Impact Assessment - Glaucous star thistle (Carthamus glaucus) 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 Glaucous star thistle

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: Glaucous star thistle
Scientific name: Carthamus glaucus

Question	Comments	Reference	Rating
Recreation
1. Restrict human access?	Grows up to 80 cm high (Walsh & Entwisle 1999). Weed is spine-tipped thistle. Weed would have a low nuisance value.	ML	H
2. Reduce tourism?	Flowers in spring and summer (Walsh & Entwisle 1999). Has a purple flower and grows up to 80 cm high with spine-tipped leaves. Weed may have a minor effect on both aesthetics and recreational uses.	ML	H
3. Injurious to people?	Lobes of weed are spine-tipped (Walsh & Entwisle 1999). Likely that weed would cause minor damage from spines at certain times of the year.	ML	H
4. Damage to cultural sites?	Flowers in spring and summer (Walsh & Entwisle 1999). Has a purple flower and grows up to 80 cm high with spine-tipped leaves. Little or negligible effect on aesthetics.	L	H
Abiotic
5. Impact flow?	Terrestrial species.	L	H
6. Impact water quality?	Terrestrial species.	L	H
7. Increase soil erosion?	Insufficient information to determine whether the weed would increase soil erosion. Score medium.	M	L
8. Reduce biomass?	Grows amongst crops (Solh & Pala 1990). In these situations there would be a direct replacement of biomass by invader.	ML	H
9. Change fire regime?	Insufficient information to determine whether weed would affect frequency or intensity of fire. Score medium.	M	L
Community Habitat
10. Impact on composition (a) high value EVC	EVC= Chenopod grassland (BCS =E); CMA=Mallee; Bioreg=Murray mallee; CLIMATE potential=VH. Grows amongst crops (Solh & Pala 1990). Very little displacement of any indigenous species.	L	H
(b) medium value EVC	EVC= Riverine chenopod woodland (BCS =E); CMA=Wimmera; Bioreg=Murray mallee; CLIMATE potential=VH. Grows amongst crops (Solh & Pala 1990). Very little displacement of any indigenous species.	L	H
(c) low value EVC	EVC= Coastal tussock grassland (BCS =E); CMA=Port Phillip; Bioreg=Gippsland Plain; CLIMATE potential=L. Grows amongst crops (Solh & Pala 1990). Very little displacement of any indigenous species.	L	H
11. Impact on structure?	Grows amongst crops (Solh & Pala 1990). In these situations it would only effect one of the strata.	L	H
12. Effect on threatened flora?12. Effect on threatened flora?	This species is not documented as posing an additional risk to threatened flora.	MH	L
Fauna
13. Effect on threatened fauna?	This species is not documented as posing an additional risk to threatened fauna.	MH	L
14. Effect on non-threatened fauna?	Not enough information to determine the effect the weed would have on non-threatened fauna species. Score as medium.	M	L
15. Benefits fauna?	Insufficient information to determine whether the weed provides benefits or facilitates the establishment of indigenous fauna. Score as medium.	M	L
16. Injurious to fauna?	Lobes of weed are spine-tipped (Walsh & Entwisle 1999). Insufficient documented evidence to determine the extent the weed affects indigenous fauna. Score as medium.	M	H
Pest Animal
17. Food source to pests?	Insufficient documented evidence to determine the extent the weed provides a food source to assist in success of pest animals. Score as medium.	M	L
18. Provides harbor?	Insufficient evidence to determine the extent the weed provides harbour for serious pests. Score as medium.	M	L
Agriculture
19. Impact yield?	‘The major weed species associated with chickpea in West Asia and North Africa include … Carthamus syriacus. …In winter sown chickpea weeds present a serious threat to the crop and yield losses up to 98% have been reported’ (Solh & Pala 1990). Recorded as a common weed of Iran in Holm et al (1979). Has capacity to have a major impact on quantity of produce.	MH	H
20. Impact quality?	‘The contamination of produce with weed seeds reduces the crop quality’ (Solh & Pala 1990). Weed may have a minor impact on quality.	ML	H
21. Affect land value?	Not enough documented evidence to determine whether the weed affects land value. Score as medium.	M	L
22. Change land use?	Insufficient evidence to determine whether the weed would cause a change in priority of land use. Score as medium.	M	L
23. Increase harvest costs?	Insufficient evidence to determine the extent the presence of the weed increases the cost of harvest. Score as medium.	M	L
24. Disease host/vector?	Insufficient evidence to determine whether the weed acts as a host or vector for disease of agriculture. Score as medium.	M	L

This table can also be viewed as a PDF document (printer friendly).

Impact Assessment Record - Glaucous star thistle (PDF - 68KB)
Impact Assessment Record - Glaucous star thistle (DOC - 63KB)
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.

Page top