Impact of commercial forest management on geophilous carabid beetles (Coleoptera: Carabidae) in tall, wet Eucalyptus obliqua forest in southern Tasmania

The impact of silvicultural practices (clearfelling, slash burning and sowing) on carabid beetle communities in tall wet Eucalyptus obliqua forests in southern Tasmania was examined using traplines of pitfalls in a chronosequence of regenerating coupes. Total species richness (n = 18) was modest compared to other temperate forests and was nor systematically changed by forest management, although it was considerably lower in 20 year old regrowth than in younger regrowth or old-growth controls, possibly due to habitat simplification. The Shannon-Weiner Index was at a minimum in intermediate aged regeneration. TWINSPAN analysis assisted recognition of beetle communities typical of broad stages in the forest succession, with a major dichotomy between most old-growth sites plus young sires and intermediate plus advanced regeneration sites. Vector fitting of environmental variables in an ordination of the sites by non-metric multidimensional scaling revealed a significant influence for the age of regeneration and litter depth, but not bare ground percentage or soil pH. Survival of carabids in the habitat mosaic created by commercial forestry activity is likely to depend on both reinvasion from edges and survival of individuals in the fire-protected refuges that exist within the coupes. Pioneer species were winged, small in size, and non-endemic whereas the opposite was true of the fauna in the older sites. Carabids in eucalypt forests have good potential as indicators but their seasonality in occurrence demands that sampling be extended over most of the year.