Tree Hollow Requirements of Leadbeater's Possum and Other Possums and Gliders in Timber Production Ash Forests of the Victorian Central Highlands.

Abstract

A model is presented of relationships between the density of Leadbeater's possum (Gymnobelideus leadbeateri) and other tree-hollow dependent possums and gliders and the density of potential nest trees (PNT) in Eucalyptus regnans/E. delegatensis forests, where PNT are defined as all living or dead trees with d.b.h. more than or equal to 0.5 m and ht. more than or equal to 6 m. The total density of all possums and gliders increased linearly with PNT density, in an approx. 1:1 ratio, then plateaued at an av. max. density of 11.3 animals per 3 ha once PNT density exceeded 12 per 3 ha. Regression models predict that G. leadbeateri will be absent from the majority of sites with less than 4.2 PNT per 3 ha and will increase linearly in density to an av. max. of 7.8 animals (or 3.1 colonies) per 3 ha on sites with more than 10 PNT per 3 ha. The absence of G. leadbeateri from sites with fewer than 4.2 PNT per 3 ha was attributed to: competition for hollows from other species; use of more than one PNT by individual colonies; and unsuitability of hollows in up to 2 out of every 3 PNT. Regression models predict that current logging prescriptions in ash forests, which call for retention of a minimum of 15 trees for every 10 ha clear felled, will result in elimination of G. leadbeateri from the majority of clearfelled coupes, and will reduce the total number of hollow-dependent possums and gliders to less than one-eighth of their av. max. density in unlogged forest. A range of forest management options are presented and discussed to ensure the continued availability of PNT for hollow-dependent arboreal mammals in timber production forests.