Effects of three short rotation prescribed fires in spring on surface-active arthropods in dry sclerophyll eucalypt forest of west-central Victoria

Abstract

Summary The effects of three prescribed low intensity fires varying from means of 80 to 209 kWm−1 within six years on invertebrates in litter/upper soil were assessed. The 8.6 year study was based on 88 934 arthropod specimens, representing 35 ordinal or lower level taxa contained in 3520 pitfall trap samples from a site burnt three times in spring and an unburnt control site within a 30.7 ha area. The three fires had no discernible effect on total taxa, total non-insects, Araneae (spiders), Acarina (mites), Collembola (springtails), total insects and Formicidae (ants), although activity of the Coleoptera (beetles) decreased significantly after the second and third fires while that of the Diptera (flies) increased over the same period. However, as Coleoptera and Diptera activity on the unburnt control site decreased and increased respectively over the same period, it is uncertain whether the changes in activity were due to the fires or other non fire-related environmental factors. Futhermore, these changes in activity resulted from one or two of the spring fires only, and not all three, further questioning whether the fires were the contributing causal factors. Three prescribed low-intensity fires in spring appear therefore, not to impact adversely on the activity of major forest litter arthropod groups, although the situation of the Coleoptera and Diptera is less clear due to similar activity on the unburnt control site in both cases. This therefore suggests that any fuel reduction burning in spring be conducted at intervals of not less than three years in order to minimize any impact on litter arthropods. Where a period of drought has occurred, burning should be delayed until the drought period has ended.