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Dr Trudi Ryan Homeleigh Cottage Wallaroo Rd Hall ACT 2618 [email protected] 0417 210 643 October 10, 2003 Re: Inquiry into the regulation, control and management of invasive species and the Environment Protection and Biodiversity Conservation Amendment (Invasive Species) Bill 2002 Thank you for the opportunity to respond to the Inquiry into the regulation, control and management of invasive species. Most of my comments relate to my PhD research on the ecology and invasion impacts of the native invasive plant, Sweet Pittosporum (Pittosporum undulatum) (Mullett 1999, 2001, 2002). The views expressed in this submission are solely those of the author and do not represent the views or policy of any associated organisation or agency. Trudi Ryan Terms of Reference 1: The regulation, control and management of invasive species, being non-native flora and fauna that may threaten biodiversity, This inquiry only considers non-native flora as invasive species yet a growing number of native Australian plants are regarded as invasive species in natural and semi-natural Australian ecosystems. My research on the ecology of a native invasive plant species, Pittosporum undulatum, demonstrated that this species exerted significant invasion impacts in a range of habitats both within and beyond its natural range (Mullett 1999, 2001, 2002). These results support the growing consensus in the weed literature, that invasive native plants can be as ecologically destructive as invasive plants introduced from outside Australia (Humphries et al. 1991; Groves 2001). Invasion of natural ecosystems by native plant species is a conservation problem experienced by all States and Territories of Australia. Over 100 native plants are now considered invasive in Victorian ecosystems and at least 50 native plants also function as environmental weeds in South Australia (Groves 2001). Sixty-four native species, including 22 Western Australian species, are considered invasive in natural Western Australian environments. Such inter-regional invasions are likely to be on the increase. The incidence of native plants as weeds was the subject of a symposium hosted by Monash University in 2001 (see references for details). Some native species can function as invasive plants in their natural, indigenous habitats, if the ecological conditions that previously contained the species have been modified. The tall native shrub, P. undulatum, is native to the wet forests of south-eastern Australia and is a serious invader of dry sclerophyll forest and other vegetation communities both within and beyond its natural ecological range. This adaptable species has exploited changes in natural disturbance regimes (principally the suppression of fire regimes) and increased dispersal opportunities to spread from abundant garden plantings into native vegetation communities, where it displaces indigenous plant species and reduces habitat diversity. 1a) the nature and extent of the threat that invasive species pose to the Australian environment and economy Weed invasions cost Australian agriculture $3.3 billion p.a. in control and lost production. The cost of weed invasion to Australia’s natural environments is beyond calculation. Weed invasions are recognised as second only to vegetation clearing as a cause of species decline. Invasive plants reduce access to recreational activities, diminish the aesthetic values of natural areas and homogenise the regional distinctiveness of natural ecosystems. Pittosporum undulatum poses a very serious threat to the native plant communities that it invades. Significant declines in plant species richness and abundance has been recorded at sites throughout this species current geographic range in south-eastern Australia (Mullett 1999, 2001, 2002). Simplification of community composition, structure and function are principal effects of invasion. Once set in train, the degradation of biodiversity values is perpetuated at invaded sites as the rate and direction of community succession moves towards a more simplified state. Habitat opportunities for native fauna are also reduced with increasing weed invasion. 1b) The estimated cost of different responses to the environmental issues associated with invasive species, including early eradication, containment, damage mitigation and inaction It is difficult to estimate the cost of early eradication versus containment strategies. My data on the population structure and invasion impacts of P. undulatum indicate that the cost of control increases with time since invasion. The potential for eradication may also decrease with time since invasion. Early eradication is the key to successful weed management. Inaction against plant invasion will result in the loss of biodiversity. 1c) the adequacy and effectiveness of the current Commonwealth, state and territory statutory and administrative arrangements for the regulation and control of invasive species. Current Commonwealth, state and territory statutory and administrative arrangements are failing to address the threat posed by invasive species. Greater political commitment to the principles of weed related policy and legislation is required. For example, the invasion by P. undulatum into habitats outside its natural range in Victoria was listed as a ‘potentially threatening process’ in 1994 under Schedule 3 of the Victorian Flora and Fauna Guarantee Act 1988. An Action Statement has not yet been developed for this listing, despite the legislative requirement that this occurs as soon as possible after the listing process. 1d) the effectiveness of Commonwealth-funded measures to control invasive species At the current rate of investment, most invasive plants are increasing both in distribution and abundance. Volunteer groups conduct the majority of onground environmental weed control in Australia. Greater technical and financial support needs to be supplied to volunteer groups if the onus of weed management remains on the community. 1e) Whether the Environment Protection and Biodiversity Conservation Amendment (Invasive Species) Bill 2002 could assist in improving the current statutory and administrative arrangements for the regulation, control and management of invasive species. The Bill could improve the management of invasive species but it would need to include native weeds in its definition of invasive species and expand its focus to a broader range of introduced plants than those listed in the terms of reference. The underlying causes of weed invasion will need to be addressed in Threat Abatement Plans and adequate funding and support to address these causes should be provided. Cited References Groves R.H. (2001) Can some Australian plants be invasive? Plant Protection Quarterly 16, 114-17. Humphries S.E., Groves R.H. & Mitchell D.S. (1991) Plant invasions of Australian Ecosystems: a Status Review and Management Directions. Kowari 2, 1-134. Mullett T.L. (1999) The Ecology of Pittosporum undulatum Vent (Pittosporaceae), an Environmental Weed in south east Australia. PhD Thesis, Deakin University, Victoria. Mullett T.L. (2001) Effects of the native environmental weed, Pittosporum undulatum Vent. (sweet pittosporum) on plant biodiversity. Plant Protection Quarterly 16, 117-21. Mullett T.L. (2002) The Biology of Australian Weeds 41. Pittosporum undulatum Vent. Plant Protection Quarterly 17, 130-9. See also: Proceedings of a Symposium on Native Plants as Weeds published in Plant Protection Quarterly (2001) Volume 16, Issue 3 Contents: Can some Australian plants be invasive? (R.H. Groves) Effects of the native environmental weed Pittosporum undulatum Vent. (sweet pittosporum) on plant biodiversity. (Trudi L. Mullett) Transcontinental invasions of vascular plants in Australia, an example of natives from south-west Western Australia weedy in Victoria. (J.P. Pigott) Australian plants as weeds in Victoria. (G.W. Carr) NGIA initiatives in environmental weed management. (Jolyon Burnett) Native plants as environmental weeds on the Mornington Peninsula. (Scott Coutts) Biological control of weedy native plants in Australia. (Eligio Bruzzese and Ian Faithfull) A challenge for our values: Australian plants as weeds. (Tim Low).