How to manipulate landscapes to improve the potential for range expansion

Summary Climate change is a global threat to species, and their capacity to adapt could be limited by habitat fragmentation. Many initiatives to restore habitats, increase connectivity and/or ensure ‘functioning ecological networks’ are explicitly or implicitly trying to address this threat. However, existing methods of analysing networks mainly treat the landscape as static, and it is difficult to use these to plan restoration. We use a recent method to approximate the speed of a species’ range expansion through a landscape by an analogy to an electrical circuit, which takes into account both the rates of colonisation between patches and the rates at which occupied habitat produces new emigrants. Based on this, we propose and test two methods that can help to optimise the spatial arrangement of habitat for range expansion. First, high current flowing through a habitat patch indicates that it should be a priority for conservation, and this can be the basis of an algorithm for iteratively dropping the least valuable patches. Secondly, high power in a link between two patches indicates that it is a bottleneck in the circuit, and this can be the basis of an algorithm for iteratively adding new patches in the most efficient places. We show that these methods perform well for a variety of realistic landscape patterns, assuming known and fixed dispersal ability and source/target locations. The calculations involved for each parameter set are fast enough to be used as building blocks in a larger optimisation for practical planning of landscapes for multiple species. Thus, we lay the foundation for a new genre of systematic conservation planning, which efficiently proposes restoration as well as minimising loss.