Post-disturbance ice-wedge degradation in Alaskan tundra fire scars using space-for-time substitution remote sensing

Abstract The severity and frequency of tundra fires in Arctic permafrost landscapes is expected to increase with ongoing climate change. By burning the insulating organic layer of soils, tundra fires impact the soil thermal regime for underlying permafrost and can accelerate thaw in the years following the burn. In this paper, we address the scarcity of long-term studies on post-fire permafrost degradation in ice-wedge landscapes by using a space-for-time substitution analysis spanning a chronosequence (pseudo-time series) of up to 67 years of remote sensing data from Alaskan tundra fire scars. We use computer vision and graph analysis on high-resolution digital elevation models derived from airborne lidar of fire-affected areas in Western Alaska to investigate the effects of tundra fires on the post-fire development of microtopography and surface hydrology in polygonal ice-wedge landscapes. Our analysis indicates a modest overall trend toward recovery of polygonal surface structure over timescales of 70+ years, though considerable variability among fire scars highlights that post-fire trajectories are not uniform.