Silver spike grass (Achnatherum calamagrostis)

Present distribution

Scientific name:	Achnatherum calamagrostis (L.) P. Beauv.
Common name(s):	silver spike grass

This invasive plant/weed is not known to be naturalised in Victoria

Habitat:

Native to Europe. Found in badlands and on other disturbed, highly eroded sites such as road cuttings and mine spoils (Guardia et al 2000). Species not known as naturalised in Victoria (DSE 2004, ANH 2006).

Potential distribution

Potential distribution produced from CLIMATE modelling refined by applying suitable landuse and vegetation type overlays with CMA boundaries

Map Overlays Used

Land Use:
Pasture dryland; pasture irrigated

Broad vegetation types
Coastal scrubs and grassland; grassland

Colours indicate possibility of Achnatherum calamagrostis infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.

Red= Very high	Orange = Medium
Yellow = High	Green = Likely

Impact

QUESTION	COMMENTS	RATING	CONFIDENCE
Social
1. Restrict human access?	Tussock forming grass (Guardia et al 2000). Grows in highly disturbed areas and forms scattered tussocks up to two metres in diameter (Guardia et al 2000). Unlikely to impact upon human access.	l	h
2. Reduce tourism?	Advertised (in the US) as ‘a very showy, fountain-shaped, free-flowering, mid-size clump-forming grass’ (NWOG 2006). Found in highly eroded areas, on edge of roads and mine spoils (Guardia et al 2006). Not found in many recreational areas but if it was then weed would have minor effect on aesthetics.	ml	mh
3. Injurious to people?	Weed not documented as being injurious to people.	l	mh
4. Damage to cultural sites?	Advertised (in the US) as ‘a very showy, fountain-shaped, free-flowering, mid-size clump-forming grass’ (NWOG 2006). If found on cultural sites, weed would have a moderate visual effect.	ml	m
Abiotic
5. Impact flow?	Terrestrial species (Guardia et al 2000).	l	h
6. Impact water quality?	Terrestrial species (Guardia et al 2000).	l	h
7. Increase soil erosion?	Grows in highly areas where soil highly eroded. Forms tussocks on bare patches of land (Guardia et al 2006). Land already subject to erosion so unlikely to further contribute to large scale soil movement and may even act to bind soil.	l	h
8. Reduce biomass?	In its natural habitat the population consists of ‘scattered tussocks amidst extensive areas of bare soil’ (Guardia et al 2000). In these situations, biomass may increase.	l	h
9. Change fire regime?	‘Tillers are annual and emerge seasonally .. die almost simultaneously and during the winter the tussocks remain as buds among a substantial accumulation of litter’ (Guardia et al 2000). Mainly grows in highly degraded areas with minimal vegetation but in some situations plant does have potential to have a minor change on the intensity of fire.	ml	h
Community Habitat
10. Impact on composition (a) high value EVC	EVC=Plains grassland (BCS = E); CMA=North central; Bioreg=Victorian riverina; CLIMATE potential=M. In its natural habitat the population consists of ‘scattered tussocks amidst extensive areas of bare soil’ .. ‘patchy structure of A. calamagrostis populations in badlands’ (Guardia et al 2000). Sparse / scattered infestations.	l	h
(b) medium value EVC	Not likely to occur in medium value EVCs in Victoria.	l	h
(c) low value EVC	Not likely to occur in low value EVCs in Victoria.	l	h
11. Impact on structure?	In its natural habitat the population consists of ‘scattered tussocks amidst extensive areas of bare soil’ .. ‘patchy structure of A. calamagrostis populations in badlands’ (Guardia et al 2000). Plant would have a minor effect on the lower strata.	l	h
12. Effect on threatened flora?	This species is not documented as posing an additional risk to threatened flora.	mh	l
Fauna
13. Effect on threatened fauna?	This species is not documented as posing an additional risk to threatened fauna.	mh	l
14. Effect on non-threatened fauna?	Weed grows in highly disturbed areas with little vegetation present (Guardia et al 2000). Very unlikely to have an effect on non-threatened fauna species.	l	m
15. Benefits fauna?	Weed grows in highly disturbed areas with little vegetation present (Guardia et al 2000). Would provide very little support to desirable species.	h	m
16. Injurious to fauna?	Weed not documented as being injurious to fauna.	l	mh
Pest Animal
17. Food source to pests?	This species is not known as a food source to assist in the success of pest animals.	l	mh
18. Provides harbour?	This species is not known to provide harbour to pest species.	l	mh
Agriculture
19. Impact yield?	Not a weed of agriculture.	l	mh
20. Impact quality?	Not a weed of agriculture.	l	mh
21. Affect land value?	Weed not documented to affect land value.	l	mh
22. Change land use?	Weed not known to cause a change in the priority of land use.	l	mh
23. Increase harvest costs?	Not a weed of agriculture.	l	mh
24. Disease host/vector?	Not known as a host or vector of disease for agriculture.	l	mh

