BIODIVERSITY ESTIMATES: ANT COMMUNITES AND THE RARE ANT SPECIES (HYMENOPTERA: FORMICIDADE) IN A FAUNA OF A SUB-TROPICAL ISLAND.

Harold Gordon FOWLER[1]

§    ABSTRACT: Using pitfall traps and honey and sardine baits, the ground ant fauna of the Atlantic Forest Ilha do Cardoso State Park was sampled in 2 fixed point grids of 7 X 7 (2 m separation) at 6 dates. A total of 51 species were record using all sampling techniques, with pitfall trapping sampling significantly more species than baits. Log-series estimates, mean-variance relations, and Poisson models for sampling intensity were compared. Log-series estimates of diversity produced consistently higher estimates for pitfall trapping than for baiting studies, as well as comparative number or sampling technique specific species. Faunal similarities were highest for the number of individuals collected at sardine baits and pitfall traps, and lowest for honey baits. Presence-absence and point occupied data provided lower similarities. Given the high frequency of "rare" species ( < 0.1 individual) and the aggregated nature of ant species, an infestimal number of samples would be needed to detect these rare species in the Poisson model, increasing even more when baits and not pitfall traps are used. Pitfall trapping is recomended if more unbaised estimates of the ground fauna are criteria priorities.

§    KEYWORDS: Sampling; rarity; ants; biodiversity; Atlantic Forest; Brazil.

 



[1] Departamento de Ecologia - Instituto de Biociências - UNESP - 13506-900 - Rio Claro - SP.