Reeve, J. D., K. J. Haynes and J. T. Cronin. 2008. Diffusion models for animals in complex landscapes: incorporating heterogeneity among substrates, individuals and edge behaviors. Journal of Animal Ecology 77: 898-904.
ABSTRACT
1. In real landscapes, dispersing herbivores must contend with a variety of vegetation types (both host patches and a diversity of non-host patches) and boundaries between them. We develop a diffusion model for movement of a habitat specialist (e.g., monophagous herbivore) that allows diffusion rates to vary with substrate and among individuals. Edge behavior was modeled as a biased random walk. This general model was applied to the planthopper Prokelisia crocea which inhabits a heterogeneous landscape of host-plant patches (cordgrass) and two dominant matrix types (mudflat and brome).
2. The models were parameterized using observations of planthopper movement in arenas of pure cordgrass, brome, and mudflat, as well as cordgrass adjoining a matrix of brome or mudflat. The best fits were provided by models that incorporated distinct sessile and mobile classes of individuals, different diffusion rates for cordgrass, brome, and mudflat, and edge behavior dependent on the matrix.
3. Diffusion rates were similar for cordgrass and brome but much higher for mudflat. Edge behavior was also dependent on the matrix, with most planthoppers reflected at cordgrass-mudflat but not cordgrass-brome edges. Our results suggest that cordgrass patches surrounded by brome would “leak” planthoppers and thus be more likely to go extinct than those surrounded by mudflat.
4. The dispersal models could be readily extended to a mosaic of habitat types with distinct diffusion rates and edge behaviors.
Keywords: Dispersal, habitat mosaic, edge behavior, Prokelisia, Spartina
