Woody paludiculture as an after-use option for peat extraction fields

As peat extraction for energy has declined in Europe, extensive areas released from peat production require sustainable after-use. This land use change provides opportunities to mitigate climate change, halt biodiversity loss and support socially fair and rewarding solutions for communities. Here we present the first results from PaluWise project’s large 50 ha peat extraction area converted into demonstration site of paludiculture i.e., the productive land use of rewetted peatlands that preserves the peat soil and thereby reduces carbon dioxide (CO₂)  and nitrous oxide (N₂O) emissions and subsidence. The risks related to paludiculture include increased methane (CH₄) emissions, high nutrient losses and wetting the surrounding fields. We also reviewed evidence from climate change mitigation potential of common after-use options in agriculture and forestry for peat extraction areas in Northern Europe (ALFAwetlands project). Our data synthesis of annual greenhouse gas (GHG) fluxes revealed that boreal paludiculture showed a net loss of carbon (C) based on the net ecosystem C balance at least in the short term after rewetting cultivated peat soil. A woody crop, short rotation coppice of willow had more favourable greenhouse gas balance than forage and set-aside treatments during 4 years after transition. Options enhancing C input to the soil without rewetting may stop net annual C losses from a former peat extraction site just in one year: Afforestation on Scots pine with fertilization turned the site fast into a CO₂ sink, as measured by eddy covariance technique. We hypothesize that woody crops having low nutrient requirements and potential for added value products may offer a win-win after-use solution for rewetted peat extraction areas. We examined biomass and CO₂, CH₄ and N₂O fluxes from stands of downy birch and colonizing wild vegetation at our demonstration site. We found that the first Sphagnum mosses co-occur with downy birch, indicating favourable conditions for enhanced C sequestration. We expect that land use decisions may optimize many targets: climate, biodiversity, water quality, and economy simultaneously. Confounding factors, e.g. time perspective may affect landowner’s preferences. Long-term changes in peat carbon stock under any after-use option require further study.