Impact Assessment - Chinese rain tree (Koelreuteria elegans ssp. formosana) 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 Chinese rain tree
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: Chinese rain tree
Scientific name: Koelreuteria elegans ssp. formosana
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | Grows to approximately 5 meters tall (up to 18 metres under ideal conditions). Has ‘a dense rounded crown and may achieve a spread of 10-15 m when mature (CRC for Australian Weed Management 2003). No record of the plant forming clusters. Would have minimal or negligible impact. | L | M |
| 2. Reduce tourism? | ‘Abundant, colourful yellow flowers and pink, inflated fruit’ (CRC for Australian Weed Management 2003). Grows up to 5 metres with dense crown. May have minor effect on aesthetics. | ML | M |
| 3. Injurious to people? | Although species may cause ‘vomiting, abdominal pain, and in some cases diarrhoea, there is no evidence that it is consumed’ (PIER 2005). | L | MH |
| 4. Damage to cultural sites? | ‘Abundant, colourful yellow flowers and pink, inflated fruit’ (CRC for Australian Weed Management 2003). Grows up to 15 metres with dense crown. Moderate visual effect. | ML | M |
| Abiotic | |||
| 5. Impact flow? | Terrestrial species (PIER 2005). | L | MH |
| 6. Impact water quality? | Terrestrial species (PIER 2005). | L | MH |
| 7. Increase soil erosion? | Deciduous tree. Would leave some of the ground exposed for a period of time. Can occur in gullies but unlikely to contribute to large-scale soil erosion. | L | M |
| 8. Reduce biomass? | Because of ‘its rapid growth habit and high seed viability.. may crowd out native plant populations (CRC for Australian Weed Management 2003). Would depend on the area that the plant establishes but likely to be a direct replacement of biomass. | ML | M |
| 9. Change fire regime? | Tree is of low flammability (PIER 2005). Small or negligible effect on fire risk. | L | MH |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | Potential distribution of Koelreutaria elegans excludes Victoria. No impact on EVCs in Victoria. | L | H |
| (b) medium value EVC | Potential distribution of Koelreutaria elegans excludes Victoria. No impact on EVCs in Victoria. | L | H |
| (c) low value EVC | Potential distribution of Koelreutaria elegans excludes Victoria. No impact on EVCs in Victoria. | L | H |
| 11. Impact on structure? | Because of ‘its rapid growth habit and high seed viability.. may crowd out native plant populations (CRC for Australian Weed Management 2003). Would have a major effect on less than 60% of the floral strata. | MH | M |
| 12. Effect on threatened flora? | This species is not documented as posing an additional risk to threatened flora. | MH | L |
| Fauna | |||
| 13. Effect on threatened fauna? | This species is not documented as posing an additional risk to threatened flora. | MH | L |
| 14. Effect on non-threatened fauna? | Not documented as having an effect on non-threatened fauna. | L | M |
| 15. Benefits fauna? | No evidence that the plant benefits fauna. | H | M |
| 16. Injurious to fauna? | Plant not documented to be toxic or have burrs or spines (PIER 2005). | L | MH |
| Pest Animal | |||
| 17. Food source to pests? | No evidence that the plant provides a food source to pest species. | L | M |
| 18. Provides harbor? | No evidence that the plant provides harbour for pest species. | L | M |
| Agriculture | |||
| 19. Impact yield? | Not recorded as a weed of agriculture (PIER 2005). | L | MH |
| 20. Impact quality? | Not a weed of cropping (PIER 2005). | L | MH |
| 21. Affect land value? | No evidence that the weed would effect land value. Can be well controlled by herbicides (PIER 2005). | L | MH |
| 22. Change land use? | No evidence that the weed would cause a change in priority of land use. Can be well controlled by herbicides (PIER 2005). | L | MH |
| 23. Increase harvest costs? | Not a weed of agriculture (PIER 2005). | L | MH |
| 24. Disease host/vector? | Not a known host or vector for disease of agriculture. | L | M |
This table can also be viewed as a PDF document (printer friendly).
Impact Assessment Record - Chinese rain tree (PDF - 71KB)
Impact Assessment Record - Chinese rain tree (DOC - 49KB)
To view the information PDF requires the use of a PDF reader. This can be installed for free from the Adobe website (external link).
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