Emergence of beavers as ecosystem engineers in the New Arctic

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In recent decades, beavers have reportedly extended their range from the boreal forest into the arctic tundra, altering tundra streams and surrounding permafrost at local to regional scales. In lower latitudes, beaver damming can convert streams, backwaters, and lake outlets into connected ponds, which in turn can change the course of channels, temperature of streams, sediment loads, energy exchange, aquatic habitat diversity and nutrient cycling, and riparian vegetation. In the Arctic, effects of beavers may include enhanced thawing of permafrost, increased stream temperatures, and changes in seasonal ice in streams, as well as complex ecosystem responses. This study will 1) document movement of beavers from the forest into tundra regions, 2) understand how stream engineering wrought by beavers will change the arctic tundra landscape and streams, and 3) predict how beavers will expand into tundra regions and alter stream and adjacent ecosystems. Results will be of interest to local communities and resource managers, and the team of investigators will convene a scientist and stakeholder workshop in Fairbanks, Alaska to synthesize observations, compare results from studies in temperate ecosystems, and clarify impacts of beaver expansion unique to the tundra biome. The project also includes support for a postdoctoral scientist.In this project, the investigators will combine a novel remote sensing technique that detects beavers in satellite imagery, a field campaign that includes drone imaging, and beaver habitat modeling to understand how beaver expansion in Alaska is altering arctic stream and riparian ecosystems. They will use a semi-automated workflow to analyze Landsat imagery, high resolution satellite imagery, and historic aerial photography to identify the formation and disappearance of beaver ponds and map beaver dispersal into and impacts on arctic tundra regions of Alaska since 1950. To document the short- and long-term effects of beavers on the physical environment, the team will focus on field sites with chronosequences of beaver establishment, as well as those where beavers are absent. Landscape models will use attributes of current beaver habitat to identify other suitable habitat across the Alaskan arctic tundra and compare it to beaver habitat in temperate ecosystems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.