Threatened stag beetles in Tasmania's production forests : single-species studies contributing to biodiversity conservation

Although many formal reservation targets have been attained under Tasmania's Comprehensive, Adequate and Representative (CAR) reserve system, a large proportion of habitats important for threatened species, particularly invertebrates, remain in the off-reserve landscape. The development of conservation management strategies for species whose habitat coincides with areas subject to intensive forestry practices has been severely hampered by a lack of knowledge of the characteristics, spatial distribution and extent of habitats they occupy, and the of the planned disturbance regimes. The distribution, habitat and conservation requirements of three species of stag beetles (Coleoptera: Lucanidae) listed under the schedules of the Tasmanian Threatened Species Protection Act 1995, Hoplogonus simsoni, Lissotes latidens, and L. menalcas, were investigated in order to inform the development of management strategies for the conservation of their habitat throughout production forests. All three species are still restricted to small portions of the State, however this study found that they have wider distributions than previously recorded. Wet eucalypt forest and mixed/rainforest constituted potential habitat for all three species. Through relatively fine-scale predictive habitat modelling it was possible to identify with a reasonable level of confidence the spatial distribution of quality habitat for the litterdwelling lucanid H. simsoni, and the areas where this habitat overlaps most strongly with planned forestry activities. The abundance of H. simsoni was related to a particular forest structure, in addition to altitude, aspect and slope. Only broad forest types proved to be a reliable predictor of the occurrence of the obligate log-dwelling lucanid, L. menalcas, and the soil-dwelling L. latidens. However, as with H. simsoni, the abundance of L. latidens was associated with a particular forest structure, but also the quantity of coarse woody debris (CWD). The conversion of potential wet forest habitat to plantation resulted in the local extinction of H. simsoni. Given their association with CWD, it is expected that this practice would have a similar effect on the two Lissotes sp. Whilst all three species occurred in silvicultural regeneration following clearfelling, there was insufficient evidence to determine the effects of such practices on the long-term viability of populations of the species. Of concern for all three species is the loss of structural habitat features identified as important to the species through clearfell, burn and sow (CBS) forestry practices. There is an urgent need to determine the ecological sustainability of present forest management practices, such as CBS, in relation to the maintenance of CWD over successive rotations. All three species were inadequately reserved across their ranges with the bulk of their habitat coinciding with areas managed as production forest. A multi-scaled approach to the conservation of the three species' habitats, incorporating the maintenance of forest structural elements identified as important to each species, is recommended throughout their ranges. In particular, 'off-reserve' conservation strategies for the species need to include limits on the area of potential habitat that may be converted to plantation. The conservation requirements of these three threatened species illustrate the need to expand the focus of habitat conservation from static, set-aside approaches to strategies that incorporate the temporal dynamics of habitat maintenance. The value of single-species studies to the conservation of forest biodiversity in general is discussed.