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 [...]
Summary
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. The proposed work will investigate (1) impacts and trajectories of YKD tundra and permafrost following wildfire, (2) changes in surface water since circa 1950, and (3) future changes in landscape vulnerability to fire resulting from lake drainage and post-fire shifts in vegetation. Investigations will integrate time-series analysis of remote sensing datasets, with intensive field measurements along gradients of wildfire age and intensity. The products of this work will inform YKD resource managers and local stakeholders on the dynamics and trajectories of terrestrial and aquatic habitats following tundra wildfire. This work will leverage 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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Purpose
Funds under this award will be used to characterize and document the ecological changes and trajectories of warm permafrost landscapes of the Yukon-Kuskokwim Delta (‘YKD’) following two widespread landscape-change processes: tundra wildfire and lake drainage. This will be achieved through characterizing (a) the spatial and functional relationships between tundra wildfire, permafrost degradation, and lake drainage and (b) the influence on landscape vulnerability to future fire of lake drainage and post-fire changes to tundra vegetation. Central to activities addressing each of these goals will be (c) attention to disseminating the findings through written and oral means as well as making the resulting data products publically discoverable, accessible, and usable by others. Activities addressing each of these goals will be designed to address the information needs expressed by stakeholders (including biological resource managers, regional non-profits, and western Alaska communities) to better understand and project how these environmental change processes may influence important wildlife habitats and the region’s culturally vital, subsistence-based communities. This work will also fill important knowledge gaps regarding ecological disturbance, recovery, and permafrost dynamics in arctic tundra as current research efforts on these topics overwhelmingly focus on the colder tundra ecosystems of northern Alaska.
The abovementioned project goals will be achieved through specific research activities designed to meet the following objectives:
1. Collect, compile, analyze and synthesize ecological field measurements along gradients of wildfire age and severity in loess uplands of the YKD to determine post-fire trajectories and the biophysical factors that most influence landscape vulnerability or stability over multi-decadal timescales after a fire;
2. Compile, map and summarize ’permanent’ state-changes in aquatic-terrestrial habitat condition (i.e., lake drainage and terrestrial vegetation development) in burned and unburned loess uplands of the YKD (see Figure 1 of associated Statement of Work) for three observational periods beginning in 1948 to determine trends in surface water, with special reference to the role of waterbodies as fire breaks;
3. Compile, map, summarize, and compare seasonal water frequencies at 30 meter resolution for burned and unburned loess uplands of the YKD for bi-monthly periods (May–September) for circa 1999–2004 and 2011–2016 to evaluate how seasonal water dynamics have changed in recent decades;
4. Synthesize field and remote sensing datasets to characterize impacts of tundra wildfire and burn severity on vegetation recovery and permafrost and, as a result, on changes in surface water cover and water body dynamics;
5. Develop spatial models of landscape vulnerability to fire to characterize the influence that recent changes in surface water extent and tundra vegetation have had on future fire susceptibility and behavior;
6. Communicate resulting information and implications to regional stakeholders and the scientific community and make documented data products publicly discoverable and accessible.
