Impact Assessment - Feathertop (Pennisetum villosum) 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 Feathertop (white foxtail).
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: Feathertop (white foxtail)
Scientific name: Pennisetum villosum
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | Tussock-forming perennial grass 30-70 cm high (Parsons & Cuthbertson 1992), likely to have minimal impact on human access. | L | MH |
| 2. Reduce tourism? | As a tussock forming grass (Walsh & Entwisle 1994) it could be mistaken for a native species and not likely to be obvious as a weed to the ‘average visitor’. | L | MH |
| 3. Injurious to people? | No information was found to suggest this species possesses properties injurious to people. | L | M |
| 4. Damage to cultural sites? | Not documented as having an impact on cultural sites or infrastructure, and as a grass to 70 cm high (Walsh & Entwisle 1994), it is likely to have little effect on the aesthetics or structure of sites. | L | MH |
| Abiotic | |||
| 5. Impact flow? | A terrestrial species (Carr et al 1992), so no likely effect on water flow. | L | MH |
| 6. Impact water quality? | A terrestrial species (Carr et al 1992), so no likely effect on water quality. | L | MH |
| 7. Increase soil erosion? | Rhizomatous, densely tussock-forming perennial grass (Parsons & Cuthbertson 1992, Walsh & Entwisle 1994), with characteristics suggesting it would decrease the probability of soil erosion. | L | MH |
| 8. Reduce biomass? | As a tussock-forming perennial grass to 70 cm high (Parsons & Cuthbertson 1992), it is similar in stature to some native tussock grasses so, ‘direct replacement of biomass’ is likely. | ML | MH |
| 9. Change fire regime? | No information was found to indicate it would have any significant affect on fire regime of habitats in which it occurs and would likely replace other grasses that have similar flammability. | L | M |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | EVC = Plains Grassland (E); CMA = Corangamite; Bioregion = Otway Plain; VH CLIMATE potential. ‘It may occasionally become an environmental weed of grassy woodlands and grasslands (South East Weeds 2008)’, and can occur in coastal areas and along creeks and river banks (Parsons & Cuthbertson 1992). It forms spreading clumps (Kleinschmidt & Johnson 1977), and is described as being a ‘potential threat to one or more vegetation formations in Victoria (Carr et al 1992)’. However, no information was found on the level of impact it is having, or could have, on EVCs in Victoria. | M | L |
| (b) medium value EVC | EVC = Riverine Grassy woodland (D); CMA = North Central; Bioregion = Victorian Riverina; VH CLIMATE potential. ‘It may occasionally become an environmental weed of grassy woodlands and grasslands (South East Weeds 2008)’, and can occur in coastal areas and along creeks and river banks (Parsons & Cuthbertson 1992). It forms spreading clumps (Kleinschmidt & Johnson 1977), and is described as being a ‘potential threat to one or more vegetation formations in Victoria (Carr et al 1992)’. However, no information was found on the level of impact it is having, or could have, on EVCs in Victoria. | M | L |
| (c) low value EVC | EVC = Coastal Tussock Grassland (LC); CMA = West Gippsland; Bioregion = Gippsland Plain; VH CLIMATE potential. ‘It may occasionally become an environmental weed of grassy woodlands and grasslands (South East Weeds 2008)’, and can occur in coastal areas and along creeks and river banks (Parsons & Cuthbertson 1992). It forms spreading clumps (Kleinschmidt & Johnson 1977), and is described as being a ‘potential threat to one or more vegetation formations in Victoria (Carr et al 1992)’. However, no information was found on the level of impact it is having, or could have, on EVCs in Victoria. | M | L |
| 11. Impact on structure? | ‘It may occasionally become an environmental weed of grassy woodlands and grasslands (South East Weeds 2008)’, and can occur in coastal areas and along creeks and river banks (Parsons & Cuthbertson 1992). It forms spreading clumps (Kleinschmidt & Johnson 1977), and is described as being a ‘potential threat to one or more vegetation formations in Victoria (Carr et al 1992)’. However, no information was found on the level of impact it is having, or could have, on the structure of vegetation communities. | M | L |
| 12. Effect on threatened flora? | No reference to its impact on threatened flora was found in the literature. | MH | L |
| Fauna | |||
| 13. Effect on threatened fauna? | No reference to its impact on threatened fauna was found in the literature. | MH | L |
| 14. Effect on non-threatened fauna? | There is no indication this species possess any properties hazardous to fauna, but also no information of the impact this weed has on faunal habitat. However, effects to non-threatened fauna are likely to be minor as this species often invades disturbed areas (Parsons & Cuthbertson 1992) that are already likely of poor habitat quality. | ML | M |
| 15. Benefits fauna? | Young shoots may be eaten but the long serrated leaves of mature plants are unpalatable and rarely grazed by stock (Parsons & Cuthbertson 1992). May provide some assistance as a food source to desirable species. | MH | M |
| 16. Injurious to fauna? | There is no suggestion that this species possess any properties injurious to fauna. | L | M |
| Pest Animal | |||
| 17. Food source to pests? | Young shoots may be eaten but the long serrated leaves of mature plants are unpalatable and rarely grazed by stock (Parsons & Cuthbertson 1992). It may provide some food source to grazing pest animals but this is likely to be minimal and was not found documented in the literature. | L | M |
| 18. Provides harbor? | As a tussock-forming perennial grass 30-70 cm high (Parsons & Cuthbertson 1992) does not have the capacity to provide harbour to serious pests, but because it invades urban and agricultural areas (Parsons & Cuthbertson 1992) may provide harbour for minor pest animals such as introduced rodents. | ML | M |
| Agriculture | |||
| 19. Impact yield? | Produces large dense clumps, which over time tend to dominate infested pastures and reduce the available grazing area (Parsons & Cuthbertson 1992). ‘Chokes out useful grasses (North West Weeds 2006)’ and ‘being unpalatable reduces carrying capacity (South East Weeds 2008)’. Because not specified, a moderate level of impact is assumed. | M | M |
| 20. Impact quality? | Described as a contaminant in wool (North West Weeds 2006), however, the level of impact on agricultural quality is not clear from available information. | M | ML |
| 21. Affect land value? | Summer cultivation gives effective control but must be repeated regularly until weed is eliminated. A single cultivation only, spreads rhizomes to clean areas (Parsons & Cuthbertson 1992). Not specifically documented, but unlikely to affect land value, as effective control is achievable using normal farm management practises. | L | M |
| 22. Change land use? | Summer cultivation gives effective control but must be repeated regularly until weed is eliminated (Parsons & Cuthbertson 1992). Not specifically documented, but unlikely to cause a change in priority of land use, as effective control is achievable using normal farm management practises. | L | M |
| 23. Increase harvest costs? | Summer cultivation gives effective control but must be repeated regularly until weed is eliminated. A single cultivation only, spreads rhizomes to clean areas (Parsons & Cuthbertson 1992). The need for repeated control, and thus increased time and labour costs, may lead to a minor increase in overall production costs. | M | MH |
| 24. Disease host/vector? | Not described as an alternative host or vector for diseases of agriculture. | L | M |
This table can also be viewed as a PDF document (printer friendly).
Impact Assessment Record - Feathertop (PDF - 74KB)
Impact Assessment Record - Feathertop (DOC - 60KB)
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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