Wetland conservation and restoration contribute to improved watershed functions through providing both water quantity benefits in terms of flood attenuation and water quality benefits such as retention of sediment and nutrients. However, it is important to quantify these environmental benefits for informed decision making. This study uses a ''hydrologic equivalent wetland'' concept in the Soil and Water Assessment Tool to examine the effects of various wetland restoration scenarios on stream flow and sediment at a watershed scale. The modeling system was applied to the 25,139 ha Broughton's Creek watershed in western Manitoba in Canada. As a representative prairie watershed, the Broughton's Creek watershed experienced historic wetland losses from 2,998 ha in 1968 to 2,379 ha in 2005. Modeling results showed that if wetlands in the Broughton's Creek watershed can be restored to the 1968 level, the peak discharge and average sediment loading can be reduced by 23.4 and 16.9%, respectively at the watershed outlet. Based on wetland and stream drainage areas estimated by the model and empirical nutrient export coefficients, the corresponding water quality benefits in terms of reductions in total phosphorus and nitrogen loadings were estimated at 23.4%. The modeling results are helpful for designing effective watershed restoration strategies in the Broughton's Creek watershed. The developed methodology can be also applied to other study areas for examining the environmental effects of wetland restoration scenarios.
Although the American black duck (Anas rubripes) has been designated a priority species in eastern North America, no systematic survey has been done in the agricultural lowlands of southern Québec, where the species is suspected to be relatively abundant and cohabits with the mallard (Anas platyrhynchos), often considered as a competing species. During the spring of 1998 and 1999, we surveyed breeding waterfowl in 343 4‐km2 plots distributed in the lowlands of the St. Lawrence Valley and Lac‐Saint‐Jean, Canada, and in agricultural areas of Abitibi‐Témiscamingue, Canada. American black duck densities were higher in dairy farm and forested landscapes (>39 indicated breeding pairs [IBPs]/100 km2) than in cropland landscapes (8 IBPs/100 km2). Mallard densities were similar across all landscape types (30–43 IBPs/100 km2). Habitat modeling using data derived from satellite imagery indicated that the presence of black ducks decreased with increasing areas of corn, ploughed fields, and deciduous forests, whereas it was favored in areas where topography was undulating with slopes of 10–15%. The same parameters had the opposite effect on mallard presence. The odds of black ducks being present were doubled where mallards were present, indicating that both species seem to be attracted to areas supporting adequate habitats, which contradicts the hypothesis of competition between these 2 species to explain for recent declines in the black duck population. Results of our habitat analyses support the hypothesis that habitat changes may be a primary factor leading to these declines. Dairy farm landscapes are of great importance for black ducks, and the conversion of this type of landscape toward a cropland landscape represents a threat to an important portion of the population of this species.
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