THE GEOMORPHIC AND ECOLOGICAL IMPACTS OF SOIL DEFLATION IN WEST GREENLAND

Soil deflation has had profound geomorphic and ecological impacts on the tundra landscape in the Kangerlussuaq region of West Greenland since the beginning of the Little Ice Age (~1300-1800 AD). Strong katabatic winds off the Greenland Ice Sheet (GrIS) have eroded soil down to the underlying glacial till or bedrock, creating distinct deflation patches that provide geomorphic evidence of past aeolian erosion. Ecologically, deflation patches are colonized by biological soil crusts (biocrusts), and while relatively unproductive, may provide unique habitat for some herbaceous species in an otherwise shrub-dominated ecosystem. Here we use remote sensing, lichenometry, soil isotope analysis, and vegetation surveys to understand past and present soil deflation dynamics.

Satellite remote sensing shows that deflated ground covers 22% of the terrestrial landscape surveyed. Soil deflation is more frequent closer to the GrIS, but becomes restricted to south-facing slopes farther away from the ice sheet margin. Using lichenometry, we estimate that over the past few hundred years, erosional fronts have moved across the landscape at an average rate of 2.5 cm yr^-1. The initiation of widespread soil deflation occurred during the Little Ice Age, with a heightened period of deflation-patch formation 800-230 years ago.

Biocrusts play an important role in nutrient cycling in the disturbed soils within deflation patches. Carbon, nitrogen, and δ¹⁵N of both lichen and soil samples provide evidence that the common lichen Stereocaulon alpinum actively fixes N₂, increasing the nutrient content of the underlying soil. Results from vegetation surveys within and outside of deflation patches will address the hypothesis that aeolian disturbance creates habitat for some herbaceous species, increasing the overall biodiversity of the terrestrial landscape.

Continued soil deflation in the Kangerlussuaq region has the potential to reduce ecosystem productivity and alter nutrient storage and cycling. With warming temperatures potentially outpacing increases in precipitation, Kangerlussuaq may become even more arid and susceptible to aeolian processes. Understanding the past and present geomorphic and ecological impacts of soil deflation will enable us to better predict future landscape trajectories in a changing climate.