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Impact Assessment - Cretan trefoil (Lotus creticus) 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 Cretan trefoil.

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: Cretan trefoil
Scientific name: Lotus creticus

Question
Comments
Rating
Confidence
Recreation
1. Restrict human access?The species is described as a prostrate herbaceous plant (Vignolio et al 2002). It is therefore presumed not to have minimal potential of restricting access.
L
H
2. Reduce tourism?The species is described as a prostrate herbaceous plant and occurs on beaches and dunes systems (Vignolio et al 2002; Willmer 1986). The species is therefore unlikely to inhibit any recreational activities; however it may have some aesthetic impact.
ML
M
3. Injurious to people?There is no evidence of this occurring.
L
M
4. Damage to cultural sites?Unknown.
M
L
Abiotic
5. Impact flow?The species is largely a coastal species and is not reported in riparian areas and is therefore unlikely to impact on water flow.
L
M
6. Impact water quality?The species is largely a coastal species and is not reported in riparian areas and is therefore unlikely to impact on water quality.
L
M
7. Increase soil erosion?Recommended for use as a vegetation cover in soil restoration projects to prevent wind and water erosion (Vignolio et al 2005).
Used for sand dune stabilisation in Israel (Tsuriell 1974).
Therefore the species is considered to decrease the probability of soil erosion.
L
H
8. Reduce biomass?The species is a prostrate herb, which occurs in beach and dune systems (Vignolio et al 2002; Willmer 1986).
Invading bare sand the species would therefore increase biomass; however it is unlikely to act as a significant carbon sink.
ML
MH
9. Change fire regime?Unknown.
M
L
Community Habitat
10. Impact on composition
(a) high value EVC
EVC= Spray-zone Coastal Shrubland (E); CMA= Glenelg Hopkins; Bioreg= Glenelg Plain; VH CLIMATE potential.
The species is reported to dominate the vegetation of the beach and fore-dunes in its native Israel (Willmer 1986).
The species therefore has potential to cause major displacement of species if it is able to dominate the vegetation of the lower strata of invaded beach and fore-dunes.
MH
MH
(b) medium value EVCEVC= Spray-zone Coastal Shrubland (R); CMA= Glenelg Hopkins; Bioreg= Bridgewater; VH CLIMATE potential.
The species is reported to dominate the vegetation of the beach and fore-dunes in its native Israel (Willmer 1986).
The species therefore has potential to cause major displacement of species if it is able to dominate the vegetation of the lower strata of invaded beach and fore-dunes.
MH
MH
(c) low value EVCEVC= Coastal Dune Scrub (LC); CMA= Glenelg Hopkins; Bioreg= Bridgewater; VH CLIMATE potential.
The species reportedly becomes less common within a few hundred meters inland from the coast (Willmer 1986).
Therefore the species may be present in this vegetation but is unlikely to cause any significant displacement.
L
H
11. Impact on structure?The species is reported to dominate the vegetation of the beach and fore-dunes in its native Israel (Willmer 1986).
The beach and fore-dune vegetation is often only comprised of the lower strata. Therefore if the species is capable of dominating the vegetation as it does in its native range, it could have a minor effect on more than 60% of the flora.
MH
MH
12. Effect on threatened flora?Unknown.
MH
L
Fauna
13. Effect on threatened fauna?Unknown.
MH
L
14. Effect on non-threatened fauna?Unknown.
M
L
15. Benefits fauna?It is reported to be grazed by sheep and pollinated by insects (Snowball 2002; Tsuriell 1977; Willmer 1986). It may therefore provide some assistance in way of food to desirable species.
MH
H
16. Injurious to fauna?There is no evidence of this reported.
L
M
Pest Animal
17. Food source to pests?It is reported to be grazed by sheep and pollinated by insects (Snowball 2002; Tsuriell 1977; Willmer 1986). It may therefore provide some food to pest species such as feral bees and goats.
ML
MH
18. Provides harbor?The species is a prostrate herb (Vignolio et al 2002). It is unlikely therefore to provide any significant cover.
L
MH
Agriculture
19. Impact yield?Not reported as a weed of agriculture.
L
M
20. Impact quality?Not reported as a weed of agriculture.
L
M
21. Affect land value?Not reported as a weed of agriculture.
L
M
22. Change land use?Not reported as a weed of agriculture.
L
M
23. Increase harvest costs?Not reported as a weed of agriculture.
L
M
24. Disease host/vector?Not reported as a weed of agriculture.
L
M

This table can also be viewed as a PDF document (printer friendly).

Impact Assessment Record - Cretan trefoil (PDF - 69KB)
Impact Assessment Record - Cretan trefoil (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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