How does shrub encroachment fundamentally change mammal communities

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Farley-Lehmer 1, Tamika, Penman 2, Trent, McCarthy 3 Michael and Pascoe 4, Jack
1 School of Agriculture, Food and Ecosystem Science, University of Melbourne, Victoria, 3052


Tamika Farley-Lehmer (she/her) began working in the fire space as a forest firefighter in 2019, before moving into fire ecology. In her ecologist role, she focussed on implementing science-based burning regimes in the Otways region with the Conservation Ecology Centre. She collaborated on various projects studying the relationships between fire, plants and animals, including animal movement, predator and prey interactions, habitat utilisation, and post-fire plant responses. This experience ignited her passion for applied landscape ecology, particularly in the context of active fire management and ecological responses to fire disturbance. Starting in 2023, she continues to explore this ongoing research as part of her PhD. Her research employs fieldwork and modelling techniques to understand how fire management decisions influence the ecological structure and function of natural systems.

Irregular autumn burns and bushfires promote woody-shrub encroachment, a phenomenon observed globally.

Some present-day Victorian shrublands were once graminoid-dominated and managed through Indigenous burning practices prior to European colonization. This suggests that changing fire regimes may shift ecosystems between vegetation states. Recognising these transitions is crucial, as they may impact habitat structure, resource availability, and predation risk for ground-dwelling mammals.

Previous studies have examined how mammals respond to habitat structure and fire after a single fire event. However, little research has explored the long-term changes in vegetation communities due to altered fire regimes and their consequent impacts on mammal communities.

To address this gap, we aim to link ground-dwelling mammal species occupancy and activity to habitat structure, and habitat structure to shrub encroachment in a wet heathland system.

Our goal is to understand how these different vegetation states, resulting from varying fire regimes, influence mammal communities. For instance, the wet heathlands east of Cape Conran, Victoria, were burnt by the 2020 bushfires. Despite the same time-since-fire, these landscapes vary between shrubdominated and graminoid-dominated areas. We anticipate that these vegetation states will drastically alter habitat structure and function, thereby influencing the mammal community.

Currently, the biodiversity cost of transitioning from graminoid-dominated to shrub-dominated systems is understudied. Therefore, understanding the desired distribution of possible vegetation states across a landscape to enhance faunal diversity is vital for developing conservation-minded burning regimes.