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	Fruit dispersal occurs in late summer or autumn and seeds exhibit dormancy and germinate the following summer (Guardia et al 2000). Requires natural seasonal conditions for germination.	mh	h
2. Establishment requirements?	Ideal growing conditions are ‘part shade’ (Lake 2006). Can establish under a moderate canopy.	mh	m
3. How much disturbance is required?	Found in badlands in highly eroded areas. Also on road cuttings and mine spoils (Guardia et al 2000). Establishes in highly disturbed natural ecosystems.	ml	h
Growth/Competitive
4. Life form?	Perennial grass (Guardia et al 2000). Life-form - grass	mh	h
5. Allelopathic properties?	None described.	l	mh
6. Tolerates herb pressure?	In available literature, no reference made to herbivory. Score medium.	m	l
7. Normal growth rate?	Climatic conditions influence growth rates (Guardia et al 2000). Rate of growth ‘average’ (Lake 2006). Maximum growth rate less than many species of the same life form.	ml	m
8. Stress tolerance to frost, drought, w/logg, sal. etc?	‘During drought periods, tussocks would only barely maintain their size. ‘During the winter the tussocks remain as buds’. Can reproduce through rhizomes (assume tolerance to fire) (Guardia et al 2000). Can ‘tolerate poor soil with ample water’ (Lake 2006). Tolerant of fire salinity and frost, susceptible to drought.	mh	m
Reproduction
9. Reproductive system	Reproduces by both seed and rhizomes (Guardia et al 2000). Vegetative and sexual reproduction.	h	h
10. Number of propagules produced?	‘Each tiller can produce one to three new tillers each year’. Tussocks can have up to 1000 tillers. ‘Seed production in A. calamagrostis is .. relatively high compared to other perennials’ (Guardia et al 2000).	h	h
11. Propagule longevity?	‘Erosion rates [in the badlands] makes the seed bank insignificant’ (Guardia et al 2006). Plant tends to be found in highly eroded sites but insufficient information to determine propagule longevity.	m	l
12. Reproductive period?	‘Tillers are annual and emerge seasonally’. ‘A. calamagrostis may colonise’ steeper backslopes and harsher habitats (Guardia et al 2000). Potential to form self-sustaining dense monocultures.	h	h
13. Time to reproductive maturity?	‘Tussocks develop from plants that are at least 2 years old’ (Guardia et al 2000). 2 – 5 years.	ml	h
Dispersal
14. Number of mechanisms?	Lemma has an awn to facilitate wind dispersal. Most seeds fall near parent plant (Guardia et al 2000). Spread by wind and gravity.	mh	h
15. How far do they disperse?	Lemma has an awn to facilitate wind dispersal although most seeds fall near parent plant (Guardia et al 2000). Most will be less than 20m.	l	h

References

Australian National Herbarium (ANH) 2006, Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research, viewed, http://www.anbg.gov.au/avh/

Department of Sustainability and Environment (DSE) 2004, Flora information system [CD-ROM], Biodiversity and Natural Resources Section, Viridans Pty Ltd, Bentleigh.

Global Biodiversity Information Facility (GBIF) 2006, Global Biodiversity Information Facility, Data portal, viewed 01 Aug 2006, http://www.gbif.org/

Guardia, R., Raventos, J. and Caswell, H. 2000, ‘Spatial growth and population dynamics of a perennial tussock grass (Achnatherum calamagrostis) in a badland area’, Journal of Ecology, vol. 88, pp. 950-963.

Lake, C. 2006, Achnatherum calamagrostis – spear grass, needle grass, silver spike grass, Bluestem Nursery, viewed 29 Aug 2006, http://www.bluestem.ca/achnatherum-calamagrostis.htm

Northwest Ornamental Grasses (NWOG) 2006, Achnatherum calamagrostis, Northwest Ornamental Grasses Online catalogue, viewed 09 Aug 2006, http://shop2.pageland.com/Item-Nwog.cfm?StoreID=20&BasketID=JTwLBWDujweXvme&RefID=&CID=&ItemID=5813&Search=

Real Jardin Botanico 2006, Proyecto ANTHOS, Database, viewed 28 Aug 2006, http://www.programanthos.org/anthos.asp

Global present distribution data references

Australian National Herbarium (ANH) 2006, Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research, viewed, http://www.anbg.gov.au/avh/

Global Biodiversity Information Facility (GBIF) 2006, Global Biodiversity Information Facility, Data portal, viewed 01 Aug 2006, http://www.gbif.org/

Guardia, R., Raventos, J. and Caswell, H. 2000, ‘Spatial growth and population dynamics of a perennial tussock grass (Achnatherum calamagrostis) in a badland area’, Journal of Ecology, vol. 88, pp. 950-963.

Real Jardin Botanico 2006, Proyecto ANTHOS, Database, viewed 28 Aug 2006, http://www.programanthos.org/anthos.asp

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