Title: Nassella neesiana Trin & Rupr.

Scientific Name:

Nassella neesiana Trin & Rupr.

Common Name:

Chilean needle grass




Source & more images (via ALA)

Habitat: Seasonally dry environments, as well as a wide range of other climatic conditions (Champion, 1995; Gardener et al, 1996). Tends to be found on basalt soils, but has been reported on other soil types at several locations in Victoria (Gardener et al, n.d.). Very invasive and forms dense stands in pastures, parkland, roadsides and near watercourses (Gardener, 1996; Walsh and Entwisle, 1994). Chilean needle grass can vigorously invade native grasslands and open woodlands (Liebert, 1996).



Distribution:



Original source via GBIF


Invasiveness Assessment

ESTABLISHMENT


1. Germination requirements? Seedlings emerged predominantly in autumn & spring, but emergence was also observed at other times of the year when sufficient moisture was available. However, lemma must be broken for germination (Gardener et al, 1999).

2. Establishment requirements? Require 'gaps', thus access to light. However, it is known to occur in grassy woodland (Eucalyptus microcarpa woodland) (Gardener et al, 1999; McLaren, pers coms).

3. How much disturbance is required? Establishes in bushland / conservation areas, e.g. grassland and flora reserves (DNRE, 1996; Gardener et al, 1999)

GROWTH / COMPETITIVE


4. Life form? Grass - belongs to the speargrass group of grasses (DNRE, 1996).

5. Allelopathic properties? None described.

6. Tolerates herb pressure? Tolerates heavy grazing by livestock (DNRE, 1996; Gardener et al, 1996)

7. Normal growth rate? Highly invasive sp. with rapid population growth. Lack of effective competition from agricultural or native vegetation (Liebert, 1996; Champion, 1995).

8. Stress tolerance to frost, drought, w/logg, sal. etc? Tolerates drought, climatic & soil variation & fire. Presumably also waterlogging, as occurs in damp depressions (e.g. drainage lines) (DNRE, 1996; Liebert, 1996).

REPRODUCTION


9. Reproductive system? Sexual (seeds) & asexual (asexual seeds are produced underground at the base of tillers) (DNRE, 1996; Liebert, 1996).

10. Number of propagules produced? Up to 15,000 seeds per square meter can be found in the seed bank beneath infestations (DNRE, 1996).

11. Propagule longevity? Seedbank long-lived; [a seedbank of 7100 seeds m-2 can] take 12.4 years to reach 10 seeds m-2 (Gardener et al, 1999).

12. Reproductive period? Perennial sp.; forms dense stands (self-sustaining monocultures) in pasture, bushland and parkland (Liebert, 1996).

13. Time to reproductive maturity? Fast growing grass, whose seeds emerge between spring & autumn & other times of year in favourable conditions (Liebert, 1996).

DISPERSAL


14. Number of mechanisms? Propagules spread animals (usually stock), machinery, hay, soil, gravel, floodwater, even rubber tyres (Liebert, 1996).

15. How far do they disperse? Car / machinery could disperse seeds many km in short time. Seed (which has a long viability) can remain in sheep wool for > 6 months, & in that time disperse > 1 km, but more will disperse between 200 - 1000 metres (Liebert, 1996).


Impact Assessment

RECREATION


1. Restrict human access? “Chilean needle grass is a perennial tussock-forming grass. It usually forms dense clumps, and in the absence of grazing can grow to 1 m in height.” (ARMCANZ). Dense clumps may impede individual access.

2. Reduce tourism? “Chilean needle grass is a vigorous competitor spreading in extremely dense swards. The seeds cause discomfort for dogs and humans.” (Liebert, 1996). Tussocks in dense swards may affect some recreational uses, particularly during flowering.

3. Injurious to people? “The seeds cause discomfort for dogs and humans which presents a problem in recreational reserves.” (Liebert, 1996).

4. Damage to cultural sites? “An infestation of Chilean needle grass changes the natural appearance of native environment, downgrading it’s (sic) aesthetic value.” (Liebert, 1996). Dense clumps would create a negative visual effect.

ABIOTIC


5. Impact flow? Terrestrial species.

6. Impact water quality? Terrestrial species.

7. Increase soil erosion? “Chilean needle grass is a perennial tussock-forming grass. It usually forms dense clumps.” (ARMCANZ). “Landowners at Hawke’s Bay have noted that it…provides good cover for erosion control.” (Slay, 2002). Not likely to increase soil erosion.

