Long-term, landscape patterns of past fire events in a montane ponderosa pine forest of central Colorado

Parameters of fire regimes, including fire frequency, spatial extent of bur ned areas, fire severity, and season of fire occurrence, influence vegetati on patterns over multiple scales. In this study, centuries-long patterns of fire events in a montane ponderosa pine - Douglas-fir forest landscape sur rounding Cheesman Lake in central Colorado were reconstructed from fire-sca rred trees and inferences from forest stand ages. We crossdated 153 fire-sc arred trees from an approximately 4000 ha study area that recorded 77 total fire years from 1197 to the present. Spatial extent of burned areas during fire years varied from the scale of single trees or small clusters of tree s to fires that burned across the entire landscape. Intervals between fire years varied from 1 to 29 years across the entire landscape to 3 to 58 year s in one stand, to over 100 years in other stands. Large portions of the la ndscape did not record any fire for a 128 year-long period from 1723 to 185 1. Fire severity varied from low-intensity surface fires to large-scale, st and-destroying fires, especially during the 1851 fire year but also possibl y during other years. Fires occurred throughout tree growing seasons and bo th before and after growing seasons. These results suggest that the fire re gime has varied considerably across the study area during the past several centuries. Since fires influence plant establishment and mortality on the l andscape, these results further suggest that vegetation patterns changed at multiple scales during this period. The fire history from Cheesman Lake do cuments a greater range in fire behavior in ponderosa pine forests than gen erally has been found in previous studies.