Impact Assessment - European Privet (Ligustrum vulgare) in Victoria
Back | Table | Feedback
Assessment of plant invasiveness is done by evaluating biological and ecological characteristics such as germination requirements, growth rate, competitive ability, reproduction methods and dispersal mechanisms. Assessment of plant impacts, however, is determined by the extent to which a plant affects a land manager’s environmental, economic and social resources.
The relative importance of these resources varies depending upon the value people place on them and, as such, the assessment process is subjective. For example, a farmer is likely to place a higher emphasis on the impact of a plant on production (economic resource) than its impact on areas of natural vegetation occurring on the farm. Conversely, a Landcare or Friends group would value environmental or social resources more than economic resources.
Recognising that the value of resources vary between different land tenures, plant impact assessments allow a prioritisation of resources by land managers. Assessments can apply at a local, regional or state level, and the relative values of each resource identified may differ at each level.
The impact assessment method used in the Victorian Pest Plant Prioritisation Process uses three broad resource categories: social, environmental and agricultural, each with a number of related attributes. For example, social resources include such attributes as how the plant affects human access for recreation, or if it creates a health risk due to toxicity or by producing allergens.
| Each resource attribute, or criterion, is assessed relative to a list of intensity ratings. Depending upon information found in relation to each criterion, a rating of Low, Medium Low, Medium High or High is assigned. Descriptions of the impact criteria and intensity ratings used in this process can be viewed here. |
The following table provides information on the impact of European privet.
A more detailed description of the methodology of the Victorian Weed Risk Assessment (WRA) method can be viewed below:
Victorian Weed Risk Assessment (WRA) method (PDF - 630 KB)
Victorian Weed Risk Assessment (WRA) method (DOC - 1 MB)
To view the information PDF requires the use of a PDF reader. This can be installed for free from the Adobe website (external link).
Common Name: European privet
Scientific name: Ligustrum vulgare
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | Reported to invade riparian habitats, the species can form dense impenetrable thickets (Weber 2003). This species could therefore pose a major impediment to access to waterways and require significant works to provide access. | H | MH |
| 2. Reduce tourism? | While the species has not been reported to impact on tourism or recreation, its ability to form dense thickets and its toxic nature however could mean it has the potential to do so. | M | L |
| 3. Injurious to people? | The fruits and leaves of this species are toxic and in severe cases of the plant being eaten death has occurred (Everist 1974). Can cause allergies. | H | MH |
| 4. Damage to cultural sites? | Unknown. | M | L |
| Abiotic | |||
| 5. Impact flow? | Unknown; a similar species can reportedly impact on the flow of water along drainage lines (Blood 2001, Muyt 2001). | M | L |
| 6. Impact water quality? | Chemicals released from the leaves of the similar species L. sinense have been reported to impact on aquatic macro invertebrates (Llewellyn 2005). The species does occur in riparian areas, and could have some impact on water quality by changing light levels and nutrient imputes. There has been however no quantifiable reports of this species impacting upon water quality. | M | L |
| 7. Increase soil erosion? | The species has been found to not to have a penetrating root system and while the species can have a large root system it is largely shallow (Jia-rong et al 2007). Therefore areas invaded by the species are viewed to have a moderate probability of large scale soil erosion. | ML | H |
| 8. Reduce biomass? | The species is reported to form dense thickets and crowd out the existing species (Weber 2003). This is similar to other Ligustrum species which have been reported to cause a reduction in biomass of the lower strata when this occurs (Muyt 2001; Swarbrick, Timmins & Bullen 1999). Invasion by the species is therefore considered to result in a net increase in biomass due to the significant increase in the middle strata. | L | MH |
| 9. Change fire regime? | The similar species L. lucidum is reported to reduce the biomass within the grass/herb layer which can limit a fire from spreading, instead in SE Queensland during dry winters the species can defoliate which allows a hot fire to be carried (Swarbrick, Timmins & Bullen 1999). As L. vulgare is also able to form dense stands within the shrub layer it is thought to have the same potential of altering both fire intensity and timing. | MH | MH |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | EVC=Damp Forest (E); CMA= West Gippsland; Bioreg= Strzelecki Ranges; VH CLIMATE potential. The species is able to displace native species and form dense thickets within the understorey (Weber 2003). The species is therefore able to dominate a single layer and cause displacement of species. | MH | MH |
