THE INTEGRATION OF TREE-RING AND ALLUVIAL FAN RECORDS OF FIRE HISTORY AT THE MISSIONARY RIDGE FIRE, DURANGE, COLORADO 

BIGIO, E. (1), SWETNAM, T.W. (1), BAISAN, C. (1) AND FRECHETTE, J. (2)

(1) Laboratory of Tree-Ring Research and Geosciences, University of Arizona; (2) Department of Earth and Environmental Sciences, University of New Mexico

The Missionary Ridge Fire burned through more than 70,000 acres of forest near Durango, Colorado, in June of 2002.  Several debris flow and flood events following the fire incised older alluvial fan sediments.  This study focuses on one watershed where 3,000 years of fire-related depositional events have been preserved in the alluvial fan sediments.  We use the recently exposed sediment record to compare the frequency and type of post-fire depositional events with tree-ring records of fire in the same drainage.  Tree-ring records indicate that fire spread as frequent low severity surface fires, with patches of crown fire occurring at longer intervals.  The aim is to assess how the geomorphic response to past fires correlates with the fire behavior determined by the tree-ring record over the past 300 years.  The comparison and integration of both records allows for a fuller understanding of the frequency, extent and severity of fires throughout the late Holocene.  This information provides a new context for interpreting the recent large and severe fires in the Southwest, as well as an opportunity to analyze the fire and climate relationship over millennial time scales.