Conservation planning in a subdivided world
The identification of priority areas for conservation tends to take place over two fundamentally different spatial extents. First, there are analyses conducted at global or large biogeographic extents. Second, there are those conducted within geopolitical units. In this paper we show, using data for North American mammals, that spatial extent can have a profound effect both on the number and locations of the priority areas identified to attain a particular conservation goal. For example, applying the same selection target to obtaining just a single representation of each species, the numbers of areas required increased by approximately an order of magnitude between treating North America as a single unit and treating the provinces separately. Although this scenario is undoubtedly extremely simplistic, such large differences are maintained with greater occurrence targets. Balancing the benefits and disadvantages of conservation planning at different spatial extents is not straightforward. However, a multi-scale approach that exploits the respective benefits and downplays the disadvantages when focussing on smaller or larger extents would seem valuable.