Ecosystem Dynamics and Fate of Warm Permafrost after Tundra Wildfire and Lake Drainage on the Yukon-Kuskokwim Delta

Ecosystem Dynamics and Fate of Warm Permafrost after Tundra Wildfire and Lake Drainage on the Yukon-Kuskokwim Delta

The Yukon-Kuskokwim Delta (YKD) encompasses the southernmost, warmest parts of the arctic tundra biome and is renowned for its high biological productivity and large subsistence-based human population. Ice-rich permafrost currently is widespread and strongly influences terrestrial and aquatic habitats, including local topography, vegetation, soil hydrology, and the water balance of lakes. Ground temperatures are near the freezing point, however, and recent projections indicate that the YKD is poised for widespread loss of permafrost by the end of this century. This has implications for the region’s extensive and heretofore stable terrestrial and aquatic habitats. Tundra wildfire is a common ecological “pulse” disturbance and a potent permafrost stressor on the YKD. The summer of 2015 yielded an exceptional number of wildfires on the YKD, affecting nearly 300,000 acres of mostly permafrost-affected uplands where vegetation and soils are conducive to fire. This fire activity was preceded by widespread loss of upland lakes and ponds in recent decades. Aquatic-terrestrial state transitions fundamentally alter wildlife habitats, and have secondary impacts associated with increased landscape vulnerability to fire. ABR performed field surveys and analyzed remote sensing datasets to (1) characterize impacts and trajectories of YKD tundra and permafrost following wildfire, (2) quantify changes in surface water since circa 1950, and (3) project future changes in landscape vulnerability to fire resulting from lake drainage and post-fire shifts in vegetation. The products of this work informed YKD resource managers and local stakeholders on the dynamics and trajectories of terrestrial and aquatic habitats following tundra wildfire. This work leveraged logistical and scientific synergies on the YKD with ongoing research funded by NASA’s Arctic Boreal Vulnerability Experiment and USFWS bird monitoring efforts.

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