Impact Assessment - Bluebell creeper (Billardiera heterophylla / Billardiera fusifomis) 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 Bluebell creeper.
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)
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: Blue-bell creeper
Scientific name: Billardiera heterophylla / Billardiera fusifomis (formally known as Sollya heterophylla Lindl.)*
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | ‘Blue-bell creeper scrambles to head height on middle storey plants forming an almost impenetrable barrier that is difficult to treat or transverse with equipment (Hill 1997)’. High nuisance value, people access with difficulty. | MH | M |
| 2. Reduce tourism? | ‘Blue-bell creeper scrambles to head height on middle storey plants forming an almost impenetrable barrier that is difficult to treat or transverse with equipment (Hill 1997)’. There is a possibility of it having a minor affect on recreational use if it grew across walking paths. It is also described as forming large colonies (Blood 2001), that could impact on the aesthetics of an area. | ML | MH |
| 3. Injurious to people? | ‘It contains toxins, which can cause skin irritation and nausea, so it is important that gloves are worn when handling’. Mildly toxic. | ML | MH |
| 4. Damage to cultural sites? | Though not specifically documented, as a climbing species that can reach up to 4 metres in height (DNRE 2002), there is potential for it to have a moderate visual affect on the aesthetics of a cultural site or infrastructure. | ML | ML |
| Abiotic | |||
| 5. Impact flow? | As a terrestrial species it is unlikely to impact on water flow. | L | M |
| 6. Impact water quality? | As a terrestrial species it is unlikely to impact on water quality. | L | M |
| 7. Increase soil erosion? | ‘It affects sites on slopes and with loss of biodiversity as a result of invasion this could lead to increased erosion risks e.g. at Arthur’s seat (R. Adair pers. com.)’. Its ability to smother and eliminate other vegetation (Muyt 2001, DNRE 1997) particularly those with extensive root systems, could lead to an increase in soil erosion, especially as it often inhabits coastal areas (Muyt 2001). It has the potential to impact on erosion but the extent of its impact is unclear. | M | M |
| 8. Reduce biomass? | Appears to increase biomass in communities due to development of heavily tangled shrub layer (R. Adair pers. com.). | L | MH |
| 9. Change fire regime? | ‘Likely to increase fire risk due to increase in fine fuel loads (R. Adair pers. com.)’. This species invades many diverse ecosystems with varying fire regimes. An increase in fine fuel loads could cause a moderate change to both fire frequency and intensity. For example in a ‘shrubby wet forest’ habitat (White 2007), it could moderately increase fire frequency but decrease fire intensity. | MH | MH |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | Large colonies many metres across can be formed (Blood 2001) and isolated plants can develop into aggressive invading fronts that smother all vegetation in their path, forming virtual monocultures (Taylor 1997, Hill 1997). | H | MH |
| (b) medium value EVC | Large colonies many metres across can be formed (Blood 2001) and isolated plants can develop into aggressive invading fronts that smother all vegetation in their path, forming virtual monocultures (Taylor 1997, Hill 1997). | H | MH |
| (c) low value EVC | Large colonies many metres across can be formed (Blood 2001) and isolated plants can develop into aggressive invading fronts that smother all vegetation in their path, forming virtual monocultures (Taylor 1997, Hill 1997). | H | MH |
| 11. Impact on structure? | Large colonies many metres across can be formed (Blood 2001) and isolated plants can develop into aggressive invading fronts that smother all vegetation in their path, forming virtual monocultures (Taylor 1997, Hill 1997). Can impact on all strata including tree stratum due to lower availability of niches for seedling establishment (R. Adair pers.com.). | H | MH |
| 12. Effect on threatened flora? | White (1997) identified 45 flora taxa that are threatened by habitat alteration as a result of invasion through direct competition for regeneration sites, light, water and space. However, no description of its specific impact on individual threatened flora species was documented. | MH | M |
| Fauna | |||
| 13. Effect on threatened fauna? | White (1997) identified 16 fauna taxa that are threatened by habitat alteration as a result of invasion, due to structural degradation, changed fire regimes, trophic disintegration, and loss of prey or food plants. However, no description of its impact on specific threatened fauna taxa was documented. | MH | M |
| 14. Effect on non-threatened fauna? | White (1997) identifies that habitat alteration as a result of invasion threatens fauna, through structural degradation, changed fire regimes, trophic disintegration, and loss of prey or food plants. Reduction in habitat and food source would likely lead to a reduction in the number of individuals in a population. | MH | MH |
| 15. Benefits fauna? | ‘A range of fauna including frugivorous birds, mammals and possibly reptiles (Bachmann and Johnson in prep) disperse seeds (White 2007)’. Likely to provide some assistance as a food source to desirable fauna species. | MH | MH |
| 16. Injurious to fauna? | No reference was found in the literature to suggest that this species possesses any properties injurious to fauna. | L | M |
| Pest Animal | |||
| 17. Food source to pests? | Foxes are described as a seed disperser (Blood 2001, White 2007). Provides food to one serious pest species. | MH | MH |
| 18. Provides harbor? | The nature of its habit suggests it is unlikely to provide harbour for serious pests like rabbits or foxes, and no information was found documented to indicate that it provides harbour for any minor pest species. | L | M |
| Agriculture | |||
| 19. Impact yield? | B. heterophylla is not described as a weed of agriculture. | L | M |
| 20. Impact quality? | B. heterophylla is not described as a weed of agriculture. | L | M |
| 21. Affect land value? | B. heterophylla is not described as a weed of agriculture. | L | M |
| 22. Change land use? | B. heterophylla is not described as a weed of agriculture. | L | M |
| 23. Increase harvest costs? | B. heterophylla is not described as a weed of agriculture. | L | M |
| 24. Disease host/vector? | B. heterophylla is not described as a weed of agriculture. | L | M |
* A revision of Billardiera and other closely related genera has been recently undertaken by Cayzer et al (2006). Analyses indicated that the genus Billardiera should incorporate Sollya, and the former species Sollya heterophylla has been reclassified as two species Billardiera heterophylla and Billardiera fusiformis.
This table can also be viewed as a PDF document (printer friendly).
Impact Assessment Record - Blue-bell creeper (PDF - 98KB)
Impact Assessment Record - Blue-bell creeper (DOC - 62KB)
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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