Forest disturbance, forest wildlife conservation and the conservative basis for forest management in the mountain ash forests of Victoria—Comment

Abstract

A recent review by Attiwill outlined a range of aspects of disturbance regimes in forests and attempted to demonstrate their value in developing a basis for the “conservative management” of wood production areas. One of the key themes in these papers—that natural disturbance regimes should be a model for forest management, is a good one. However, there are major difficulties in determining the intensity, frequency and extent of timber harvesting operations that mimic “natural disturbance regimes“ and, in turn, form the basis of “conservative management” strategies which account for the full spectrum of forest values. This paper highlights a few of the many key considerations for truly integrated multiple-use forest management that were overlooked by Attiwill and which are an essential component of ecologically sustainable forest management. These relate to aspects of the conservation of forest wildlife that are sensitive to forest disturbances resulting from timber harvesting operations. Many of the examples of the response of wildlife to forest disturbance outlined by Attiwill were from the mountain ash ( Eucalyptus regnans) forests of Victoria, south-eastern Australia. Unlike the impression given by Attiwill, the results of the array of detailed long-term studies on forest fauna in mountain ash forests that have been completed to date clearly indicate that balancing the multiple values of mountain ash forests will be a complex task requiring some major modifications to present multiple forest-use management strategies. This is because of the potential for current forestry activities to both: (1) produce long-term modifications to key components of vegetation structure and thus habitat suitability for fauna (e.g. old growth elements such as trees with hollows) and (2) fragment remaining patches of suitable habitat and create sub-divided populations that may not be viable in the long-term. Moreover, because a given species has survived disturbance regimes in the past, it is premature to suggest that it will persist in the future when new and recent forms of forest perturbation such as clearfelling are intensively and extensively applied throughout large areas of the forest landscape. In mountain ash forests, a conservative basis for forest management will require much more than the creation of a series of ages of regrowth forest as implied by Attiwill, but also the establishment of more and larger areas of old growth forest and/or modifications of clearfelling regimes to better allow for the development of suitable habitat for wildlife that are sensitive to the impacts of timber harvesting, such as the endangered arboreal marsupial Leadbeater's possum ( Gymnobelideus leadbeateri). Until management strategies that are more sympathetic to wildlife conservation are embraced, there remains a high probability that Leadbeater's possum, and other species with similar habitat requirements, could be eliminated from some wood production areas, implying that current forestry practices are not ecologically sustainable in the long-term.