Impact Assessment - Rosewood (Tipuana tipu) in Victoria

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Assessment of plant invasiveness is done by evaluating biological and ecological characteristics such as germination requirements, growth rate, competitive ability, reproduction methods and dispersal mechanisms. Assessment of plant impacts, however, is determined by the extent to which a plant affects a land manager’s environmental, economic and social resources.

The relative importance of these resources varies depending upon the value people place on them and, as such, the assessment process is subjective. For example, a farmer is likely to place a higher emphasis on the impact of a plant on production (economic resource) than its impact on areas of natural vegetation occurring on the farm. Conversely, a Landcare or Friends group would value environmental or social resources more than economic resources.

Recognising that the value of resources vary between different land tenures, plant impact assessments allow a prioritisation of resources by land managers. Assessments can apply at a local, regional or state level, and the relative values of each resource identified may differ at each level.

The impact assessment method used in the Victorian Pest Plant Prioritisation Process uses three broad resource categories: social, environmental and agricultural, each with a number of related attributes. For example, social resources include such attributes as how the plant affects human access for recreation, or if it creates a health risk due to toxicity or by producing allergens.

Each resource attribute, or criterion, is assessed relative to a list of intensity ratings. Depending upon information found in relation to each criterion, a rating of Low, Medium Low, Medium High or High is assigned. Descriptions of the impact criteria and intensity ratings used in this process can be viewed here.

The following table provides information on the impact of Rosewood.

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)
To view the information PDF requires the use of a PDF reader. This can be installed for free from the Adobe website (external link).

Common Name: Rosewood
Scientific name: Tipuana tipu

Question	Comments	Rating	Confidence
Recreation
1. Restrict human access?	As a tree to 23 m with a main trunk and elevated crown (Henderson, 2001), human access should not be impeded.	L	MH
2. Reduce tourism?	As a deciduous tree, invading creek banks and woodlands (CRC Weed Management, 2003) this plant would be obviously out of place to the average visitor, however it should not affect recreational use.	ML	M
3. Injurious to people?	No spines, burrs or toxicity noted in Henderson (2001).	L	MH
4. Damage to cultural sites?	This large tree (Henderson, 2001) has the potential to have a visual effect on cultural sites.	ML	MH
Abiotic
5. Impact flow?	Invades riverbanks (Henderson, 2001), but not recorded in waterways and horticultural recommendations are for well-drained soil (Page & Olds, 1998 eds.) so unlikely to impact flow.	L	MH
6. Impact water quality?	This “large, massively branched deciduous tree” invades riverbanks (Henderson, 2001), and so has the potential to drop large amounts of leaf litter into waterways, which could lead to increased algal growth, with the potential to decrease light and oxygen levels in the water.	ML	MH
7. Increase soil erosion?	See q. 5. As it is not recorded in waterways it is unlikely to increase soil erosion. “It is used for…erosion control” (Cruz et al, 2002).	L	MH
8. Reduce biomass?	In the roadsides and riverbanks, savannahs (Henderson, 2001), woodland and open grassland areas that it invades (CRC Weed Management, 2003), this large tree (Henderson, 2001) is likely to increase carbon sequestering biomass.	L	MH
9. Change fire regime?	“It’s ability to spread rapidly into woodlands, firebreaks, tracks, roadsides and other open areas has the potential to affect fire regimes” (CRC Weed Management, 2003). As a large plant it is likely to increase both the intensity and the frequency of fires in these landscapes, although the degree of change would depend on the infestation, so a medium value was chosen.	M	M
Community Habitat
10. Impact on composition (a) high value EVC	Climate modelling shows that this species is not likely to occur as an invasive plant in Victoria.	L	H
(b) medium value EVC	Climate modelling shows that this species is not likely to occur as an invasive plant in Victoria.	L	H
(c) low value EVC	Climate modelling shows that this species is not likely to occur as an invasive plant in Victoria.	L	H
11. Impact on structure?	As a tree to 10 m with a main trunk and elevated crown (CRC Weed Management, 2003), the plant is likely to compete for sunlight with small trees, tall and medium shrubs, grasses and groundcovers. In most of communities that it invades this would comprise most strata, but the degree of impact would depend on the level of infestation.	MH	MH
12. Effect on threatened flora?	Climate modelling shows that this species is not likely to occur as an invasive plant in Victoria.	L	H
Fauna
13. Effect on threatened fauna?	Climate modelling shows that this species is not likely to occur as an invasive plant in Victoria.	L	H
14. Effect on non-threatened fauna?	“Grows in woodland and open grassland areas” (CRC Weed Management, 2003). May reduce the available food for fauna that depend on ground-level vegetation. May be browsed by larger fauna.	ML	M
15. Benefits fauna?	“Since [native long-tailed pal-blue] butterflies are often seen round specimens of tipu tree…they probably breed on this too” (CaLM, 2005).	MH	MH
16. Injurious to fauna?	No spines, burrs or toxicity noted in Henderson (2001).	L	MH
Pest Animal
17. Food source to pests?	As a tree (Henderson, 2001), provides little to no food for pest species.	L	MH
18. Provides harbour?	As a deciduous tree (Henderson, 2001), would provide little or no harbour to pest species.	L	MH
Agriculture
19. Impact yield?	“Valued as a shade tree, a source of ‘rosewood’ timber and, in some circumstances, fodder for stock…It is popular in the Queensland pastoral industry for fattening stock during the winter period…cattle will eat new growth and thus kill rosewood seedlings.” (CRC Weed Management, 2003). Soil improvement by rhizomatous roots and leaf litter improve the nutrient content and texture of soil “leading to increased pasture quality” (Cruz et al, 2002). Impact on yield likely to be positive rather than negative.	L	MH
20. Impact quality?	See Q. 19, not likely to reduce the quality of stock nor to contaminate crop harvests.	L	MH
21. Affect land value?	See Q.19, no reason to reduce land value.	L	MH
22. Change land use?	See Q. 19, no reason to change land use.	L	MH
23. Increase harvest costs?	See Q. 19 no increase in harvest costs.	L	MH
24. Disease host/vector?	Not recorded as a host of agricultural disease.	L	L

Impact Assessment Record - Rosewood (PDF - 23KB)
Impact Assessment Record - Rosewood (DOC- 64KB)
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