Habitat Suitability and the Distrbution of Species

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

Plant species characterized by short-distance dispersal (e.g. ant-dispersed species) are hypothesized to be absent from suitable habitat due to dispersal limitation while species characterized by long-distance dispersal (e.g. bird-dispersed species) are often present in unsuitable (sink) habitat due to frequent re-colonization and rescue. These two hypotheses are being tested in a study of the demography and distribution of six forest-understory herb species in a region extending from the lower Piedmont of Georgia to the upper elevations of the Blue Ridge. Among the goals of the study are 1) to develop a rigorous method of delineating suitable habitat by measuring the demographic response of each species to environmental variation, with particular emphasis on responses to soil moisture and light availability, and 2) to use this methodology to test hypotheses about how habitat suitability, demography, and dispersal interact to influence species distributions. In addition to continuing to follow the demography of approximately 15,000 marked individuals, the proposed research will test hypotheses specific to the biology of each of the six study species. The proposed research will help understand and evaluate the impact of climate and land-use change on biological diversity. A detailed knowledge of factors controlling the distribution of the study species will help policy analysts evaluate the potential negative impacts of global change and help resource managers better protect threatened species in times of global change. Graduate and undergraduate students will participate actively in all aspects of the research, gaining experience in experimental design, demographic studies, data management, statistical analysis, and preparation of results for presentations and publication.