Comparison of Charcoal and Tree-Ring Records of Recent Fires in The Northern Rocky Mountains, Kalispell, MT, USA

In the Northern Rocky Mountains, climate and vegetation histories have been developed using charcoal and pollen deposits in the sediment of lakes to determine the effect of changing climate on species distribution and disturbance regimes through time. However, few studies have been done on the spatial and temporal accuracy of these charcoal and pollen sediment strata analyses. In this study we created a dendrochronological fire history using fire-scarred trees in the watershed of Foy Lake in the Flathead Valley, MT, to determine the synchronicity between two fire proxies: the watershed’s tree fire scar chronology and the dated charcoal in the sediment lake strata. I also compared Foy Lake’s charcoal profile to six other tree-ring based fire histories that were developed within 120 kilometers of Foy Lake to evaluate the registry of regional fires in Foy Lake’s charcoal sediment fire history. I found that of the 31 fire years shared among tree-ring fire history sites in the region, 12 registered as significant charcoal peaks in Foy Lake. Of those 12 fire years, eight of them took place in the Foy Lake watershed. Also, of the 19 filtered fire years with two or more scars found in the Foy Lake watershed, only seven corresponded with charcoal peaks in the lake with little or no lag time, but fire years with only one scar found matched most and left few charcoal peaks unaccounted for. This study will enable paleoecologists to better interpret charcoal sediment results, assured that local charcoal deposition is likely the primary contributor to a lake’s sediment charcoal record. Large fire years that did not occur in the local watershed may not register in the lake strata, and climate inferences from charcoal particle presence in a single lake may be skewed