My students and I work to identify and explain patterns in the distribution and abundance of of species. We work with a variety of terrestrial taxa (plants, invertebrates, and vertebrates). While concentrating on those patterns that occur at large spatial spatial scales, our research spans scales and levels within the ecological hierarachy from decisions made by individual organisms to global patterns of biodiversity. By understanding patterns in the distribution of and abundance of species we can make better decisions in our changes to the environment and we can better conserve biodiversity.
My program of research has two distinct parts. The first of these examines the dynamics of the geographic ranges of species from a biogeographical perspective. The second examines how species vary in abundance across their range and how this may translate, across several species, into community structure.
Despite their depiction in field guides as relatively stable, geographic ranges are dynamic, increasing or decreasing as environmental conditions change. This is obvious in the most extreme cases declining species or invading species. In addition to a reduction in abundance, most declining species show some contraction in their geographic range. Species that have been intentionally or accidentally introduced by humans to new regions tend to show dramatic increases in their geographical distribution.
The principal questions in the conservation of declining species are when, where, and how conservation resources should be used to aid these species. In my research, I hope to help answer these questions by identifying patterns in the contraction of the geographic ranges of species that can be used to better manage these species.
As species expand into new regions, they can disrupt the ecological relationships and processes native to the region. The identification and control of these invading species is of major concern to conservation biology. In my research, I hope to be able to predict how the species' geographic range will expand and where and how conservation resources can best be used to contain this expansion.
The species that occur at any given site or within any community are determined by the combination of the conditions at the site and the regional species pool from which the species are drawn. If conditions at the site are not right for the species, then the species will not occur at the site even if it occurs in the region. If the conditions for the species are right, but the species does not occur in the region, then the species will not occur at the site. This combination of factors is further complicated by the interactions among species that may encourage or discourage the occurrence of other species. In my research, I hope to contribute to our understanding of community structure (the identity of and abundance of species that occur at a site) by examining the large-scale patterns of species abundance and distribution.