Competition and coexistence of ants in a small patch of rainforest canopy in Peruvian Amazonia
Journal of the New York Entomological Society
1997
Journal Article
105
1-2
105-112
Parque Nacional del Manu ecology Hymenoptera Insecta Arthropoda Invertebrata Animalia Azteca Dolichoderus bispinosus Dolichoderus decollatus animals arthropods insects invertebrates abundance biomass diversity coexistence competition habitat heterogeneity canopy Cocha Cashu Paraponera clavata inventories small spatial scales Madre de Dios Bibliography
A structurally complex patch of forest canopy in Manu National Park (Peruvian Amazonia), consisting of two trees and eleven associated vines, was sampled using insecticidal fog. Approximately 62,000 ants were collected and sorted to species. The total biomass (dry weight) of adult ants in the sample was close to 49 g. Dolichoderus bispinosus, the dominant species in the sample, made up 64.2% of the ant biomass and 69.0% of the individual ants. The four most abundant species (Dolichoderus bispinosus, Dolichoderus decollatus, Azteca sp. 1, and Paraponera clavata) together comprised nearly 95% of the biomass and individuals in the sample. In spite of the clear dominance of the sample by a few species, a total of 85 species in 29 genera were found, making this the most species-rich point sample of a canopy ant fauna ever documented. Sampled at the level of a small number of trees, the rainforest canopy ant fauna reveals a pattern of remarkable species richness accompanied by strikingly low equitability in the rankabundance distribution, or ecological diversity. A small number of species overwhelmingly dominate the ant assemblage but fail to exclude other ant species. Competition appears to limit the number of dominant species that can coexist in small areas, but a large majority of species present do not compete with the dominants and exist to a greater or lesser extent independently of them. The low ecological diversity observed in the sample may be in part a function of the spatial scale of sampling, and increased sampling should lead to a change in this pattern. The extent to which the species abundance distribution would become more equitable cannot be determined at this time. Finally, the structural complexity of the canopy may promote high species richness by creating microhabitat-linked species associations that effectively function as separate, non-competing ant assemblages.