THE CONSERVATION OF ARBOREAL MARSUPIALS IN THE MONTANE ASH FORESTS OFTHE CENTRAL HIGHLANDS OF VICTORIA, SOUTH-EASTERN AUSTRALIA .7. MODELING THE PERSISTENCE OF LEADBEATERS POSSUM IN RESPONSE TO MODIFIED TIMBER HARVESTING PRACTICES

A computer model for Population Viability Analysis (PVA) was used to s imulate the relationship between the persistence of populations of the endangered species, Leadbeater's possum, Gymnobelideus leadbeateri an d the implementation of a range of possible modified timber harvesting practices in two wood production blocks within the montane ash forest s of the central highlands of Victoria, south-eastern Australia. The r esults of our analyses revealed that under the existing conservation s trategies there was a high probability of extinction over the next 150 years in both blocks. Given that timber production areas comprise mor e than 75% of the distribution of G. leadbeateri, our findings highlig ht a need for additional conservation measures to enhance the survival prospects of the species. The range of upgraded conservation strategi es that were examined included (1) extending the rotation time between logging operations, (2) modifying silvicultural practices to increase the amount of forest retained within each harvested coupe; and (3) pe rmanently withdrawing areas from wood production. All of each of these approaches were found significantly to reduce the probability of exti nction of populations of G. leadbeateri. However, when the relative me rits of the various strategies were compared, the permanent withdrawal of potential logging coupes from timber harvesting was predicted to b e the most efficient approach. Importantly, this strategy would have a number of practical advantages including that it overcomes both (1) t he logistic difficulties of ensuring the long-term survival of retaine d trees within logged areas; and (2) human safety issues arising from implementing modified silvicultural practices. This practical applicat ion of PVA to compare the merits of different potential management opt ions has provided new information that will enhance present efforts to conserve G. leadbeateri in wood production areas.