Thermokarst-pond plant community characteristics and effects on ice-wedge degradation in the Prudhoe Bay region, Alaska (2021-2022)

This thesis was prepared by Emily Watson-Cook as part of a Master of Science degree in Biological Sciences at the University of Alaska Fairbanks.
Ice-wedge thermokarst ponds are forming in many areas of the Arctic as a result of climate warming and infrastructure development. Previous research suggests that the development of aquatic vegetation within these ponds may play a protective role in the process of ice-wedge degradation by reducing pond-bottom temperatures and seasonal thaw depths. To evaluate the potential insulative role of aquatic vegetation on sediment temperatures and thaw, plant communities were characterized in 39 vegetation plots located in 29 thermokarst ponds of varying sizes and ages at two adjacent research sites in the Prudhoe Bay region of Alaska.
Analyses grouped vegetation plots into three broad types: moss-dominated, forb-dominated, and sparsely vegetated. Vegetation cover, moss thickness, and organic layer thickness were all negatively correlated with thaw depth. While sediment temperature was only monitored over a five-week period from mid-July to late-August, vegetation cover was found to be negatively correlated with temperature. Most notably, results indicate that aquatic plant communities with high moss biomass have a high capacity for insulation that potentially reduces permafrost thaw and ice-wedge degradation, leading to ice-wedge stabilization. The study provides descriptions of relatively understudied aquatic plant communities that play an important role in permafrost landscape change.