Research

What fire regimes can maintain biodiversity in northern Australia’s savanna landscapes, and how do we implement them?

Inappropriate fire regimes threaten biodiversity in many landscapes, yet we have a limited understanding of fire regimes that should be implemented. Focussing on the savanna landscapes of the Tiwi Islands and the Arnhem Plateau, this project integrates a range of approaches, from field-based surveys to simulation modelling and decision analysis, to: (1) critically evaluate the hypothesis that spatially and temporally variable fire regimes are required to maintain biodiversity; (2) identify optimal fire regimes for biodiversity conservation; and (3) develop strategies for implementing such regimes. This work provides a critically-needed framework for managing fire for biodiversity conservation in fire-prone landscapes globally.

  • Project leader: Brett Murphy
  • Project support: Australian Research Council (Discovery Early Career Researcher Award)
  • Students: Hugh Davies (PhD), Fin Roberts (MSc)
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Early dry season prescribed burning being carried out in the Stone Country (Arnhem Plateau) of Kakadu National Park. (Photo: Clay Trauernicht)

Aboriginal patch burning and the quest for sustainable fire management

This project documents historical changes in the spatial grain of the patch burning mosaic in (1) an Arnhem Land savanna with an unbroken history of management by Aboriginal people, and (2) adjacent areas where traditional management has ceased. The mosaic’s spatial grain is inferred by mapping the individual ages of the long-lived conifer Callitris intratropica (northern cypress-pine). Prior research has shown that Callitris individuals can be reliably aged, and population structures are very sensitive to fire regimes: sapling only establish if unburnt for 10 years. This research provides a direct test of the hypothesis that Aboriginal people maintained fine-grained fire mosaics, and will inform bushfire policy debates.

  • Project leader: David Bowman (University of Tasmania)
  • Project support: Australian Research Council (Discovery Projects)
Callitris intratropica in Kakadu National Park

Northern cypress-pine (Callitris intratropica) in Kakadu National Park. (Photo: Clay Trauernicht)

Arresting declines of arboreal mammals in the tropical savannas

Northern Australia’s mammals are in severe decline, and arboreal species are among those to have fared worst. There is abundant anecdotal evidence that arboreal species are limited by the abundance of tree hollows, and that historical increases in the frequency of intense fires may be reducing hollow abundance. Working in the Kimberley and the Top End, the last regions on the Australian mainland with an intact mammal fauna, we are evaluating this hypothesis. We are exploring management options for increasing the availability of denning sites for arboreal mammals (e.g. fire management, artificial nest boxes), and evaluating the likely impact of such actions on mammal populations across northern Australia.

  • Project leader: Brett Murphy
  • Project support: WA Department of Parks and Wildlife, Holsworth Wildlife Research Endowment, Australian Academy of Science (Margaret Middleton Fund)
  • Collaborators: Ian Radford (WA DPaW), Michael Lawes (Charles Darwin University), Graeme Gillespie (NT DLRM), Brendan Wintle (University of Melbourne), John Woinarski (Charles Darwin University), Sue Carthew (Charles Darwin University)
  • Students: Michael Hitchcock (PhD), Alyson Stobo-Wilson (PhD)
The brushtail possum (Trichosurus vulpecula) is a semi-arboreal mammal in decline in the northern savannas. (Photo: Peter Firminger)

The brushtail possum (Trichosurus vulpecula) is a semi-arboreal mammal in severe decline in the northern savannas. (Photo: Peter Firminger)

Fire ecology and status of small mammals on the Tiwi Islands

that feral cat

“That Feral Cat” – Kaye Kessing

The Tiwis, north of Darwin, have retained a diverse assemblage of small mammals, most of which have declined significantly on the adjacent mainland. This project has two broad aims: (1) to understand the impacts of varying fire frequencies on small mammal assemblages (making use of a fire experiment being conducted on Melville Island by CSIRO and the Tiwi Land Council); and (2) evaluate the extent to which small mammals have declined on the Tiwis since the early 2000s, when an extensive biological survey was undertaken. We will address the question of whether the patterns of decline seen on the mainland (e.g. Kakadu) are apparent on the Tiwis.

BFTR and Hugh

Hugh Davies and a black-footed tree-rat (Mesembriomys gouldii) on Melville Island.

  • Project leader: Brett Murphy
  • Project support: Tiwi Land Council, CSIRO, NT Department of Land Resource Management, Hermon Slade Foundation, Holsworth Wildlife Research Endowment
  • Collaborators: Emily Nicholson (Deakin University), Kate Hadden (Tiwi Land Council), Alan Andersen (CSIRO), Euan Ritchie (Deakin University), Dale Nimmo (Deakin University), Graeme Gillespie (NT DLRM), Ron Firth (360 Environmental), Mick McCarthy (University of Melbourne)
  • Students: Hugh Davies (PhD), Hayley Geyle (Honours), Bill La Marca (Masters)
Some native mammals of the Tiwi Islands (many now rare on the mainland). Photos: Hugh Davies

Some native mammals of the Tiwi Islands (many now rare on the mainland). Photos: Hugh Davies

Do fire regimes affect northern Australia savanna kangaroo abundance?

