The distribution and abundance of terrestrial vertebrates in the jarrah (Eucalyptus marginata) forest, south-western Australia, in relation to habitat at multiple temporal and spatial scales

[Truncated] Understanding the factors associated with species distributions and abundance is an integral part of biodiversity conservation and management. The identification of valuable habitats where management resources can be targeted is one way of increasing the likelihood of successful species conservation. This thesis explores patterns of distribution and abundance in terrestrial vertebrates in relation to habitat characteristics at multiple spatial and temporal scales in a globally recognised biodiversity hotspot in south-western Australia. The study is centred on the Upper Warren region, which has relatively high abundances of a diverse array of threatened mammals and multiple land uses including nature conservation, timber harvesting and agriculture. The region is centrally important to the conservation of the critically endangered Bettongia penicillata or woylie and includes a large fenced exclosure (Perup Sanctuary) designed to protect the woylie from predation by introduced species. Patterns in the distribution and abundance of terrestrial vertebrates were explored in the recently constructed Perup Sanctuary and across the Upper Warren region. This research was conducted in order to understand the relationship between woylies and habitat in the context of dramatic changes in the abundance of the woylie from both the perspective of the ecology of the species itself, as well as other co-occurring fauna that may be vulnerable to and indirectly affected by changes in woylie abundance. The causes of a recent and substantial woylie decline are not well understood and this research may help to inform what factors may be involved and where conservation actions in relation to the woylie and biodiversity in the Upper Warren more generally should be directed to deliver greater conservation outcomes.

Typically conservation management focuses on single species, often with limited consideration of the dynamic nature of ecology over space and time. While managing habitat for the conservation of one species, managers must be aware and consider the consequences of that management on other species within the ecosystem. In terms of the potential impact woylies as ecosystem engineers may have on co-occurring species, small terrestrial vertebrate species are potentially the most sensitive to conservation actions directed at woylies because they inhabit the same ground storey and soil layer utilised by woylies. This thesis takes a more holistic ecological approach and contextualises the relationship between woylies and habitat in regard to the habitat associations of co-occurring small terrestrial vertebrates, vegetation across multiple spatial scales and landscape disturbance. I specifically ask a) what is the relative value of broad habitat types for small terrestrial vertebrates (frogs, reptiles and small mammals), b) within those habitats, what fine scale environmental characteristics might be influencing the abundance of those species, c) how do woylies utilise space and habitats inside and outside the fenced exclosure, d) over time and during substantial population change, do landscape characteristics associated with disturbance help explain the distribution and abundance of woylies, and e) post population decline, do fine-scale vegetation and landscape characteristics help explain the presence of woylies across the region?