Tuesday, 21 June 2016: 1:30 PM
Arches (Sheraton Salt Lake City Hotel)
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 (FCH4). Closed chambers were placed to capture the effects of plant structure and hydrological condition on NEE and FCH4. 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, FCH4 from restored peat communities was significantly lower. FCH4 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.
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