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Impact Assessment - African daisy (Senecio pterophorus) 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.

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 African daisy.

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 - 1026 KB)
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: African daisy
Scientific name: Senecio pterophorus

Question
Comments
Reference
Rating
Recreation
1. Restrict human access?Woody, bushy shrub. Invades dry sclerophyll forest and woodland. Generally 1 to 1.5 m in height. “In rainfall areas >500 mm pa can reach 3 m height and 2 – 2.5 m in diameter.” Potential to limit the activities of bushwalkers.
ML
2. Reduce tourism?Weeds presence is obvious, particularly during flowering, November to autumn. Major negative affect on aesthetics.
P & C (2001)
MH
3. Injurious to people?Not known to affect humans.
L
4. Damage to cultural sites?Existence of plant is quite noticeable, but is not likely to cause any structural changes.
P & C (2001)
ML
Abiotic
5. Impact flow?Terrestrial sp.
P & C (2001)
L
6. Impact water quality?Terrestrial sp.
P & C (2001)
L
7. Increase soil erosion?Perennial. Fibrous, densely branching roots to 20 cm depth and up to 6 m in diameter.
P & C (2001)
L
8. Reduce biomass?“It competes aggressively with developing pastures and crops, and becomes dominant in the early years of infestation.” Bushy property of plant suggests biomass not negatively affected. However, in woodland areas it is likely to reduce biomass.
P & C (2001)
Carr et al (1992)
ML
9. Change fire regime?While predominantly a weed of open areas (e.g. pastures, wasteland), as a woody, bushy shrub, it may have a minor impact on frequency of fire in native ecosystems.
Carr et al (1992)
ML
Community Habitat
10. Impact on composition
(a) high value EVC
EVC=Plains grassy woodland (E); CMA=Glenelg Hopkins; Bioreg=Goldfields; VH CLIMATE potential
In the Mt Napier State park, it occurs in, “large patches significantly altering native vegetation.” Invades lowland grassland & grassy woodlands, dry sclerophyll forest and woodlands. Major displacement of species within different strata.
DNRE (1996)1
Carr et al (1992)
MH
(b) medium value EVCEVC=Box-Ironbark forest (D); CMA=Glenelg Hopkins; Bioreg=Goldfields; VH CLIMATE potential
Can occur on forest margins. Minor impact on grasses/forbs.
P & C (2001)
ML
(c) low value EVCEVC=Montane dry woodland (LC); CMA=West Gippsland; Bioreg=Highland Southern Falls; VH CLIMATE potential. Can occur on forest margins. Minor impact on grasses/forbs.
P & C (2001)
ML
11. Impact on structure?In the Mt Napier State park, it occurs in, “large patches significantly altering native vegetation.” Invades lowland grassland & grassy woodlands, dry sclerophyll forest and woodlands. Likely to have a minor impact on lower strata.
DNRE (1996)
Carr et al (1992)
ML
12. Effect on threatened flora?
Fauna
13. Effect on threatened fauna?
14. Effect on non-threatened fauna?“In natural areas the plant is a strong competitor, forming dense thickets that exclude native species.” Reduction in habitat for non-threatened fauna.
LC0196 (2000)2
ML
15. Benefits fauna?None recorded.
H
16. Injurious to fauna?Plant contains alkaloids. May be hazardous.
P & C (2001)
H
Pest Animal
17. Food source to pests?See comment at Q16.
P & C (2001)
L
18. Provides harbor?“In natural areas the plant is a strong competitor, forming dense thickets.” This growth habit may provide harbor for birds.
LC0196 (2000)
ML
Agriculture
19. Impact yield?“Competes aggressively with developing pastures and crops…and often becomes dominant in early years of infestation rendering infested lands unproductive.”
P & C (2001)
H
20. Impact quality?No recorded impact on agricultural quality.
L
21. Affect land value?“…heavily infested lands (become) unproductive.”
P & C (2001)
M
22. Change land use?See question 23 above. “Left undisturbed, however, it gradually thins out and is rarely a problem in well managed pastures and cereal crops.”
P & C (2001)
L
23. Increase harvest costs?No evidence of increased harvest costs. “…it is rarely a problem in well managed cereal crops.”
P & C (2001)
L
24. Disease host/vector?Not evident.
L

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

Impact Assessment Record - African daisy (PDF - 32 KB)
Impact Assessment Record - African daisy (DOC - 59 KB)
To view the information PDF requires the use of a PDF reader. This can be installed for free from the Adobe website (external link).

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