BIOLOGICAL-CONTROL OF WEEDS AND FIRE MANAGEMENT IN PROTECTED NATURAL AREAS - ARE THEY COMPATIBLE STRATEGIES

Biological control of weeds has been traditionally associated with pas toral or cultivated land-use systems. Recently though, there has been increasing discussion of the possibility of biological control of weed s that have invaded national parks and native forests. However, a comp letely different set of management strategies applies in such land-use systems, the aims of which may conflict with those of classical biolo gical control. In Australia, one such practice is the use of regular p rescription bunting to control the incidence and severity of wild fire s. This paper reports data collected between 1981 and 1987 on an infes tation of St John's wort Hypericum perforatum, and its biological cont rol agent, Chrysolina quadrigemina, in eucalypt forest that was burnt twice during the study period The fires both promoted development of t he weed population and retarded that of the control agent. However, a subsequent indirect effect of fire was to favour population build-ups of C. quadrigemina and a recently released agent, Aphis chloris, throu gh increased plant nutrient levels. This indicates that the compatibil ity of biological control with existing management strategies must be considered when it is proposed as an option for the control of invasiv e weeds in protected natural areas. (C) 1996 Elsevier Science Ltd