Can multiscale models of species’ distribution be generalized from region to region? A case study of the koala

Abstract

Summary 1.While various studies have evaluated the habitat requirements for wildlife in fragmented forest landscapes at multiple spatial scales, few have considered whether there is regional variation in the most important factors. This is a conundrum for managers of any species with a broad geographical range: to what extent should studies in one region inform decisions in another? 2. We addressed this question using a case study of the koala, Phascolarctos cinereus , in three biogeographically different fragmented forested landscapes in eastern Australia. Mixed-effect logistic models were applied to predict koala occurrence from explanatory variables captured at four spatial scales: the individual tree, the stand ( < 1 ha), the patch (1-100 ha) and the landscape (100-1000 ha). 3. We used model averaging to account for model and parameter uncertainty, and tested the cross-regional discrimination ability of the models. 4. We discovered that multiscale models of koala distribution cannot be readily generalized from region to region, and that specific conservation actions for each region, rather than the entire geographical range, are more appropriate. We found a strong justification for adopting a hierarchical landscape approach to koala conservation across its range. However, cross-regional differences in habitat relationships occurred within this hierarchy. Exceptions were landscape context, which showed a consistently strong effect and high rank in all regions, and the presence of individual preferred tree species of the genus Eucalyptus , which showed modest consistency in its interaction with large-diameter trees across the regions. In contrast, the remaining habitat variables, including patch size (a key management factor), showed moderate to strong cross-regional variation attributed to the interaction of edaphic factors, landscape history and contemporary land-use patterns. 5. Synthesis and applications . Adopting a uniform conservation programme over a large geographical area is attractive to policy-makers and conservation planners. However, our study confirms the lack of generality of species distribution models over large areas. Consequently, we argue against adopting a uniform conservation programme for species with a large geographical range.

Palatability mapping: a koala's eye view of spatial variation in habitat quality

“…However, conservation professionals and landscape ecologists generally work at scales beyond the 7-ha reserve that we studied. For example, one previous multiscale model of koala habitat selection considered factors operating from the tree scale through the stand scale and patch scale to factors varying at a landscape scale of hundreds to thousands of hectares (McAlpine et al 2008). Reynolds (2008) has commented that two major challenges in spatial ecology are to understand the effects of landscape heterogeneity on animal movement and to translate observations taken at small spatial and temporal scales into expected patterns at greater scales.…”

Combining vessel-based surveys and tracking data to identify key marine areas for seabirds

“…AUC values were estimated in each simulation for both training and test datasets. After the 1000 simulations, the mean and upper and lower 95% CI of the AUC of both training and test dataset were used as a cross-validation measure of the predictive performance of the averaged model (McAlpine et al 2008). If the lower 95% CI limit does not include the 0.5 value, then there is evidence that the model has an ability to discriminate between the 2 groups (Hanley & McNeil 1982).…”

The dietary preferences of koalas,Phascolarctos cinereus, in southwest Queensland

“…Food availability and quality have been found to be important in determining the viability of koala populations (Gordon et al 1988;McAlpine et al 2008), so habitats with more favourite food trees would be preferred by koalas and used more frequently. Results of this study suggest that habitats with higher water availability, mainly riparian habitat, provide higher food availability and quality for koalas, which agrees with the findings of previous studies.…”