Connecting habitat to promote range shifts

Originally, scientists promoted corridors as a way to increase the persistence of populations isolated in habitat fragments. Researchers are now asking if the corridor strategy is the best way to cope with new threats. Climate change forces species to track their suitable habitat conditions, resulting in range shifts towards the poles or higher elevations under warming. Ideally, the same corridors we use to increase population connectivity will also promote range shifts across a species’ distribution. Jenny Hodgson and others test whether this rosy picture holds and describe how a landscape conserved with climate change in mind differs from a landscape that minimizing habitat fragmentation.

Hodgson and others simulate different species dispersing across a real, 200×200-kilometer landscape in England. Six conservation strategies are tested for their ability to promote movement from one end of the landscape to the other, for different dispersal abilities and in four habitat types. The researchers found that, with a limited amount of habitat to add, connecting existing patches with corridors does not always lead to the fastest range shifts. For example, wetland species move best when new habitat is established evenly across the landscape. One surprise is how poorly two commonly used conservation strategies performed. Increasing the quality of existing habitat (through restoration, for instance) and increasing the size of the largest patches did not promote dispersal, even though these may increase the size of the population. The takeaway message is that corridors perform well at permitting species to shift their ranges, but may not be the ideal option for all habitats or all arrangements of patches.

Resources

Hodgson, J. A., C. D. Thomas, S. Cinderby, H. Cambridge, P. Evans, and J. K. Hill. 2011. Habitat re-creation strategies for promoting adaptation of species to climate change. Conservation Letters, 4, 289–297.