Pyrogeography: integrating and evaluating existing models of Australian fire regimes to predict climate change impacts

The working group aimed to address important knowledge gaps in the biogeography of fire in Australia by:

(1) Developing an approach to classifying and mapping broad fire regimes at a continental scale. A continental description of the diversity of fire regimes is a key step in understanding the global drivers and constraints of landscape fire, as well as illuminating possible climate change effects by providing potential analogues for future fire activity

(2) Reviewing drivers of variation in fire regimes and their relative importance

(3) Developing a framework for assessing the vulnerability of fire regimes to change.

We found that Australia’s fire regimes are closely correlated with the latitudinal gradient in summer monsoon activity. Frequent, low intensity fires occur in the monsoonal north, and infrequent, high intensity fires in the temperate south, demonstrating a trade-off between frequency and intensity. Fire is rare in dense-canopied vegetation, such as arid Acacia shrublands, due to sparse fine fuels, and rainforests, due to the combination of sparse fine fuels and infrequent microclimatic conditions suitable for fire.

The approach we have developed to define continental-scale fire regimes, using a combination of remote sensing and thematic data, expert elicitation and literature review, will provide insights into the spatiotemporal patterns of fire, informing models that predict effects of climate change on fire regimes. Our approach can be applied globally, providing opportunities to undertake comparative pyrogeographic analyses.

We expect that fire regimes in high rainfall areas, such as southern Australia, will be most strongly affected by changes in the frequency of severe fire weather, while fire regimes in low rainfall areas, such as central Australia, will be most affected by changes in productivity and fuel abundance, possibly as a result of changes in rainfall or atmospheric CO2 concentration.