Title: Asparagus asparagoides – Western Cape form

Scientific Name:

Asparagus asparagoides – Western Cape form

Common Name:

Western Cape form bridal creeper



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Habitat: Currently it is found within the higher rainfall border region of South Australia and Victoria (Austrlia). Predictive mapping shows that it can potentially grow along all Australian coastlines with a Mediterranean climate. It shows resistance to the common bridal creeper rust fungus (Puccinia myrsiphylli) biocontrol agent, therefore, it has the potential to infest regions recently treated by the Asparagus asparagoides (common form) biocontrol agent.

Distribution:

Present Distribution

Potential Distribution


Invasiveness Assessment

ESTABLISHMENT


1. Germination requirements? “Seedlings usually emerge in autumn” … initial growth is not dependent on any seasonal rainfall triggers. (Muyt 2001) “Seeds germinate in autumn or early winter” (Muyt 2001). Initial vegetative growth from tubers is rapid, independent of external stimulation, and is dependent only on the stored reserves of moisture and energy (Cooke and Robertson 1990). Seeds germinated at various temperatures (10 – 23 degrees C) (Cooke and Robertson 1990). Opportunistic germinator, can germinate at any time whenever water is available.

2. Establishment requirements? “Tolerates shade or part shade” (Blood 2001). Bridal creeper occurs primarily in dappled shade, or at the edges of dense shade … in [full] shade situations long prostrate stems are produced [that] produce little, or no, fruit (Kleinjan & Edwards 1999).
Can establish under moderate canopy or litter.

3. How much disturbance is required? Occurs in undisturbed vegetation e.g. heath land and Mallee shrubland (Carr et al. 1992). “It invades disturbed and undisturbed vegetation across a wide range of habitats” (Raymond 1996). Establishes in healthy AND undisturbed natural ecosystems.

GROWTH / COMPETITIVE


4. Life form? Perennial climber that dominates ground flora, and can form “dense curtains smothering shrubs and the lower canopy of trees” (Muyt 2001). Shoots grow upright to twine amongst nearby trees, shrubs, and smother other supports. (NAWMC 2006). Most reliable way to distinguish between the A. asparagoides (common form) and the Western Cape form is to dig up and compare the tubers of mature plants. (NAWMC 2006). Climber.

5. Allelopathic properties? None found described in literature reviewed.

6. Tolerates herb pressure? “…During … flowering season … large numbers of buds were recorded, but very few flowers or fruits were produced, possibly due to extensive herbivore damage … noted at the time... (Kleinjan & Edwards 1999). Extensive herbivore damage to the foliage can significantly reduce fruiting (Kleinjan & Edwards 1999). Herbivory by the bridal creeper leafhopper (Zygina spp.) is a permitted means of biocontrol for A. asparagoides (common form), Western Cape form has been observed to be damaged by such herbivory (the extent to the damage is as yet unclear) (NAWMC 2006). Bridal creeper is a palatable specimen and is not an agricultural weed due to grazing by stock (Carr 1996). Consumed and recovers slowly. Reproduction strongly inhibited by herbivory but still capable of vegetative propagules production (tubers); weed may still persist. NB. It is noteworthy that the common form of A. asparagoides is currently under a successful biocontrol program with the rust fungus Puccinia myrsiplylli. In current trials Western Cape form has shown itself to be resistant to this biocontrol agent. Tubers of Western Cape form found growing well on soil surface where previous rust release on common form; when dug down approx. 10cm below Western Cape form tubers, found recently deceased common form tubers. Whether this indicates Western Cape form out-competing common form, reinfesting areas of dead common form (through biocontrol action, or other means of local eradication) it is too early to assess (Hay 2007).

7. Normal growth rate? Initial shoot growth is rapid to out compete plants of a similar habit (NAWMC 2006), however, its growth rate appears slower than the common form of A. asparagoides (Holland Clift 2005). Maximum growth rate less than many species of the same life form.

8. Stress tolerance to frost, drought, w/logg, sal. etc? Bridal creeper is common in coastal zones … occurs primarily in dappled shade, or at the edges of dense shade (NB. in full shade long prostrate stems are produced [that] produce little, or no, fruit. … along the banks of estuaries (Kleinjan & Edwards 1999). Although spp. reportedly not found in very saline conditions, it has been found thriving on sand dunes adjacent to South Australian beaches (Hay 2007). Grows in shady, moist conditions. (NAWMC 2006). The tubers provide and store water, energy, and nutrient that enable the plant to survive over summer [dry periods] (NAWMC 2006). Bridal creeper tolerates drought conditions via dormant rhizomes and tubers (Muyt 2001). Highly tolerant of salinity, waterlogging, drought; tolerant of shade.

