CHARCOAL MORPHOLOGY AND RECONSTRUCTION OF FIRE HISTORY AND TAPHONOMIC PROCESSES IN THREE LAKES FROM BRITISH COLUMBIA, CANADA

ENACHE, M AND CUMMING, B.F.

Quantitative analysis and variations in morphological features of charcoal were undertaken in sediment cores from Prosser, Big, and Opatcho Lake (B.C., Canada). Seven morphological types of charcoal were defined by particle shape, structural features and progradation to unburned material. Charcoal type distributions were assessed as a proxy to recorded fire events, and to subsequent mechanisms of transportation-sedimentation to lake sediments. Non-parametric cross-correlation and regression analyses revealed poor relationships of most charcoal types with recorded fires in study lakes. Unlike the total charcoal, fragile-type charcoal fragments (Type M) displayed strong correlation to fire burn surfaces in Prosser Lake (r² = 0.65; p = 0.001) and weaker but significant (r² = 0.3; p = 0.01) correlation in Opatcho Lake. The particular fragility of Type-M prevents the preservation through surface flow, limiting its occurrence to levels related to fire events. Big Lake displayed overall very poor relationship to recorded fires. Its very large watershed and lake area likely contributed to increasing fragmentation of charcoal types through taphonomic processes and resulted in a paucity of charcoal types and destruction of Type-M charcoal. This technique was used to analyze charcoal types and reconstruct fire history over the past 400 years.