Multiscale influences of spatial and environmental variability on ant community structure

The organization of local communities has traditionally been viewed as a process directed by local scale species sorting or very broad scale biogeographical factors.  The importance of landscape scale habitat variation has only recently begun to receive stronger attention.  I explored the ways in which environmental and spatial variation at multiple scales influences community structure in ants.  Ground-dwelling ant communities were sampled in sandhill habitat throughout northern Florida, USA.  Sites were of similar habitat quality locally, but spanned a range of heterogeneity in the surrounding landscape.  Richness and diversity did not change between sites.  However, variance partitioning of local, landscape, and spatial datasets indicated that community composition was significantly influenced by spatial and environmental variability across a range of scales.  Spatial dependence in local communities was correlated with different types of environmental variation, such as the amount of particular habitats at distinct spatial scales.  Therefore, local ant communities may be simultaneously structured by different processes that occur at separate spatial scales.  Further, habitat generalists appear to replace habitat specialists at sites with high proportions of matrix habitat in the surrounding landscape, even though local habitat conditions are similar among sites.  Conversely, habitat specialists appear to replace habitat generalists at sites with more sandhill habitat in the surrounding landscape.  Such results would suggest that source-sink interactions with surrounding habitats, in addition to local species sorting mechanisms, may be important for community organization in sandhill ants.  These results illustrate the importance of considering multiscale influences on patterns of organization in ant communities.