Factors at multiple scales affecting distribution patterns and their implications for animal conservation – Leadbeater's Possum as a case study

Abstract

Detailed field and modelling studies have been completed at different spatial scales for the endangered arboreal marsupial, Leadbeater's Possum (Gymnobelideus leadbeateri); a species virtually confined to the ash-type eucalypt forests in the Central Highlands of Victoria, south-eastern Australia. These forests are also subject to considerable pressure to produce timber and paper products. The studies of Leadbeater's Possum highlighted the factors influencing the distribution and abundance of the species ranging from broad distribution patterns, the occupancy of habitat patches at the landscape scale, and the use of individual den sites and the quality of trees that provide food within particular stands. These scales correspond to the entire known range of the species, sub-populations within a metapopulation occupying an ensemble of patches at the landscape scale, and colonies occupying den trees in individual stands. Information on the factors influencing the distribution of Leadbeater's Possum at one spatial scale were found to be important for informing processes at another. For example, an understanding of the species‘ habitat requirements informed the spatial distribution of habitat patches at the landscape level which, in turn, gave insights into predicted metapopulation dynamics. Each spatial scale of ecological investigation of Leadbeater's Possum had a corresponding scale of forest management, and they included: virtually the entire ash-type eucalypt resource in the region, the location of large reserves, the design of corridors and retained patches within production forest landscapes, silvicultural practices employed in individual stands, and the retention of individual trees and clusters of trees on logged sites. This range of forest management scales, and the corresponding-scaled array of ecological studies, have particular implications for the conservation of Leadbeater's Possum. The results of investigations to date have revealed that conservation efforts must focus on ash-type eucalypt forests in the Central Highlands of Victoria because populations of Leadbeater's Possum are virtually confined to these areas. Within the broadscale limits of the distribution of the species, the long-term conservation of Leadbeater's Possum will not only be dependent on large reserves, but also intermediate-scale reserves and corridors within wood production areas, as well changed silvicultural practices to better provide suitable habitat on logged sites. While each strategy will make a contribution to the persistence of Leadbeater's Possum, it also has important limitations; an outcome which highlights the need for a multi-scale approach to attempts to conserve the species. Notably, the overaching implications for the design of an array of different conservation strategies for Leadbeater's Possum could not have been derived from any single study at a particular spatial scale. Thus, the case study on Leadbeater's Possum suggests that consideration of factors at a range of scales should be an integral part of management and conservation planning, not only for this species, but for wildlife per se.