An Examination of Wetland Conversion and Resulting Effects on Landscape Connectivity in Southern Ontario Municipalities.

Abstract

The few wetlands that remain in the human-dominated landscape of southern Ontario are affected by degradation and conversion to other land use and land cover types. Conversion has negative impacts on wetland-provisioned ecosystem services, such as aquatic species habitat, water filtration and flood prevention. Impacts on the latter services are especially concerning, given the increase of flood events that likely will be exacerbated by a changing climate. Stormwater management (SWM) ponds are constructed to control urban runoff, but do not have the same form and function as wetlands. This study examined recent (2002-2011) trends and drivers of wetland conversion (i.e. wetland loss and SWM pond gain) in seven southern Ontario municipalities. Following this, a Markov model was constructed to project future conversion given specific land use and land cover types. Network analytical approaches were then used to investigate effects of conversion on landscape connectivity. Results show that most wetlands lost were smaller than 2 hectares. While the total area of SWM ponds gained was greater than that of wetlands lost, the size of the average SWM pond gained was less than the size of the average wetland lost. Wetland conversion is projected to continue under all examined land use and land cover types, with losses particularly high in extractive and urban land uses. Overall, wetland conversion corresponded with decreased connectivity. Wetlands appeared to be more connected over the landscape compared to SWM ponds. However, SWM ponds likely acted as stepping-stones between wetlands and compensated somewhat for connectivity losses. The results provide further evidence for the need to halt wetland losses, especially for small wetlands, while showing the potential for connectivity improvements by SWM ponds. By conserving wetlands, policy makers can help to protect human life and property that rely on the critical ecosystem services provided by wetlands.