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

Abstract

The effects of two prescribed low intensity fires (from 73 to 123 kW m −1) within 5 yrs on invertebrates in litter/upper soil were assessed. The 7.8-yr study was based on 98 159 arthropod specimens representing 34 ordinal or lower level taxa contained in 3200 pitfall trap samples from a twice burnt site and an unburnt control site within a 29.9 ha area. The two fires had no discernible effect on total insects, Araneae (spiders), Coleoptera (beetles) and Diptera (flies), though activity of total arthropods and total non-arthropods decreased significantly after the first fire due largely to Collembola (springtails), although within 5 yrs, the activity of these groups had recovered to prefire levels. However, there was no change in activity in these three groups following the second fire, leaving the question open as to whether fire was the cause for the change following the first fire. The activity of Formicidae (ants) increased and Dermaptera (earwigs) decreased following the second fire although effects other than fire are believed to be the cause. As the increase in Formicidae and decrease in Collembola and Dermaptera activity were confined to a single postfire period only, it is not possible to determine whether or not these changes were fire-related. Two consecutive fires in autumn appear to have a minimal effect on activity of major arthropod groups in the forest litter layer. The interval of prescribed fires in autumn should be not less than 5 yrs. Further research is required on families and species comprising the major arthropod groups before precise prescriptions on fire frequency can be formulated. In forest where protracted drought has supervened, a second burn should be delayed until the drought has broken.