There is concern that the cessation of Aboriginal patch burning is causing tropical savanna kangaroo populations to decline. We will use: (1) surveys to determine if fire regime (frequency, extent and season of fires) affects kangaroo abundance; and (2) experiments to discover how season of burning influences forage quality and quantity, and the degree non-native large herbivores compete with kangaroos for forage. This research will enabling contrasting the effects of traditional Aboriginal and contemporary fire management on kangaroo abundance, and lead to improvements in tropical savanna fire management.

  • Project support: Wunambal Gaambera Aboriginal Corporation, Bush Heritage Australia
  • Project leader: David Bowman (University of Tasmania)
  • Other collaborators: Tom Vigilante (Wunambal Gaambera Aboriginal Corporation), Jim Radford (Bush Heritage Australia)
  • Students: Angie Read (PhD)
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Agile wallaby (Macropus agilis). Photo: Jurgen Otto

 Shifting fire regimes of the United States, Australia and Brazilian Amazonia: the roles of climate change, land use, and mitigation efforts

Fire is an integral but poorly understood component of the Earth system. Interdisciplinary research is needed to estimate future climate change effects upon the fire environment and resultant feedbacks with human land use and mitigation efforts. We are investigating the propensity for extreme fire occurrence as functions of climate, land cover and land use/management across 3 continents; Australia (entire), North America (lower 48 states U.S.) and South America (Brazilian Amazonia). We will provide comparable tests of proposed hypotheses and estimation of future climate change effects across multiple ecoregions within most of the world’s terrestrial biome types (boreal tundra and taiga will be the only major vegetated biome types not examined). We will quantify changes in fire danger since 1901 (since 1948 in Amazonia) as well as fire incidence and fire effects in recent decades. The probability and locations of exacerbated fire regimes under projected future climate scenarios will be investigated.

The project will make use of NASA assets (Landsat, MODIS) and produce the first multicontinent analyses of fire regime shifts due to climate and land use changes and also estimate the effectiveness of ongoing mitigation efforts. Only through large scale analyses is it possible to determine the degree to which climate may be changing landscape level fire behaviour and the propensity for future extreme fire events to occur. Such knowledge is critical for society in order for proper development planning, regional adaptation and mitigation efforts to take place.

Our work will address four of the five requested components: (1) Characterize the nature, magnitude, and distinguishing attributes of extreme fire events; (2) Assess many natural (ecological, biogeochemical, climatic, biogeographic) and human (land use, conservation, socio-economic) aspects of extreme fire disturbances; (3) Quantify the effectiveness of many types of fire mitigation efforts over large regions; (4) Investigate the Earth system feedbacks among climate and land use changes and the placement, timing and characteristics of extreme fires over time. By applying what we learn to our analyses of projected future climate changes and simulated increases in climate variability, we will provide a solid understanding of when and in which ecoregions altered fire regimes may pose a risk to both human and natural resources. If large-scale, integrated, multidisciplinary research such as this is not conducted, then fire’s function in the Earth system will remain poorly understood and humanity will be left increasingly vulnerable to unforeseen and potentially catastrophic fire regime shifts as the climate continues to change.

  • Project support: NASA (Interdisciplinary Science Program)
  • Project leader: Mark Cochrane (South Dakota State University)
  • Other collaborators (on the project’s Australian component): David Bowman (University of Tasmania), Grant Williamson (University of Tasmania), Lynda Prior (University of Tasmania)
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(A) Variation in fire activity (annual density of active fire detections) for the period 2000-2012, mean annual rainfall, net primary productivity (NPP), and tree cover throughout Earth’s tropical and temperate climate zones. (B, C) Plotted in environmental space, fire activity displays a ‘humped’ relationship with mean annual rainfall, which is positively correlated with NPP and tree cover. In (C), closed canopy vegetation is defined as tree cover >60%. Active fire detections, NPP and tree cover are MODIS satellite-derived datasets; mean annual rainfall is from the WordClim dataset. From: Bowman DMJS, Murphy BP, Williamson GJ, Cochrane MA (2014) Pyrogeographic models, feedbacks and the future of global fire regimes. Global Ecology and Biogeography 23, 821-824.

Measuring fuel loads in central Australian mulga.

Measuring fuel loads in central Australian mulga for the NASA fire project.

Fire and vegetation in the Australian Alps

The examines how fire activity varies according to landscape, vegetation type, land tenure and management history, including grazing and burning, in the Australian Alps. It evaluates the impact of changing fire regimes on vulnerable communities, such as tall eucalypt forests dominated by one of Earth’s tallest obligate seeding trees, alpine ash (Eucalyptus delegatensis).

  • Project support: National Environmental Research Program (Landscapes and Policy Hub)
  • Project leader: David Bowman (University of Tasmania)
  • Other collaborators: Grant Williamson (University of Tasmania), Lynda Prior (University of Tasmania)
Burnt alpine ash (Eucalyptus delgatensis) forest. (Photo: Elizabeth Donoghue)

Burnt alpine ash (Eucalyptus delegatensis) forest. (Photo: Elizabeth Donoghue)

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