Temporal and Spatial Dynamics of Pre-Euro-American Fire

Our understanding of fire as a process in the complex landscapes of the southern Sierra Nevada prior to Euro-American settlement is poor relative to contemporary ecosystem processes. Information primarily consists of fire return intervals from a relatively small number of sites that does not adequately represent past dynamics of fire at a watershed scale. To obtain a better landscape perspective on fire history I used a network of sites located throughout the coniferous zone in the East Fork watershed of the Kaweah River drainage and reconstructed fire regime attributes such as area burned annually and frequency patterns relating to aspect, vegetation type, and elevation. Initial analysis suggested striking differences in the fire regime between north and south aspects with differences strongest at mid-elevations. Fire return intervals on north aspects were less than half that observed on south aspects. Estimates of annual area burned, derived from Thiesson polygons, also showed considerable variability. During certain years fire extended throughout much of the drainage and in a some cases adjacent watersheds also. Pattern and variability in annual area burned were strongly influenced by aspect and annual climate variation. They underscored the importance of climate and topography as controllers of spatial and temporal patterns of fire occurrence. The patterns also suggested strong linkages between fire and ecosystem dynamics with important implications for resource managers restoring fire in the southern Sierra