Effect of fire retardant application on heathland surface-dwelling families of the Order Coleoptera (beetles) in Victoria, Australia

The effects of the application of fire retardant at varying rates on surface-dwelling Coleoptera at family level 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 of 2843 specimens representing 17 Colepotera families contained in 5400 pitfall trap samples were collected. It was concluded that despite the application of fire retardant at varying rates, there was no significant effect on invertebrate activity at ground level amongst the Coleoptera family groups Pselaphidae, Staphylinidae, Carabidae, Elateridae, Tenebrionidae, Cryptophagidae and the categories Total Minor Families and Decomposers across both study sites. These taxonomic groups appear to form a stable component of the heathland invertebrate community across both sites. However, significant increases in activity on retardant treated sites were observed within the family Scydmaenidae at Marlo, due to increases in activity of the species Syndicus macrosticta (Lea). Evidence suggests that retardant application may cause increased foliage mortality and associated litter accumulation, and weed coverage leading to the creation of habitat favourable for increased Scydmaenidae activity when combined with prevailing suitable climatic conditions. Further research is required to establish whether a link between litter accumulation, climate and increased activity exists. When assessed in terms of general diversity, taxon richness and community evenness, Coleoptera family groups were unaffected by retardant application at both study sites. Further study is required to determine whether retardant application impacts at other lower taxonomic levels. The combined effect of fire and retardant on invertebrate communities also requires further study.