This thesis reports on the habitat requirements of arboreal marsupials in the dry sclerophyll forests of south-east Queensland, Australia. The objective was to provide information for prescriptions for use in a "Code of Practice" to achieve Ecological Sustainable Management of timber production in State Forests in the region. However, the results of this research could also be applied to achieve ecologically sustainable management of the large areas of leasehold and freehold forested land outside these crown lands.
The species richness and abundance of arboreal marsupials in these forests was positively correlated with the proportion of total stand basal area occupied by Lemon-scented Gum (Corymbia citriodora) and the height of the tallest trees. The proportion of total stand basal area occupied by C. citriodora was associated with differences in the availability of the foliar nutrients, nitrogen, phosphorus and potassium, with higher levels found as the proportion of C. citriodora increased. Common Brushtail Possums (Trichosurus vulpecula) and Greater Gliders (Petauroides volans) more often selected tree species, including C. citriodora, that had higher levels of these three nutrients although flowering events affected tree selection as well. The height of the tallest trees was an indicator of the overall productivity of the forest type with the taller forests having greater rates of wood production.
Hollow-bearing tree density also had an influence on species richness and abundance of arboreal marsupials, with fewer species and lower densities of arboreal marsupials being found at sites with low densities of hollow-bearing trees. There were also lower species richness and abundance of arboreal marsupials at sites with high densities of hollow-bearing trees. This apparently anomalous finding is explained by the fact that the forests now with low densities of hollow-bearing trees are also the best quality forests that have been intensively logged in the past. The forests now containing the higher densities of hollow-bearing trees are sites of poorer quality.
At some more intensively logged sites the density of living hollow-bearing tree is now too low to support the full range of arboreal marsupials, but arboreal marsupial numbers are being maintained by hollow-bearing stags (standing dead trees). However, these hollow-bearing stags have a short standing time of <50 years. A survey was undertaken to assess the rates at which hollows developed in aging trees of various species. This found that the remaining standing time of stags was much less than the age at which most tree species began to form hollows, which was 190-240 years, suggesting a deficit in the number of hollow-bearing trees could develop in the future. However, there are enough larger trees of all species still available that are likely to form hollows within the next 50 years and thus meet the requirements of arboreal marsupials, provided the prescriptions in the current Code of Practice for native forests are adhered to.
In addition, trees with a large diameter and an overmature or senescent growth-stage tend to have more hollows with larger entrances than younger and smaller trees. These larger trees with more entrances to hollows and large entrances (>7 cm diameter) were also more likely to be occupied by the larger arboreal marsupials (the Common Brushtail Possum, Greater Glider and Yellow-bellied Glider (Petaurus australis)) than smaller hollow-bearing trees. Squirrel Gliders (Petaurus norfolcensis) and Sugar Gliders (Petaurus breviceps) occupied hollow-bearing trees evenly across the size range and were able to occupy trees with small entrances (<7 cm diameter) as well.
Due to the present lower than-natural-densities of hollow-bearing trees in dry sclerophyll forests managed for timber production, arboreal marsupials may need to have the ability to co-occupy hollow-bearing trees with other species. At a site where the density of hollow-bearing trees was similar to those specified by prescriptions in the Code of Practice for wood production forests in south-east Queensland, there was a high proportion of co-occupancy of hollow-bearing trees by five species of arboreal marsupials. These species were the Common Brushtail Possum, Greater Glider, Yellow-bellied Glider, Squirrel Glider and Sugar Glider. There was also a high incidence of co-occupancy of the hollow-bearing trees during the same day while Common Brushtail Possums and Greater Gliders co-occupied the same hollows with temporal separation. Hollow-bearing trees that had a large diameter at breast height (DBH), numerous entrances to hollows and the largest entrances to hollows were more likely to be occupied by more than one species of arboreal marsupials.
These findings suggest that arboreal marsupial populations can successfully be maintained in areas with the hollow-bearing tree densities that are suggested in the code of practice and that hollow-bearing trees with a large DBH, multiple entrances and with some large entrances were the best for retention as habitat trees for all arboreal marsupials. This means that the prescriptions in the present Code of Practice can provide adequate protection for arboreal marsupial populations in State forests, although some modification will be necessary.