Fire ants and native ants, Part 2: Experimental evidence that disturbance and fire ants reduce native ant abundance and diversity

Exotic species and ecological disturbance negatively affect native species. However, most exotic species occur only in disturbed habitats, making it difficult to separate their effects from the effects of disturbance. To test the separate and combined effects of both an exotic species and habitat disturbance on native ant species, we treated experimental plots in the Apalachicola National Forest, Florida to mowing, plowing, or no disturbance. To each of these disturbance treatments, we transplanted mature fire ant colonies, or soil without colonies, or nothing. This set of 9 treatments was replicated 5 times at different sites, and monitored for native ants over three years. These data showed that (1) plowing greatly diminished native ant abundance and diversity, and (2) fire ants diminished some, but not all, native ant abundance and diversity. The effect of disturbance by itself was sufficient to significantly reduce the entire ant fauna while the combined effect of disturbance and fire ants was greater than either disturbance or fire ants alone. The plowing caused a significant increase in several species, in addition to increasing the abundance of fire ants. The results of this study suggest new directions for the study of exotic species and the assembly of ant communities.