The influence of roads and buffer depth on habitat core areas and connectivity in the northeastern United States

Land development pressures that threaten habitat core areas and connectivity are intensifying across the nation and extending beyond urbanized areas in the form of exurban and rural residential development. This is particularly true in the temperate forests of the northeastern U.S. If current trends continue, increased conversion and fragmentation of many roadless areas by development is likely, exacerbating the likelihood of local species extinctions and complicating efforts to preserve intact functional ecosystems. We used a suite of nationally available data sets to identify roadless areas of the northeastern USA including impervious cover (urbanized and developed areas), road networks (and derived density), and forest cover (canopy density). We analyzed the influence of different types of unimproved roads and amount of forest cover on identification of the extent and configuration of roadless areas, and then assessed these areas in terms of land ownership (public, private) and management (parks, refuges, multi-use, etc.). We also derived patch connectivity metrics using a graph theory approach, making use of cost surfaces that accounted for the above variables and associated landscape metrics. Because of the great interest generated for its reintroduction in the northeast, we used the gray wolf, Canis lupus, as an example of a keystone species to assess current landscape connectivity between high quality habitat areas in upper New England, from the Adirondacks of New York to the Canadian border. Our results suggest a starting point for the construction of a more comprehensive and ecologically functional reserve network for the region.