Effects of arctic ground squirrel abundance and distribution on carbon cycling and ecosystem dynamics
Increasing atmospheric greenhouse gases have caused global warming, resulting in considerable shifts in ecosystem function and structure, particularly in sensitive cold climates like the Arctic. As the Arctic continues to warm, the ground thaws and permafrost degrades, resulting in changes to shrub communities. These changes can cause northern tundra soils, which have twice as much below ground carbon (C) as atmospheric carbon, to shift from sinks to sources of C. The fate of this large C pool may be driven not only by climatic conditions, but also by ecosystem changes brought about by arctic animal populations. For example, grazing, burrowing, and defecating are expected to alter nutrients and soil decomposition, although this area of research has not been well explored. In this project I will quantify the effects of arctic ground squirrels, Urocitellus parryii, activity on soil respiration and other characteristics in interior Alaska. Ground squirrels create subterranean burrows that mix soil layers, increase aeration, alter soil moisture and temperature, and redistribute soil nutrients, all of which may impact microbial decomposition. I will compare habitat characteristics of areas with and without ground squirrels to measure differences in C inputs and decomposition between sites utilizing long-term incubation experiments. I will then compare thaw depth, soil respiration, and other habitat characteristics to estimate the effects of climate-induced shifts in ground squirrels distribution. I will use these results to examine impacts of ground squirrels on permafrost and soil C vulnerability under future warming scenarios of habitat shifts in the Arctic. Results will improve understanding of biological feedbacks on C mobilization and serve as a model for how to use wildlife activity to reduce uncertainty in global earth climate model projections of carbon flux. In addition, this research will provide information for natural resource planning to conserve arctic habitat by identifying the extent of risk for ground squirrels from climate change and highlighting conservation priorities.