Doctoral Dissertation Research: Examining the effects of small mammal structures and population changes on biogeochemical cycling in Arctic soils

Arctic tundra covers approximately 6% of the earth's land surface yet stores 25% of the world’s soil carbon. As the climate warms, this stored carbon is released to the atmosphere, further enhancing climate warming; properly modeling this feedback requires information on what controls the carbon cycle in Arctic soils. To date, most studies of the Arctic carbon cycle have neglected the possible roles played by Arctic animals in controlling soil biogeochemical cycles.

One important way that animals may affect these cycles is by building structures such as burrows, trails, latrines, and nests, each of which disturbs the soil and alters its biogeochemistry. In addition, because the effects of each species’ structures may be different, changes in the population distribution of animal species as the climate warms may lead to changes in Arctic soil cycles.

This project is combining these two factors – herbivore structures and community change – and examining how changes in either may affect carbon and nutrient cycling in Arctic ecosystems. This research is expanding our understanding of Arctic systems and can be used to improve predictions of how the Arctic may respond to environmental change. This project includes mentorships of K-12 and college-aged students, public outreach in arctic communities, and dissemination of science to the public.

Arctic herbivores, including small mammals, impact environmental processes that feedback on ecosystem function. While most research has focused on effects through herbivory, small mammals may also act as ecosystem engineers, modifying the biophysical environment around them. This project is examining how, and through what mechanisms, small mammal structures influence nutrient availability and microbial activity.

The researchers are also evaluating how differences in the functional roles and abundances of two competitor small mammal species (brown and collared lemmings) may alter soil biogeochemical cycling. Near Utqiaġvik, Alaska, researchers are sampling soils from beneath four types of small mammal structures (runways, winter nests, latrines, and burrows) from each species to examine their impacts on soil biogeochemical responses.

Using the proportional cover of each activity type on the landscape and their relative impacts on biogeochemical cycling, the data are then used to model the impacts of each species during the peak of their population cycle. This research is incorporating herbivores into the greater understanding of Arctic ecosystem function and is being used to improve a pre-existing ecosystem model to better predict carbon cycling in the Arctic.

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.