Modelling the impact of timber harvesting on a rare carnivorous land snail (Tasmaphena lamproides) in northwest Tasmania, Australia

A stage-structured, stochastic metapopulation model was developed for a rare carnivorous snail, Tasmaphena lamproides, occurring in production forest in northwest Tasmania, Australia. The model was used to investigate the impact of a range of plantation options and harvesting strategies. These included: (i) a proposed ‘District plan’ with a combination of plantation conversion and native-forest harvesting; (ii) a ‘plantation’ scenario where all suitable areas within the forest are converted to plantation; and (iii) a ‘native forest’ scenario where all areas are harvested to a schedule and regenerated to native forest. The model facilitates exploration of management options and their consequences in terms of their effects on average population sizes and risk of decline of T. lamproides. The results suggest that retention of contiguous areas regenerated to native forest, the timing of harvest activities, and the management of dispersal barriers may be important elements of a successful management strategy for T. lamproides. A detailed analysis was conducted to determine the sensitivity of the model to small changes in parameter estimates and assumptions. This sensitivity analysis can be used to highlight the features of the model that require a more extensive investigation and to guide future research into the conservation of T. lamproides.