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Downy Rose Myrtle (Rhodomyrtus tomentosa)

Present distribution


Scientific name:

Rhodomyrtus tomentosa (Aiton) Hassk.
Common name(s):

Downy Rose Myrtle

This weed is not known to be naturalised in Victoria
Habitat:

A large shrub to small tree R. tomentosa is widespread in the tropics but has been reported to occur to 2400m in Hawaii (Langeland & Craddock Burks 1998). Reported in a range of habitats including open forest particularly pine forests, woodland, riparian vegetation, coastal vegetation including on the seashore, heath, grassland and wetland margins, this is reportedly rare however, it has also been reported as a weed of pasture (Hill, Peart & Dong-Sheng 2004; Langeland & Craddock Burks 1998; PIER 2007; Starr, Starr & Loope 2003; Turner, Ong & Tan 1995; Weber 2003).


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:
Forest private plantation; forest public plantation; pasture dryland; pasture irrigation

Broad vegetation types
Coastal scrubs and grassland; coastal grassy woodland; heathy woodland; lowland forest; heath; swamp scrub; box ironbark forest; inland slopes woodland; sedge rich woodland; dry foothills forest; moist foothills forest; montane dry woodland; montane moist forest; sub-alpine woodland; grassland; plains grassy woodland; valley grassy forest; herb-rich woodland; sub-alpine grassy woodland; montane grassy woodland; riverine grassy woodland; riparian forest; rainshadow woodland; wimmera / mallee woodland

Colours indicate possibility of Rhodomyrtus tomentosa infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.
map showing the potential distribution of downy rose myrtle
Red= Very highOrange = Medium
Yellow = HighGreen = Likely

Impact

QUESTION
COMMENTS
RATING
CONFIDENCE
Social
1. Restrict human access?Can grow to a 3m tall tree and form impenetrable thickets (Weber 2003). This would create access difficulty even for a vehicle.
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2. Reduce tourism?Ornamental which can create thickets (Weber 2003). Therefore it may impact upon both aesthetics and the recreational use of an area, there is no evidence of this occurring however.
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3. Injurious to people?The fruits are edible (Starr, Starr & Loope 2003). There is no evidence reported of the species causing injury or allergy.
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4. Damage to cultural sites?Ornamental which can create thickets (Weber 2003). Therefore the species has the potential to impact upon aesthetics, there is no evidence of this occurring however.
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Abiotic
5. Impact flow?Terrestrial species therefore unlikely to significantly impact upon water flow.
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6. Impact water quality?Terrestrial species therefore unlikely to significantly impact upon water quality.
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7. Increase soil erosion?Is being trailed in conjunction with Vetiver and other native Chinese species to control erosion on slopes of up to 50 (Kong et al 2003). Therefore as a large shrub with a presumably large root system and it ability to grow on exposed site, it will potentially decrease the probability of soil erosion.
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8. Reduce biomass?Reported to replace the existing vegetation with a dense thicket (Starr, Starr & Loope 2003). This is likely to be a direct replacement to increase in biomass.
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9. Change fire regime?Reported to have some capacity as a fire retardant species (MoEF 2002). In wet habitats this may have no impact, however if the plant invaded vegetation such as grassland it would therefore have potential to decrease fire frequency, and the increase in biomass that R.tomentosa would create could increase fire intensity. It is unknown to what extent R.tomentosa would impact on the fire regime.
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Community Habitat
10. Impact on composition
(a) high value EVC
EVC= Grassy Woodland (E); CMA= North Central; Bioreg= Goldfields; M CLIMATE potential.
Can form a monoculture within the shrub layer (Weber 2003). However as the species only has a medium CLIMATE match its competitive ability would be presumably reduced and is likely to cause major not total displacement.
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(b) medium value EVCEVC= Herb-rich Foothill Forest (D); CMA= North Central; Bioreg= Goldfields; M CLIMATE potential.
Can form a monoculture within the shrub layer (Weber 2003). However as the species only has a medium CLIMATE match its competitive ability would be presumably reduced and is likely to cause major not total displacement.
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(c) low value EVCEVC= Scrub-pine Woodland (LC); CMA= North Central; Bioreg= Goldfields; M CLIMATE potential.
Can form a monoculture within the shrub layer (Weber 2003). However as the species only has a medium CLIMATE match its competitive ability would be presumably reduced and is likely to cause major not total displacement.
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11. Impact on structure?Can form a monoculture within the shrub layer (Weber 2003). However as the species only has a medium CLIMATE match its competitive ability would presumably be reduced, while it may not form a monoculture within the shrub layer, displacement within the shrub layer and lower strata would impact upon more than 60% of the floral strat.
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12. Effect on threatened flora?There is no specific evidence of this occurring.
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Fauna
13. Effect on threatened fauna?There is no specific evidence of this occurring.
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14. Effect on non-threatened fauna?Unknown; however significant alteration of the vegetation in terms of species composition and structure is likely to significantly impact on habitat values for fauna species.
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15. Benefits fauna?The species fruits are eaten by birds and mammals (Starr, Starr & Loope 2003).
The dense thickets it forms may be used as habitat (Weber 2003).
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16. Injurious to fauna?There is no evidence of this reported.
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Pest Animal
17. Food source to pests?Fruit may be eaten and spread by bird species such as blackbirds (Corlett 1998).
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18. Provides harbor?The dense thickets it forms may be used as habitat (Weber 2003). This may include species such as rabbits and foxes.
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Agriculture
19. Impact yield?Invasion of pasture would reduce carrying capacity (PIER 2007).
Invades pine forest (Weber 2003). This may reduce growth rates through competition.
Unknown to what extent this will reduce yield.
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20. Impact quality?There is no evidence of the species impacting upon quality of products.
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21. Affect land value?There is no evidence of this occurring.
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22. Change land use?Unknown.
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23. Increase harvest costs?Can form dense thickets within pine forest (Weber 2003). This is likely to impede maintenance operations and increase labour costs.
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24. Disease host/vector?Unknown.
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Invasive

