Thursday, 20 November 2003: 10:30 AM
Fire history of Whiskeytown National Recreation Area, Shasta County, California
The forests in the Klammath mountains are very diverse in both species composition and topography and it is unknown how past fires affected this ecosystem. Some have hypothesized that forest fires in this region were of relatively high severity and more infrequent than other pine dominated ecosystems. Dendrochronology was used to quantify past fire regimes in ponderosa pine/mixed conifer forests in Whiskeytown National Recreation Area (WNRA) in northern California. Climate reconstruction indices were also used to assist in the analysis of fire occurrence with climatic patterns. Fire was a common ecosystem process until approximately 1930. The composite median fire return intervals for all six sampling clusters ranged from 3 to 5 years (mean range: 4.6-7.8 years). At all composite scales, there was a significant difference in mean fire intervals between all six sampling clusters (0.25-2.0 ha in size). These clusters differ by aspect and species composition. There was a general trend of increasing mean fire interval with increasing elevation. Past fires on this site probably occurred late in the dry season (late Fall) as the majority of fire scars were found in the latewood and dormant wood (approximately 95%). For some of the clusters there was a significant difference in fire intervals between time periods (1700-1850 and 1851-2002). This time period break represents the approximate time when land use practices such as mining and logging began and probably influenced fire patterns on this site. Superposed epoch analysis was used to determine if large spatial scale fire years were significantly correlated to drought and high precipitation years. Significant drought years have been correlated to large-scale fires in the southern Sierra Nevada pine dominated ecosystems but this has not been reported in the southern Klamath mountains. Information from this study can assist in development of plans fire management and restoration plans for the WNRA.