Short-term effects of fen peatland restoration through the moss layer transfer technique on the soil CO2 and CH4 efflux

摘要

Northern peatlands store approximately one third of the global soil carbon (C) stocks. Peat extraction for horticulture changes C fluxes turning these soils from sinks into large sources of C emitted to the atmosphere as greenhouse gases. Restoring hydrological conditions may not be enough for returning the C sink function of these ecosystems and a recovery of the original Sphagnum-dominated vegetation cover could be necessary. Here we tested the effects of the moss layer-transfer technique (MLTT) on the CO2 and CH4 fluxes three years after restoration of a minerotrophic cutover peatland in Quebec, Canada. Gas emissions were compared to nearby undisturbed plots, and plots with restored hydrology but without vegetation transfer. The main drivers for the observed emissions were inferred from the relationships with relevant environmental variables (vegetation cover, water table depth and temperature). Restoration of the extracted minerotrophic fen through the MLTT produced significant changes in the exchange of CO2, bringing these fluxes closer to undisturbed plots than plots with restored hydrology only, which remained C sources throughout the study. Methane emissions were generally low across all the restored plots and far from natural levels, with only a slight increase at the MLTT restored plots observed during the third year. Even though the MLTT failed to recover the original bryophyte-dominated vegetation, the observed changes in the emissions of CO2 and CH4 at the restored plots were strongly associated with changes in vegetation cover (i.e. increase in vascular plants), supporting the use of this restoration technique to recover the C sink function of harvested minerotrophic peatlands.