Invasiveness Assessment - Athel pine, tamarisk (Tamarix aphylla) in Victoria (Nox)

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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 Athel pine (tamarisk).

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 - 1026 KB)
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Common Name: Athel pine, tamarisk
Scientific name: Tamarix aphylla

Question	Comments	Rating	Confidence
Establishment
Germination requirements?	Germinates all year round so long as moisture is available (ARMCANZ, 2000). Opportunistic germinator.	H	MH
Establishment requirements?	Requires extended periods of soil saturation for establishment (PAC, 2005). Thrives in full sun conditions (Parsons & Cuthbertson, 2001). No evidence to support that the tree can establish under moderate canopy.	ML	MH
How much disturbance is required?	Generally restricted to watercourses and commonly occurs on salt flats, springs and along streams and rivers (ARMCANZ, 2000; Forest Service, 2003).	MH	MH
Growth/Competitive
Life form?	Evergreen tree (PAC, 2005). Other.	L	MH
Allelopathic properties?	None described.	L	L
Tolerates herb pressure?	Foliage has few leaf-eating insects with no known pests in Australia but does have natural pests in native habitat (Beckmann, 1990). Leaves unpalatable to livestock and wildlife (PAC, 2005).	H	MH
Normal growth rate?	Can out compete native vegetation. Seedlings establish readily and growth is also rapid. Displaces Eucalypts and other native vegetation (ARMCANZ, 2000).	H	MH
Stress tolerance to frost, drought, w/logg, sal. etc?	Can tolerate saline water. Highly fire resistant and drought resistant (ARMCANZ, 2000). Flooding can be used to control it if root crowns stay submerged for at least three months (PAC, 2005).	MH	MH
Reproduction
Reproductive system	Capable of both sexual and vegetative (roots or stems) production although vegetative production from broken branches is more common [than from seeds] as it is believed the seeds are only viable for a very short period of time (ARMCANZ, 2000).	H	MH
Number of propagules produced?	‘A single [tree] may produce hundreds of thousands of seeds’ (WSDE 2004).	H	MH
Propagule longevity?	Seeds remain viable for a few weeks only (Beckmann, 1990).	L	H
Reproductive period?	Aggressive coloniser often forming monotypic stands (WSDE, 2004).	H	MH
Time to reproductive maturity?	Start producing seeds after 2 to 3 years in reasonably good conditions (Beckmann, 1990).	ML	H
Dispersal
Number of mechanisms?	Light seeds well adapted to wind dispersal (ARMCANZ, 2000). Dispersed by water (especially floodwaters). May be dispersed by animals and birds (Parsons & Cuthbertson, 2001).	H	MH
How far do they disperse?	Thought to spread long distances in floodwaters and as also spread by birds (Parsons & Cuthbertson, 2001) it is very likely that some propagules will disperse greater than 1 km.	H	MH

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