Wildfire combustion and carbon stocks in the southern Canadian boreal forest: Implications for a warming world.

Autor: Dieleman CM; Department of Integrative Biology, University of Guelph, Guelph, ON, Canada., Rogers BM; Woods Hole Research Center, Falmouth, MA, USA., Potter S; Woods Hole Research Center, Falmouth, MA, USA., Veraverbeke S; Faculty of Science, Earth and Climate, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands., Johnstone JF; Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada.; Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA., Laflamme J; Department of Integrative Biology, University of Guelph, Guelph, ON, Canada.; Woods Hole Research Center, Falmouth, MA, USA., Solvik K; Woods Hole Research Center, Falmouth, MA, USA., Walker XJ; Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA., Mack MC; Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA., Turetsky MR; Department of Integrative Biology, University of Guelph, Guelph, ON, Canada.
Jazyk: angličtina
Zdroj: Global change biology [Glob Chang Biol] 2020 Nov; Vol. 26 (11), pp. 6062-6079. Date of Electronic Publication: 2020 Jun 12.
DOI: 10.1111/gcb.15158
Abstrakt: Boreal wildfires are increasing in intensity, extent, and frequency, potentially intensifying carbon emissions and transitioning the region from a globally significant carbon sink to a source. The productive southern boreal forests of central Canada already experience relatively high frequencies of fire, and as such may serve as an analog of future carbon dynamics for more northern forests. Fire-carbon dynamics in southern boreal systems are relatively understudied, with limited investigation into the drivers of pre-fire carbon stocks or subsequent combustion. As part of NASA's Arctic-Boreal Vulnerability Experiment, we sampled 79 stands (47 burned, 32 unburned) throughout central Saskatchewan to characterize above- and belowground carbon stocks and combustion rates in relation to historical land use, vegetation characteristics, and geophysical attributes. We found southern boreal forests emitted an average of 3.3 ± 1.1 kg C/m 2 from field sites. The emissions from southern boreal stands varied as a function of stand age, fire weather conditions, ecozone, and soil moisture class. Sites affected by historical timber harvesting had greater combustion rates due to faster carbon stock recovery rates than sites recovering from wildfire events, indicating that different boreal forest land use practices can generate divergent carbon legacy effects. We estimate the 2015 fire season in Saskatchewan emitted a total of 36.3 ± 15.0 Tg C, emphasizing the importance of southern boreal fires for regional carbon budgets. Using the southern boreal as an analog, the northern boreal may undergo fundamental shifts in forest structure and carbon dynamics, becoming dominated by stands <70 years old that hold 2-7 kg C/m 2 less than current mature northern boreal stands. Our latitudinal approach reinforces previous studies showing that northern boreal stands are at a high risk of holding less carbon under changing disturbance conditions.
(© 2020 John Wiley & Sons Ltd.)
Databáze: MEDLINE
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