Impact Assessment - Fountain grass (Pennisetum setaceum) 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 Fountain grass.
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: Fountain grass
Scientific name: Pennisetum setaceum
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | Robust tussock forming perennial about 1 m high with creeping underground stems with inflorescences 30 cm long (Richardson et al, 2006). Densely tufted perennial grass growing to 1.5 m (Groves et al, 2005, Johnson) that can form dense monoculture stands that can exclude all other plants (Johnson; Poulin et al, 2005). Once the plant forms dense infestations it is likely to be of high nuisance value impeding both pedestrian and vehicular access. | MH | MH |
| 2. Reduce tourism? | Flower heads are 8-30 cm long (Walsh and Enwisle, 1996) and are a long feathery spike which makes it attractive for garden cultivations (Groves et al, 2005). In a dry environment it remains attractive and in humidity it flowers constantly and bears fruits throughout the whole year (Medio ambiente Canarias, 1999). It makes a dramatic statement anywhere in the landscape (Floridata). Furthermore it is a densely tufted perennial grass growing to 1.5 m (Groves et al, 2005, Johnson) that can form dense stands that can exclude all other plants (Johnson). Its attractive flowerhead is obvious and is likely to have major impacts on aesthetics, however visitors may judge the display as aesthetically pleasing. Its ability to dominate and densely invade landscapes indicates that the plant is likely to have significant impact on recreation activities if invading such areas. | MH | ML |
| 3. Injurious to people? | No reports of the plant being injurious to people (Walsh and Enwisle, 1996, Richardson et al, 2006). | L | MH |
| 4. Damage to cultural sites? | Flowerheads are 8-30 cm long (Walsh and Entwisle, 1996) and are a long feathery spike which makes it attractive for garden cultivations (Groves et al, 2005). In a dry environment it remains attractive and in humidity it flowers constantly and bears fruits throughout the whole year (Medio ambiente Canarias, 1999). It makes a dramatic statement anywhere in the landscape (Floridata). On this basis infestation of this plant on cultural sites it is likely to have a moderate visual effect. | ML | MH |
| Abiotic | |||
| 5. Impact flow? | This species is terrestrial it is unlikely to have an affect on water flow. | L | MH |
| 6. Impact water quality? | This species is terrestrial it is unlikely to have an affect on water quality. | L | MH |
| 7. Increase soil erosion? | The species is rhizomatous, forming large tussocks (Walsh and Entwisle, 1996) however it is shallow rooted (Litton et al, 2006). The plant has been noted as being good for erosion control (Floridata) and has been used for soil stabilisation (Johnson). However the plant is an aggressive species that can displace native species forming dense stands (Johnson) but maintains soil integrity by replacing existing species. | L | M |
| 8. Reduce biomass? | In a study conducted by Litton et al, (2006) the site used was formerly a forested site that has been converted to P. setaceum dominated grassland. The presence of a dense P. setaceum understorey will lead to the eventual conversion of remaining forest fragments to grasslands without active control of P. setaceum (Litton et al, 2006). Formerly extensive Heteropogon grasslands have been reduced to remnants surrounded by Pennisetum (Carino and Daehler, 2002). The species can destroy dry forests through increased fire frequency (Poulin et al, 2005). Therefore, this species has the capacity to significantly decrease the biomass of areas by replacing forested systems with grasslands. | H | MH |
| 9. Change fire regime? | Alters natural fire regime in Hawaii, it raises fuel load, which increases the intensity and spread of a fire subsequently threatening native flora (NPCI). Fountain grass has been noted to produce 51% more total biomass than native Hawaiian grass (California Uni) hence increasing fuel loadings (Tunison, 1992). Subsequently increasing the intensity and spread of a fire (Lloyd, 1992; PCA, 2005). P. setaceum produces large quantities of fine fuels that promote fire (Litton et al, 2006). The natural fire regime in Hawaii has been markedly altered by the rapid spread of alien grasses particularly P. setaceum amongst others (Smith and Tunison, 1992). Fountain grass turns brown and dry in the winter and becomes extremely flammable (Floridata). Dense stands are extreme fire hazard. By enhancing the fuel load it endangers native plant communities that are not fire tolerant (California Uni). Fires fuelled by fountain grass impact on ground- nesting birds and terrestrial animals as well (California Uni). P. setaceum is likely to greatly change the frequency and/or intensity of fire. | H | H |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | EVC= Plains Grassland (E) ; CMA=Mallee; Bioregion= Lowan Mallee; VH CLIMATE potential The plant typically forms dense monospecific stands in the understorey that can exclude all other plants (Johnson; Tunison, 1992). Has exhibited universally superior competitive performance compared to native species (Daehler, 2003). The presence of a dense P. setaceum understorey will lead to the eventual conversion of remaining forest fragments to grasslands without active control of P. setaceum (Litton et al, 2006). The species is aggressive and extremely competitive and is likely to dominant and displace existing vegetation in the lower stratum. | H | H |
