Habitat corridors are a common management solution in fragmented landscapes. These thin strips of habitat connect otherwise isolated patches, and have demonstrated positive effects such as increasing movement and diversity. However, concerns exist that corridors provide connections that could increase negative factors such as invasive species and disease. These negative effects of corridors have rarely been quantified. We investigated patterns of two co-occurring antagonistic interactions that can negatively effect the growth and fitness of Solidago odora. These two factors, foliar fungus and galling insects vary in dispersal mechanism, and are wind and animal dispersed respectively. We used six experimental landscapes to analyze the difference in these movement patterns. Each of these six landscapes consisted of habitat patches of equal area that vary in shape and connectivity. Patches are either connected to a central patch, or lack this connection. Also, patches are either of high or low edge-to-area ratio, which tests for changes in patch shape associated with corridors. These patches of open habitat are located within a matrix of dense pine plantation that limits dispersal between patches through the matrix. We surveyed clones of S. odora for foliar fungal and gall infection in the edges and interiors of each of the three patch types.
Results/Conclusions
Foliar fungus infected a greater percentage of leaves in the interiors as compared to the edges of patches, but there was no difference found among patch types. Galling insects showed an interaction between patch type and distance from edge. In unconnected patches, regardless of shape, galling insects infected significantly higher numbers of plants on the edges than the interiors. However, this effect was mediated by corridors in that in the connected patches, infection rates were equally high in both the edge and interior. These rates were similar to those of the edges in the unconnected patches. These results suggest that corridors work to increase some types of negative factors for plants, while playing no role in altering movement patterns of others.
