The Nature Conservancy of Canada works with a scientific base. They do an evaluation of what the eco-sensitive areas within Canada are and where there are priorities for them to acquire land or some interest in land. They would then purchase or get an easement from a landowner, and then protect and conserve the ecological integrity of that land.
A well-known one would be the Flathead River Valley land in British Columbia, where, in partnership with the provincial government and a number of other organizations, they've managed to conserve quite a large area of eco-sensitive land.