Native vegetation across parts of Western Australia has been cleared for agriculture.

Fire, fragmentation and conservation in the western wheat belt

Researchers with CSIRO and Western Australia’s Department of Environment and Conservation (DEC) are studying the impact of fire and fragmentation on regional plant diversity.

• 4 July 2007 | Updated 14 October 2011

• Patterns of fire
• Fire frequency
• Studying fire for conservation

A three-year CSIRO-DEC project is focusing on the impact of fire and fragmentation on native plant communities, with a view to finding ways to better manage fire for biodiversity conservation.

The Western Australian (WA) wheat belt, in the south-west of the state is part of a globally recognised biodiversity ‘hotspot’ for its unique and diverse plant communities.

However, native vegetation across large parts of the region has been cleared for agriculture.

The subsequent fragmentation of vegetation poses significant threats to plant diversity in the region.

These interacting threats include:

• weed invasion
• changing environment
• altered species interactions (such as pollination and seed predation)
• changes in fire regimes.

Patterns of fire

The WA wheat belt has experienced a long history of fires, such that many regional plant species possess traits that enable them to persist and prosper in a fire-prone environment.

However, patterns of fire ignition, spread and suppression may be different in different patches of remnant vegetation, compared with uncleared land.

These different fire regimes are likely to have a substantial impact on plant communities.

Fire frequency

Remnant patches often have long intervals between fires. This current fire regime is likely to be very different from the one experienced prior to land clearance, and also to the regimes experienced by the uncleared portions of the landscape.

Having long intervals between fires risks the decline (by a reduction in local population size or local extinction) of plant species that germinate and grow predominantly in a post-fire environment. This occurs if the interval between fires is longer than the life of the plant or seed. Another potential outcome is an ecologically detrimental abundance of fire-susceptible plant species.

Alternatively, fires that are too frequent can cause the decline of plant species, either directly (if fire frequency is less than the juvenile period for species killed by fire), or indirectly, through encouraging weed invasion.

Studying fire for conservation

The CSIRO-DEC study looks at which fire regimes may be beneficial for biodiversity conservation in the WA wheat belt.

Specifically, researchers are:

• mapping recent fire histories across the study area in the southern wheat belt to determine if differences in fire regime, such as fire frequency, season, intensity and extent, are related to remnant size
• determining the upper and lower limits of fire frequency needed to maintain plant community diversity.

This research is jointly supported by CSIRO Sustainable Ecosystems and by the Science Division and the Great Southern District of the WA Department of Environment and Conservation.

Read more about CSIRO's research on Biodiversity & Ecology.