PARENT SESSION
Symposium #5: Forest edges: unifying concepts and key research needs..
Organized by: CR Nelson and J Chen
Monday, August 5. 1:00 PM to 3:45 PM. Crystal Ballroom, TCC.
Influence of forest edges on vegetation: a synthesis of three decades of research in temperate ecosystems.
NELSON, CARA*,1, 1 University of Washington, Seattle, Washington
ABSTRACT- Concern over forest fragmentation, and the resultant expansion of edge zones, has led to an increasing number of investigations of edge-related phenomena. However, there have been few attempts to synthesize research findings, especially with respect to vegetation responses. Toward that end, I reviewed 41 studies of vegetation patterns across temperate forest edges. This collection includes relevant studies that (1) are indexed in AGRICOLA or TREE CD databases and (2) were published between 1970 and 2001. Reported distances over which species and plant communities respond to edges were highly variable both within and among ecosystems, and ranged from 0 to 200 m. Variability in responses can be attributed, in part, to inherent differences in stand structure, physical environment, edge-orientation, edge contrast, or time since edge creation. However, a potentially large impediment to understanding spatial gradients in vegetation response, especially with respect to understory species, lies in the methods used to infer vegetation pattern. With the exception of one investigation, all studies employed a retrospective or chronosequence approach to reconstruct spatial or temporal patterns of edge-related response. Unless highly replicated, these approaches often fail to account for the patchy distributions of most forest understory herbs and shrubs, and potentially confound edge-related responses with variation in the original abundance or distribution of species. There is a need for experimental approaches that account for initial distributions and explicitly test potential mechanisms that underlie observed responses.
KEY WORDS: edges, vegetation, forest, forest-borders