Impact Assessment - Madeira vine (Anredera cordifolia) 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.

Question	Comments	Rating	Confidence
Recreation
1. Restrict human access?	‘Has spread along the waterways and through forests’ ‘ Because of its thick fleshy leaves and bunches of tubers, it is the heaviest of the problem vines and can smash the branches of trees by its weight’ (Wilsons Creek Huonbrook Landcare 2003). Climbs vigorously over shrubs and trees with rope-like stems, up to a few centimetres in diameter (Muyt 2001). Would have a low nuisance value with the ability to impede individual access.	ML	MH
2. Reduce tourism?	‘Starting to noticeably expand its range’ (Environment Waikato 2002). ‘It is highly visible, and receiving adverse comments from landholders..’ (BREC 2004). Weed has the potential to have a minor effect on the aesthetics of the land.	ML	M
3. Injurious to people?	No known toxic principles.	L	M
4. Damage to cultural sites?	‘Can completely smother indigenous vegetation and prevent natural regeneration’ (Blood 2002). Weed could have a moderate visual effect.	ML	MH
5. Impact flow?	Terrestrial species.	L	MH
6. Impact water quality?	Terrestrial species.	L	MH
7. Increase soil erosion?	Has tap and fibrous roots systems. ‘Spreads over the ground, smothering native groundcover plants and preventing regeneration’ (Eurobodalla Shire Council 2003). As it is an evergreen vine assume a low probability of large-scale soil movement.	L	M
8. Reduce biomass?	‘Climbs over shrubs and trees, smothering and breaking them down. Also spreads over the ground, smothering native groundcover plants and preventing regeneration’ (Eurobodalla Shire Council 2003). Likely that the biomass may increase.	L	M
9. Change fire regime?	Suppression of all indigenous vegetation may reduce fire risk. Thrives in moist habitats (Muyt 2001). Not likely to have an effect on the frequency or intensity of fires.	L	MH
Community Habitat
10. Impact on composition (a) high value EVC	EVC=Sedgy Riparian Woodland (V); CMA=Corangamite; Bioreg=Otway Ranges; CLIMATE potential=VH. ‘Capable of obliterating all indigenous vegetation. Vines climbing vigorously over shrubs and trees while trailing stems smother all ground-flora and prevent any regeneration’ (Muyt 2001). Displaces all species in all layers.	H	MH
(b) medium value EVC	EVC= Riparian Scrub (D); CMA=Glenelg Hopkins; Bioreg=Glenelg Plains; CLIMATE potential=VH. ‘Capable of obliterating all indigenous vegetation. Vines climbing vigorously over shrubs and trees while trailing stems smother all ground-flora and prevent any regeneration’ (Muyt 2001). Displaces all species in all layers.	H	MH
(c) low value EVC	EVC= Riparian Forest (LC.); CMA=Corangamite; Bioreg=Otway Ranges; CLIMATE potential=VH. ‘Capable of obliterating all indigenous vegetation. Vines climbing vigorously over shrubs and trees while trailing stems smother all ground-flora and prevent any regeneration’ (Muyt 2001). Displaces all species in all layers.	H	MH
11. Impact on structure?	‘By time, invaded forests become degraded and displaced with vine growth, preventing the establishment of native trees’ (Weber 2003). ‘Capable of obliterating all indigenous vegetation. Vines climbing vigorously over shrubs and trees while trailing stems smother all ground-flora and prevent any regeneration’ (Muyt 2001). Capable of having a major effect on all layers.	H	MH
12. Effect on threatened flora?	‘This part of the creek area is heavily infested with Madeira vine, camphor laurel and other weeds, while the vine is killing melaleucas and putting at risk rainforest trees’ (BREC 2004). This species is not documented as posing an additional risk to threatened flora in Victoria.	MH	M
Fauna
13. Effect on threatened fauna?	This species is not documented as posing an additional risk to threatened fauna in Victoria.	MH	L
14. Effect on non-threatened fauna?	In Queensland, an area which is heavily infested with weeds including Anredera cordifolia ‘needs an urgent upgrade … to provide access for fauna and facilitation of movement’ (BREC 2004). Suggests that the weed could have a minor impact upon wildlife corridors.	ML	M
15. Benefits fauna?	In a forest in NSW ‘ the Madeira vine… took over the exposed understorey, further impeding regeneration… Flying foxes found the increasing number of sun-warmed gaps one of the few places left ideally suited for them’ (BCI 1987). Provides very little support to desirable species.	H	ML
16. Injurious to fauna?	‘Suspected of poisoning livestock’ (Blood 2002). No documented evidence to suggest that fauna would eat the weed. Unlikely to have an effect on indigenous fauna.	L	MH
Pest Animal
17. Food source to pests?	‘Suspected of poisoning livestock’ (Blood 2002). Unlikely to provide a food source for pest animals.	L	MH
18. Provides harbor?	‘Involved the total removal of exotic weeds [including Anredera cordifolia] from .. a riparian habitat, which harboured a high density of native rodent, Uromys caudimaculatus’ (Ward, Tucker & Wilson 2003). May provide harbour for minor pest spp.	ML	MH
Agriculture
19. Impact yield?	Not known as a weed of agriculture.	L	MH
20. Impact quality?	Not known as a weed of agriculture. Not likely to impact upon agricultural quality.	L	MH
21. Affect land value?	Not known as a weed of agriculture. Unlikely that the weed would affect land value.	L	MH
22. Change land use?	Not known as a weed of agriculture. Unlikely that there will be a change in priority of land use.	L	MH
23. Increase harvest costs?	Not known as a weed of agriculture.	L	MH
24. Disease host/vector?	None evident	L	MH