Fire and Flood in a Canyon Woodland: The Effects of Floods and Debris Flows on the Past Fire Regime of Rhyolite Canyon, Chiricahua National Monument: Final Report

Abstract

Prior research in the Rhyolite Canyon area of Chiricahua National Monument (Swetnam et. al. 1989) revealed an anomalous 50 year fire-free interval between 1901 and 1851. Disruption of fire spread resulting from flooding and mass soil movement (debris flows) were postulated as potential causes of this long interval. The present study gathered additional evidence of fire and floods in the canyon system. Sampling of flood-scarred trees along stream channels successfully identified several flood events in Rhyolite canyon. Pulses of pine regeneration on debris flow deposits were associated with one of these events. However, no definitive linkage of flood events with changes in fire regime was established. Analysis of new fire scar samples combined with previous results indicated that the area affected by the change in fire regime includes the uplands between Jesse James Canyon and Rhyolite drainage. Source areas for fires prior to 1900 were not identified within the study area indicating that ignitions outside the present monument boundaries may have been important in the past. Evidence from the maximum ages of overstory conifers within Rhyolite Canyon suggests the occurrence of a major disturbance within this drainage prior to 1600.