Wildfire Dynamics in Mid-Siberian Larch Dominated Forests

Abstract

The long-term wildfire dynamics, including fire return interval (FRI), in the zone of larch dominance and the “larch-mixed taiga” ecotone were examined. A wildfire chronology encompassing the fifteenth through the twentieth centuries was developed by analyzing tree stem fire scars. Average FRI determined from stem fire scar dating was 82 ± 7 years in the zone of larch dominance. FRI was found to be dependent on site topography. FRI on north-east facing slopes in the zone of larch dominance was 86 ± 11 years. FRI was significantly less on south–west facing slopes at 61 ± 8 years and flat terrain at 68 ± 14 years. For bogs FRI was found to be much longer at 139 ± 17 years. The FRI decreased from 101 years in the nineteenth century to 65 years in the twentieth century. Connection of this phenomenon with natural and anthropogenic factors was analyzed. The relationship of extreme fire events with summer air temperature deviations at the regional and sub-continental levels was presented. Wildfire impact on permafrost thawing depth was analyzed. The implications of the observed trends on the larch community are discussed.