Impact Assessment - Tree tobacco (Solanum mauritianum) 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 Tree tobacco
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: Tree tobacco
Scientific name: Solanum mauritianum
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | Can form thickets, reaching over 6 m (Walsh 1956). From an image in Walsh (1956) access for people or machinery would be with difficulty. | MH | MH |
| 2. Reduce tourism? | There is no evidence that this species impacts upon recreational areas. It has however been grown as an ornamental, but is often dumped as it can become shabby and unappealing, therefore it may alter the aesthetics of such areas (Blood 2001). | ML | M |
| 3. Injurious to people? | The immature (green) fruit and leaves are poisonous (Blood 2001; Shepherd 2004). There have been fatal cases of poisoning after ingestion of the fruit (Van Dyck 1979). The plant can also produce fruit all year (Drew & Hooper 1983). Hairs can also be an irritant (Dept. of Conservation 2005). | H | H |
| 4. Damage to cultural sites? | It has been grown as an ornamental, but is often dumped as it can become shabby and unappealing, therefore it may alter the aesthetics of such areas (Blood 2001). | ML | M |
| Abiotic | |||
| 5. Impact flow? | Terrestrial species, there is no evidence to suggest that it impacts on water flow. | L | M |
| 6. Impact water quality? | Terrestrial species, there is no evidence to suggest that it impacts on water quality. | L | M |
| 7. Increase soil erosion? | It is reported as a fast growing pioneer species, therefore it could quickly invade bare ground and reduce the probability of erosion occurring (Blood 2001). | ML | MH |
| 8. Reduce biomass? | Short lived pioneer species (Blood 2001). Where it invades open areas, this would be an increase in biomass and it does allow shade tolerant species to establish and succession to occur (Harden, Fox & Fox 2004). | ML | MH |
| 9. Change fire regime? | Unknown relationship with fire regime. Fast growing species which is killed by fire but germination is stimulated. Can alter biomass and therefore elevated fuels, unknown flammability. | M | L |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | EVC= Coastal Tussock Grassland (V); CMA= Corangamite; Bioreg= Warrnambool Plain; VH CLIMATE potential. Fast growing pioneer species (Blood 2001). Becomes most dominant after a disturbance (Olckers & Zimmermann 1991). Dominance by this species could impact the mid to lower strata and potentially the re-establishment of the higher strata as it has been reported to out compete seedlings in a plantation situation (Jarvel & Pallett 2002; Olckers & Zimmermann 1991). In rainforest, it has allowed for succession, as it does allow shade tolerant species to establish while preventing the establishment of other weed species including lantana (Harden, Fox & Fox 2004; Van Dyck 1979). Overall This species itself causes minor displacement. | ML | MH |
| (b) medium value EVC | EVC= Grassy Dry Forest (D); CMA= Corangamite; Bioreg= Central Victorian Uplands; VH CLIMATE potential. Fast growing pioneer species (Blood 2001). Becomes most dominant after a disturbance (Olckers & Zimmermann 1991). Dominance by this species could impact the mid to lower strata and potentially the re-establishment of the higher strata as it has been reported to out compete seedlings in a plantation situation (Jarvel & Pallett 2002; Olckers & Zimmermann 1991). In rainforest,it has allowed for succession, as it does allow shade tolerant species to establish while preventing the establishment of other weed species including lantana (Harden, Fox & Fox 2004; Van Dyck 1979). Overall This species itself causes minor displacement. | ML | MH |
| (c) low value EVC | EVC= Wet Forest (LC); CMA= Corangamite; Bioreg= Otway Plain; VH CLIMATE potential. Fast growing pioneer species (Blood 2001). Becomes most dominant after a disturbance (Olckers & Zimmermann 1991). Dominance by this species could impact the mid to lower strata and potentially the re-establishment of the higher strata as it has been reported to out compete seedlings in a plantation situation (Jarvel & Pallett 2002; Olckers & Zimmermann 1991). In rainforest, it has allowed for succession, as it does allow shade tolerant species to establish while preventing the establishment of other weed species including lantana (Harden, Fox & Fox 2004; Van Dyck 1979). Overall This species itself causes minor displacement. | ML | MH |
