Changes in the abundance and activity of certain soil and litter fauna in the jarrah forest of Western Australia after a moderate intensity fire

Abstract

Soil coring and pitfall trapping in high quality jarrah forest from December 1979 until November 1982 evaluated the effect of a moderate intensity fire on the abundance and activity of the larger invertebrates inhabiting soil and litter. A burnt plot subject to a moderate intensity fire (780 kW m-1) in January 1980 was compared with an adjacent unburned control plot. Differences between the plots in the invertebrate fauna collected on 17 sampling dates after the fire were assessed by the Wilcoxon non-parametric test. Ten taxa in the soil cores showed no significant difference in density between plots from February 1980 to November 1982: Megascolecidae (earthworms), Araneae (spiders), Isopoda (daters), Isoptera (termites), Dermaptera (earwigs), Orthoptera part (crickets), Coleoptera (beetle) larvae, Coleoptera adults, Diptera (fly) larvae and Formicidae (ants). Diplopoda (millipedes) occurred at significantly greater densities in the burnt plot, and Chilopoda (centipedes), Thysanura (silverfish) and Blattodea (cockroaches) at significantly lower densities in the burnt plot. The total number of taxa and the density and biomass of that part of the invertebrate fauna studied did not differ significantly between plots. Similar numbers of 12 taxa were captured in pitfall traps in both plots: earthworms, spiders, Pseudoscorpionida (pseudoscorpions), centipedes, termites, cockroaches, earwigs, adult beetles, fly larvae, Hemiptera (bugs), Lepidoptera larvae (caterpillars) and Orthoptera part (grasshoppers). Crickets, beetle larvae and ants were captured in greater numbers in the unburnt plot. Similar numbers of taxa and of individuals (of all taxa combined) were captured in the plots. Therefore, all but three taxa recovered in density within three years of a moderate intensity fire in the jarrah forest. The relative abundance and/or activity of three other taxa remained depressed on the burned plot during the same period.