Post Glacial Fire Frequency and its Relation to Longterm Vegetational and Climatic Changes in Yellowstone Park

Abstract

The paleoecologic record provides unique insights into the response of communities to environmental perturbations of different duration and intensity. Climate is a primary agent of environmental change and its long-term effect on the vegetation of the Yellowstone/Grand Teton region is revealed in a regional network of pollen records. Fire frequency is controlled by climate, and as climate changes, so too does the importance of fire in shaping and maintaining spatial patterns of vegetation. The prehistoric record of Yellowstone's Northern Range, for example, shows the response of vegetation to the absence of major fires in the last 150 years (Whitlock et al. 1991; Engstrom et al. in press). In longer records spanning the last 13,000 years, periods of frequent fires are suggested by sediments containing high percentages of lodgepole pine (Pinus contorta) and Douglas-fir (Pseudotsuga menziesii) and high amounts of charcoal (Barnosky et al. 1987; Whitlock in prep.).