Symposium: Landscape Ecology and Wildlife Habitat Evaluation: Critical Information for
Ecological Risk Assessment, Land-Use Management Activities, and Biodiversity Enhancement
Practices
Paper Title: Estimating Functional Connectivity of Wildlife Habitat and Its Relevance to
Ecological Risk Assessment
Authors: Alan R. Johnson1, Craig R. Allen2, and Kristi A.N. Simpson1
1
2
Department of Environmental Toxicology, Clemson University, Pendleton, South Carolina.
South Carolina Cooperative Fish and Wildlife Research Unit, Clemson University, Clemson,
South Carolina
Abstract: Habitat fragmentation is a major threat to the viability of wildlife populations and the
maintenance of biodiversity. Fragmentation relates to the degree of habitat sub-division into
disjunct patches. Usually coincident with fragmentation per se is loss of habitat, a reduction in
the size of the remnant patches, and increasing distance between patches. Natural and
anthropogenic processes leading to habitat fragmentation occur at many spatial scales, and their
impacts on wildlife depend on the scales at which species interact with the landscape. Landscape
ecologists have introduced the concept of functional connectivity to capture this organism-based
view of the relative ease of movement or degree of exchange between physically disjunct habitat
patches. Precise estimation of the functional connectivity of a given habitat arrangement for a
given wildlife species depends on many details of the organism’s life history and behavioral
ecology. However, for broad categories of species, quantities such as home range size and
dispersal distance scale allometrically with body mass. These relationships can be incorporated
into spatial analyses to model functional connectivity, which can be quantified in terms of an
index, or displayed graphically in maps of functionally connected clusters. We present a review
of indices and GIS-based approaches to estimating functional connectivity, presenting examples
from the literature and our own work on mammalian species distributions in the state of South
Carolina. Such analyses can be readily incorporated within an ecological risk framework.
Estimates of functional connectivity may be useful in a screening-level assessment of the impact
of habitat fragmentation relative to other stressors, and may be crucial in detailed population
modeling and viability analysis.