School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemLinking fire, climate, connectivity and animal conservation( 2023-05)Australia’s forests and woodlands have been severely fragmented by agriculture, urbanisation and forestry, resulting in loss of habitat for native species. Habitat loss and fragmentation affect landscape structure, defined as the composition and configuration of land cover types. Species persistence in modified landscapes depends on the landscape structure and the availability of resources, which may be altered through management practices, such as prescribed fire. Fire can be used in the ecological management of many terrestrial ecosystems, where its application or suppression alter habitat structure and the availability and configuration of key resources. Current approaches to ecological fire management do not consider the influence of the surrounding landscape or the effect of fire on animal movement (connectivity) within or among habitat patches. The implications of current fire regimes for long-term population persistence are also overlooked. Connectivity is linked to persistence because it maintains dispersal, gene flow and genetic diversity, helping species combat environmental change and avoid extinction. Incorporating connectivity into fire management will help conserve biodiversity in fragmented landscapes. In my research program I investigated how 1) species richness and mammal community composition and 2) individual species respond to habitat, fire and landscape structure using data from remote-sensing cameras collected in south-eastern Australia. Additionally, I combine fire simulation modelling and connectivity analyses using genetic data to 3) compare future connectivity for two small mammals, yellow-footed antechinus (Antechinus flavipes) and heath mouse (Pseudomys shortridgei) under alternative fire regimes and predicted climate scenarios. These findings will inform an understanding of how fire, habitat and climate influence mammal communities, and species’ distributions, connectivity, and persistence. In Chapter 2, my first data chapter, I evaluate the relative influence of fire (time since fire and fire frequency), vegetation type, land use diversity and annual rainfall on ground-dwelling mammal community composition and species richness. Findings suggest that vegetation type and rainfall have the greatest influence on the mammal community and the vegetation type treeless heath is of great importance to critical weight range mammals. In Chapter 3, I focus on 1) the influence of vegetation structure, fire, and annual rainfall on the occurrence of 18 mammal species in two vegetation types (heathy woodland and treeless heath) at the local and landscape scale and 2) if species’ life history traits influence their responses to local and landscape scale predictors. At the local scale understory complexity influenced the occurrence of nine species in both vegetation types. In the woodland species occurrences were also influenced by annual rainfall and basal area while in treeless heath time since fire and fire frequency were important drivers. At the landscape scale, the extent of mature vegetation was most influential in the treeless heath while fire age-class diversity and the extent of native vegetation was most influential in the woodland. All tested species life history traits (size, diet, nest requirement, mean annual offspring and native status) were found to influence species responses at the site scale while only one trait (mean annual offspring) was found to predict species responses at the landscape scale. In Chapter 4, I combine fire simulations and connectivity analyses to compare future connectivity under four alternative fire regimes (0%, 1%, 2% and 4% of total available area burnt per year) and predicted future climate, for two small mammals, heath mouse (Pseudomys shortridgei) and yellow-footed antechinus (Antechinus flavipes). Genetic modelling found that heath mouse and yellow-footed antechinus considered the early post-fire age class low resistance (high connectivity) and pastural farmland to be high resistance (low connectivity). The results of the simulations suggest that the composition of the future landscape will shift towards more recently burnt vegetation, increasing connectivity for the heath mouse and yellow-footed antechinus. Overall, my research has provided new insights into how vegetation type and structure, fire and landscape structure influence mammal species distributions and contributed new information towards an important knowledge gap; how fire regimes influence animal movement and connectivity. Collectively, the findings will inform how fire regimes may influence species distributions and connectivity for long-term persistence in fire-prone landscapes.