8. Reduce biomass? “It can almost completely displace perennial native grasses.” (Liebert, 1996). It produces a denser sward than native grasses and is greater in height. Biomass likely to increase.

9. Change fire regime? “As a fire hazard, Chilean needle grass poses a greater threat than native grasses due to the greater height and density of the sward.” (Liebert, 1996). Greatly changes the frequency of fire risk.

COMMUNITY HABITAT


10(a) Impact on composition of high value EVC? EVC=Plains grassy woodland (E); CMA=Glenelg Hopkins; Bioreg=Victorian Volcanic Plain; VH CLIMATE potential. “…Chilean Needle Grass can vigorously invade…native grasslands and open woodlands where it finds little competition.” “…forms dense stands in…bushland and parkland.” Serious impact on ground flora. (Gardener et al, 1996; Liebert, 1996).

10(b) Impact on medium value EVC? EVC=Grassy dry forest (D); CMA=North Central; Bioreg=Goldfields; VH CLIMATE potential. Impact similar to 10(a) above, however, it is most commonly found in open habitats. Plant growth and population density may be restricted. (Gardener et al, 1996; Liebert, 1996).

10(c) Impact on low value EVC? EVC=Heathy dry forest (D); CMA=North Central; Bioreg=Goldfields; VH CLIMATE potential. Impact similar to 10(b) above, however, population density may be restricted by competition from native plants. (Gardener et al, 1996; Liebert, 1996).

11. Impact on structure? “…Chilean Needle Grass can vigorously invade…native grasslands and open woodlands where it finds little competition.” (Liebert, 1996). Major impact on ground flora.

12. Effect on threatened flora? This species is not documented as posing an additional risk to threatened flora.

FAUNA


13. Effect on threatened fauna? This species is not documented as posing an additional risk to threatened fauna

14. Effect on non-threatened fauna? “It can almost completely displace perennial native grasses. Stock will only eat Chilean needle grass when it is young, not tall and stemmy.” (Liebert, 1996). Potential to reduce available food source for native species.

15. Benefits fauna? No known benefits.

16. Injurious to fauna? “…the sharp seed are troublesome, penetrating the hides of sheep. Cattle hides are too thick for the seed to penetrate.” (Gardener et al, 1996) “…irritation and potential blindness of stock from the seeds, causing loss of thrift.” (Liebert, 1996). Potentially harmful to fauna species.

PEST ANIMAL


17. Food source to pests? Not known as a food source to pests.

18. Provides harbor? Not known to provide harbor for pest animals.

AGRICULTURE


19. Impact yield? “It is unpalatable to stock [when flowering]. Chilean needle grass is highly invasive and competes with desirable pasture species.” (Liebert, 1996). "Productivity has been decreased by as much as 50% due to heavy infestations of Chilean needle grass.” (ARMCANZ, n.d.) Serious impacts on quantity.

20. Impact quality? “Chilean needle grass seeds contaminate wool and hay. [The seed also contributes to] vegetable fault in wool, abscesses in meat and holes in hides.” (Liebert, 1996). Serious impact on quality. Potential for rejected product.

21. Affect land values? “The competitive ability of and efficient reproductive mechanisms of S. neesiana have led this grass to dominate large areas of highly productive pastures in NSW and Victoria. Traditional control methods…have been tried…with little success.” (Gardener, n.d.). Invasive nature, difficulty of control and impact on agricultural productivity suggest that land values would decrease significantly.

22. Change land use? “Attempts at controlling N. neesiana have failed. In light of this knowledge perhaps it is better that we consider N. neesiana as an intermediate quality pasture species and manage it as such.” (Gardener et al, 1996). During flowering, cattle can be substituted for sheep. Cattle hides are too thick for the seed to penetrate. Some change in land use may be required.

23. Increase harvest costs? Not known to affect harvesting.

24. Disease host/vector? None evident.




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Assessment ratings originally made by the Victorian Department of Primary Industries.
The entry of this assessment was made possible through the generous support of The Weed's Network.






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Date: 9 November 2009; 5:01:10 PM AEDT

Author Name: Jessica Mackay
Author ID: mackayj