Australian Fire Regimes: Contemporary Patterns (April 1998 - March 2000) and Changes Since European Settlement

Australia: State of the Environment Second Technical Paper Series (Biodiversity), Series 2
J Russell-Smith, R Craig, AM Gill, R Smith & J Williams
Department of the Environment and Heritage, 2002
ISBN 0 642 54801 3

A Review of Fire Regimes of the Forested Region of South-western Australia with Selected Examples of their Effects on Native Biota

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Abstract

New methods for the detection of fire regimes hold great promise. Added to the limited use of charcoal in sediments, tree rings and fire scars, plant life histories, statistical records and maps, are the stains on stems of Xanthorrhoea. The last of these suggest that fires have occurred on average every three years in jarrah forest during the period immediately prior to white settlement but that the interval between fires increased subsequently. Statistical records for the past 40-50 years show that prescribed burning has dominated the between-fire interval. The interval between fires decreased during the 1960s but increased thereafter. In a comparison of two modern periods, data from Departmental maps in the Collie District suggested that there has been a decrease in the spread of burning season and in the variation in the between-fire interval. Fire intensities have varied throughout history but, with a predominance of prescribed fires, fire intensities will be predominately low in jarrah forest. What the effects of the fire regimes have been in the southwest is difficult to say due to the lack of data from any systematic monitoring program and the historically changing effects of settlement, silviculture and Phytophthora disease. However, available case histories demonstrate the value of very long intervals (or no fires at all) to some species (e.g. to maximize populations of the noisy scrub bird) and the neutral effect of current fire regimes on studied plant communities in jarrah forest. Thicket-generating fires have been seen as part of the management for woylie populations but, with the control of the exotic fox, the need for thickets may be less than it was. It is suggested that further study be undertaken on the effects of fire regimes on orchids and certain species of frogs. A concerted effort should be made to find species which are the most vulnerable to shifts in fire regimes and to quantify their vulnerability. Any evaluation of the significance of fire regimes and their historical changes should take place within the context of explicit management aims. In the present case-history, the conservation of the native biota has been the focus, not wood products, water or recreation.

Author

A Malcolm Gill
Centre for Plant Biodiversity Research
CSIRO Plant Industry
Retired August 31, 2000; presently an Hononary Research Fellow, CSIRO Plant Industry.

Citation

AM Gill (2002) A Review of Fire Regimes of the Forested Region of South-western Australia with Selected Examples of their Effects on Native Biota. In Australian Fire Regimes: Contemporary Patterns (April 1998 - March 2000) and Changes Since European Settlement, Russell-Smith, J., Craig, R., Gill, A.M., Smith, R. and Williams, J. 2002. Australia State of the Environment Second Technical Paper Series (Biodiversity), Department of the Environment and Heritage, Canberra. http://www.ea.gov.au/soe/techpapers/index.html