Alluvial vegetation is structured by the hydrologic connectivity of bottomland habitats and propagule movement downstream, often resulting in a pattern of longitudinal floristic continuity. However, consistency of vegetation composition may vary at different spatial scales as a result of different processes driving community assembly. In riparian landscapes, variation in the composition of alluvial vegetation types may reflect the boundaries of river basins, with the highest compositional consistency at the spatial scale of a single river basin owing to hydrologic connectivity; on the other hand, compositional consistency is expected to decrease across basin boundaries where habitat connectivity is decreased. Here we present an analysis of the variation of alluvial plant communities based upon data collected in five North Carolina river basins in the southeastern Piedmont region: the Catawba, the Yadkin, the Cape Fear, the Neuse, and the Tar-Pamlico.  We explored compositional consistency of vegetation types at two spatial scales: within a single basin and across the five basins.  

Results/Conclusions

Compositional consistency patterns confirm our expectation; consistency of vegetation types is highest within a single river basin.  This analysis has important restoration implications; if consistency is minimal across the boundaries of river basins, restoration targets for riparian areas may be more appropriately defined within the spatial scale of a single basin.