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Impact Assessment - Italian lily (Arum italicum) 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 Italian lily.

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: Italian lily
Scientific name: Arum italicum

Question
Comments
Rating
Confidence
Recreation
1. Restrict human access?Only grows to 60 cm, however as contact with the sap can cause serve skin irritation this may impede individual access (Shepherd 2004).
ML
MH
2. Reduce tourism?It is an ornamental species and as the flowers can smell like stale urine or decaying meat, this plant could alter aesthetics (Albre, Quilichini & Gibernau 2003; Spencer 2005).
ML
MH
3. Injurious to people?All parts of the plant are poisonous, contact can cause serve skin irritation and if eaten, it can cause death (Shepherd 2004).
H
MH
4. Damage to cultural sites?It is an ornamental species and as the flowers can smell like stale urine or decaying meat, this plant could alter aesthetics (Albre, Quilichini & Gibernau 2003; Spencer 2005).
ML
M
Abiotic
5. Impact flow?Terrestrial species, not reported to impede water flow in any significant way even when occurring in riparian habitats.
L
MH
6. Impact water quality?Terrestrial species, not reported to impact on water quality in any significant way even when occurring in riparian habitats. Its tissues do contain toxic substances which may impact on an aquatic ecosystem if released into the water (Shepherd 2004).
L
M
7. Increase soil erosion?Has a tuberous root system which would help to bind the soil, it does however die back over summer which could leave the soil surface exposed (Boyce 1993).
ML
MH
8. Reduce biomass?A low growing herbaceous species, not reported to impact significantly on vegetation structure. It is likely that there would be direct replacement.
ML
M
9. Change fire regime?Dies back in summer (Boyce 1993). This could alter fuel loads and there is less biomass during the fire season and therefore alter fire intensities.
ML
M
Community Habitat
10. Impact on composition
(a) high value EVC
EVC= Riparian Forest (V); CMA= Corangamite ; Bioreg= Otway Plain ; VH CLIMATE potential.
Anecdotally this species has been reported to crowd out garden beds and even displacing crabgrass (Dave’s Garden 2007). Therefore at least some minor displacement in a natural ecosystem is predicted.
ML
ML
(b) medium value EVCEVC= Sedgy Riparian Woodland (D); CMA= Corangamite ; Bioreg= Otway Plain ; VH CLIMATE potential.
Anecdotally this species has been reported to crowd out garden beds and even displacing crabgrass (Dave’s Garden 2007). Therefore at least some minor displacement in a natural ecosystem is predicted.
ML
ML
(c) low value EVCEVC= Lowland Forest (LC); CMA= Glenelg Hopkins; Bioreg= Victorian Volcanic Plain; VH CLIMATE potential.
Anecdotally this species has been reported to crowd out garden beds and even displacing crabgrass (Dave’s Garden 2007). Therefore at least some minor displacement in a natural ecosystem is predicted.
ML
ML
11. Impact on structure?Anecdotally this species has been reported to crowd out garden beds and even displacing crabgrass (Dave’s Garden 2007). Therefore at least some minor displacement in the lower strata of a natural ecosystem is predicted, this would still not realistically impact on more than 20% of the total vegetation community.
L
ML
12. Effect on threatened flora?Unknown, there is no evidence reported.
MH
L
Fauna
13. Effect on threatened fauna?Unknown, there is no evidence reported.
MH
L
14. Effect on non-threatened fauna?Not exactly known, unlikely however to significantly alter the habitat.
ML
ML
15. Benefits fauna?Provides fruit for bird species, but only invertebrates such as aphids and slugs and snails are reported to eat the leaves (Boyce 1993).
H
MH
16. Injurious to fauna?May cause skin irritation, illness and death (Connor 1977; McBarron 1977; Shepherd 2004).
H
MH
Pest Animal
17. Food source to pests?Eaten by slugs snails and aphids (Boyce 1993).
ML
MH
18. Provides harbor?Only 60 cm high and contact can cause irritation, unlikely to provide significant harbour (Shepherd 2004).
L
M
Agriculture
19. Impact yield?Only a very minor weed of crops (Hidalgo, Saavedra & Garcia-Torres 1990).
Can cause poisoning and death in stock (Connor 1977; McBarron 1977). Significant stock losses have not been reported.
ML
MH
20. Impact quality?Unknown.
M
L
21. Affect land value?Anecdotally people have moved house, due to frustration of trying to control this species (Dave’s Garden 2007).
M
ML
22. Change land use?Unknown.
M
L
23. Increase harvest costs?May require stock to be restricted and moved more regularly to prevent poisoning and deaths.
M
L
24. Disease host/vector?Can be effected by aphids and slugs and snails (Boyce 1993).
M
MH

Impact Assessment Record - Italian lily (PDF - 96KB)
Impact Assessment Record - Italian lily (DOC - 56KB)
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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