Impact Assessment - Karamu (Coprosma robusta) 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 Karamu.
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 - 1 MB)
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: Karamu
Scientific name: Coprosma robusta
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | Although not specifically documented, as a large shrub or small tree to 6 m (Blood 2001) that forms dense thickets (R. Adair pers. com). Potential to restrict human access particularly as it is found growing in riparian areas (Marden et al 2005). | M | M |
| 2. Reduce tourism? | As a large shrub or small tree to 6 m (Blood 2001) that forms dense thickets (R. Adair pers. com) it is likely to have minor affects to the aesthetics of an area, but it is not documented to affect recreational uses. | ML | MH |
| 3. Injurious to people? | No information to suggest it possesses any properties injurious to people. | L | M |
| 4. Damage to cultural sites? | No information to suggest it would cause damage to cultural sites or infrastructure. | L | M |
| Abiotic | |||
| 5. Impact flow? | Occurs in riparian areas, including those subject to tidal effects and inundation. ‘It establishes in a narrow inundation zone not occupied by much other than Juncus spp and Phragmites australis (A. Crane pers. com.)’. Though not specifically documented, there is potential for it to have some impact on water flow in these circumstances. | M | M |
| 6. Impact water quality? | Occurs in riparian areas, including those subject to tidal effects and inundation. ‘It establishes in a narrow inundation zone not occupied by much other than Juncus spp and Phragmites australis (A. Crane pers. com.)’. Not documented occurring in permanent water so unlikely to cause noticeable affects on dissolved oxygen or light levels. | L | M |
| 7. Increase soil erosion? | ‘Karamu is one of most useful plants for controlling soil erosion…Its dense fibrous root system makes it good for stabilising soil (TFS 2007)’. Has growth attributes well suited to colonising steep and unstable riparian slopes (Marden et al 2005). Likely to decrease the probability of soil erosion. | L | MH |
| 8. Reduce biomass? | Large shrub or small tree to 6 m (Blood 2001) that forms dense thickets (R. Adair pers. com). Potential to increase community biomass. | L | M |
| 9. Change fire regime? | ‘Definite fire hazard - Karamu's height will increase risk of fire reaching the crown….many of the Peninsulas Woodland EVCs have very low understorey with sparse middle storey (J. Lynch pers. com.). Potential for moderate change to fire intensity. | M | M |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | EVC= Damp Forest (BCS= E); CMA= West Gippsland; Bioreg= Strzelecki Ranges; CLIMATE potential=VH Described as a ‘very serious threat’ to wet and damp sclerophyll forest in Victoria (Carr et al 1992). Forms dense thickets (R. Adair pers. com.). ‘…effective at replacing native shrubs such as Leptospermum, as well as suppressing the growth of trees (Acacia melanoxylon, A. dealbata)’ (A. Crane pers. com.). Able to ‘destroy understorey vegetation within 2 - 3 years (Pers. com. J. Lynch)’. Potential to displace all species within the ground and middle strata. | H | M |
| (b) medium value EVC | EVC= Herb-rich Foothill Forest (BCS= D); CMA= Corangamite; Bioreg= Otway ranges; CLIMATE potential=VH Described as a ‘very serious threat’ to wet and damp sclerophyll forest in Victoria (Carr et al 1992). Forms dense thickets (R. Adair pers. com.). ‘…effective at replacing native shrubs such as Leptospermum, as well as suppressing the growth of trees (Acacia melanoxylon, A. dealbata)’ (A. Crane pers. com.). Able to ‘destroy understorey vegetation within 2 - 3 years (Pers. com. J. Lynch)’. Potential to displace all species within the ground and middle strata. | H | M |
| (c) low value EVC | EVC= Shrubby Wet Forest (BCS= LC); CMA= Corangamite; Bioreg= Otway ranges; CLIMATE Described as a ‘very serious threat’ to wet and damp sclerophyll forest in Victoria (Carr et al 1992). Forms dense thickets (R. Adair pers. com.). ‘…effective at replacing native shrubs such as Leptospermum, as well as suppressing the growth of trees (Acacia melanoxylon, A. dealbata)’ (A. Crane pers. com.). Able to ‘destroy understorey vegetation within 2 - 3 years (Pers. com. J. Lynch)’. Potential to displace all species within the ground and middle strata. | H | M |
| 11. Impact on structure? | Forms dense thickets (R. Adair pers. com.). Able to ‘destroy understorey vegetation within 2 - 3 years’, ‘forms monocultures’ and ‘seems to contribute to dieback of upper storey species (Pers. com. J. Lynch)’. ‘…effective at replacing native shrubs such as Leptospermum, as well as suppressing the growth of trees (Acacia melanoxylon, A. dealbata)’ (A. Crane pers. com.). Appears to have the potential to significantly affect all layers and form monocultures. | H | M |
| 12. Effect on threatened flora? | Able to ‘destroy understorey vegetation within 2 - 3 years (Pers. com. J. Lynch)’. Likely to impact on threatened flora but not specifically documented. | MH | L |
| Fauna | |||
| 13. Effect on threatened fauna? | ‘Some of the areas provide habitat for endangered species such as the powerful owl (Pers. com. J. Lynch)’. However, not documented as having a specific impact on a threatened species. | MH | ML |
| 14. Effect on non-threatened fauna? | ‘…effective at replacing native shrubs such as Leptospermum, as well as suppressing the growth of trees (Acacia melanoxylon, A. dealbata)’ (A. Crane pers. com.). ‘…likely to be replacing habitat for small native bird species (e.g. insectivores such as thornbills and wrens) (A. Crane pers. com.). Likely to reduce habitat leading to a reduction in numbers of individuals. | MH | M |
| 15. Benefits fauna? | Red berries consumed by brush tailed possums (Williams et al 2000) and birds (Blood 2001). Forms dense thickets (R. Adair pers. com). Would provide some assistance in food and shelter to desirable species. | MH | H |
| 16. Injurious to fauna? | Not described as injurious to fauna. | L | M |
| Pest Animal | |||
| 17. Food source to pests? | Foxes disperse C. repens seeds (Blood 2001) so would also likely consume the similar bright red berries of C. robusta (Muyt 2001). C. robusta seedlings also documented to be consumed by rabbits (Bryan et al 2005). Potential to provide food to serious pest/s but the extent is unknown. | MH | M |
| 18. Provides harbour? | Though not documented, as a large shrub (Blood 2001) that forms dense thickets (R. Adair pers. com.) has the capacity to provide harbour for foxes. | M | M |
| Agriculture | |||
| 19. Impact yield? | Not known as weed of agriculture. | L | M |
| 20. Impact quality? | Not known as weed of agriculture. | L | M |
| 21. Affect land value? | Not known as weed of agriculture. | L | M |
| 22. Change land use? | Not known as weed of agriculture. | L | M |
| 23. Increase harvest costs? | Not known as weed of agriculture. | L | M |
| 24. Disease host/vector? | Not known as weed of agriculture. | L | M |
Impact Assessment Record - Karamu (PDF - 98KB)
Impact Assessment Record - Karamu (DOC - 98KB)
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