Impact Assessment - Topped lavender (Lavandula stoechas) 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 shrub, commonly about 60 cm high.” Minimal impact on human access	P & C (2001) Carr et al (1992)	L
2. Reduce tourism?	During flowering, the presence of the plant is obvious. Dense patches may have a minor impact on recreational activities.		ML
3. Injurious to people?	No spines, burrs or toxic properties.		L
4. Damage to cultural sites?	Dense infestations may create a negative visual impact.		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 was advocated for sand-binding in the early days.” Not likely to contribute to soil erosion.	P & C (2001)	L
8. Reduce biomass?	“In Australia, it occurs as a weed of neglected areas and poor pastures.” A shrub, biomass would increase in such situations.	P & C (2001)	L
9. Change fire regime?	No data available. Assume negligible effect on risk of fire.		L
Community Habitat
10. Impact on composition (a) high value EVC	EVC=Grassy Woodland (E); CMA=Goulburn Broken; Bioreg=Central Victorian Uplands; VH CLIMATE potential. “…occurs in disturbed grassy woodlands…dense stands eliminate all other ground flora and smaller shrubs while severely impeding overstorey regeneration.” Major displacement of species in the lower strata.	Muyt (2001)	MH
(b) medium value EVC	EVC=Box Ironbark forest (D); CMA=Goulburn Broken; Bioreg=Goldfields; VH CLIMATE potential. Impact as in 10(a) above.	Muyt (2001)	MH
(c) low value EVC	EVC=Lowland forest (LC); CMA=Corangamite; Bioreg=Victorian Volcanic Plain; VH CLIMATE potential. “It grows most prolifically in open, sunny position.” Similar impact as in 10(a), though overstorey cover may limit population density.	Muyt (2001)	MH
11. Impact on structure?	“As a weed it forms dense patches which eliminate most other vegetation.” Infestations would have a major impact on grasses and forbs.	P & C (2001)	ML
12. Effect on threatened flora?
Fauna
13. Effect on threatened fauna?
14. Effect on non-threatened fauna?	In Victoria, it occurs on mallee scrubland and lowland grassland & grassy woodland in medium to large populations. “As a weed it forms dense patches which eliminate most other vegetation and, because it is not eaten by stock, the loss of production can be considerable.” Reduces availability of fodder.	Carr et al (1992) P & C (2001)	ML
15. Benefits fauna?	No known benefits.		H
16. Injurious to fauna?	Not injurious to fauna		L
Pest Animal
17. Food source to pests?	Birds are known to disperse seeds. Possibly, pest species are implicated.	P & C (2001) Carr et al (1992)	ML
18. Provides harbor?	“Dense patches also provide harbour for rabbits.”	P & C (2001)	H
Agriculture
19. Impact yield?	“As a weed it forms dense patches which eliminate most other vegetation and, because it is not eaten by stock, the loss of production can be considerable.” Serious impacts on quantity of agricultural produce.	P & C (2001)	H
20. Impact quality?	Not known as a weed of cropping, or as contaminant in agricultural produce.		L
21. Affect land value?	“As a weed it forms dense patches which eliminate most other vegetation and, because it is not eaten by stock, the loss of production can be considerable.” Land value may be somewhat affected.	P & C (2001)	M
22. Change land use?	In grazing situations, it occurs mostly on poorer pastures. Land use unlikely to change.	P & C (2001)	L
23. Increase harvest costs?	Not known to affect harvest costs.		L
24. Disease host/vector?	None evident.		L

Impact Assessment Record - Topped lavender (PDF - 31KB)
Impact Assessment Record - Topped lavender (DOC - 58KB)
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