| (b) medium value EVC | EVC=Wet Forest (D); CMA= West Gippsland; Bioreg= Strzelecki Ranges; VH CLIMATE potential. The species is able to displace native species and form dense thickets within the understorey (Weber 2003). The species is therefore able to dominate a single layer and cause displacement of species. | MH | MH |
| (c) low value EVC | EVC= Wet Forest (LC); CMA= West Gippsland; Bioreg= Wilsons Promontory; VH CLIMATE potential. The species is able to displace native species and form dense thickets within the understorey (Weber 2003). The species is therefore able to dominate a single layer and cause displacement of species. | MH | MH |
| 11. Impact on structure? | The species is able to displace native species and form dense thickets within the understorey (Weber 2003). The species could therefore impact upon more than 605 of the flora strata, displacing species of the middle and lower strata and potentially preventing the regeneration of canopy species. | MH | M |
| 12. Effect on threatened flora? | Unknown. | MH | L |
| Fauna | |||
| 13. Effect on threatened fauna? | The increased food privet species provide through the fruit load supports increased populations of aggressive bird species such as currowongs (Blood 2001; Swarbrick, Timmins & Bullen 1999). This then has the potential to impact on other bird species populations, it has not however been reported to specifically impact upon a threatened species. | MH | L |
| 14. Effect on non-threatened fauna? | The increased food privet species provide through the fruit load supports increased populations of aggressive bird species such as currowongs (Blood 2001; Swarbrick, Timmins & Bullen 1999). This then has the potential to impact on other bird species populations, quantitative evidence of the impact on such species has not been reported however. | M | L |
| 15. Benefits fauna? | Being a large fruit producing shrub, the species is likely to provide some assistance in either food or shelter to desirable species (Webb, Sykes & Garnock-Jones 1988). | MH | MH |
| 16. Injurious to fauna? | Reported toxic to horses, cattle, sheep and people and can result in death (Everist 1974). There has been no evidence reported on if this species is toxic to native fauna and if so to what extent it impacts on them. | M | L |
| Pest Animal | |||
| 17. Food source to pests? | Blackbirds and starlings are also reported to eat fruit of other Ligustrum species (Swarbrick, Timmins & Bullen 1999). | ML | M |
| 18. Provides harbor? | The species is not reported to provide shelter for any one pest species, however it is reported to form dense thickets (Weber 2003). Therefore there is the potential for the species to provide cover for pest species. | M | L |
| Agriculture | |||
| 19. Impact yield? | The species is reported to be toxic and potentially fatal to horses, cattle, and sheep (Everist 1974). It is unknown to what extent this species could impact on yield, it is suspected however to be minor. | M | L |
| 20. Impact quality? | Honey collected from privet species is reported to smell like fish (Swarbrick, Timmins & Bullen 1999). It is unknown to what extent this species could impact on product quality, it is suspected however to be minor. | M | L |
| 21. Affect land value? | The species has been used widely as an ornamental (Blood 2001; Weber 2003). It is therefore unlikely to have any significant impact upon land values. | L | M |
| 22. Change land use? | Unknown however as the species is considered to be largely an environmental weed this is unlikely. | L | M |
| 23. Increase harvest costs? | Unknown however as the species is considered to be largely an environmental weed this is unlikely. | L | M |
| 24. Disease host/vector? | The species can be a host of Plum pox virus (Polák 2006). | M | H |
This table can also be viewed as a PDF document (printer friendly).
Impact Assessment Record - European privet (PDF - 78KB)
Impact Assessment Record - European privet (DOC - 57KB)
To view the information PDF requires the use of a PDF reader. This can be installed for free from the Adobe website (external link).
Feedback
Do you have additional information about this plant that will improve the quality of the assessment?
If so, we would value your contribution. Click on the link to go to the feedback form.
© State of Victoria (Agriculture Victoria) 1996 - .
This work, Victorian Resources Online, is licensed under a Creative Commons Attribution 4.0 licence. You are free to re-use the work under that licence, on the condition that you credit the State of Victoria (Agriculture Victoria) as author, indicate if changes were made and comply with the other licence terms.
The licence does not apply to ‘branding’ or some ‘images or photographs’ that may be owned by third parties. We ask you to seek prior approval to use images using the VRO feedback form. Access to higher quality images can also be provided on request.
This page was last updated on .