Quantifying Species Interactions in Experimental Native vs. Exotic Grassland Plant Communities

Native ecosystems are currently being replaced by novel, exotic-dominated ecosystems worldwide. Exotic ecosystems differ from native ecosystems in several important ways. For example, exotic ecosystems are often less diverse than native ecosystems, and often contain species without a shared evolutionary history. Previously we found that biodiversity rapidly declined in experimental exotic communities because the mechanisms that maintained diversity in experimental native communities were reduced. Further investigation is needed to explicitly quantify species interactions in native vs. exotic communities. Here we test the hypothesis that exotic species will exhibit more competition, or less facilitation, than ecologically similar native species.