Carbon dioxide fluxes and vegetation structure in rewetted and pristine peatlands in Finland and Estonia

Vast areas of peatlands have been drained for forestry endangering their carbon sink function. Peatland rewetting aims at mitigating the situation through restoring the hydrology and vegetation of these areas. We compared the carbon dioxide (CO2) fluxes and phytomass on four pairs of rewetted and pristine peatland sites in Finland and Estonia, and described correlations between phytomass and CO2 fluxes. We measured the net ecosystem exchange of CO2 (NEE), respiration and photosynthesis over one growing season using manual chambers, and biomass of plant functional types (PFT) on rewetted sites and their pristine counterparts. Although pair-wise differences in the vegetation were small, pristine sites were on average stronger CO2 sinks than rewetted sites. Respiration was higher in hummocks while no differences were found in photosynthesis between hummocks and hollows. No clear relationship between the biomasses of PFTs and NEE was found. Generally, however, CO2 uptake decreased with increase in Sphagnum biomass.