Abstract
This thesis comprises two parts. In part one, encapsulated in chapters two, three, and four, I investigated the interaction between fire, people, and flora in the semi-arid spinifex grasslands of Western Australia. Species in fire-prone ecosystems are dependent on the spatiotemporal patterning of fire, or the ‘fire regime’. Indigenous people have shaped fire regimes for millennia and continue to in many areas around the world. It is increasingly evident that species are dependent on Indigenous fire regimes, which often create ‘pyrodiverse’ landscapes with diverse temporal and spatial fire histories. In part two encapsulated in chapter five, I investigated the response of fungal communities to fire in the semi-arid heathlands of south-eastern Australia. Fire is a key driver of fungal communities, but the response of fungal communities to fire are not well understood.
Chapter one provides a brief introduction to the thesis. In chapter two, I examined how Indigenous people shape landscape pyrodiversity by investigating how travel time from Indigenous communities (used as a proxy for land-use intensity) affected aspects of the visible fire mosaic (i.e., time-since-fire diversity and maximum landscape area burnt) and invisible fire mosaic (i.e., number of years burnt, diversity of fire frequency patches, and number of unique fire histories). Indigenous burning creates diverse visible and invisible fire mosaics, which dwarf the pyrodiversity of distant areas, and limits fire size.
In chapter three, I examined how time-since-fire and fire frequency affected several plant richness and diversity variables (including edible plants), vegetation structure, and plant composition. Fire was a strong driver of plant communities, with spinifex playing a key role. Patterns in plant richness and diversity largely followed the "initial floristic composition” model. Additionally, burning enhanced the productivity of areas for Indigenous people; edible plant richness peaked shortly after fire and frequent fires enhanced edible plant availability.
In chapter four, I explored whether pyrodiversity maintained by Indigenous people promoted plant richness and diversity, by comparing landscapes that ranged from highly pyrodiverse under active Indigenous burning, in both visible and invisible fire diversity, to more coarse-scale and less diverse mosaics under lightning fire regimes. Indigenous created pyrodiversity enhanced several plant richness and diversity variables, but mid-
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successional stages were particularly important for enhancing plant diversity. Additionally, plant diversity declined when maximum landscape area burnt increased.
Collectively, results from chapters two, three, and four suggest that by increasing the frequency that landscapes are burnt, increasing diversity in the visible and invisible fire mosaic, and reducing fire size, Indigenous people enhance plant diversity and enhance the productivity of landscapes for people. Indigenous-led burning could offer solutions to restoring appropriate fire regimes and conserving global biodiversity.
In chapter five, I investigated how time-since-fire and fire frequency influenced the richness and composition of all fungi, ectomycorrhizas, saprotrophs, and pathogens. Saprotrophic richness increased with time-since-fire, but direct and indirect effects had opposing impacts. Distinct fungal communities arose under different post-fire successional stages and fire frequency classes, with substantial differences in ectomycorrhizal species composition. Fire is a key driver of fungal communities in semi-arid heathlands.
Chapter one provides a brief introduction to the thesis. In chapter two, I examined how Indigenous people shape landscape pyrodiversity by investigating how travel time from Indigenous communities (used as a proxy for land-use intensity) affected aspects of the visible fire mosaic (i.e., time-since-fire diversity and maximum landscape area burnt) and invisible fire mosaic (i.e., number of years burnt, diversity of fire frequency patches, and number of unique fire histories). Indigenous burning creates diverse visible and invisible fire mosaics, which dwarf the pyrodiversity of distant areas, and limits fire size.
In chapter three, I examined how time-since-fire and fire frequency affected several plant richness and diversity variables (including edible plants), vegetation structure, and plant composition. Fire was a strong driver of plant communities, with spinifex playing a key role. Patterns in plant richness and diversity largely followed the "initial floristic composition” model. Additionally, burning enhanced the productivity of areas for Indigenous people; edible plant richness peaked shortly after fire and frequent fires enhanced edible plant availability.
In chapter four, I explored whether pyrodiversity maintained by Indigenous people promoted plant richness and diversity, by comparing landscapes that ranged from highly pyrodiverse under active Indigenous burning, in both visible and invisible fire diversity, to more coarse-scale and less diverse mosaics under lightning fire regimes. Indigenous created pyrodiversity enhanced several plant richness and diversity variables, but mid-
Page Ι 15
successional stages were particularly important for enhancing plant diversity. Additionally, plant diversity declined when maximum landscape area burnt increased.
Collectively, results from chapters two, three, and four suggest that by increasing the frequency that landscapes are burnt, increasing diversity in the visible and invisible fire mosaic, and reducing fire size, Indigenous people enhance plant diversity and enhance the productivity of landscapes for people. Indigenous-led burning could offer solutions to restoring appropriate fire regimes and conserving global biodiversity.
In chapter five, I investigated how time-since-fire and fire frequency influenced the richness and composition of all fungi, ectomycorrhizas, saprotrophs, and pathogens. Saprotrophic richness increased with time-since-fire, but direct and indirect effects had opposing impacts. Distinct fungal communities arose under different post-fire successional stages and fire frequency classes, with substantial differences in ectomycorrhizal species composition. Fire is a key driver of fungal communities in semi-arid heathlands.
Original language | English |
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Qualification | Doctor of Philosophy |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 31 Mar 2023 |
Place of Publication | Australia |
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Publication status | Published - 31 Mar 2023 |