COS 197-4 - Areas Important for Ecological Connectivity Throughout Canada: A Wall-to-Wall, Omnidirectional, Circuit Theory Analysis

Background/Question/Methods

Governments around the world have acknowledged the importance of conserving ecological connectivity to help reverse the decline of biodiversity. While many studies have assessed connectivity within various regions in Canada for various species, none have produced a nation-wide, multi-species map of omnidirectional connectivity at a resolution sufficient to support local land-management decisions. To rectify this shortcoming, we employed recent methodological developments in circuit theory and used the wall-to-wall, omnidirectional mode of Circuitscape to assess ecological connectivity throughout Canada. We developed a movement cost surface with a limited number of thematic categories using the most recently updated land cover data available for the country. We tested the sensitivity of current density outputs to cost values assigned to land covers as well as the sensitivity to tile sizes. Independent wildlife data from across the country was used to validate the results.

Results/Conclusions

Consistent with previous studies, we found that current density estimates were relatively insensitive to the absolute cost values assigned to land cover features so long as their rank order was maintained, even for study areas much larger and more varied than previously tested. We also found that current densities become relatively insensitive to tile sizes > 1.7 million pixels, which was far smaller than the tile size we could efficiently analyse on our computers (40 million pixels, or 3,600,000 km²). This allowed us to divide the country into 17 square tiles for the analysis. The resulting raw current density map of Canada revealed heterogenous patterns of current density across the country, strongly influenced by geography, natural barriers, and human development. Validation of the output current density map with independent wildlife data from across the country found that mammal locations were predicted by areas of high current density but herpetofauna road-kill data was not. We believe our current density map can be used to identify areas important for connectivity for many species throughout Canada and thereby contribute to efforts to conserve biodiversity.