REPRODUCTION


9. Reproductive system? “Reproduces by seed and rhizomes. (Muyt 2001). Bridal creeper can regrow from rhizome fragments (Cooke & Robertson 1990) Bridal creeper is self-fertile (NAWMC 2006). Both vegetative and sexual reproduction.

10. Number of propagules produced? “Plants produce hundreds of fruits annually, each containing up to nine seeds. Seed viability approaches 90% (Muyt 2001). Fruit production may exceed 1,000 berries/m2 (NAWMC 2006). Greater than 2,000.

11. Propagule longevity? Bridal creeper has a relatively short-lived seed bank of several years (NAWMC 2006). Bridal creeper can regrow from rhizome fragments (Cooke & Robertson 1990). The rhizomes remain viable (although they may lie dormant) as long as they contain moisture and with a growing apex (Cooke & Robertson 1990), therefore it has viable propagules for the life of the plant. Vegetative propagules may survive for greater than five years, at present they are known to survive at least five years from experimental work of five years’ duration, this is still on-going, thus the longevity is still unknown. Vegetative propagules, and > 25% of seeds, may survive 5 – 10 years.

12. Reproductive period? Unknown from literature reviewed.

13. Time to reproductive maturity? Three years from germination before flowering (NAWMC 2006).
Seedlings develop their first tubers within ten weeks (Muyt 2001).
Produces vegetative propagules that have the capacity to form separate individuals in under a year.

DISPERSAL


14. Number of mechanisms? Viable seeds spread in emu scats, main vectors are birds, foxes and possibly rabbits (Cooke & Robertson 1990; NAWMC 2006). Dumping of garden waste, trading / sharing of plants by gardeners (Cooke & Robertson 1990; NAWMC 2006) and road making (Cooke and Robertson 1990) are the main sources of vegetative spread. Edible fruit dispersed by highly mobile animals (birds, foxes).

15. How far do they disperse? “Most seed dispersal events are restricted to < 100 metres … [but] … rare long distance dispersals, up to several kilometres, have been reported (Stansbury 2001) …” (NAWMC 2006). Likely that at least one propagule will disperse greater than one kilometre.


Impact Assessment

RECREATION


1. Restrict human access? Western Cape form supposedly not meant to grow in saline conditions, but found thriving on sand dunes adjacent to SA beaches (Hay 2007). Perennial climber that dominates ground flora, and can form “dense curtains smothering shrubs and the lower canopy of trees” (Muyt 2001). Whilst the plant does occur in riparian areas, it is most vigorous on lighter well-drained soils. Its presence proves a nuisance value to humans, impeding individual access to waterways and walking tracks.

2. Reduce tourism? Perennial climber that dominates ground flora, and can form “dense curtains smothering shrubs and the lower canopy of trees” (Muyt 2001; Holland Clift 2005). The smothering curtains that this species creates would present a major negative impact on aesthetics.

3. Injurious to people? This species seemingly presents no harmful or toxic properties to humans.

4. Damage to cultural sites? No specific mention of damage to cultural sites found in literature reviewed. However, as Western Cape form grows prolifically in coastal areas (Hay 2007; Kleinjan et al. 1999) where Aboriginal middens are present, the reviewer has no hesitation in assuming that it has the potential to obscure, if not smother, sites of significance. It has also been mentioned that Western Cape form can grow over and smother trees and small buildings, therefore Aboriginal scar trees, cemetery plots, and other sites of significance MAY be at risk (NB. Cemeteries were mentioned as ‘at risk’ by smothering by bridal veil and the common form of bridal creeper; the extrapolation to Western Cape form seemed quite acceptable). Assumption of potential to cause major structural and/or visual effect to culturally significant sites,that MAY adversely affects the heritage/cultural feature.

ABIOTIC


5. Impact flow? Western Cape form is a terrestrial species. It has not been found growing within waterbodies, although it is very vigorous in riparian areas. According to many sources, including Muyt (2001), “… It is usually most vigorous on lighter, well-drained soils.” It MAY reduce the volume of runoff in riparian areas where it is growing rampantly. Western Cape form appears to have little, or negligible, effect on water flow within waterbodies.

