Charcoal Reflectance Reveals Early Holocene Boreal Deciduous Forests Burned at High Intensities

• DOI: 10.1371/journal.pone.0120835
• Publication Date: 2015-04-08T14:14:45Z
• Authors: Victoria A. Hudspith; Claire M. Belcher; Ryan Kelly; Feng Sheng Hu
• Keywords: Black spruce; Charcoal; Fire regime

Wildfire size, frequency, and severity are increasing in the Alaskan boreal forest response to climate warming. One of potential impacts this changing fire regime is alteration successional trajectories, from black spruce mixed stands dominated by aspen, a vegetation composition not experienced since early Holocene. Such changes may consequently alter intensity fires, influencing feedbacks ecosystem. Paleorecords document past wildfire-vegetation dynamics as such, imperative for our understanding how these ecosystems will respond future For first time, we have used reflectance measurements macroscopic charcoal particles (>180μm) an lake-sediment record estimate ancient charring temperatures (termed pyrolysis intensity). We demonstrate that increased markedly interval birch tundra 11 ky ago (mean 1.52%Ro; 485°C), expansion trees on landscape ∼10.5 ago, remaining high present 3.54%Ro; 640°C) irrespective stand composition. Despite differing flammabilities adaptations fire, highest intensities derive two intervals with distinct compositions. 1) aspen woodland at 10 cal. kyr BP, 2) establishment spruce, modern 4 BP. Based analysis, infer predicted deciduous into could lead intensity, but low potentially moderating climate-fire feedbacks.