Greenhouse gas emissions and carbon sequestration potential in restored wetlands of the Canadian prairie pothole region

Abstract

North American prairie pothole wetlands are known to be important carbon stores. As a result there is interest in using wetland restoration and conservation programs to mitigate the effects of increasing greenhouse gas concentration in the atmosphere. However, the same conditions which cause these systems to accumulate organic carbon also produce the conditions under which methanogenesis can occur. As a result prairie pothole wetlands are potential hotspots for methane emissions. We examined change in soil organic carbon density as well as emissions of methane and nitrous oxide in newly restored, long-term restored, and reference wetlands across the Canadian prairies to determine the net GHG mitigation potential associated with wetland restoration. Our results indicate that methane emissions from seasonal, semi-permanent, and permanent prairie pothole wetlands are quite high while nitrous oxide emissions from these sites are fairly low. Increases in soil organic carbon between newly restored and long-term restored wetlands supports the conclusion that restored wetlands sequester organic carbon. Assuming a sequestration duration of 33 years and a return to historical SOC densities we estimate a mean annual sequestration rate for restored wetlands of 2.7 Mg C ha -1 year -1 or 9.9 Mg CO 2 eq. ha -1 year -1 . Even after accounting for increased CH 4 emissions associated with restoration our research indicates that wetland restoration would sequester approximately 3.25 Mg CO 2 eq. ha -1 year -1 . This research indicates that widescale restoration of seasonal, semi-permanent, and permanent wetlands in the Canadian prairies could help mitigate GHG emissions in the near term until a more viable long-term solution to increasing atmospheric concentrations of GHGs can be found.

Effects of land use on greenhouse gas fluxes and soil properties of wetland catchments in the Prairie Pothole Region of North America

“…As data have become available and coarse-scale models refined, a variety of studies have recognized the contribution of inland aquatic ecosystems (e.g., wetlands, peatlands, reservoirs) to the terrestrial carbon budget (Armentano and Menges, 1986;Gorham, 1991;Algesten et al, 2003;Bridgham et al, 2006Bridgham et al, , 2013Cole et al, 2007;Downing et al, 2008;Battin et al, 2009). Despite this, soil organic carbon (OC) and greenhouse gas (GHG) flux data characterizing wetland ecosystems are relatively sparse, often region-or classificationspecific, and associated with a high degree of uncertainty (Bridgham et al, 2006(Bridgham et al, , 2013Euliss et al, 2006;CCSP, 2007;Phillips and Beeri, 2008;Gleason et al, 2009;Badiou et al, 2011;Pennock et al, 2010;Finocchiaro et al, 2014).…”

“…1) covers approximately 821,859 km 2 and includes portions of five U.S. states and three Canadian provinces . The PPR is characterized by relatively small (often b5 ha), highly productive, mineral-soil wetlands dispersed throughout an agriculture-dominated landscape, and prairie pothole wetlands have potential to be important ecosystems in terms of the North American carbon balance (Bridgham et al, 2006;Euliss et al, 2006;Badiou et al, 2011). Studies from North America, including the PPR, have shown that minimally disturbed wetland catchments in native grasslands have relatively high soil OC levels, and soils of wetland catchments in an agricultural setting are capable of sequestering OC when restored to a similar natural state (Follett et al, 2001;Desjardins et al, 2005;Euliss et al, 2006;Gleason et al, 2008Gleason et al, , 2011Badiou et al, 2011).…”

“…The PPR is characterized by relatively small (often b5 ha), highly productive, mineral-soil wetlands dispersed throughout an agriculture-dominated landscape, and prairie pothole wetlands have potential to be important ecosystems in terms of the North American carbon balance (Bridgham et al, 2006;Euliss et al, 2006;Badiou et al, 2011). Studies from North America, including the PPR, have shown that minimally disturbed wetland catchments in native grasslands have relatively high soil OC levels, and soils of wetland catchments in an agricultural setting are capable of sequestering OC when restored to a similar natural state (Follett et al, 2001;Desjardins et al, 2005;Euliss et al, 2006;Gleason et al, 2008Gleason et al, , 2011Badiou et al, 2011). Consequently, natural resource organizations have promoted the benefits of conservation and restoration programs for moderating atmospheric GHG levels, as well as for providing numerous other ecosystem services (Gebhart et al, 1994;Litynski et al, 2006;Gleason et al, 2008;PCOR, 2008;Hansen, 2009;Brinson and Eckles, 2011;Gleason et al, 2011).…”

Quantifying climate change mitigation potential in the United States Great Plains wetlands for three greenhouse gas emission scenarios

“…Restoration or creation may be justified in estuarine wetlands where low methane emissions and enhanced sequestration lower net radiative forcing. In freshwater wetlands, outcomes are uncertain; restoration or creation may increase net radiative forcing with increased methane emissions (Bridgham et al 2006) or may have the potential to become net radiative sinks (Badiou et al 2011;Mitsch et al 2012).…”

“…The most notable programs include the U.S. Department of Agriculture Cropland Reserve Program (CRP) and Wetlands Reserve Program (WRP), the U.S. Fish and Wildlife Service Partners for the Fish and Wildlife Program, and land protection programs of Ducks Unlimited Inc., a non-governmental organization (Badiou et al 2011; USDA Natural Resources Conservation Service 2012). Particular to the Great Plains, DU has partnered in its easement program with the Plains Carbon Dioxide Reduction (PCO 2 R) Partnership, a collaboration of over 80 U.S. and Canada stakeholders to protect 10,643 ha of native grassland in the prairie pothole region under perpetual conservation easements that will be donated to the U.S.…”