Invasiveness Assessment - Miconia (Miconia spp.) in Victoria

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Plant invasiveness is determined by evaluating a plant’s biological and ecological characteristics against criteria that encompass establishment requirements, growth rate and competitive ability, methods of reproduction, and dispersal mechanisms.

Each characteristic, or criterion, is assessed against a list of intensity ratings. Depending upon information found, a rating of Low, Medium Low, Medium High or High is assigned to that criterion. Where no data is available to answer a criterion, a rating of medium (M) is applied. A description of the invasiveness criteria and intensity ratings used in this process can be viewed here.

The following table provides information on the invasiveness of Miconia.

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)
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Common Name: Miconia
Scientific name: Miconia spp.

Question	Comments	Rating	Confidence
Establishment
Germination requirements?	‘Germination and seedling growth can occur under light levels as low as 0.02% of full sun’. In a laboratory experiment, some seeds germinated when exposed to light and moisture (Csurhes 1997). Opportunistic germinator.	H	H
Establishment requirements?	‘Germination and seedling growth can occur under light levels as low as 0.02% of full sun. This attribute facilitates the plant’s persistence in deep shade beneath rainforest canopies’ (Csurhes 1997). Can establish without additional factors.	H	H
How much disturbance is required?	Miconia calvescens ‘persists in a wide range of habitats including primary and secondary rainforest in mesic and wet environments .. in areas of primary rainforest it appears to invade areas that show no obvious signs of disturbance’ (Csurhes 1997). ‘Occurs in coastland, disturbed areas, natural forest, planted forests, riparian zones, scrubs/ shrublands, urban areas, wetlands’ (ISSG 2005). Can establish in relatively intact natural ecosystems.	MH	H
Growth/Competitive
Life form?	Tree (Csurhes 1997). Life form –other.	L	H
Allelopathic properties?	None described in Csurhes (1997).	L	H
Tolerates herb pressure?	The most damaging species is the Chinese rose beetle (Adoretus sinicus) which ‘causes up to 50% defoliation but does not cause tree mortality’ (Csurhes 1997). Capable of flowering / seed production under moderate herbivory pressure.	MH	H
Normal growth rate?	Medium-sized tree. ‘Under favourable conditions, juvenile specimens can grow up to 1.5 m/year’ (Csurhes 1997). ‘Fast-growing’ (Weber 2003). Moderately rapid growth that will equal competitive species of the same life form.	MH	H
Stress tolerance to frost, drought, w/logg, sal. etc?	Native to tropical America and found in other tropical rainforests. Unlikely to be frost tolerant. Thrives in wet forests with annual precipitation between 1800-2000 mm. (ISSG 2005). ‘Can tolerate otherwise poor growing conditions if adequate moisture is available’ Drought intolerant. Can tolerate saline conditions. Tolerant to at least 2 and susceptible to at least 2.	ML	MH
Reproduction
Reproductive system	Capable of both self and cross pollination. Does not naturally reproduce vegetatively but can through cuttings (ISSG 2005).	ML	MH
Number of propagules produced?	‘A young tree with only two panicles can produce ca. 200,000 seeds in its first fruiting season, whereas an older tree, with over 50 panicles, can produce over 5 million seeds per annum’ (Csurhes 1997).	H	H
Propagule longevity?	‘Seeds can remain viable for at least four years’ (Csurhes 1997). ‘Longevity of the soils seed bank > 6-8 years’ (ISSG 2005).	L	H
Reproductive period?	In Tahiti Miconia calvescens has ‘naturalized over 65% of the island and has formed dense, monospecific stands over 25% of the island’ (Csurhes 1997). Species forms self-sustaining dense monocultures.	H	H
Time to reproductive maturity?	‘Reproduce when four to five years old’ (Csurhes 1997).	ML	H
Dispersal
Number of mechanisms?	‘Although most fruit falls beneath the parent tree, the seed is small enough to be moved by wind and water’. Bird and rodent dispersed. Can adhere to mud and vehicles (Csurhes 1997).	H	H
How far do they disperse?	‘Individual birds can carry thousands of seeds at least up to 2 km (ISSG 2005). Very likely that some propagules will disperse greater than 1 km.	H	MH

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