The impact of the European olive (Olea europaea L. subsp. europaea) on grey box (Eucalyptus microcarpa Maiden) woodland in South Australia
Neville D. Crossman, Environmental Weeds Group, School of Geography, Population and Environmental Management, Flinders University, GPO Box 2100, Adelaide 5001, Australia.
Summary
The European olive (Olea europaea L. subsp. europaea) is an introduced plant that has naturalized in several areas of Australia. Originating from the Mediterranean region, O. europaea was imported to Australia and cultivated for its oil content. Escapees from cultivated olive groves have invaded native vegetation communities, including grey box (Eucalyptus microcarpa Maiden) woodland of conservation significance in South Australia. This paper examines the history of and processes leading to O. europaea invasion, the impact of O. europaea invasion on E. microcarpa woodland, and the relevance of olives as an environmental weed.
Results of this study show that O. europaea invasion leads to a reduction in native species richness and abundance in E. microcarpa woodland. Invasion also alters the canopy structure of the woodland. Species most at risk are E. microcarpa, golden wattle (Acacia pycnantha Benth.) and sticky hop-bush (Dodonaea viscosa Jacq.). It is argued that the reduction in light infiltration caused by the dense canopy of O. europaea prevents regeneration of native species. Olea europaea should be considered a serious threat to the integrity of vegetation communities it invades.
Plant Protection Quarterly (2002) 17 (4) 140-146.