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Evaluating Anthropogenic Risk of Grassland and Forest Habitat Degradation Using Land-Cover Data
Citation:
Riiters, K. H., J. D. WICKHAM, AND T. G. WADE. Evaluating Anthropogenic Risk of Grassland and Forest Habitat Degradation Using Land-Cover Data. Landscape Online. International Association for Landscape Ecology, Chapter Germany, Bonn, Germany, 13:1-14, (2010).
Impact/Purpose:
It is the custom of humans to farm and build things, often in otherwise natural environments, and conversely to preserve and create natural environments within human-dominated landscapes. Society views the resulting anthropogenic interface zones from a variety of utilitarian perspectives such as security from wildfire or access to green space, and ecological perspectives are equally diverse and observer-dependent. As a result, while most people may agree that assessments of the spatial patterns of land use and land cover are important, there is no general agreement on how to conduct an assessment of land-cover patterns. Ecologists often focus assessments by adopting‚biodiversity’ perspective such that land-cover approximates habitat, and land-cover patterns represent different aspects of habitat quality. Within that perspective, popular pattern metrics of land-cover edge, patch size, and patch isolation are motivated by concerns for habitat edge effects (Murcia 1995, Harper et al. 2005) and habitat isolation (MacArthur & Wilson 1967). However, when those metrics are applied to large-area land-cover maps, it is difficult to interpret them with respect to land-cover patterns (Hargis et al. 1998; Tischendorf 2001; Neel et al. 2004; Riitters et al. 2004), let alone habitat quality or biodiversity (Bissonette & Storch 2002; McGarigal & Cushman 2002). To achieve a synthesis of anthropogenic effects on habitats and ultimately biodiversity across species and biomes, there is a need for better ways to use and interpret the available land-cover data at continental to global scales.
Description:
The effects of landscape context on habitat quality are receiving increased attention in conservation biology. The objective of this research is to demonstrate an approach to mapping and evaluating the anthropogenic risks of grassland and forest habitat degradation by examining habitat context as defined by intensive anthropogenic land uses at multiple spatial scales. A landscape mosaic model classifies a given location according to the amounts of intensive agriculture and intensive development in its surrounding landscape, providing measures of anthropogenic risks attributable to habitat isolation and edge effects at that location. The model is implemented using a land-cover map (0.09 ha pixel-1) of the conterminous United States and six landscape sizes (4.4, 15.2, 65.6, 591, 5300, and 47800 ha) to evaluate the spatial scales of anthropogenic risk. Statistics for grassland and forest habitat are extracted by geographic overlays of the maps of land-cover and landscape mosaics. Depending on landscape size, 81 to 94 percent of all grassland and forest habitat occurs in landscapes that are dominated by natural landcover including habitat itself (grassland, forest, shrub/scrub, water, and wetland). Within those naturaldominated landscapes, 50 percent of grassland and 59 percent of forest is within 590 m of intensive agriculture and/or intensive developed land which is typically a minor component of total landscape area. The conclusion is that anthropogenic risk attributable to habitat patch isolation affects much less grassland or forest habitat area than risks associated with edge effects.
URLs/Downloads:
Evaluating Anthropogenic Risk of Grassland and Forest Habitat Degradation Using Land-Cover Data
WICKHAM 09-081 FINAL JOURNAL ARTICLE..PDF (PDF, NA pp, 5221 KB, about PDF)