Incorporating metapopulation dynamics of greater gliders into reserve design in disturbed landscapes

A metapopulation model of the greater glider (Petauroides volans), an Australian forest-dependent, arboreal marsupial, was developed that accounted for changes in habitat quality of patches in response to fire. Spatial correlation in the incidence of fire was incorporated in the model, with correlations within and among habitat patches. The correlation in the incidence of fire declined with the distance between points in the landscape. The spatially correlated disturbance regime allowed the model to simulate partial burning of patches, with the chance of partial burning depending on the size of patches. Including spatial correlation in the model tended to increase risks of extinction by incorporating correlation between patches but also decreased risks by incorporating imperfect correlation within patches. The model was used to investigate the design of nature reserves that are exposed to disturbance by fire in mountain ash (Eucalyptus regnans) forests of southeastern Australia. We used a number of scenarios to investigate the influence of the spatial configuration of reserves (size, number, and location of patches) on the risk of extinction of greater gliders. The model indicated that large, contiguous areas of old-growth forest were important for the persistence of greater gliders. However, in timber production forests in the Central Highlands region of Victoria, old-growth forest is rare and fragmented. Within a typical timber management area of ~6700 ha, the predicted risk of extinction for greater gliders within 300 yr in the reserved old-growth remnants was 0.44. To reduce the risk of extinction below 0.10, an additional 650 ha of regrowth forest should be reserved from timber harvesting, with these areas concentrated around the largest old-growth patches. The results of our study highlight the importance of considering disturbance regimes (particularly aspects of spatial correlation) in reserve design and metapopulation dynamics.