Building on the idea of nearest-neighbor distances, a buffer radius calculates the number of occupied habitat patches or total number ofindividuals ofa species within a given distance. The metric uses more information than nearest-neighbor distances, potentially improving its accuracy, and it can also be calculated at multiple spatial scales. The spatial scale of relevance will depend on typical movement distances and consequently movement data could greatly improve the utility of buffer radius connectivity metrics. A related idea is captured in Ilkka Hanski's incidence function model approach, which includes an explicit function ofthe number ofindividuals in habitat patches at different distances and these are weighted by distance in a power function. The approach can also be adapted to use information just on patch occupancy, or patch area as a surrogate measure, if the number of individuals per patch is not known. The approach has been tried and tested with a variety of taxa and appears to work well when organisms occur in discrete patches and are limited in their dispersal ability. As a minimum, information on patch occupancy or colonization is required and this needs to be complete spatially, without missing (uncensused) habitat patches in the study area. Such approaches are mainly limited by the high data requirements and limited areas that can be censused.
Was this article helpful?