6. Impact water quality? Western Cape form is a terrestrial species. Western Cape form has no noticeable effect on dissolved O2, or light levels, within waterbodies.

7. Increase soil erosion? Western Cape form is a terrestrial species. It has not been found growing within waterbodies, although it is very vigorous in riparian areas. According to many sources, including Muyt (2001), “… It is usually most vigorous on lighter, well-drained soils.” Western Cape form MAY temporarily aid in bank stabilisation whilst it is smothering undergrowth and impeding the access to riverbanks by visitors; however, as it kills the substrate it MAY leave the bank less stable than prior to its infestation. Low probability of large scale soil movement.

8. Reduce biomass? It smothers pre-existing vegetation and prevents other plants from growing. (Holland Clift 2005) Biomass may increase.

9. Change fire regime? Dead and dry matter may significantly add to the fuel load, which in turn may increase the intensity of a local fire. NB. “Bridal creeper (inc. Western Cape form) is often the first plant to emerge post-fire, therefore herbicides can be carefully applied before native plants regenerate (NAWMC 2006).” Minor change to the intensity of fire risk.

COMMUNITY HABITAT


10(a) Impact on composition of high value EVC? EVC = Coastal Headland Scrub (V); CMA = Glenelg Hopkins; Bioregion = Bridgewater; VH CLIMATE potential. Predictive mapping shows that it can potentially grow along all Australian coastlines with a Mediterranean climate. It smothers pre-existing vegetation and prevents other plants from growing. (Holland Clift 2005) Monoculture within a specific layer; displaces all spp. within a strata/layer.

10(b) Impact on medium value EVC? EVC = Coastal Dune Scrub/Coastal Dune Grassland Mosaic (D); CMA = Corangamite; Bioregion = Victorian Volcanic Plain; VH CLIMATE potential. Predictive mapping shows that it can potentially grow along all Australian coastlines with a Mediterranean climate. It smothers pre-existing vegetation and prevents other plants from growing (Holland Clift 2005). Monoculture within a specific layer; displaces all spp. within a strata/layer.

10(c) Impact on low value EVC? EVC = Coastal Alkaline Scrub (LC); CMA = Glenelg Hopkins; Bioregion = Bridgewater; VH CLIMATE potential. Predictive mapping shows that it can potentially grow along all Australian coastlines with a Mediterranean climate. It smothers pre-existing vegetation and prevents other plants from growing. (Holland Clift 2005) Monoculture within a specific layer; displaces all spp. within a strata/layer.Monoculture within a specific layer; displaces all spp. within a strata/layer.Monoculture within a specific layer; displaces all spp. within a strata/layer.

11. Impact on structure? It smothers pre-existing vegetation and prevents other plants from growing. (Holland Clift 2005) The tubers act as a barrier to impede the root growth of other plants, and often prevents their seedling establishment (NAWMC 2006). Major effects on all layers. Forms monoculture.

12. Effect on threatened flora? As Western Cape form’s habit often results in smothering of all flora in its way, any floral VROT species in its way MAY also be smothered, resulting in localised reductions in populations that may be significant. Although no such records could be found by the assessor at this time, this does not exclude it from the realm of probability within any vegetation communities that occur within Western Cape form’s preferred habitats. Western Cape form forms monoculture in preferred habitats.

FAUNA


13. Effect on threatened fauna? As Western Cape form’s habit often results in smothering of all flora in its way, any floral VROT species in its way MAY also be smothered, resulting in localised reductions in populations that may be significant food sources to local fauna (inc. faunal VROT). This MAY lead to local extinctions, reduction of local numbers of individuals, or local reduction in habitat for threatened species. Although no such records could be found by the assessor at this time, this does not exclude it from the realm of probability within any bio-communities that occur within Western Cape form’s preferred habitats. Reduction in habitat for threatened species, leading to reduction in local numbers of individuals, OR maybe local extinctions.

14. Effect on non-threatened fauna? As Western Cape form’s habit often results in smothering of all flora in its way, resulting in localised reductions in populations that may be significant food sources to local fauna. This MAY lead to local extinctions, reduction of local numbers of individuals, or local reduction in habitat for threatened species. Although no such records could be found by the assessor at this time, this does not exclude it from the realm of probability within any bio-communities that occur within Western Cape form’s preferred habitats. Reduction in habitat for threatened species, leading to reduction in local numbers of individuals, OR maybe local extinctions.

