pole pine, subalpine fir, and Engelmann spruce at high elevations, and by ponderosa pine, aspen, and Douglas-fir at lower elevations. We defined the HRV reference period for the BNF as approximately 1600 to 1890.