Arctic Ground Squirrels as Ecosystem Engineers of Projected Tundra Shrub Encroachment

Holarctic warming temperatures are leading to an expansive and rapid greening of the Arctic. Yet herbivores may play a role in mediating shrub expansion. The Arctic ground squirrel is an omnivorous ecosystem engineer with Holarctic distribution, likely altering local plant communities and modifying edaphic properties in and around burrow systems. This thesis investigates the role of Arctic ground squirrels in shaping local vegetation near Toolik Field Station on the North Slope of Alaska. The approach is two-fold 1) quantifying foraging intensity in experimental foraging patches along a heath-graminoid-shrub tundra gradient and 2) examining the effects of squirrels on local shrub productivity via satellite and isotopic analyses.