THREAT ABATEMENT ADVICE FOR A KEY THREATENING PROCESS
This threat abatement advice has been developed based on the best available information at the time of development (July 2014).
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About this advice
‘Loss and degradation of native plant and animal habitat by invasion of escaped garden plants, including aquatic plants’ was listed as a key threatening process in January 2010 under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.
This threat abatement advice was prepared by the Department in consultation with key stakeholders to provide guidance at national, state and local levels on activities and research needed to abate the threat.
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The purpose of this threat abatement advice is to identify key actions and research to abate the key threatening process listed under the Environment Protection and Biodiversity Conservation Act 1999 (Cth.) (EPBC Act), ‘Loss and degradation of native plant and animal habitat by invasion of escaped garden plants, including aquatic plants’. Abatement of this process can help ensure the conservation of assets including listed species and ecological communities.
This advice provides information and guidance for stakeholders at national, state, regional and local levels. It intends to increase awareness of activities relevant to abating the threats of this key threatening process. It suggests on-ground activities that can be implemented by local communities, natural resource management groups or interested individuals, such as landholders. It also suggests actions that can be undertaken by government agencies, local councils, research organisations, industry bodies or non-government organisations.
The intention of this advice is to highlight those actions considered to be of highest priority and which are feasible, rather than to comprehensively list all actions which may abate the threat and impacts posed by the key threatening process. Relevant groups or individuals may determine their capacity to undertake the abatement activities included in this advice.
Objectives for better management of the threat include to:
- prevent further introductions of potentially invasive plants
- develop understanding of the extent and impact of infestation by escaped garden plants
- identify and prioritise key assets and areas for strategic management
- reduce the establishment and spread of garden plants into areas with key ecological assets
- support and facilitate coordinated on-ground management in high-priority areas
- raise awareness among stakeholders of the impacts of escaped garden plants
- build capacity among stakeholders to abate the threat
- monitor, evaluate and report on the efficacy of management programmes.
Description of the key threatening process
The key threatening process addressed by this threat abatement advice covers all escaped garden plants (defined as plants currently or historically used in gardens for ornament or utility that have invaded, or threaten to invade, natural and other areas).
Historically, escaped garden plants have been the main source of Australia’s population of weeds. Garden plants may spread from the confines of a garden and enter native bushland via natural dispersal vectors such as wind, water, and animals. Introduction and spread of garden plants can also occur through inappropriate sale and plantings, dumping of waste from gardens, ponds and aquariums (including the deliberate wild cultivation of invasive aquatic species for the aquarium trade) and accidental spread, for example, by the use of machinery along roadsides.
Escaped garden plants can have a number of adverse impacts on native species and communities through: competing for resources; preventing recruitment; altering various ecosystem processes such as geomorphological processes, hydrological cycles and nutrient dynamics; preventing animal movements or replacing habitat used by native animals; and altering disturbance regimes such as fire.
An increasing number of environmental weeds are Australian plants that have been used in both horticulture and land rehabilitation projects outside of their native range. These can be just as invasive as introduced species. In addition, they have the capacity to interbreed with indigenous species, and so change the nature of the local gene pool. Like introduced species, they may also display a recruitment advantage over some indigenous species after a fire event, thereby further changing the structure and function of already challenged ecosystems.
The threats posed by escaped garden plants may add an additional component to a suite of threats already applying considerable pressure to some species and ecological communities. Land clearing, ecosystem fragmentation, climate change and altered fire regimes are just a few of the threats that have considerable impacts on species, biodiversity and environmental function and resilience. Protecting species and ecological communities will require strategies to address many of these threats holistically, not just those caused by escaped garden plants.
For further information on the key threatening process, see the advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee on amendments to the list of key threatening processes under the Environment Protection and Biodiversity Conservation Act 1999: Loss and degradation of native plant and animal habitat by invasion of escaped garden plants, including aquatic plants.
‘Loss and degradation of native plant and animal habitat by invasion of escaped garden plants, including aquatic plants’ is listed as a key threatening process under the Environment Protection and Biodiversity Conservation Act 1999 (Cth.) (EPBC Act).
This process meets section 188(4)(a), section 188(4)(b) and section 188(4)(c) of the EPBC Act and is eligible to be listed as a key threatening process because:
- it could cause Troides richmondia (Richmond birdwing butterfly) to become eligible for listing as threatened under the EPBC Act
- it could cause the Cumberland Plain Woodlands ecological community to become eligible for listing as critically endangered under the EPBC Act
- it is adversely affecting population numbers and geographic distribution of at least three listed threatened species (Pimelea spicata (spiked rice-flower), Pterostylis arenicola (sandhill greenhood orchid) and Lasiopetalum pterocarpum (wing-fruited Lasiopetalum)) and two listed threatened ecological communities (the Blue Gum High Forest of the Sydney Basin Bioregion and the Littoral Rainforest and Coastal Vine Thickets of Eastern Australia), primarily through competition and habitat degradation.
State and territory legislation
The following are listed as potentially threatening processes under the Victorian Flora and Fauna Guarantee Act 1988:
- Invasion of native vegetation by Blackberry Rubus fruticosus L. agg.
- Invasion of native vegetation by ‘environmental weeds’
- Introduction and spread of Spartina to Victorian estuarine environments
- Spread of Pittosporum undulatum in areas outside its natural distribution
New South Wales
The following are listed as key threatening processes under the NSW Threatened Species Conservation Act 1995 (TSC Act):
- Loss and degradation of native plant and animal habitat by invasion of escaped garden plants, including aquatic plants (2011). This listing was supported by previous listings, including:
- Invasion and establishment of exotic vines and scramblers
- Invasion and establishment of Scotch Broom (Cytisus scoparius)
- Invasion of native plant communities by bitou bush & boneseed
- Invasion of native plant communities by exotic perennial grasses
- Invasion of native plant communities by African Olive Olea europaea subsp. cuspidata (Wall. ex G. Don) Cif.
- Invasion, establishment and spread of Lantana (Lantana camara L. sens. lat)