Feeling the heat(h): Can reindeer grazing stabilize soil organic matter in arctic and alpine tundra heath under climate warming?

Plants, microbes, and their interactions determine soil carbon (C) and nitrogen (N) cycling and stocks.

Climate warming is shifting plant and microbial communities in arctic and subarctic tundra, potentially altering ecosystem services and the livelihood of indigenous peoples.

Reindeer grazing may regulate these changes by preventing tree and shrub expansion and by influencing soil N availability and microbial functioning.This project aims to understand how reindeer grazing interacts with soil C and N cycling in tundra ecosystems, and how related ecosystem services are affected along a gradient of reindeer grazing intensity.

I will use a unique set of soils collected within and outside of long-term reindeer exclosures in 20 areas distributed across the Arctic.

Firstly, I will quantify the global importance of grazing intensity for soil C and N stocks in relation to vegetation, soil, microbial and climatic factors.

Secondly, I will characterize mechanisms underlying soil organic matter stability in tundra heath in a litter bag experiment.

Thirdly, I will study reindeer grazing effects on these mechanisms and on ecosystem services provided by soils, particularly soil C sequestration and regulation of greenhouse gas (GHG) emissions.This research should unravel the drivers of soil C and N cycling in grazed tundra and support decision makings on land-use to promote optimal grazer management that enhances soil C storage and reduces GHG emissions.