Playing with fire
Taking the guesswork out of fire mosaics
Fire is one of our more visible land-management tools. Most of the time its sole objective is fuel reduction for asset protection, but fire management also has important implications for biodiversity conservation. Frequent fire and the complete suppression of fire have both been implicated in species' declines.
With fire benefitting some species, but having detrimental effects for others, the obvious solution is to maintain a mosaic in which there are areas burnt at different times in the past. But what is the appropriate range of times-since-fire? Do burns of similar age need to be next to each other to allow colonisation, and what's the appropriate size of the management fires? Currently there are no answers to these questions, and so designing fire mosaics is guesswork, with no guarantee that it will meet conservation objectives.
Dr Don Driscoll at the Fenner School for the Environment and Society is working to fill these knowledge gaps. Along with colleagues at Flinders University, Wollongong University, the NSW Department of Environment and Climate Change and the SA Department of Environment and Heritage, he has designed a three-pronged research program to gather the necessary information.
"The first prong involves studying reptiles, birds and plants in the field," says Dr Driscoll. "Researchers will examine how wildlife use habitat, animal behaviour, reproduction and how survival is affected by the time since the last fire.
"Next, the researchers will take to the lab and use genetic methods to understand the dispersal of different species to discover if time-since-fire influences movement. Combined with direct evidence of dispersal in the field and demographic and habitat data, this will enable a description of the mechanisms that influence each species' response to fire.
"The third prong is still being planned, but will involve a post-doctoral research fellow doing computer simulation modelling using the detailed biological data that's been collected. With cleverly designed simulation models based on solid field evidence about how the study system works, we will be able to model the responses of multiple species to contrasting fire mosaics. Our ambition is to be able to conduct virtual experiments that could never be done in the field because replication at the necessary scale is impossible and the duration of each experiment is prohibitively long."
Fire management for biodiversity is set to become an increasingly important role of land managers as climate change takes effect. The frequency of high fire-risk days is expected to increase, bringing with it more, and potentially larger fires. The modelling phase of the project will enable the researchers to examine the consequences of increased fire intensity, and they hope to tease apart the benefit for biodiversity conservation of contrasting management options in the face of climate change.
"We also hope to examine the interaction of fire and habitat fragmentation," explains Dr Driscoll. "In fragmented landscapes, fire suppression is the dominant management regime and this may disadvantage fire-loving species. When remnants do burn, they are entirely incinerated, so any fire-sensitive species will not have the benefit of unburned refuges from where they can recolonise. Cycles of fire suppression followed by a large fire could therefore ratchet down biodiversity in fragmented landscapes. Using a combination of detailed field research and simulation modelling, we hope to identify management strategies that will maintain species diversity across the landscape."