Sandhill Fen Constructed Watershed — Oil Sands Peatland Reclamation Trial (Alberta, Canada)

Alberta's Athabasca oil sands region holds one of the largest reserves of boreal peatland in the world, and open-pit mining has already required stripping it away. A 2012 peer-reviewed study by Rooney, Bayley and Schindler (University of Alberta, published in PNAS) found that currently approved mines would destroy 29,555 hectares of peatland - a 67% reduction across the mined landscape - releasing an estimated 11.4-47.3 million tonnes of stored carbon and permanently cutting the region's carbon-sequestration capacity by roughly 5,700-7,200 tonnes of carbon per year, since approved closure plans replace peatland with upland forest and tailings-pond lakes rather than restoring wetland.

In response to that evidence, Syncrude Canada, working with about two dozen university researchers (including teams from the University of Waterloo and University of Alberta), constructed the Sandhill Fen Watershed in 2012 on a former mine pit at its Mildred Lake lease: a 50-hectare in-pit watershed including a 15-hectare fen, built to test whether peat-forming wetland function can be re-established on mine spoil, with monitoring planned over 10-20 years.

Three years of eddy-covariance flux measurements, published in a peer-reviewed carbon-exchange study, found that only the saturated lowland zone of the constructed fen had become a net carbon sink (about 77 g C/m2 in year three), while the drier midland and upland zones remained net carbon sources despite similar plant productivity. A parallel vegetation survey recorded 124 plant species establishing after three years, 48% of them peat-forming species including 24 bryophytes. Sandhill Fen is presented here as an honest, mixed case: it demonstrates that partial peatland carbon function can be engineered on post-mining land, but the reclaimed area remains tiny next to the peatland destroyed, and most of the constructed watershed had not yet become a carbon sink after three years.

Read the full analysis: https://www.pnas.org/doi/10.1073/pnas.1117693108