Carbon flux on barren-ground caribou migratory trails in the tundra

The hundreds of thousands of barren ground caribou (Rangifer tarandus) that migrate through low-Arctic tundra affect the landscape, by trampling and grazing, on lichens, herbaceous plants, and deciduous shrubs along the migratory pathways they use biannually. The impacts by caribou have implications for carbon uptake and release in the vegetation and soils of these migratory trails. The objective of this research is to quantify the impacts of caribou trampling on the three main habitats they use during spring and fall migration. Ecosystem respiration, plant biomass, and soil temperature and water content on migratory trails were measured relative to adjacent control areas in dry esker, mesic birch-hummock, and wet sedge meadow habitats. Preliminary results show that respiration was higher on migratory trails than off, and mesic sites had higher respiration than dry and wet sites.  Dry and mesic sites were significantly warmer than wet sites. Trampling on trails caused the soils on the trails to be wetter than off the trails, and the dry and mesic sites were drier than the wet sites.  These results indicate that caribou affect habitat by reducing vegetation on trails and altering soil characteristics, but the magnitude of change varies by habitat type.