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Impact Assessment - Canary Island St John's wort (Hypericum canariense) in Victoria

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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 Canary island st john's wort

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: Canary island st john's wort
Scientific name: Hypericum canariense

Question
Comments
Rating
Confidence
Recreation
1. Restrict human access?Many-branched shrub which can grow from one to 5 metres tall (Randall 2002). Species can be used in borders. Plant is likely to impede individual access.
ML
H
2. Reduce tourism?Has ‘numerous bright yellow flowers and an attractive shrubby habit (Randall 2002). Most noticeable during its flowering period (spring ) (Starr et al 2003). Weed would have minor effect on aesthetics.
ML
H
3. Injurious to people?Weed not documented to be injurious in any way.
L
MH
4. Damage to cultural sites?Has ‘numerous bright yellow flowers and an attractive shrubby habit (Randall 2002). Most noticeable during its flowering period (spring ) (Starr et al 2003). Weed would have a moderate visual effect.
ML
H
Abiotic
5. Impact flow?Terrestrial species.
L
H
6. Impact water quality?Terrestrial species.
L
H
7. Increase soil erosion?Shrub is dense and multi-stemmed. Although foliage drops, unlikely that soil would be exposed for any length of time. Low probability of large scale soil movement.
L
MH
8. Reduce biomass?‘Highly competitive plant which displaces virtually all lower storey species’ (Randall 2002). Biomass may increase.
L
H
9. Change fire regime?Multi-stemmed scrub with foliage dropping in late summer (Dlugosch 2004). ‘Dense growth in dry environments, carries few leaves’ (PIER 2005). Plant would have minor effect on fire risk.
ML
MH
Community Habitat
10. Impact on composition
(a) high value EVC
EVC= Plains Grassy Woodland (E.); CMA=Glenelg Hopkins; Bioreg=Victorian Volcanic Plain; CLIMATE potential=VH.
Major displacement of some dominant species within the lower storey.
MH
H
(b) medium value EVCEVC= Grassy Woodland (D); CMA=West Gippsland; Bioreg=Highland Southern Fall; CLIMATE potential=VH.
Major displacement of some dominant species within the lower storey.
MH
H
(c) low value EVCEVC= Granitic Hills Woodland (LC); CMA=Goulburn Broken; Bioreg=Northern Inland Slopes; CLIMATE potential=VH.
Major displacement of some dominant species within the lower storey.
MH
H
11. Impact on structure?‘Highly competitive plant which displaces virtually all lower storey species’ (Randall 2002). Major effect on less than 60% of floral strata.
MH
H
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?Plant not documented to have an effect on non-threatened fauna.
L
MH
15. Benefits fauna?Plant not known to provide benefits to indigenous fauna.
H
MH
16. Injurious to fauna?Plant doesn’t have burrs or spines (PIER 2005) and not known to be toxic.
L
MH
Pest Animal
17. Food source to pests?Weed not documented as a food source to pest animals.
L
MH
18. Provides harbor?Weed not known to provide harbour for pest species.
L
MH
Agriculture
19. Impact yield?Not known as a weed of agriculture (Randall 2002).
L
H
20. Impact quality?Not a weed of cropping (Randall 2002).
L
H
21. Affect land value?Weed not documented to affect land value. Can be controlled by herbicides (PIER 2005).
L
MH
22. Change land use?Not documented to cause a change in priority of land use. Can be controlled by herbicides (PIER 2005).
L
MH
23. Increase harvest costs?Not known as a weed of agriculture (Randall 2002).
L
H
24. Disease host/vector?Not documented as a host or vector for disease of agriculture.
L
MH

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

Impact Assessment Record - Canary island st john's wort (PDF - 69KB)
Impact Assessment Record - Canary island st john's wort (DOC - 52KB)
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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