Impact Assessment - Perennial veldt grass (Ehrharta calycina) 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 Perennial veldt 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: Perennial veldt grass
Scientific name: Ehrharta calycina

Question	Comments	Rating	Confidence
Recreation
1. Restrict human access?	Tufted or rarely stoloniferous perennial grass to 0.7 m high (Jacobs & Hastings 1993; Smith et al. 1999). Unlikely to limit human access.	L	M
2. Reduce tourism?	Tufted or rarely stoloniferous perennial grass to 0.7 m high (Jacobs & Hastings 1993; Smith et al. 1999). Unlikely to be obvious to the average visitor.	L	M
3. Injurious to people?	Leaf blades described as glabrous (without hairs) with a ciliate (hairy) ligule (Oram 1990). Not described as having features that might be injurious to people, such as silicas that can give leaves a sharp edge. “No known health risks” (Virtue & Melland 2003).	L	M
4. Damage to cultural sites?	Tufted or rarely stoloniferous perennial grass to 0.7 m high (Jacobs & Hastings 1993; Smith et al. 1999). Negligible effect on aesthetics of a site.	L	M
Abiotic
5. Impact flow?	Does not tolerate waterlogging (Frey 2005) and not described in association with waterways. Unlikely to impact on aquatic environments.	L	M
6. Impact water quality?	Does not tolerate waterlogging (Frey 2005) and not described in association with waterways. Unlikely to impact on aquatic environments.	L	M
7. Increase soil erosion?	Used for erosion control (Frey 2005) although this species can become dormant over winter under heavy frosts (Oram 1990). However, it does have an extensive root system (Frey 2005) that may still allow it to bind soil, even when dormant. No record was found of this species failing as erosion control.	L	MH
8. Reduce biomass?	Tufted or rarely stoloniferous perennial to 0.7 m high (Jacobs & Hastings 1993). Able to suppress germination of shrub seedlings (Frey 2000) and under-storey and tree seedlings and even some larger perennial vegetation (Virtue & Melland 2003). Capable of replacing woody vegetation, significantly reducing biomass.	H	MH
9. Change fire regime?	“E. erecta’s extensive root system may increase the fuel load in forested systems. [This] may change the intensity or frequency of fires” (Frey 2005).	ML	MH
Community Habitat
10. Impact on composition (a) high value EVC	EVC=Parila Mallee (BCS =E); CMA=Mallee; Bioreg=Murray Mallee; CLIMATE potential=VH. Tufted or rarely stoloniferous perennial to 0.7 m high (Jacobs & Hastings 1993). “Demonstrated capacity to form understorey monocultures in remnant native vegetation in SA” (Virtue & Melland 2003). Displaces all species within the understorey.	H	MH
(b) medium value EVC	EVC=Hills herb rich woodland (BCS =D); CMA=North Central; Bioreg=Goldfields; CLIMATE potential=VH Tufted or rarely stoloniferous perennial to 0.7 m high (Jacobs & Hastings 1993). “Demonstrated capacity to form understorey monocultures in remnant native vegetation in SA” (Virtue & Melland 2003). Displaces all species within the understorey.	H	MH
(c) low value EVC	EVC=Heathy woodland (BCS =LC); CMA=West Gippsland; Bioreg= Gippland plain; CLIMATE potential=VH. Tufted or rarely stoloniferous perennial to 0.7 m high (Jacobs & Hastings 1993). “Demonstrated capacity to form understorey monocultures in remnant native vegetation in SA” (Virtue & Melland 2003). Displaces all species within the understorey.	H	MH
11. Impact on structure?	“This species appears to be rapidly changing the composition and dynamics of California central coastal dune systems.” Able to suppress germination of shrub seedlings (Frey 2000) and under-storey and tree seedlings and even some larger perennial vegetation. “Demonstrated capacity to form understorey monocultures in remnant native vegetation in SA” (Virtue & Melland 2003). Major effect on all vegetation layers.	H	MH
12. Effect on threatened flora?	The “demonstrated capacity to form understorey monocultures in remnant native vegetation in SA” (Virtue & Melland 2003) suggests that this species could have a significant impact on threatened forbs, however no specific information was found.	MH	L
Fauna
13. Effect on threatened fauna?	Weed invasion by this species threatens native vegetation in Kiata that provide habitat for the Eltham copper butterfly that is listed as a threatened taxon in Schedule 2 of the Flora and Fauna Guarantee Act 1988 (Webster 2003; Groves & Adair 1998). There are, however, at least 5 other sites that provide habitat for this subspecies. May reduce numbers of species, but not lead to extinction.	MH	MH
14. Effect on non-threatened fauna?	Due to its “demonstrated capacity to form understorey monocultures in remnant native vegetation in SA” (Virtue & Melland 2003) and ability to suppress germination of shrub seedlings (Frey 2000) and under-storey and tree seedlings and even some larger perennial vegetation (Virtue & Melland 2003), this species is likely to reduce habitat for fauna species, leading to reduction in numbers, but not to local extinction.	MH	MH
15. Benefits fauna?	Introduced as a forage crop (Frey 2005), so may provide some food for grazing animals. Provides food source for butterfly larvae for species such as the white-banded grass dart and marbled xenica (Grund 2006), however other food sources are available for these species.	MH	ML
16. Injurious to fauna?	Introduced as a forage crop (Frey 2005), so unlikely to be toxic. Leaf blades described as glabrous (without hairs) with a ciliate (hairy) ligule (Oram 1990). Not described as having features that might be physically injurious to animals, such as silicas that can give leaves a sharp edge.	L	MH
Pest Animal
17. Food source to pests?	Introduced as a forage crop (Frey 2005) and highly palatable, so likely to provide a food source for serious browse pests such as rabbits.	MH	M
18. Provides harbour?	Tufted or rarely stoloniferous perennial grass to 0.7 m high (Jacobs & Hastings 1993; Smith et al. 1999). Unlikely to harbour pest species.	L	MH
Agriculture
19. Impact yield?	An important and highly palatable pasture species in low rainfall areas with sandy soil (Virtue & Melland 2003) and a dominant grass in otherwise sparse pasture (Frey 2005). Not a weed of agriculture.	L	MH
20. Impact quality?	An important and highly palatable pasture species in low rainfall areas with sandy soil (Virtue & Melland 2003) and a dominant grass in otherwise sparse pasture (Frey 2005). Not a weed of agriculture.	L	MH
21. Affect land value?	An important and highly palatable pasture species in low rainfall areas with sandy soil (Virtue & Melland 2003) and a dominant grass in otherwise sparse pasture (Frey 2005). Not a weed of agriculture.	L	MH
22. Change land use?	An important and highly palatable pasture species in low rainfall areas with sandy soil (Virtue & Melland 2003) and a dominant grass in otherwise sparse pasture (Frey 2005). Not a weed of agriculture.	L	MH
23. Increase harvest costs?	An important and highly palatable pasture species in low rainfall areas with sandy soil (Virtue & Melland 2003) and a dominant grass in otherwise sparse pasture (Frey 2005). Not a weed of agriculture.	L	MH
24. Disease host/vector?	Introduced as a forage crop (Frey 2005). Not found to be a host to pests or diseases of agriculture.	L	M

Impact Assessment Record - Panic veldt grass (PDF - 92KB)
Impact Assessment Record - Panic veldt grass (DOC - 60KB)
This table can also be viewed as a PDF document (printer friendly). 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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