Impact Assessment - Amsinckia (Amsinckia spp.) in Victoria (Nox)

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.

Question	Comments	Reference	Rating
Recreation
1. Restrict human access?	Amsinckia is an erect annual herb that grows to a height of 70 cm. While infestations can be of the order of 90 plants per square metre, it is not likely to impede human traffic.	P & C (2001)	L
2. Reduce tourism?	Its presence is clearly noticeable during flowering. The plant would have a major effect on aesthetics.	Carr et al (1992) P & C (2001)	MH
3. Injurious to people?	No recorded affect on humans, but the stiff hairs or bristles on the leaves and stems may cause some discomfort for a person on foot.	P & C (2001)	L
4. Damage to cultural sites?	Presence of the plant is quite noticeable during flowering. It would have a moderate negative visual effect.	P & C (2001)	ML
Abiotic
5. Impact flow?	Terrestrial spp.	P & C (2001)	L
6. Impact water quality?	Terrestrial spp.	P & C (2001)	L
7. Increase soil erosion?	Predominantly a weed of crops. Not likely to increase soil erosion.	P & C (2001)	L
8. Reduce biomass?	Competes with crops; replaces existing biomass.	P & C (2001)	ML
9. Change fire regime?	No known to affect fire regime.		L
Community Habitat
10. Impact on composition (a) high value EVC	EVC=Plains grassland (E); CMA=North Central; Bioreg=Victorian Riverina; VH CLIMATE potential. It occurs on a wide range of soils, particularly dry, sandy soils, in moderately warm, unshaded situations. Annual; competes with annual grasses/forbs. Occurs rarely in small populations.	P & C (2001)	ML
(b) medium value EVC	EVC=Broombush mallee (D); CMA=Goulburn Broken; Bioreg=Northern Inland Slopes; VH CLIMATE potential As above	P & C (2001)	ML
(c) low value EVC	EVC=Sand heathland (LC); CMA=Glenelg Hopkins; Bioreg=Victorian Volcanic Plains; VH CLIMATE potential As above	P & C (2001)	ML
13. Impact on structure?	Not known as a problem in environmental situations. It occurs in lowland grassland and grassy woodland vegetation, but its distribution is rare and it occurs in small populations. Minor effect on > 20% of the floral strata.	Carr et al (1992)	ML
14. Effect on threatened flora?
Fauna
15. Effect on threatened fauna?
16. Effect on non-threatened fauna?	No recorded effects on habitat or food source of non-threatened fauna. Predominantly a weed of cropping; few if any fauna co-existing in situation.	P & C (2001) Carr et al (1992)	L
17. Benefits fauna?	“Birds are known to eat the seed.” But bird spp. not specified (native or introduced). “Bristles on the leaves and stems make the plant unattractive to stock and it is generally unpalatable.” Annual spp. dying back in summer; no harbor. Very limited benefit, if at all.	P & C (2001) Faithfull (1998)	H
18. Injurious to fauna?	Not evident, though “…one spp. causes liver disease which killed 2000 cattle in the United States, but deaths have not be recorded in Australia.” Generally unpalatable; limited potential to injure to fauna.	P & C (2001)	L
Pest Animal
19. Food source to pests?	“Birds are known to eat the seed.” Not known if native or introduced species. Not known to provide a significant source of food.	P & C (2001)	L
20. Provides harbor?	An erect, annual herb that dies back in late spring or early summer. Not likely to provide harbor.	P & C (2001)	L
Agriculture
21. Impact yield?	Very competitive in cereal crops. Recorded instance of 48% reduction in wheat yield in NSW.	P & C (2001)	H
22. Impact quality?	It is claimed Amsinckia seed imparts a peculiar taint to flour and fragments of the black seedcoat discolour flour. The “bristly calyx becomes an impurity in wool.”	P & C (2001)	MH
23. Affect land value?	Considering its potential impact on both yield and quality, the presence of this weed would reduce land value. It can be controlled with appropriate mechanical and chemical treatments.	P & C (2001)	M
24. Change land use?	See above. No chemicals are registered for use against Amsinckia in broad-leaved cereal crops. Therefore, farmers wishing to cultivate broad-leaved winter crops in lieu of winter cereals may have to temporarily change land use.	P & C (2001)	M
25. Increase harvest costs?	“Human activities are most important [in dispersal] resulting in spread [of seed] through the movement of contaminated harvesting equipment, hay balers and seed graders.” Farm machinery used on affected properties must be thoroughly cleaned to eliminate the presence and subsequent dispersal of the seed. This could increase harvesting costs.	P & C (2001)	M
26. Disease host/vector?	None evident		L