Research project PRIMETIME: Rhizosphere priming – Quantifying plant impacts on CO2 emissions from a warming Arctic

Arctic environments are warming at rates four-times the global average, resulting already now in wide-spread permafrost thaw that exposes previously frozen soil organic matter to microbial decomposition. At the same time, the Arctic also shows increasing plant growth and vegetation shifts, including the northward expansion of trees and large shrubs. These already-observed changes are expected to continue and intensify as temperature rises, resulting in increasing rates of CO2 uptake by plants and CO2 release by soil respiration. The balance between these two processes determines the future Arctic greenhouse gas balance. Plants influence soil processes near their roots through different mechanisms that can overall accelerate soil decomposition to CO2. PRIMETIME aims to understand how different tundra plants influence soil processes, and to quantify the total impact of expected vegetation changes on the CO2 balance of a warming Arctic. We combine Arctic field work, laboratory experiments in Stockholm and modelling to achieve this goal.