Examining the link between competition and negative co-occurrence patterns

Negative species co-occurrence patterns have long intrigued ecologists because of their potential link to competition. Although manipulative field experiments have consistently revealed evidence of competition in natural communities, there is little evidence that this competition produces negative co-occurrence patterns. Evidence does suggest that abiotic variation, dispersal limitation, and herbivory can contribute to patterns of negative co-occurrence among species; it is possible these influences have obscured a link with competition. Here, we test for a connection between negative co-occurrence and competition by examining a small-scale, relatively homogeneous old-field plant community where the influence of abiotic variation was likely to be minimal and we accounted for the impact of herbivory with an herbivore exclosure treatment. Using three years of data (two biennial periods), we tested whether negatively co-occurring pairs of species, when occasionally found together, experien...