Effects of fire retardant application on heathland surface-dwelling ant species (Order Hymenoptera; Family Formicidae) in Victoria, Australia

Abstract

The effects of fire retardant application at varying rates on surface-dwelling ants in heathland communities were assessed over a 1-year period from March 2001 to March 2002. The study was conducted at two sites, one in East Gippsland at Marlo and the other in the Grampians region of south-west Victoria where a total across both sites of 6407 specimens representing 18 ant species contained in 5400 pitfall trap samples were collected. It was concluded that despite retardant application, no significant effect was observed within the major ant species Rhytidoponera metallica (Smith) and Pheidole sp. at both sites. These species appear to form a stable component of the heathland ant community. However, significant decreases in activity were observed for Camponotus terebrans (Lowne) at the Grampians site and Paratrechina sp. at the Marlo site. Evidence suggests that retardant application when combined with prevailing suitable climatic conditions, leads to foliage mortality, litter accumulation and weed invasion, leading to potential creation of habitat less suitable for activity of these species. When assessed in terms of taxon richness and community evenness, ant species were unaffected at the Grampians, while at Marlo, community evenness was affected due to the smaller number of individuals collected in the medium retardant treatment. When assessed by their functional groupings, the Subordinate Camponotini showed significantly reduced activity on the retardant treated sites at the Grampians directly as a result of C. terebrans activity. Further study is required to determine the combined effects of fire and retardant on ant species, as well as any longer-term effects past 1 year.