15. Benefits fauna? Some bird species, Zosterops lateralis (Silvereye) and Corvus bennetti (Little Crow) are known to feed on the fruit. (Stansbury 1996).
Western Cape form provides some food to desirable species.

16. Injurious to fauna? No documented adverse effects to fauna found in literature reviewed.

PEST ANIMAL


17. Food source to pests? Bird species, both native and introduced, are known to feed on the fruit. “… the introduced starling was identified as feeding on bridal creeper fruits in South Australia.” (Stansbury 1996). Potential to supply food to one, or more, minor pest species.

18. Provides harbor? The dense growth, which occurs in late winter, may provide some temporary harbour, particularly for birds. No documented harbour for pest animals found in literature reviewed.

AGRICULTURE


19. Impact yield? Adversely affects pine plantations (Blood 2001) and citrus orchards (Blood 2001, Kwong et al. 2002). In citrus bridal creeper infestation is known to reduce fruit production (Blood 2001, Kwong et al. 2002). [Amount unknown.] Minor impact on quantity of produce (eg. ~ 10% assumed, if it was significant assume amount stated).

20. Impact quality? Adversely affects pine plantations (Blood 2001) and citrus orchards (Blood 2001, Kwong et al. 2002). In citrus bridal creeper infestation is known to reduce air movement, increasing local humidity, leading to Septoria spot on fruit (Blood 2001, Kwong et al. 2002). [Amount unknown.] Impact on quality of produce (~ 10%).

21. Affect land values? Adversely affects pine plantations (Blood 2001) and citrus orchards (Blood 2001, Kwong et al. 2002). In citrus bridal creeper infestation is known to reduce fruit production and quality [amount unknown.], thus reducing the value on land used for citrus orchards (Blood 2001, Kwong et al. 2002). Decreases in land value ~ 10%.

22. Change land use? Adversely affects pine plantations (Blood 2001) and citrus orchards (Blood 2001, Kwong et al. 2002). In citrus bridal creeper infestation is known to reduce fruit production and quality [amount unknown.], thus reducing the value on land used for citrus orchards leading to a change in land use (Blood 2001, Kwong et al. 2002). Downgrading of the priority land use.

23. Increase harvest costs? Adversely affects pine plantations (Blood 2001) and citrus orchards (Blood 2001, Kwong et al. 2002). In citrus bridal creeper infestation is known to leave a large volume of dead stems reducing the ease of access whilst harvesting fruit (Blood 2001, Kwong et al. 2002). [Amount unknown.] Minor increase in cost of harvesting.

24. Disease host/vector? Adversely affects pine plantations (Blood 2001) and citrus orchards (Blood 2001, Kwong et al. 2002). In citrus bridal creeper infestation is known to leave a large volume of dead stems that serve as a disease reservoir for reinfestation of Septoria spot on fruit (Blood 2001, Kwong et al. 2002). [Amount unknown.] Host to severe disease of citrus.




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Attachments:
Present Distribution Asparagus asparagoides - wcf.doc
Potential Distribution Asparagus asparagoides wcf.doc
bridal_creeper_infestation.jpg
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wra1040: Common Name - W (via Western Cape form bridal creeper)wra825: Common Name - B (via bridal creeper - western cape form)
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Categories: :wra:a, :wra:inv1, :wra:invh, :wra:inv2, :wra:invmh, :wra:inv3, :wra:inv4, :wra:invml, :wra:inv5, :wra:invm, :wra:inv6, :wra:inv7, :wra:inv8, :wra:inv9, :wra:inv10, :wra:inv11, :wra:inv12, :wra:inv13, :wra:inv14, :wra:inv15, :wra:imp1, :wra:impml, :wra:imp2, :wra:impmh, :wra:imp3, :wra:impl, :wra:imp4, :wra:imph, :wra:imp5, :wra:imp6, :wra:imp7, :wra:imp8, :wra:imp9, :wra:imp10a, :wra:imp10b, :wra:imp10c, :wra:imp11, :wra:imp12, :wra:imp13, :wra:imp14, :wra:imp15, :wra:imp16, :wra:imp17, :wra:imp18, :wra:imp19, :wra:impm, :wra:imp20, :wra:imp21, :wra:imp22, :wra:imp23, :wra:imp24
Date: 27 October 2009; 2:14:30 PM AEDT

Author Name: Shana Nerenberg
Author ID: nerenbergs