Competitive reversals inside ecological reserves: the role of external habitat degradation |
| |
Authors: | Robert Stephen Cantrell Chris Cosner William F Fagan |
| |
Institution: | (1) Department of Mathematics and Computer Science, University of Miami, Coral Gables, Florida 33124, USA. e-mail: rcs@cs.miami.edu, US;(2) Department of Biology, Arizona State University, Tempe, AZ 85287, USA, US;(3) National Center for Ecological Analysis and Synthesis, 735 State Street, Suite 300, Santa Barbara, CA 93101, USA, US |
| |
Abstract: | Habitat degradation is the slow – and often subtle – deterioration in habitat quality that accompanies human activities through
increases in road density, pesticide use, hunting pressure, etc. Such degradation is of particular concern in fragmented habitats
where economic or jurisdictional boundaries rather than ecological ones determine the level of exploitation adjoining habitat
patches endure. To examine the consequences habitat degradation might have on species interactions, we posited a patch of
pristine habitat surrounded by “matrix” habitat whose degradation level was variable. Using a coupled pair of diffusive Lotka–Volterra
competition equations with Robin (mixed) boundary conditions, we modeled the dynamics of two competing species inhabiting
the pristine patch and incorporated matrix degradation through a tunable “hostility” parameter representing species’ mortality
rates in the matrix. We found that the numerical range of competition coefficients over which one species is the competitive
dominant and the other inferior may grow or shrink as matrix quality deteriorates. In some cases, degradation of the exterior
habitat would bring about a complete competitive reversal inside the preserve. This result, wherein a formerly inferior species supplants a formerly dominant one – even inside the “protected”
remnant patch itself – has policy implications for both nature reserve design and management of human activities outside park
boundaries.
Received: 30 April 1997 |
| |
Keywords: | : Competition Edge effects Reaction diffusion Lotka Volterra Ecological reserves |
本文献已被 SpringerLink 等数据库收录! |
|