Diversity, Seasonality and Community Organization of Ants at Adjacent Heath and Woodland Sites in Southeastern Australia

Abstract

Adjacent heath and woodland sites at Wilsons Promontory in Victoria support at least 50 species of ants, with the most abundant being Rhytidoponera victoriae, Iridomyrmex spp. (nitidiceps group), Notoncus hickmani, Aphaenogaster longiceps, Camponotus ?intrepidus and Plagiolepis sp. Total numbers of individuals and species in the woodland were twice that in the heath; this was probably caused by the greater structural complexity of vegetation there, which increased the availability of nesting and foraging sites, the level of insolation of the ground, and possibly also food supply. Total ant activity followed seasonal cycles which correlated with changes in temperature and probably also food supply, and, within these constraints, was regulated by prevailing weather conditions. Individual species displayed distinctive foraging schedules which possibly play an important role in species coexistence. Community organization is analysed according to a scheme derived from studies of ants in arid Australia, where taxa are classified according to their physical requirements and their relationships with dominant species. Although the major species in the present study were separated by differences in body size, food type, and time of foraging, interspecific competition appears to be less important than it is in arid regions. At both sites, opportunistic species (Rhytidoponera) predominated, cryptic species (those associated with soil and litter, such as Plagiolepis sp. and Solenopsis sp.) were abundant, and Iridomyrmex appeared to have a relatively weak influence on the abundance of other ants. This contrasts with the situation in arid regions, where species of Iridomyrmex are extremely important, and opportunistic and cryptic species are often rare or absent.