Jones Benjamin M, Grosse Guido, Arp Christopher D, Miller Eric, Liu Lin, Hayes Daniel J, Larsen Christopher F
Alaska Science Center, U.S. Geological Survey, Anchorage, AK 99508, USA.
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Potsdam, Germany.
Sci Rep. 2015 Oct 29;5:15865. doi: 10.1038/srep15865.
Fire-induced permafrost degradation is well documented in boreal forests, but the role of fires in initiating thermokarst development in Arctic tundra is less well understood. Here we show that Arctic tundra fires may induce widespread thaw subsidence of permafrost terrain in the first seven years following the disturbance. Quantitative analysis of airborne LiDAR data acquired two and seven years post-fire, detected permafrost thaw subsidence across 34% of the burned tundra area studied, compared to less than 1% in similar undisturbed, ice-rich tundra terrain units. The variability in thermokarst development appears to be influenced by the interaction of tundra fire burn severity and near-surface, ground-ice content. Subsidence was greatest in severely burned, ice-rich upland terrain (yedoma), accounting for ~50% of the detected subsidence, despite representing only 30% of the fire disturbed study area. Microtopography increased by 340% in this terrain unit as a result of ice wedge degradation. Increases in the frequency, magnitude, and severity of tundra fires will contribute to future thermokarst development and associated landscape change in Arctic tundra regions.
火灾导致的多年冻土退化在北方森林中有充分的记录，但火灾在北极苔原引发热喀斯特地貌发育中的作用却鲜为人知。在此我们表明，北极苔原火灾可能会在干扰后的头七年引发多年冻土区广泛的解冻沉降。对火灾后两年和七年获取的机载激光雷达数据进行定量分析发现，在所研究的34%的火烧苔原区域检测到了多年冻土解冻沉降，而在类似的未受干扰、富含冰的苔原地貌单元中这一比例不到1%。热喀斯特地貌发育的变异性似乎受苔原火灾燃烧严重程度与近地表地冰含量相互作用的影响。沉降在严重燃烧、富含冰的高地地貌（叶德马）中最为显著，尽管该地貌仅占火灾干扰研究区域的30%，却占检测到沉降的约50%。由于冰楔退化，该地貌单元的微地形增加了340%。苔原火灾发生频率、强度和严重程度的增加将导致北极苔原地区未来热喀斯特地貌发育及相关景观变化。