| 11. Impact on structure? | Fast growing pioneer species (Blood 2001). Becomes most dominant after a disturbance (Olckers & Zimmermann 1991). Dominance by this species could impact the mid to lower strata and potentially the re-establishment of the higher strata as it has been reported to out compete seedlings in a plantation situation (Jarvel & Pallett 2002; Olckers & Zimmermann 1991). In rainforest, it has allowed for succession, as it does allow shade tolerant species to establish while preventing the establishment of other weed species including lantana (Harden, Fox & Fox 2004; Van Dyck 1979). Overall, this species itself would have a minor impact and depending on the vegetation invaded, this could be greater than 60% of the layers. | MH | MH |
| 12. Effect on threatened flora? | There is no evidence of this. | MH | L |
| Fauna | |||
| 13. Effect on threatened fauna? | There is no evidence of this. It is used as a food source especially in winter by Grey-headed Flying-fox (Pteropus poliocephalus), which is listed as a vulnerable species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (Parry-Jones & Augee 2001). | ML | L |
| 14. Effect on non-threatened fauna? | It has been reported to have negative impacts on ground-dwelling invertebrates (Florentine & Westbrooke 2003). | MH | MH |
| 15. Benefits fauna? | Fruits eaten by bird species. It is used as a food source especially in winter by Grey-headed Flying-fox (Pteropus poliocephalus), which is listed as a vulnerable species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (Parry-Jones & Augee 2001). The major host for an endemic fruit fly | ML | H |
| 16. Injurious to fauna? | Toxic to pigs and cattle (Blood 2001). Its leaves and fruits have however been reported to be eaten by a number of native species, including possums, pademelons and flying-foxes (Parry-Jones & Augee 2001; Van Dyck 1979; Wahingu, Catterall & Olsen 1999). Its not known to be toxic to native species, and if it is whether any consume it anyway. | M | M |
| Pest Animal | |||
| 17. Food source to pests? | It is a host for a number of fruit fly species, but it is not reported as a significant host of those targeted for control (Copeland & Wharton 2006; Drew 1987; Drew & Hooper 1983; Raghu et al 2004). | ML | MH |
| 18. Provides harbor? | It is a host for larvae of a number of fruit fly species and can also shelter adults over winter, but it is not reported as a significant host of those targeted for control (Copeland & Wharton 2006; Drew 1987; Drew & Hooper 1983; Raghu et al 2004). | ML | MH |
| Agriculture | |||
| 19. Impact yield? | Competes with young trees in forestry plantations and can reduce growth rate (Jarvel & Pallett 2002; Olckers & Zimmermann 1991). It has been linked to fatal cases of poisoning in pigs and cattle (Van Dyck 1979). Invasion by this species can also reduce the production area, reducing carrying capacity. Unknown to what extent this species impacts on the quantity of outputs. | M | M |
| 20. Impact quality? | Competes with seedlings and can cause stem deformation (Olckers & Zimmermann 1991). It is unknown to what extent this impacts on the final output. | M | M |
| 21. Affect land value? | Unknown. | M | L |
| 22. Change land use? | It has been recommended to alter permanent grazing to more intense rotational management. | ML | H |
| 23. Increase harvest costs? | Management time may be increased in both forestry and grazing systems. | M | MH |
| 24. Disease host/vector? | It is a host to a number of fruit fly species but it is not reported as a host of any significance of the Queensland or Mediterranean Fruit flies which are the targeted species in Victoria (Copeland & Wharton 2006; Drew 1987; Drew & Hooper 1983; Raghu et al 2004). Host species for the ginger strain Pseudomonas solanacerarum biotype 4 (Pegg & Moffett 1971). As there are a number of solanum species as commercial crops as well as native solanum any bio-control agent would have to be shown not to become a pest of these plants. | M | MH |
Impact Assessment Record - Tree tobacco (PDF - 61KB)
Impact Assessment Record - Tree tobacco (DOC - 65KB)
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