Effective land use policy to protect wetlands as nature-based solutions: the Ontario’s Greenbelt study case

Wetlands can serve as nature-based solutions for flood control, carbon sequestration, and biodiversity support but have faced increasing pressure from urban growth. This has led to the development of land protection policies such as the Greenbelt, which was designed to protect wetlands and prime farmland from the expansion of the Greater Toronto Area in Southern Ontario, Canada. This region is home to over a third of the Canadian population and one of the most productive soils in the country, fact that exacerbate competition for land between these two uses. Furthermore, urban land has substantially expanded over ecologically and socially valuable wetlands, raising questions about transition drivers and how effective the three Greenbelt designations are: Niagara Escarpment, Oak Ridges Moraine, and Protected Countryside.

This study thus investigates the role played by the three different Greenbelt designations in preventing further wetland conversion in Southern Ontario between 2000 and 2020 by estimating a land-use shares spatial model. We used remote-sense-based land use and cover maps, aggregated over 241 Ontario’s census subdivisions, and explanatory variables representing socioeconomic drivers and biophysical characteristics such as population density, farm income, temperature, precipitation, and soil suitability for agriculture.

As expected, population density, farm income, and mainly household income are major socioeconomic drivers of wetlands conversion to urban land and cropland. In terms of wetlands being converted to cropland areas, temperature and precipitation are also important drivers, although with much smaller coefficients’ magnitude compared to the socioeconomic drivers. This underscores the potential impacts of a warming climate on future conversion of wetlands and peatlands in Northern Ontario, where most of the Canadian Peatlands are located. Turning to the policy barriers to further wetland loss, both Niagara escarpment and the Oak Ridges Moraine has been effective in preventing further conversion of wetlands to urban areas, but they are not statistically significant for transitions between wetlands and croplands. These two Greenbelt designations were designed to protect the natural landscape of the Niagara Escarpment, fauna and headwaters. The protected countryside was specifically created to protect not only wetlands but also agricultural lands, and we observed that this designation did not show up statistically significant for urban expansion over cropland areas. Wetland areas have yet increased in areas within this policy area domain.

Southern Ontario is one of the most rapidly growing regions in Canada, surpassing the national average growth rate. This rate is expected to further increase as the province population is projected to grow by more than 40% in the coming three decades. Our results reveal the urgent need for continuous monitoring of land use policies aimed to protect nature-based solutions such as wetlands, especially peatlands due to their ability to act as a sink of greenhouse gases and, therefore, potential for mitigating climate change. With a warming climate, the conflict over land allocation for urban and agricultural development may push agricultural uses to the Northern part of the province, triggering unprecedented wetland and peatland disturbance and conversion.