A new habitat availability index to integrate connectivity in landscape conservation planning: Comparison with existing indices and application to a case study

Connectivity is a major concern for the maintenance of wildlife populations, ecological flows, and many other landscape functions. For these reasons many different connectivity indices have been used or proposed for landscape conservation planning; however, their properties and behaviour have not been sufficiently examined and may provide misleading or undesired results for these purposes. We here present a new index (probability of connectivity, PC) that is based on the habitat availability concept, dispersal probabilities between habitat patches and graph structures. We evaluate the performance of PC and compare it with other widespread indices through a set of 13 relevant properties that an index should ideally fulfil for adequately integrating connectivity in landscape planning applications. We found that PC is the only index that systematically accomplished all the requirements, overcoming some serious limitations of other available indices. We encourage the use of PC as a sound basis for planning decision-making. To demonstrate the use and potential of PC for practical landscape applications, we present an example of application to a case study for the goshawk (Accipiter gentilis) in Catalonia (NE Spain), where we identify those habitat areas that most contribute to overall landscape connectivity and evaluate the effectiveness and potential improvement of a protected areas network (Natura 2000) for conserving those critical habitat areas.