Impact Assessment - Ox-eye daisy (Asphodelus fistulosus) in Victoria (Nox)

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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?	An erect perennial herb commonly 30 to 60 cm high (mainly stem growth). Narrow, fleshy stems. Infestations of this plant would have minimal impact on human access.	P & C (2001)	L
2. Reduce tourism?	During flowering, the weed is quite noticeable. At distance, dense patches appear as carpets of white. The growth habit of the plant would not affect recreational activities.	P & C (2001)	ML
3. Injurious to people?	No harmful physical properties. Not toxic.	P & C (2001)	L
4. Damage to cultural sites?	“Ox-eye daisy grows so densely that it excludes almost all other vegetation.” It would create a moderate negative visual impact.	P & C (2001)	ML
Abiotic
5. Impact flow?	Terrestrial species.	P & C (2001)	L
6. Impact water quality?	Terrestrial species.	P & C (2001)	L
7. Increase soil erosion?	It occurs mostly on disturbed sites and degraded pastures and can grow so densely, “…that it excludes almost all other vegetation.” Aerial growth dies back after summer which may leave areas of soil exposed. Potential for surface soil erosion.	P & C (2001)	ML
8. Reduce biomass?	It occurs mostly on disturbed sites and degraded pastures. A strong competitor, it replaces biomass.	P & C (2001)	ML
9. Change fire regime?	Aerial growth dies back in summer leaving little material for fire.	P & C (2001)	L
Community Habitat
10. Impact on composition (a) high value EVC	EVC=Plains grassy woodland (E); CMA=Goulburn Broken; Bioreg=Central Victorian Uplands; VH CLIMATE potential. “…occurs commonly in grasslands of the British Isles. Ox-eye daisy grows so densely that it excludes almost all other vegetation.” In Victoria it occurs in large to medium populations in lowland grassland and grassy woodland. Major displacement of grass species.	P & C (2001) Carr et al (1992)	MH
(b) medium value EVC	EVC=Riparian shrubland (R); CMA=West Gippsland; Bioreg=Highlands – Southern Fall; VH CLIMATE potential. Impact as in 10(a) above.	P & C (2001) Carr et al (1992)	MH
(c) low value EVC	EVC=Damp forest (LC); CMA=West Gippsland; Bioreg=Highlands – Southern Fall; VH CLIMATE potential. Impact as in 10(a) above.	P & C (2001) Carr et al (1992)	MH
11. Impact on structure?	Where it occurs on disturbed sites and degraded pastures it, “grows so densely that it excludes almost all other vegetation.” Would have a major impact on ground flora.	P & C (2001)	ML
12. Effect on threatened flora?
Fauna
13. Effect on threatened fauna?
14. Effect on non-threatened fauna?	“Dense infestations exclude most other vegetation…[and] it is not readily grazed.” Would reduce the food source for native fauna.	P & C (2001)	ML
15. Benefits fauna?	No benefits.		H
16. Injurious to fauna?	Not known to be poisonous to animals.		L
Pest Animal
17. Food source to pests?	Not known as a food source to pests.		L
18. Provides harbour?	Growth habit is unlikely to provide harbour for pest species.		L
Agriculture
19. Impact yield?	“Ox-eye daisy grows so densely that it excludes almost all other vegetation. Because it is not readily grazed by stock, carrying capacity of infested areas is reduced, and the weed’s chances of survival and spread are enhanced.” Carr et al (1992) indicates infestations are widespread in medium to large populations. Likely to have a major impact on quantity.	P & C (2001) Carr et al (1992)	MH
20. Impact quality?	“If eaten, it imparts a disagreeable taste to milk.” Minor impact on quality.	P & C (2001)	ML
21. Affect land value?	Although infestations can be readily control by mechanical or chemical methods, the impact on yield in grazing activities may reduce the value of land in those situations.		M
22. Change land use?	No		L
23. Increase harvest costs?	No impact on harvest costs.		L
24. Disease host/vector?	“Ox-eye daisy hosts virus diseases in the United States, including the yellow dwarf virus of potatoes, but its importance in this role in Australia in not known.” It has the potential to affect Australian agriculture.	P & C (2001)	H

Impact Assessment Record - Ox-eye daisy (PDF - 32KB)
Impact Assessment Record - Ox-eye daisy (DOC - 59KB)
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