QUESTION
COMMENTS
RATING
CONFIDENCE
Establishment
1. Germination requirements?A tropical species, freshly collected seed has been planted in December and May for experimental purposes in Malaysia (Raich & Khoon 1990). This would indicate no specific requirements for germination, it is unknown if there would be any change to this in a more temperate climate.
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2. Establishment requirements?Under experimental conditions a preference has been observed for germination to occur in gaps or areas with 50% cover (Raich & Khoon 1990). As the plant is also described as invading forest habitats it is believed that the species can establish under a moderate canopy (Weber 2003).
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3. How much disturbance is required?Reported to invade woodland and riparian vegetation (Weber 2003).
Within its native range a habitat that it is present in is heath (Turner, Ong & Tan 1995). It is not reported invading such a community however.
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Growth/Competitive
4. Life form?Other; Large shrub (Weber 2003).
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5. Allelopathic properties?There is no evidence of allelopathy reported; the plant does however contain a number of different chemicals (Dachriyanus et al 2002).
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6. Tolerates herb pressure?Unknown how generalist herbivores interact with this species. Six insects are being investigated as potential biocontrol agents for Florida (Winotai, Wright & Goolsby 2005).
Annual harvesting in a grassland over a 10 year period lead to a decrease in the proportion of phytomass made up of R. tomentosa (Hill, Peart & Dong-Sheng 2004).
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7. Normal growth rate?Reported to have an aggressive growth rate and is able to out-compete the native vegetation of Hawaii (Starr, Starr & Loope 2003). Therefore presumed to be at least competitive with of the competitive species of a similar life form.
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8. Stress tolerance to frost, drought, w/logg, sal. etc?Can be damaged or killed by severe frosts (Corlett 1992). It is reported to be tolerant of temperature as low as -7C (Starr, Starr & Loope 2003).
Tolerant of saline soils (Weber 2003).
Reported to resprout after fire (Starr, Starr & Loope 2003).
Reported in Bog habitats which indicates a tolerance of waterlogging (Starr, Starr & Loope 2003).
Unknown tolerance of drought.
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Reproduction
9. Reproductive systemReproduces sexually, producing fruits containing seed (Starr, Starr & Loope 2003).
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10. Number of propagules produced?Each fruit has three cells with a double row of seeds in each cell and each plant has the potential of producing hundreds to thousands of fruits (image) (Pier 2007).
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11. Propagule longevity?Unknown.
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12. Reproductive period?Reported to form a monoculture within the shrub layer (Weber 2003).
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13. Time to reproductive maturity?Unknown.
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Dispersal
14. Number of mechanisms?Dispersed by birds and mammals including Civet, Macaque and rat species in its native range (Au, Corlett & Hau 2006).
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15. How far do they disperse?A fruit of 10-15mm diameter with numerous small seeds, could be dispersed by small and larger frugivorous birds with the potential of dispersing the seeds more than 1km.
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References

Au A.Y.Y., Corlett R.T. & Hau B.C.H., 2006, Seed rain into upland plant communities in Hong Kong, China. Plant Ecology. 186: 13-22.

