Influence of permafrost thaw on carbon cycling and vegetation communities in a northern discontinuous permafrost peatland complex at Scotty Creek, Northwest Territories

Globally, peatlands comprise an important proportion of the total belowground carbon pool. Peatlands in permafrost regions are usually considered as particularly important carbon sinks since their decomposition rate is slowed by the effects of low temperatures causing the ground to be frozen year-round. Discontinuous permafrost regions are particularly sensitive to contemporary climate changes causing rapid permafrost degradation with associated changes in land cover from forested permafrost peat plateaus to treeless, permafrost-free bogs. However, only little is known about the impact of these fundamental changes in land cover on peatland carbon cycling. Here we present an analysis based on peat cores collected in the late-winter of 2012 and summer 2013 in a discontinuous permafrost boreal forest-peatland complex located in the Northwest Territories, Canada. This site is known to show signs of rapid permafrost degradation over the last 40 years. Our results suggest that the hydrological changes that follow permafrost thaw might have a beneficial effect on carbon storage via changes in plant functional types. Pollen analyses performed on the same cores provide a comprehensive insight of the regional vegetation and fire dynamics over the Holocene period. Testate Amoebae analyses provide information in regards to local past hydrological conditions. Together, our results allow for a better understanding of the ways hydrology, vegetation and fire affect carbon cycling in a discontinuous permafrost peatland.