Bat habitat use in logged jarrah eucalypt forests of south-western Australia

1. Ecologically sustainable forest management is being implemented to address the competing demands of timber production and conservation, but its effectiveness is poorly understood. Bats play key roles in forest ecosystems and are sensitive to timber harvesting, so are potential indicators of whether management is successfully achieving biodiversity conservation in production forests. 2. We evaluated logging impacts in jarrah eucalypt forests of south-western Australia by examining insectivorous bat activity, feeding buzzes and insect biomass at four sites in each of recently logged forest, young regrowth and old regrowth. 3. Forest tracks supported higher overall activity and higher feeding activity than off-track sites, but activity was similar on-track irrespective of logging history. However, off-track activity in old regrowth was significantly higher than in either young regrowth or recently logged forest. 4. Vespadelus regulus and Nyctophilus spp. were more active in old regrowth than other logging histories. Similarly, V. regulus, Nyctophilus spp., Chalinolobus gouldii, Chalinolobus morio and Falsistrellus mackenziei activity was significantly greater on- than off-tracks, but activity was similar on-track across logging histories. 5. Increased understorey clutter was the strongest predictor of reduced bat activity in off-track sites. Reduced clutter and roost availability most probably explained greater activity in old regrowth forest. Neither insect biomass nor interactive effects of clutter and insect biomass significantly affected bat activity. 6. Synthesis and applications. Tracks provided internal linear edges within cluttered forests allowing bat species to use such areas for foraging. However, our results suggest that the retention of unlogged areas within logged forests is likely to be the most effective strategy in many forest ecosystems for conserving bat populations and achieving ecologically sustainable forest management for this group.

Paul W. Webala, Michael D. Craig, Bradley S. Law, Kyle N. Armstrong, Adrian F. Wayne and J. Stuart Bradley