A RECONSTRUCTION OF FOREST FIRES FROM JENNY LAKE, GRAND TETON NATIONAL PARK, WYOMING
We find that there was low charcoal accumulation and sparse fire activity prior to 11,500 cal yr BP when alpine and sub-alpine herb and shrub taxa such as Picea and Artemisia occupied the Jenny Lake catchment. An increase in fire activity that began at 11,000 cal yr BP was accompanied by establishment of fire tolerant conifers Pinus Contorta and Pseudotsuga. Charcoal deposition decreased between 8,500 to 7,000 cal yr BP and later increased and attained the highest levels by 4,000 cal yr BP. Fire activity gradually decreased after 4,000 cal yr BP as the modern forest of Picea, Abies, and Pinus was established. Interestingly, periods of enhanced charcoal deposition coincide with relatively high lake-levels and wetter conditions on millennial time scales. Therefore, we hypothesize that millennial variations in fire activity over the Holocene were controlled in part by terrestrial biomass abundance and fuel availability limitations. Together, this study provides insights into the relationship between vegetation, climate, and fire activity in an alpine region of the western US.