Landscape heterogeneity and plant species richness in the Southeastern US
Jennifer
Kwasny
Costanza, University of North Carolina-Chapel Hill, costanza@unc.edu
(Presenting)
Todd
Jobe, University of North Carolina-Chapel Hill, toddjobe@email.unc.edu
Aaron
Moody, University of North Carolina-Chapel Hill, aaronm@email.unc.edu
Investigating the causes and consequences of species richness patterns from local to global scales has been an important field of research in ecology for decades. It is especially important today to understand the mechanisms that influence species diversity, given threats such as global climate change and habitat loss. According to recent studies, landscape heterogeneity may be an important factor in determining species richness; however, we lack a clear understanding of how the two are related, and at what scales. Therefore, I investigate the relationship between heterogeneity and plant species richness across Virginia, North Carolina and South Carolina. I ask how this relationship varies with: 1. the grain size at which heterogeneity is characterized; 2. the spatial extent of sampling; and 3. species group, including total, native and exotic species richness. Species richness data come from more than 7000 vegetation plots located across the three-state area. Measures of habitat heterogeneity are derived from the variation in MODIS NDVI values across various grain sizes surrounding plot locations. These plot and remote sensing data provide a unique opportunity to examine the richness-heterogeneity relationship across a large extent. I show that the richness-heterogeneity relationship changes with the grain at which heterogeneity is measured. In addition, as the spatial extent of the study area increases from an ecoregion to the three-state area, the heterogeneity-richness relationship becomes less strong. Finally, heterogeneity leads to a bigger decrease in native species richness than exotic or total species richness. These results suggest that the relationship between plant species richness and heterogeneity is complex, and is the result of multiple mechanisms operating on different groups of species across a variety of spatial scales.
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