Managing remant mallee vegetation for biodiversity using fire and fox control

A project undertaken at the School of Biological Sciences, Flinders University, and the Department for Environment and Heritage South Australia. The project is supervised by Don Driscoll (Flinders Uni), and Meredith Henderson (DEH).

Mallee vegetation covered 383,000 square kilometers of Australia but 35% of that has been cleared. Remnant mallee occurs as isolated fragments throughout Australia’s wheat and sheep producing lands, and harbors important biodiversity. However, altered fire regimes are potentially a serious threat to the survival of species in isolated mallee remnants. Single large fires could burn out entire remnants, eliminating fire sensitive species, or complete fire suppression could eliminate early successional species. Because remnants are isolated, there would be no opportunity for recolonisation resulting in widespread species declines. Therefore, there may be an imperative to implement environmental burns that burn only part of a reserve, allowing early and late successional species to coexist.

The mechanism of recolonisation after fire is also poorly understood. If recolonisation from unburnt areas is an important recovery mechanism, then fires should be designed to have a high edge to area ratio which would allow rapid recolonisation. On the other hand, if most species recover after fire from remnant populations within the burnt area, then the edge-to-area ratio is not very important.

Successful application of environmental burns may be limited by fox predation. Predation by the introduced red-fox may increase in the more open post-burn environment, potentially reducing or eliminating the biodiversity benefits of environmental burning.

Our broad aim is to investigate the interacting effects of fire and fox predation, and thereby to develop solutions to the problems posed by altered fire regimes in remnant vegetation. Our study will also examine edge effects associated with fire to distinguish colonization from unburnt areas from recovery from sources within the burnt area. We will focus on remnant mallee ecosystems on the Eyre Peninsula, South Australia.

Practical Objectives
  1. Determine the impacts of fire, foxes and their interaction, on reptile and beetle populations.
  2. Understand the importance of colonization of burnt areas from unburnt areas.
  3. Develop practical management recommendations for undertaking environmental burns that take into account:

a. the proportion of fire-specialist species (and hence how important environmental burns may be),

b. the possible impact of foxes (and whether or not baiting in conjunction with burning is needed), and

c. if colonization from fire edges is important (and hence whether fires should be small and narrow, or if size does not matter).

General Methodology
We are using pit-fall traps to survey reptiles and beetles in paired long-unburnt and adjacent recently burnt mallee areas. We have six separate naturally burnt areas. After we complete our second year of surveys over summer 2005-6 we will implement experimental burns at each location, then continue to monitor changes in reptile and beetle communities over subsequent years. Related projects will assess plant and bird diversity.Volunteer field assistants are essential for completing the field surveys and enquiries are welcome ( ian.sellar@flinders.edu.au ).

 

Fig. 1. Aprasia inaurita (pink tailed mallee worm lizard), is one of five legless species trapped in mallee so far.

Fig. 2. Pseudonaja inframacula (Eyre peninsula brown snake) are rarely captured in pitfall traps, so very few lizard capture records are lost.

Fig. 3. Burnt mallee offers a more open environment compared with long unburnt mallee. How many species specialize in exploiting these post-burn environments?

Fig. 4. Volunteer Brigid Duns extracts a knob tailed gecko from a pitfall trap.