Litter ant patchiness at the 1-m scale: disturbance dynamics in three Neotropical forests.

Large-scale (>100 m/day) raids by tropical army ants have been linked to litter ant patchiness and diversity. In three Neotropical forests, densities of litter ants vary 10-20 fold at the 1-m scale. A survey of Barro Colorado Island. Panama, revealed that most army ant raids also occur on a 1-m scale with fronts ≤1 m wide. To explore the role that such small scale disturbance may play in creating litter ant patchiness, all litter ant nests were removed from 1-m plots. Control and disturbance plots were resampled 3 months later. In contrast to a previous study of large litter gaps, ant foundresses did not appear to prefer these smaller gaps. Nest densities, species richness, and species composition differed most from controls in a dry hilltop forest in Panama, second most in a wetter ravine forest nearby, and least in a Costa Rican wet forest. Disturbance may not leave a lasting signature in the wetter forests due to higher background levels of disturbance, faster recovery, or both.