Corridors and Connectivity
Habitat fragmentation poses a widespread threat to biodiversity by disrupting the dispersal of organisms. Corridors- narrow strips of habitat that join patches of similar habitat- are thought to provide a general solution by restoring dispersal among patches, thereby increasing gene flow and reducing the probability of local extinctions. Yet corridors are controversial, because their efficacy can vary greatly among systems, depending on the complex interaction between disperser behavior and landscape structure.
Our research in this area links population, community and landscape ecology in efforts to understand how landscape features, and in particular, connections between patches, affect the behavior, survival, and reproductive success of plants and animals, and how interactions between these organisms- seed dispersal and pollination, for example- are affected by connectivity We take mechanistic, experimental approaches to these questions.
Much of our work in this area takes place on large experimental landscapes developed explicitly to study the impact of connectivity. The sites are located on the Savannah River Site, in South Carolina (Fig.1). Work their includes the first experimental examination of connectivity effects on pollination and seed dispersal (Tewksbury et al. 2002), to work testing and validating alternative individual-based behavioral models, allowing the prediction of corridor effects on long-distance dispersal of seeds by birds (Levey, Bolker, Tewkbury et al. 2005). All of this work, as well as additional work on corridor effects on pollinators (Haddad and Tewksbury 2005a, b), is aimed at understanding how landscapes affect interactions between plants and animals
Our most recent work in this area focuses on the role of connectivity in maintaining plant diversity (Damschen, Haddad, Orrock, Tewksbury and Levey 2006), and our current research in this system explores linkages between plant life-histories and landscape features, in an experimental restoration context. This work responds to the need to integrate research on fragmentation and connectivity across plant-animal interactions, providing predictive frameworks for determining the types of plants that will respond to connectivity. To accomplish this, we are blending studies of whole plant demography with studies of community response to corridors, using the same experimental landscapes.
summary of current NSF-funded project
Selected Publications
Damschen, E.I., Haddad, N. M., Orrock, J. L., Tewksbury, J. J., Levey, D. J. 2006. Corridors Increase Plant Species Richness at Large Scales. Science 313: 1284-1286.
Levey, D.J., Bolker, B. M., Tewksbury, J.J., Sargent, S., and Haddad, N.M. 2005. Modeling bird movement in experimental landscapes reveals how habitat corridors affect seed dispersal. Science 309 (5731): 146-148.
Tewksbury, J. J.<, D. J. Levey, N. M. Haddad, , S. Sargent, J. L. Orrock, A. Weldon, B. J. Danielson, J. Brinkerhoff, E. I. Damschen, P. Townsend. 2002. Corridors affect plants, animals, and their interactions in fragmented landscapes. Proceedings of the National Academy of Sciences 99:12923-12926.