Restoration Method Effect on Temperate Peatland Carbon Dioxide and Methane Exchange

A goal of peatland restoration success is the return to natural carbon exchange rates; - net carbon dioxide (CO₂) sequestration and CH₄ gas release. Studies suggest that, in the early years post-restoration, the return to CH₄ flux rates similar to natural ecosystems appears delayed relative to net CO₂ uptake. Bois-des-Bel (BDB) is a 15-year post-restoration temperate bog located in eastern Quebec, a region of intensive peat extraction for horticulture. The restoration methods applied at the site, considered as best practice, include ditch blocking and infilling, reintroducing bog vegetation using the moss layer transfer technique and creating pools for biodiversity. An eddy covariance flux tower with open-path CO₂/H₂O and CH₄ analyzers was operated over two years, providing near-continuous measurements of net ecosystem CO₂ exchange (NEE) and ecosystem CH₄ flux (F_CH4). Closed chambers were placed to capture the effects of plant structure and hydrological condition on NEE and F_CH4. While plant communities at BDB showed greater uptake of CO₂ at high light (PPFD > 1000 µmol m^-2 s^-1) relative to a neighboring natural bog, F_CH4 from restored peat communities was significantly lower. F_CH4 from remnant ditches invaded by Typha latifolia consistently exceeded 200 mg CH₄ m^-2 day^-1 resulting in net ecosystem scale CH₄ release over the two growing seasons. BDB restored peat fields appear to show a delayed CH₄ flux return even after 15 years of recovery, likely due to the hydrological disconnect between the regenerated Sphagnum moss and cutover peat. When CH₄ flux hotspots (ditches and pools) were included, the annual ecosystem release was comparable to the natural site.