KoPf – Carbon in permafrost
Carbon transformation and greenhouse gas release from thawing permafrost in northeast Siberia under environmental and climate change
Permafrost regions play a pivotal role in our climate system. For millennia, permafrost-affected soils accumulated large amounts of carbon. However, warming-induced environmental changes and permafrost thaw in northeast Siberia leads to increased decomposition of the accumulated organic carbon and the release of the greenhouse gases carbon dioxide and methane from soils back to the atmosphere. At the same time, warmer temperatures may enable plants take up more carbon from the atmosphere. Thus, the feedback mechanisms between the carbon cycle and climate can enhance climate change or counteracts its effects. A better understanding of these processes and their influence on the carbon budget are therefore indispensable for understanding current and predicting future developments of the sensitive but economically relevant arctic permafrost regions. The German Federal Ministry of Education and Research (BMBF) therefore funds the multi-disciplinary joint research project “KoPf – Kohlenstoff im Permafrost”, which investigates the formation, turnover, and release of carbon from the underrepresented permafrost regions in Siberia.
The project runs for 3 years from 01 June 2017 until 31 May 2020.
Distribution of permafrost-affected soils in different permafrost zones of the northern hemisphere. Northeast Siberia is comparitivly sparsly represented (Hugelius et al., Biogeosciences 2018).
The goal of the joint research project is to examine carbon dynamics in northeast Siberian permafrost landscapes with field observations and mathematical models. Several German universities and research institutions are involved in modeling, studying microbial transformation processes, and determining carbon fluxes at the soil-plant-atmosphere interface. The vast Siberian permafrost region is not readily accessible. The long cooperation with Russian partners is therefore essential for the success of the project. A better understanding of the carbon transformation processes and the resulting greenhouse gas fluxes on the landscape-scale will improve the predictability of the future carbon balance of these ecosystems.
The central research questions are:
- How much of the in arctic soils accumulated organic carbon can be transformed to the greenhouse gases carbon dioxide and methane? How fast are these processes?
- How will the microbial community in permafrost-affected soils change and what are the effects on the long-term greenhouse gas formation?
- How much does the tundra contribute to global warming? When and under what circumstances can the Siberian tundra change from a carbon sink to a carbon source?
- What are the temporal and spatial variabilities of carbon transformation processes in Siberian permafrost landscapes?
- How will the global climate respond to environmental change in the Arctic?
To address these questions, KoPf is divided into four work packages:
The decomposition of eddy covariance-based CO2 fluxes into respiration and photosynthesis was not only applied for the overall footprint as commonly carried out, but instead for each of two vegetation classes. In this way, a differing seasonality in the net uptakes of bushes and sedges could be unveiled. Therefore, the flux decomposition proved to be a useful tool for gaining insights into both the phenological dynamic of individual vegetation classes, plus their respective functional flux to flux driver relationships with the aid of ecophysiologically interpretable parameters (Rößger et al., 2019, Biogeosciences Discuss).
20 Years Lena Expedition
German and Russian scientists, technicians, and students will meet in Saint Petersburg from October 17-19 to celebrate 20 years of successful cooperation in the Lena River Delta and Laptev Sea region. Future expeditions and joint research strategies will also be discussed. The meeting is organized by the Arctic and Antarctic Research Institute in Saint Petersburg, the Alfred Wegener Institute in Potsdam, the Melnikov Permafrost Institute in Yakutsk, and the Institute of Soil Science in Hamburg.
© T. Eckhardt: The "old" research station on Samoylov Island
Partitioning of CO2 net ecosystem exchange on the microsite scale in the Lena River Delta shows that both polygon centers and polygon rims were sinks for atmospheric CO2 during a growing season, but the sink strengths varied between the two microsites. Furthermore, it was shown that autotrophic and heterotrophic respiration fluxes react differently to changing hydrologic conditions (Eckhardt et al. Biogeoscience Discuss. 2018)
Greenhouse gas production in degrading ice-rich permafrost deposits in northeast Siberia depends on the climate conditions during deposition. Late Pleistocene Yedoma deposits generally produced more CO2 than Holocene deposits. Thus, organic matter decomposability needs to be interpreted against the paleo-environmental background. However, organic matter decomposability cannot be generalized solely based on the stratigraphic position (Walz et al. Biogeoscience 2018)