Tropical arboreal ants: why so abundant?

ANTS ARE AMONG the most numerous and readily observed arthropods of tropical forests. Indeed, based on their standing biomass and many effects on other species, ants (Formicidae) are arguably the dominant arthropod family in the canopies of lowland rain forest trees (Tobin 1995). Others have tried to account for the remarkable abundances of arboreal ants in canopy arthropod samples (see especially the works of Majer 1990 and Tobin 1991, 1994), and we attempt to extend these explanations here using stable isotopes to diagnose the trophic specializations of the most abundant ant taxa. We begin with a review of ant diversity and abundance in the tropical arboreal zone.