Use of prescribed fire to enhance control of English broom (Cytisus scoparius) invading a subalpine snowgum woodland in Victoria
D.C. RobertsonA, J.W. MorganB and M. WhiteC
A School of Agriculture, La Trobe University, Bundoora, Victoria 3083, Australia.
B School of Botany, La Trobe University, Bundoora, Victoria 3083, Australia.
C Department of Natural Resources and Environment, Alexandra, Victoria 3714, Australia. Current address: NSW National Parks and Wildlife Service, Dubbo, New South Wales 2830, Australia.
Abstract
English broom (Cytisus scoparius) is invading subalpine vegetation on the Bogong High Plains, Victoria. Current control measures involve spraying all visible plants in affected areas with herbicides but this will have limited effectiveness because C. scoparius forms a persistent soil seed bank from which re-establishment may later occur. Prescribed fire may enhance the control of C. scoparius in subalpine areas by promoting synchronized germination of seed from the soil seed bank. The resulting large seedling cohort can then be controlled by application of herbicides.
We studied the effects of a single prescribed fire in an invaded snowgum (Eucalyptus pauciflora) woodland on previously sprayed C. scoparius plants and in situ germination, and also followed the post-fire recovery of the native vegetation. All sprayed C. scoparius plants were consumed by fire. Substantial germination occurred in burnt areas in the year after fire, whereas no germination was observed in unburnt areas. All native species in the study area, and all individuals of snowgum, were capable of vegetative regeneration following fire and most (94%) native species reflowered within three years of the fire. If burning is to enhance control efficacy of C. scoparius, follow-up strategies (i.e. herbicide spraying) are necessary within four years of the fire. After this time, C. scoparius seedlings begin to flower and will replenish the depleted soil seed bank.
Plant Protection Quarterly (1999) 14 (2) 51-56.