Temperature Sensitivity of Soil Greenhouse Gas Production in Three High‐Arctic Plant Community Types at Cape Bounty, Nunavut

Abstract

Enhanced precipitation and higher temperatures are expected in the Arctic as the result of future climatic warming. To understand future contributions of high‐arctic ecosystems to the climate system, we need to understand the feedbacks between climate and greenhouse gas production, and how they might vary between plant community types distributed along soil moisture gradients. We incubated intact soil cores in the laboratory to explore the temperature sensitivity of soil greenhouse gas (CO2, CH4, N2O) production across the three main plant community types of Cape Bounty, Nunavut: polar desert, mesic tundra and wet sedge. Two sets of cores (0‐10 cm mineral soil) were incubated in the laboratory at 4, 8, and 12°C for one month. We also measured plant community differences in soil thermal regimes for one year. Mean field temperatures were highest in the polar desert during the summer months, while temperatures in the mesic tundra were lowest during this time. In the winter, soil temperatures were lowest in the polar desert and highest in the wet sedge communities. Initial incubation results demonstrate Q10 values for CO2 production ranging from 2.18 in wet sedge to 8.67 in polar desert soils. We observed a Q10 of 4.03 for CH4 output in mesic tundra soils and a Q10 of 16.42 for N2O output in wet sedge soils. Our results suggest that use of single Q10 values to predict future greenhouse gas emissions from high‐arctic ecosystems would likely underestimate the contribution of these ecosystems to the global climate system in a warmer climate.