Scientists use multiple methods to study fire history, in order to assess fire and climate relationships over a range of time scales. With tree-ring records, scientists can document the timing, severity and relative extensiveness of past fires, yet these records are limited in length. While these records have annual precision, they usually only cover the period from 1600 to the present. Evidence from lake sediments and alluvial fan deposits can provide millennial length records of fire history, which may be correlated with records of climate variability. These longer records of fire history allow scientists to evaluate fire and climate relationships throughout the Holocene period (from 10,000 years ago to present), which broadens our knowledge of the range of variability in fire regimes in southwestern forests.
This study focuses on a watershed burned by the Missionary Ridge Fire, which occurred in June 2002, in the San Juan Mountains of southwestern Colorado. Debris flows following the fire exposed a late-Holocene record of fire-related alluvial deposits in the walls of the incised channel. The exposed sediment record contains abundant charcoal within the deposits, providing an ideal opportunity to simultaneously evaluate fire-related sedimentation events and tree-ring records of fire history. The combination of these records yields information specifically about high-intensity fires.