Wildfire Consumption and Interannual Impacts by Land Cover in Alaskan Boreal Forest

[摘要] Boreal forest fires are an important source of terrestrial carbon emissions, particularly during years of widespread wildfires. Most carbon emission models parameterize wildfire impacts and carbon flux to area burned by fires, therein making the assumption that fires consume a spatiotemporally homogeneous landscape composed of predominantly spruce forests and peat bogs with deep duff layers. While recent efforts have demonstrated that boreal forest fires heterogeneously consume aboveground vegetation, little remains known about the vegetation consumed during such fires. We examined climate, land cover, area burned, and fire impacts for large fires (2002 to 2009) across the Alaskan boreal landscape to address the validity of assumptions made by carbon emissions models for boreal fires. Results indicated that while coniferous vegetation, particularly spruce forests and spruce bogs, comprised the majority of the area burned in all years, shrub land cover comprised a substantial proportion (up to 35 %) of the area burned during warmer years of the study period. Interannual climate variability significantly influenced both the proportion of vegetation classes burned and the distribution of fire impacts across years and vegetation classes. We found that surface fuel modifications were sensitive to both the vegetation type that burned and climatic conditions. Area burned is an inadequate input metric for increasingly refined carbon emissions models, and consideration of heterogeneous fire impacts may improve carbon emissions modeling.

[学科分类] 生态、进化、行为和系统

[关键词] Alaska;boreal forest;carbon;climate;dNBR;NLCD