The use of hollow-bearing trees retained in multi-aged regenerating production forest by the Tasmanian common brushtail possum (Trichosurus vulpecula fuliginosus)

Abstract

Context Hollow-bearing trees are frequently retained in timber-production areas as part of measures to mitigate against the impacts of forest harvesting on fauna, yet few studies have investigated the effectiveness of such measures. Such studies are essential for adaptive forest management. Aims The main aim of the present study was to evaluate the use of hollow-bearing trees retained in harvested and unharvested forest as den sites by the Tasmanian common brushtail possum. In particular, we examined the distribution and types of hollow-bearing trees used as den sites and whether or not their use in harvested sites was influenced by time since harvest. Methods Thirty brushtail possums were radio-tracked to their day-time den sites between March 2007–July 2007 and July 2008–October 2008, at five dry Eucalyptus forest sites (three regenerating after partial harvest with hollow-bearing trees retained inside the coupe and two in relatively undisturbed forest) in south-eastern Tasmania, Australia. Key results The brushtail possums tracked in the study denned primarily in hollow-bearing trees at both the harvested and unharvested sites. At sites regenerating 8 and 10 years after harvest, most den site locations were in trees retained outside the harvest area, in large patches. In contrast, at the site regenerating 17 years after harvest, isolated trees and small patches within the harvested area were used. Conclusions Hollow-bearing trees retained within harvest areas do provide habitat for hollow-dependent fauna such as the common brushtail possum and enable recolonisation of harvested areas in the medium term. However, in the short term these trees may not be used and hollow-bearing trees retained in the surrounding landscape are important for providing refuge as the harvested area regenerates. Implications The retention of hollow-bearing trees in harvested areas may be an effective measure at enabling recolonisation of harvested areas once suitable habitat regenerates, but it is also important to ensure that large patches of mature forest (containing hollows) are retained in the surrounding landscape to ensure the persistence of hollow-using fauna.