Nonlinear thermal and moisture dynamics of high Arctic wetland polygons following permafrost disturbance

Abstract

Low-centre polygonal terrain developing within gentle sloping surfaces and lowlands in the high Arctic have a potential to retain snowmelt water in their bowl-shaped centre and as such are considered high latitude wetlands. Such wetlands in the continuous permafrost regions have an important ecological role in an otherwise generally arid region. In the valley of the glacier C-79 on Bylot Island (Nunavut, Canada), thermal erosion gullies are rapidly eroding the permafrost along ice wedges affecting the integrity of the polygons by breaching and collapsing the surrounding rims. While intact polygons were characterized by a relative homogeneity (topography, snow cover, maximum active layer thaw depth, ground moisture content, vegetation cover), eroded polygons had a non-linear response for the same elements following their perturbation. The heterogeneous nature of disturbed terrains impacts active layer thickness, ground ice aggradation in the upper portion of permafrost, soil moisture and vegetation dynamics, carbon storage and terrestrial green-house gas emissions.