ИСТИНА

Peatlands are long-term repositories for enormous amounts of organic carbon (globally ~550 Gt) which accumulated over centuries to millenia due to water-saturated soil conditions. The huge peatland carbon pool is closely coupled with the atmospheric carbon budget by the exchange of greenhouse gases CO2 und CH4. As long as peatlands are stable sinks for atmospheric CO2, they can be considered to have a net cooling effect on the atmosphere over long time scales. However, peatlands and their ecosystem functions and services are severely threatened by climate and land use changes. Most of the pristine peatlands are situated in the arctic and boreal zones where they face the most pronounced climate changes on Earth due to the polar amplification. Due to the high diversity of pristine peatlands and the complex interlinked processes that control the hydrology and biogeochemistry of pristine peatlands, the effects of climate changes are still highly uncertain and need to be investigated more comprehensively in the future. On the other hand, it is evident that the peatlands degraded by intensive land use, which are concentrated in the temperate and tropical zones, have already lost their carbon sink and climate cooling function, and here the main question must be how to optimally restore peatland functioning. Here, we present our research on the carbon dynamics of Eurasian peatlands under climate and land use changes. About half of the global peatland area is situated in Eurasia, 0.5 x 106 km2 in Europe and 1.5 x 106 km2 in Asia. A major part of the Eurasian peatlands, 1.4 106 km2, are situated in the Russian Federation. We studied the carbon pools and greenhouse gas fluxes in arctic and boreal pristine peatlands as well as in boreal and temperate degraded and restored peatlands. The pristine peatlands of Eurasia appear to be still substantial carbon sinks. The available data suggest that the CO2 uptake as well as the CH4 emission from pristine Eurasian peatlands increases from North (tundra) to South (middle-southern taiga) and from West (Ireland) to East (Siberia) on large spatial scales. However, due to the scarcity of measurement data along the West-East transect, it is not clear if this gradient can be attributed (only) to climatic influences. A further important research need would be the investigation of “wet forests” with shallow peat layers. A better representation of these widespread transition ecosystems has the potential to significantly improve current estimates of continental greenhouse gas balances. The strongest climate change impacts on Eurasian pristine peatlands are currently observed in the permafrost-affected palsa mire landscapes of North-West Siberia, where the intensification of themokarst processes is leading to pronounced hydrology and carbon balance alterations. The degraded and intensively used peatlands of Europe represent strong anthropogenic sources of CO2 which are relevant on national and global levels. Restoration of these peatlands offers a high potential for climate change mitigation by reducing greenhouse gas emissions. However, it has been shown that sub-optimal re-wetting measures can lead to extremely high CH4 emissions which can offset the beneficial effects by the reductions in CO2 emissions. A thorough scientific understanding of the biogeochemical processes happening during re-wetting is needed to allow for successful restoration of peatland functioning.