Impact Assessment - Heather (Calluna vulgaris) 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 Heather
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: Heather
Scientific name: Calluna vulgaris
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | Grows up to 1.25 m, with woody pliable stems (CRC for Australian Weed Management 2003). ‘Varies from low and sparse to dense and bushy’ (USDA Forest Service 2004). Weed would have a minimal or negligible impact on human access. | L | MH |
| 2. Reduce tourism? | ‘The role of heather as a highly valued and major floristic component of British and European heathlands’ (Chapman & Bannister 1994). Visitors would be aware but not bothered by weed. | ML | H |
| 3. Injurious to people? | Not known to have any injurious effects. | L | MH |
| 4. Damage to cultural sites? | ‘.. alpine and subalpine areas of Victoria are threatened by C. vulgaris. Because of the cultural, environmental and recreational importance of these unique habitats..’ (CRC for Australian Weed Management 2003). If the weed did occur in cultural sites, likely to have a moderate visual effect. | ML | M |
| Abiotic | |||
| 5. Impact flow? | Terrestrial species. | L | H |
| 6. Impact water quality? | Terrestrial species | L | H |
| 7. Increase soil erosion? | ‘.. deliberately planted in gardens and for erosion control’ (CRC for Australian Weed Management 2003). Fibrous lateral root system. ‘A surface mat is formed by adventitious roots and fine branches of the main root system’ (USDA Forest Service 2004). Low probability of causing large scale soil movement. | L | MH |
| 8. Reduce biomass? | In a national park in New Zealand ‘C. vulgaris now dominates virtually all of the area previously covered in .. tussock grass-land’ (Rogers & Leathwick 1996). Has a ‘dense canopy during much of its life’ (CRC for Australian Weed Management 2003). Likely that the biomass may increase. | L | H |
| 9. Change fire regime? | ‘Dense canopy during much of its life and forms persistent leaf litter’. ‘ .. large accumulation of wood and litter’ (CRC for Australian Weed Management 2003). ‘Temperatures and [fire] intensities increased with stand age until the mature phase,’ at which point they decline in degenerate stands (USDA Forest Service 2004). Likely that the weed would contribute to a minor change in intensity of fire risk. | ML | MH |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | EVC= Clay heath (V); CMA=East Gippsland; Bioreg=East Gippsland Lowland; CLIMATE potential=VH. ‘ .. ability to dominate leads to a severe loss of biodiversity by displacing native vegetation and reducing the range and habitat available to native fauna’ (Rogers & Leathwick 1996). In a national park in New Zealand ‘C. vulgaris now dominates virtually all of the area previously covered in .. tussock grass-land’ (CRC for Australian Weed Management 2003). Major displacement of some dominant species within a strata | MH | MH |
| (b) medium value EVC | EVC= Heathy woodland (D); CMA=East Gippsland; Bioreg=East Gippsland Lowland; CLIMATE potential=VH. ‘ .. ability to dominate leads to a severe loss of biodiversity by displacing native vegetation and reducing the range and habitat available to native fauna’ (Rogers & Leathwick 1996). In a national park in New Zealand ‘C. vulgaris now dominates virtually all of the area previously covered in .. tussock grass-land’ (CRC for Australian Weed Management 2003). Major displacement of some dominant species within a strata. | MH | MH |
| (c) low value EVC | EVC= Banksia woodland. (LC); CMA=East Gippsland; Bioreg=East Gippsland Lowland; CLIMATE potential=VH. ‘.. ability to dominate leads to a severe loss of biodiversity by displacing native vegetation and reducing the range and habitat available to native fauna’ (Rogers & Leathwick 1996). In a national park in New Zealand ‘C. vulgaris now dominates virtually all of the area previously covered in .. tussock grass-land’ (CRC for Australian Weed Management 2003). Major displacement of some dominant species within a strata. | MH | MH |
| 11. Impact on structure? | ‘ .. ability to dominate leads to a severe loss of biodiversity by displacing native vegetation and reducing the range and habitat available to native fauna’ (Rogers & Leathwick 1996). In a national park in New Zealand ‘C. vulgaris now dominates virtually all of the area previously covered in .. tussock grass-land’ (CRC for Australian Weed Management 2003). Major effect on less than 60% of the floral strata | MH | H |
| 12. Effect on threatened flora? | This species is not documented as posing an additional risk to threatened flora. | MH | MH |
| Fauna | |||
| 13. Effect on threatened fauna? | This species is not documented as posing an additional risk to threatened fauna. | MH | MH |
| 14. Effect on non-threatened fauna? | ‘.. ability to dominate .. displacing native vegetation and reducing the habitat available to native fauna (CRC for Australian Weed Management 2003). Has the potential to have a minor effect on non-threatened fauna spp. | ML | M |
| 15. Benefits fauna? | ‘ the most important yearlong food of rock ptarmigan and grouse in Scotland and Denmark’. ‘Large portion of the diet of domestic sheep’ ‘ primary cover of the European red grouse .. probably also provides good cover for other upland game birds, small non-game birds, and small mammals’ (USDA Forest Service 2004). Possible that the weed could provide some assistance in either food or shelter to desirable species. | MH | MH |
| 16. Injurious to fauna? | Not known to be toxic to indigenous fauna. | L | MH |
| Pest Animal | |||
| 17. Food source to pests? | ‘Red deer and mountain hare also browse heather’ (USDA Forest Service 2004). Possible that the weed would supply food for one or more minor pest spp. | ML | MH |
| 18. Provides harbour? | ‘ primary cover of the European red grouse .. probably also provides good cover for other upland game birds, small non-game birds, and small mammals’ (USDA Forest Service 2004). May provide harbour for minor pest spp. | ML | MH |
| Agriculture | |||
| 19. Impact yield? | Not a weed of agriculture. | L | MH |
| 20. Impact quality? | Not a weed of cropping. | L | MH |
| 21. Affect land value? | Weed not known to affect value of land. | L | MH |
| 22. Change land use? | Weed not known to cause a change in priority of land use. | L | MH |
| 23. Increase harvest costs? | Not a weed of cropping. | L | MH |
| 24. Disease host/vector? | Not known 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 - Heather (PDF - 72KB)
Impact Assessment Record - Heather (DOC - 70KB)
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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