School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemThe effects of fire and landscape structure on animal communities, species, and connectivity( 2023-04)The loss and fragmentation of habitat associated with land use change is the primary driver of global biodiversity declines. Changes to fire regimes that alter habitat suitability also threaten a range of animal taxa. Fire has been increasingly recognised as an important ecological process and is now used to manage fire-prone landscapes around the world, but important questions remain about the effects of fire regimes on animals, especially in fragmented landscapes. The aim of this thesis is to determine the influence of landscape structure (the composition and configuration of landscape elements) on animals in heathy woodlands in southern Australia in terms of fire, fragmentation, and interactions between them. First, I explored post-fire growth stage and land use together as components of landscape structure and assessed their relative and interacting effects on mammal communities. I used camera traps to collect mammal presence-absence data in 2019-20 and analysed it using ordination and linear modelling. I found that land cover composition was the primary influence on community composition. The composition of the fire mosaic had a secondary, weaker effect and one that may change depending on land cover composition. Second, I explored habitat structure as a mechanism by which fire regimes may affect mammal species, using a species activity index derived from the same camera trap data. Post-fire growth stage (a categorical representation of time since fire) was not a direct predictor of any species’ activity levels, but some habitat structure attributes were linked to certain growth stages and were therefore a mediating influence on animals. Finally, I assessed how the growth stages influence functional connectivity for a litter-dwelling skink. I used genetic data, landscape resistance modelling, and circuit theory-based mapping to find the relative connectivity of land use types and growth stages. Functional connectivity varied little with growth stage, with the primary influence on connectivity being the matrix of pasture and forestry plantation. Overall, I did not find direct effects of growth stage on animal communities, species, or connectivity. However, less obvious effects such as the composition of the fire mosaic beyond the site-scale and indirect effects through habitat structure are important to consider in future fire management. The extent of native heathy woodland was also vital for native mammal communities and functional connectivity; remaining native vegetation must be protected and expanded for the best outcomes for native diversity and species persistence.