| (b) medium value EVC | EVC= Shallow Sands Woodland (D) ; CMA=Wimmera; Bioregion= Lowan Mallee; VH CLIMATE potential The plant typically forms dense monospecific stands in the understorey that can exclude all other plants (Johnson; Tunison, 1992). Has exhibited universally superior competitive performance compared to native species (Daehler, 2003). The presence of a dense P. setaceum understorey will lead to the eventual conversion of remaining forest fragments to grasslands without active control of P. setaceum (Litton et al, 2006). The species is aggressive and extremely competitive and is likely to dominant and displace existing vegetation in the lower stratum. | H | H |
| (c) low value EVC | EVC= Coastal Dune Scrub (C) ; CMA=Glenelg Hopkins; Bioregion= Glenelg Plain; VH CLIMATE potential The plant typically forms dense monospecific stands in the understorey that can exclude all other plants (Johnson; Tunison, 1992). Has exhibited universally superior competitive performance compared to native species (Daehler, 2003). The presence of a dense P. setaceum understorey will lead to the eventual conversion of remaining forest fragments to grasslands without active control of P. setaceum (Litton et al, 2006). The species is aggressive and extremely competitive and is likely to dominant and displace existing vegetation in the lower stratum. | H | H |
| 11. Impact on structure? | It is a highly aggressive, fire adapted coloniser that readily out competes native plants, prevents further regeneration of native trees and rapidly re establishes after burning (NPCI; Litton et al, 2006). The plant typically forms dense monospecific stands in the understorey that can exclude all other plants (Johnson; Tunison, 1992) and has done so in Hawaiian lowland dry forests (Litton et al, 2006). Has exhibited universally superior competitive performance compared to native species (Daehler, 2003). As a result enhancing fuel load thus endangering native woody plant communities it invades (Tunison, 1992). Hence altering existing native ecosystem structure. It is likely that the strong negative impacts associated with invasive grasses are likely to impact on the long term structure of native tree populations (Litton et al, 2006).Infestations of this species are likely to have a major effect on <60% of the floral strata. | MH | H |
| 12. Effect on threatened flora? | The effect on threatened flora is unknown. | MH | L |
| Fauna | |||
| 13. Effect on threatened fauna? | The effect on threatened flora is unknown | MH | L |
| 14. Effect on non-threatened fauna? | The plant typically forms dense monospecific stands in the understorey that can exclude all other plants (Johnson; Tunison, 1992). The presence of a dense P. setaceum understorey will lead to the eventual conversion of remaining forest fragments to grasslands without active control of P. setaceum (Litton et al, 2006). Translating to a loss of habitat for many terrestrial and avian species. Fires fuelled by fountain grass impact on ground- nesting birds and terrestrial animals as well (California Uni). It is eaten by some animals but not preferred, therefore infestations do not provide an alternative food resource (Johnson; California Uni; Sherif and Siddiqi, 1988; NPCI ). However the prominent seed heads are likely to be a good food source for birds. Therefore significantly modifying, permanently changing or eliminating habitat structure and food resources for animals subsequently affecting faunal populations. | MH | M |
| 15. Benefits fauna? | No information exists in the literature that outlines the benefits this plant has on indigenous fauna. However the prominent seed heads are likely to be a good food source for birds. Dense monospecific stands (Johnson; Tunison, 1992) are likely to provide suitable habitat. | M | L |
| 16. Injurious to fauna? | No reports on the plant being injurious to fauna (Walsh and Entwisle, 1996; Tunison, 1992). | L | M |
| Pest Animal | |||
| 17. Food source to pests? | The prominent seed heads (Walsh and Entwisle, 1996) are likely to be a good food source for pest birds. However little has been documented on how this plant assists in the success of pest animals. | M | L |
| 18. Provides harbor? | Dense monospecific stands (Johnson; Tunison, 1992) are likely to provide suitable habitat and coverage for pest species like rabbits. However little has been documented on how this plant assists in the success of pest animals. | M | L |
| Agriculture | |||
| 19. Impact yield? | This species has been noted as an aggressive effect on crops, especially vineyards (Medio ambient Canarias, 1999) overseas. A weed of pasture (Johnson) that is able to form dense monospecific stands that can exclude all other plants (Johnson; Tunison, 1992). It is not a good pasture species (MISC 2003). The impact has not been quantified, however. | M | M |
| 20. Impact quality? | Noted as a weed of agriculture, but no impacts on quality were recorded (Johnson; Tunison, 1992; MISC 2003). | L | M |
| 21. Affect land value? | Unknown. | M | L |
| 22. Change land use? | Unknown. | M | L |
| 23. Increase harvest costs? | Unknown. | M | L |
| 24. Disease host/vector? | Is pest free (Floridata). | L | ML |
This table can also be viewed as a PDF document (printer friendly).
Impact Assessment Record - Fountain grass (PDF - 83KB)
Impact Assessment Record - Fountain grass (DOC - 67KB)
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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