Canopy Ant Communities in the Semiarid Mallee Region of North-Western Victoria

Abstract

Ants were collected from the canopies of mallee eucalypts at Wyperfeld National Park in north-western Victoria by beating foliage on ten occasions from September 1979 to December 1980. The study was conducted at two adjacent sites: one that had been burnt by a wildfire during early 1977, and the other long unburnt. Both sites contained a mixture of three mallee eucalypt species: Eucalyptus dumosa, E. foecunda and E. incrassata. In contrast to the canopies of other eucalypt formations elsewhere in southern Australia, abundance and diversity of ants were very high. Ants represented 43-69% of all invertebrates, and a total of 44 ant species from 19 genera was collected. Iridomyrmex and Camponotus respectively contributed 10 and 11 species, and the most abundant ants were species of Iridomyrmex, Monomorium and Crematogaster. Ant composition was broadily similar at the two sites, and on different canopy species, although significant differences in abundance were apparent for some individual ant species. Except for tree-nesting Podomyrma adelaidae and Myrmecorhynchus sp. nr emeryi, the fauna was dominated by ground-nesting species, most of which appeared to forage on vegetation opportunistically. The unusually high abundance and diversity of the canopy ant fauna are attributed to the close proximity of the mallee canopy to the ground, coupled with an exceptionally rich ground ant fauna.