A Metric and GIS Tool for Measuring Connectivity Among Habitat Patches Using Least-Cost Distances

PURPOSE: This technical note presents a new landscape connectivity metric, as well as a user’s guide for an ESRI ArcGIS ® tool that is used to calculate it. This new metric builds and improves on the concept of the proximity index. The tool and metric are specifically intended for measuring changes in connectivity due to the loss or gain of habitat patches and/or alterations in the surrounding landscape. As such, the tool is of particular use when comparing impacts or benefits to connectivity from among various project alternatives. INTRODUCTION: Landscape connectivity has been defined as “the degree to which the landscape impedes or facilitates movement among resource patches ” (Taylor et al. 1993). It is now generally accepted that landscape connectivity plays an essential role in the dispersal of organisms among habitat patches and thus the conservation of biodiversity (Tischendorf and Fahrig 2000). Connectivity can be characterized as either functional or structural; structural connectivity describe