ANR Arctic-Peat

At high latitudes, permafrost, soil remaining below 0°C for 2 consecutive years, is rapidly evolving in relation to climate change. Permafrost soils store 50% of the global soil organic carbon stock. If this long-term sequestered organic carbon stock is released into the active carbon cycle, it could induce a positive feedback to climate change. Peatlands are disproportionally important ecosystems to study permafrost degradation impact, as they store more than one third of permafrost carbon and show the highest carbon density of the Arctic and Subarctic biomes. The potential feedback or mitigation of permafrost peatlands to climate change is controlled by the evolution of their carbon budgets following permafrost thaw: source or sink of carbon. Permafrost peatlands are diverse in the Arctic. The history of peatland initiation and the way permafrost formed can have implications on post thaw carbon cycling (initial carbon stocks, organic matter composition and lability…).

The objective of the Arctic-PEAT project is to investigate the evolution of carbon cycling in peatlands after permafrost degradation in different contexts. It will be carried out in 3 locations of discontinuous permafrost, where permafrost peatland degradation is currently occurring, with a focus on Siberia. It is organized in three tasks, interacting in a synergetic way:
-Task 1. Spatial and temporal evolution of carbon stocks and accumulation rates following permafrost peatland thaw
-Task 2. Evolution of DOM origin, lability and potential priming effect along thawing permafrost peatland chronosequences
-Task 3. Heterogeneity and drivers of carbon cycling in permafrost peatlands after permafrost thaw

Permafrost peatland degradation induces ground subsidence and the creation of new ecosystems. This allow to identify landscape features representing different time after thaw. These permafrost peatland degradation features are natural experimental devices to apply space for time strategy and define chronosequences. Along these chronosequences, pre and post thaw carbon stocks and accumulation rates will be determined. A remote sensing methodology will be developed, in order to spatially expand these results. Along the chronosequences, the project will focus on dissolved organic matter (DOM), a very dynamic component of carbon cycle. Using 14C, the origin of DOM, but also CO2, CH4 will be analysed in porewater samples. The lability and potential priming effect on permafrost peatlands organic matter of DOM will be determined during incubation experiments. The pre and post thaw carbon dynamics will be modelled using a carbon module developed for Arctic peatlands. This will be coupled available data to determine the main drivers of carbon cycling in Arctic and subarctic peatlands.

The Arctic-PEAT project will constitute a unique opportunity for the PI to develop her own research strategy and objectives. It will reinforce collaborations established with other laboratories, in France, Russia, Canada and the US. The Artic- Peat expertise (carbon cycling in peatlands, DOM characterization using stable, radiogenic isotopic and molecular composition, multi proxies for recent chronologies of peat cores, microbial ecology of Artic environments, remote sensing, and modelling of carbon cycling in terrestrial ecosystem) ensure the project’s success.

The Arctic PEAT project is expected to generate an innovative dataset on permafrost peatlands. It will contribute the international community efforts to evaluate the feedback of Arctic ecosystem degradation to climate change. In addition to results sharing with the scientific community suing classical way, the Artic-PEAT projects aims at developing a general public outreach with a series of short informative videos mixing videos on permafrost, peatlands, carbon cycle, and research at high latitudes.