abstract
- Peat excavation has altered carbon balance in large areas in the Northern Hemisphere and turned peatlands from CO2 sinks to CO2 sources. Peatland restoration aims at mitigating that situation by supporting CO2 uptake in these areas through raising the water table, in this way creating conditions for vegetation development and organic matter accumulation. We analysed the relationships between recovering vegetation and CO2 fluxes on three abandoned peat excavation sites in northern Estonia, which were rewetted and restored using the moss-layer-transfer technique three to ten years before the first measurements. Using chamber measurements, we determined whether these sites were CO2 sinks or sources during two growing seasons in 2015 (drier) and 2016 (wetter). In the drier growing season, all sites were CO2 sources from the peatland to the atmosphere (emissions from 1 to 77 g CO2 m−2), while in the wetter growing season, two sites were CO2 sinks (uptake from 13 to 210 g CO2 m−2). CO2 uptake was higher with higher plant and Eriophorum vaginatum cover, and biomass and cover of Sphagnum. The remotely sensed Normalized Difference Vegetation Index (NDVI) explained about 25% of variation in Net Ecosystem Exchange; CO2 uptake was higher in plots with higher NDVI values. This provides a potential avenue of investigation of developing remote sensing methods in assessing spatial pattern of CO2 fluxes in restored peatlands. In order to increase CO2 uptake in abandoned milled peatlands, it is essential to raise the water level and thus reduce peat oxidation and create conditions for the development of vegetation similar to pristine peatlands.