Habitat corridors are often used in practice to augment movement of species in isolated habitat patches. The positive effects of corridors have been rigorously tested, showing they facilitate the movement of a diverse range of body sizes and shapes from plant pollen to insects. However, negative effects have yet to fall under this experimental scrutiny. It has been proposed that corridors may also increase the movement of invasive species, fire and disease. We applied a predictive dispersal framework to a plant parasite system in order to understand how connectivity negatively impacts plant populations. Parasite incidence rates were measured on two early successional plant species in a replicated, large-scale landscape manipulation experiment.
Results/Conclusions
Corridor impacts depended on parasite dispersal mode. Connectivity positively influenced biotically dispersed parasites (gall forming insects), while having no affect on abiotically dispersed parasites (foliar fungi). The increase in edge habitat associated with corridor construction also influenced incidence rates, but these affects were dependent on individual species biology. Biotically dispersed parasites infected plants more commonly along patch edges, while abiotically dispersed fungi infected more plants along either patch centers or edges based on fungal genus. These results suggest a predictive pattern between dispersal mode and spatial distribution of parasite incidence at the landscape scale. With the implementation of corridors, biotically dispersed parasites are of greater concern, however the indirect effects of habitat edge creation can also impact plant antagonists.
