The conservation value of Australia's stock route network : a multi-taxonomic approach to management and planning

Stock routes have been a feature of the Australian landscape since the mid-1800s. Originally established to provide corridors of forage and shelter for livestock droved 'on the hoof', the vegetation within them remained standing while vast tracts in the surrounding landscape were cleared to make way for agriculture. However, livestock are now more commonly transported in trucks, so managing authorities no longer receive adequate income from droving permits to offset costs. At the commencement of this PhD it was being suggested that some stock routes would be lost to freehold tenure, in spite of the fact that many scientists believed them to be of great value for conservation. This project was structured into three distinct sections, aimed at providing evidence for the values of stock routes, and advice on how to best manage and plan for them into the future. The first section took the form of a literature review and spatial analysis, where I demonstrated that stock routes plays a considerable role in biodiversity conservation, recreation, tourism, preserving Indigenous cultural heritage, and as a stock refuge. I also found that they occupy fertile, low-lying areas of the landscape, and contain associated vegetation communities which have been preferentially cleared for agriculture and are under-represented in protected areas. In the second empirical section of the project I conducted surveys of three taxonomic groups which provide ecosystem services: woodland birds, wild bees, and insectivorous microbats. Data were collected from 32 stock routes which varied in width and vegetation condition, and in the fields adjacent to these stock routes. Statistical modelling was then used to quantify the response of each group to local and landscape variables characterising the survey sites. Although specific responses were different for each taxonomic group, there were some consistencies in my findings. Scattered trees in fields had a positive effect on all taxa, and the value of both native pastures and formal conservation areas close to the stock routes was also a recurring pattern. In the final section of my thesis I concentrated on the debate surrounding connectivity; whether it should be included as a goal in conservation planning, and whether this will result in trade-offs with habitat area and quality, or economic costs. It would seem logical to plan for connectivity if some stock routes are to be sold whilst others are retained for conservation purposes. Using them as a case study, I ran a Marxan minimum-set analysis which demonstrated that only certain connectivity approaches had effects on the costs and siting of reserves in conservation planning, and these effects were substantial only when conservation targets were set high. At the time of writing, the future of the stock route network remains as uncertain as it was in 2009. However, through this work I have been able to provide a much more solid foundation for potential conservation decisions than was previously available. I have also demonstrated that the stock route network is an indispensible environmental heritage asset, which should be retained and managed for conservation in perpetuity.-- provided by Candidate