Badiou P.,Institute for Wetland and Waterfowl Research |
McDougal R.,Manitoba Water Stewardship |
Pennock D.,University of Saskatchewan |
Clark B.,Environment Canada
Wetlands Ecology and Management | Year: 2011
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-1year-1 or 9.9 Mg CO2 eq. ha-1 year-1. Even after accounting for increased CH4 emissions associated with restoration our research indicates that wetland restoration would sequester approximately 3.25 Mg CO2 eq. ha-1year-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. © 2011 Springer Science+Business Media B.V.
Lumb C.E.,Manitoba Water Stewardship |
Franzin W.G.,University of Winnipeg |
Franzin W.G.,ET Water Inc |
Watkinson D.A.,University of Winnipeg
Journal of Great Lakes Research | Year: 2012
To better understand patterns of temporal and spatial variation of fish assemblages in offshore waters of Lake Winnipeg (Manitoba, Canada), midwater trawl tows were conducted near lakewide monitoring stations from 2002 to 2008. Trawl samples collected during spring, summer, and fall from the south basin, channel, and north basin were used to study effects of season and geographic region within the lake on species biomass estimates. Within each region, effect of trawl depth was explored. Greatest biomass in trawl catches was from the south basin. Of the most commonly caught species, across all seasons, greater biomass of emerald shiner (Notropis atherinoides) and cisco (Coregonus artedi) were found in the south basin and the channel, compared to the north basin. Biomass of the non-native rainbow smelt (Osmerus mordax), by contrast, was greater in the north basin compared to the south basin or the channel. Yellow perch (Perca flavescens) and introduced white bass (Morone chrysops) biomass varied temporally and spatially, with greatest biomass captured in the summer in the south basin. Estimated biomass of walleye (Sander vitreus) was greatest in the south basin, followed by the channel, and the north basin. Patterns in species distribution in Lake Winnipeg probably are influenced by a combination of factors, including species interactions and differing temperature and light conditions in the lake. As no lakewide pelagic trawl studies have been reported for this lake, these data form a baseline against which effects of changes, such as lake trophic state or establishment of non-native species, can be assessed. © 2011.
Tenuta M.,University of Manitoba |
Mkhabela M.,University of Manitoba |
Tremorin D.,University of Manitoba |
Coppi L.,University of Manitoba |
And 3 more authors.
Agriculture, Ecosystems and Environment | Year: 2010
Methane (CH4) and nitrous oxide (N2O) are potent greenhouse gases (GHG) that contribute to global warming. The objectives of this study were to evaluate the impact of (i) timing of hog slurry application and (ii) a soil moisture gradient on CH4 and N2O emission from a coarse-textured, poorly drained, grassland soil. A factorial design with three treatments and two replicates was utilized. Treatments were: (i) zero manure (Control), (ii) hog slurry applied as a split application in the fall and spring (Split), each at a rate of 72±8kgplantavailableNha-1, and (iii) a single application of hog slurry applied each spring at a rate of 148±20kgavailableNha-1 (Single). To achieve the second objective, two parallel transects each with 30 chambers placed 9m apart along a soil moisture gradient were utilized.Overall, CH4 and N2O emission from the manured treatments (Split and Single) were significantly higher (P<0.001) compared to the Control. Over the 3 years, average CH4 emission from the Control, Split and Single treatments were 2.1, 6.8 and 5.3gCha-1d-1, while N2O emission were 0.2, 2.2 and 4.9gNha-1d-1, respectively. Similarly, cumulative CH4 and N2O emission and the combined CO2 equivalents from the manured treatments were significantly higher (P≤0.01) than from the Control. Over the 3 years, mean cumulative CH4 emissions were 1.6, 3.5 and 2.7kgCha-1; cumulative N2O emission were 0.06, 0.4 and 0.8kgNha-1; while cumulative CO2 equivalent was 74, 279 and 459kgCO2ha-1 for Control, Split and Single treatments, respectively. Nitrous oxide contributed more to CO2-equivalent emission for the manure treatments with the ratio of N2O/CH4 CO2 equivalents being 0.7, 1.9 and 5 for the Control, Split and Single treatments, respectively. Soil water and NO3- content were the main determinants of both the type and quantity of GHG emitted, i.e., saturated soils with low NO3- produced highest CH4, while drier soils with high NO3- produced greatest N2O. Variation in height of the water table near the soil surface likely resulted in the high variability observed in CH4 emissions between replicates and years for individual treatments. These results suggest that: (i) split application of hog slurry to grassland has the potential to reduce emission of GHGs, in particular N2O, compared to applying all manure in spring, (ii) grassland soils with seasonally high water tables can be significant sources of CH4, and (iii) that CH4 emission increases with hog slurry application in this soil. © 2010 Elsevier B.V.
Pennock D.,University of Saskatchewan |
Yates T.,University of Saskatchewan |
Bedard-Haughn A.,University of Saskatchewan |
Phipps K.,University of Saskatchewan |
And 2 more authors.
Geoderma | Year: 2010
The characteristic feature of the Prairie Pothole Region is a complex assemblage of mineral soil wetlands embedded in the dominantly agricultural landscape. Soils in these wetlands are loci of high potential greenhouse gas (GHG) emissions, and our objective was to provide estimates of greenhouse gas emissions and the controls on these emissions for typical wetlands of this region. Three years (2004-06) of N2O and CH4 emissions were taken from a large semi-permanent pond and five ephemeral freshwater mineral soil wetlands at the St. Denis National Wildlife Area (SDNWA) near Saskatoon, Saskatchewan, Canada. Methane emissions from the semi-permanent pond were low (ranging from 0.04 to 3.33 g CH4 m- 2 yr-1) but emissions from landscape elements of the ephemeral ponds were substantially higher, with a maximum of 138.6 g CH4 m- 2 yr- 1 (or approximately 110 g CH4 m- 2 yr- 1 when corrected for mid-day sampling bias) from basin centers of these ponds in 2005. The average annual CH4 emissions averaged across the three elements of the ephemeral ponds at SDNWA were 54.8 g CH4 m- 2 yr- 1 in 2005 and 32.4 g CH4 m- 2 yr- 1 in 2006. Methane emissions were significantly inversely correlated to SO4 2 concentrations of the pond water, which are in turn related to the balance between surface runoff and groundwater inputs into the ponds. The semi-permanent pond consistently had low annual N2O emissions (< 0.4 kg N2O-N ha- 1 yr- 1). N2O emissions from landscape elements within the ephemeral ponds showed considerable inter-annual variation, ranging from 0.09 to 1.0 kg N2O-N ha- 1 yr- 1 for riparian grass elements, 0.3 to 0.6 kg N2O-N ha- 1 yr- 1 for riparian tree, and 1.0 to 2.1 kg N2O-N ha- 1 yr- 1 for basin centers. Major N2O emission events in the wetland elements were associated with periods of rapid drainage (i.e., from greater than 80% to less than 60% water-filled pore space) in the upper 15 cm of the soil. Within-year patterns of N2O and CH4 emissions from soils of the ephemeral ponds were closely related to a second hydrological control, the area and duration of inundation in the ponds but negligible differences were observed between riparian grass and tree elements. The strong interactions between hydrology, water chemistry, and emissions of N2O and CH4 demonstrate the need for a landscape-scale assessment of GHG processes in these landscapes. © 2009 Elsevier B.V. All rights reserved.