Corlett R.T., 1992, The impact of cold and frost on terrestrial vegetation in Hong Kong. Memoirs of the Hong Kong Natural History Society. 19: 133-135.

Corlett R.T., 1998, Frugivory and seed dispersal by birds in Hong Kong shrubland.

Dachriyanus, Salni, Sargent M.V., Skelton B.W., Soediro I., Sutisna M., White A.H. & Yulinah E., 2002, Rhodomyrotone, an Antibiotic from Rhodomyrtus tomentosa. Australian Journal of Chemistry. 55: 229-232.

Hill R.D., Peart M.R. & Dong-Sheng G., 2004, The effects of annual harvesting on the subsequent phytomass and species composition of grassland and fernland: A Hong Kong case. Singapore Journal of Tropical Geography. 25: 77-91.

Kong X., Lin W., Gao L. Hong H., 2003, A Preliminary experiment on slope rehabilitation with Vetiver and native plants in South China. Proceedings of the The Third International Conference on Vetiver and Exhibition. China Agriculture Press,

Langland, K.A., Craddock Burks, K., 1998. Identification and Biology of Non-Native Plants in Florida’s Natural Areas. University of Florida, Gainesville, USA.

Ministry of Environment & Forests (MoEF) 2002, Annual Report 2001-2002, Chapter 7: Research, viewed 30 May 2007, http://envfor.nic.in/report/0102/chap07.html

Pacific Island Ecosystem at Risk (PIER) 2007, Hawaii Ecosystem at Risk, viewed 25 May 2007, http://www.hear.org/Pier/wra/pacific/

Raich J.W. & Khoon G.W., 1990, Effects of canopy openings on tree seed germination in a Malaysian dipterocarp forest. Journal of Tropical Ecology. 6: 203-217.

Starr F., Starr K. & Loope L., 2003, Rhodomyrtus tomerntosa, Downy rose myrtle, Myrataceae. United States Geological Survey -- Biological Resources Division. Viewed 25 May 2007, http://www.hear.org/starr/hiplants/reports/pdf/rhodomyrtus_tomentosa.pdf

Turner I.M., Ong B.L. & Tan H.T.W., 1995, Vegetation analysis, leaf structure and nutrient status of a Malaysian heath community. Biotropica. 27: 2-12.

Weber E. 2003, Invasive plant species of the world: a reference guide to environmental weeds, CABI Publishing, Wallingford.

Winotai A., Wright T. & Goolsby J.A., 2005, Herbivores in Thailand on Rhodomyrtus tomentosa (Myrataceae), an invasive weed in Florida. Florida Entomologist. 88: 104-105.


Global present distribution data references

Atlas of Florida Vascular Plants (AFVP), 2007, Atlas of Florida Vascular Plants, Institute for Systematic Botany, viewed 25 May 2007, http://www.plantatlas.usf.edu/

Chen R., Hill R.D. & Corlett R.T., 1997, Energy and nutrient flow through the storage and consumption of upland phytomass fuel. Forest Ecology and Management. 93: 63-71.

Global Biodiversity Information Facility (GBIF) 2007, Global biodiversity information facility: Prototype data portal, viewed 23 May 2007, http://newportal.gbif.org/

Missouri Botanical Gardens (MBG) 2007, w3TROPICOS, Missouri Botanical Gardens Database, viewed 23 May 2007, http://mobot.mobot.org/W3T/Search/vast.html

Starr F., Starr K. & Loope L., 2003, Rhodomyrtus tomerntosa, Downy rose myrtle, Myrataceae. United States Geological Survey -- Biological Resources Division. Viewed 25 May 2007, http://www.hear.org/starr/hiplants/reports/pdf/rhodomyrtus_tomentosa.pdf


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