Assessing the connectivity of natural systems in the Golden Horseshoe: an application of the effective mesh size

The Golden Horseshoe (GH) is a densely populated and rapidly developing region located in southern Ontario. It houses valuable agricultural lands and sensitive ecological features, including the Niagara Escarpment, Oak Ridges Moraine, and Ontario's Greenbelt, a permanently protected band of nearly 2 million acres. Urban development in the GH has accelerated fragmentation of natural cover and degraded its connectivity and quality. As urbanisation continues to pressure natural systems, it is critical to understand impacts on natural cover by monitoring and detecting changes over time. To assess changes in natural cover fragmentation and connectivity, the effective mesh size (meff) methodology was applied standard land cover data (SOLRIS) for the GH. We analysed meff across political and ecological boundaries and tested the metric at various spatial scales. The effective mesh size declined across the study area, indicating a general loss of connectivity throughout the GH despite protective policies, notably in the Oak Ridges Moraine, which declined from 3.15 to 1.68 km2. Our findings suggest that meff has the potential to be used as an indicator, as it provides a quantitative measure of a baseline condition upon which it is possible to monitor changes and establish management and policy targets. However, to implement the effective mesh size as an environmental indicator, we recommend finer resolution and more inclusive natural cover mapping. In addition, we recommend monitoring to be complemented with field-based data to improve interpretability of the effective mesh size values and better understand the impact of fragmentation on the ecology of natural systems