Impact Assessment - Paterson's curse (Echium plantagineum) in Victoria (Nox)

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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	Reference	Rating
Recreation
1. Restrict human access?	Although a weed of agriculture, it does occur in natural habitats such as grasslands, woodlands and heathlands. It can form very extensive persistent populations. The plant can cause skin irritation. No physical barrier but skin issue covered in quest 3	Muyt (2001) P & C (2001)	L
2. Reduce tourism?	The presence of this weed is obvious to the average visitor particularly during flowering.	Groves et al (1995)	ML
3. Injurious to people?	“Some medical practitioners have established a link between the plant and hay fever.” “…the rough hairy texture of the leaves and stems causes skin irritation.”	P & C (2001)	MH
4. Damage to cultural sites?	While the presence of this plant is quite noticeable, there appears to be no evidence that it negatively affects cultural sites.		ML
Abiotic
5. Impact flow?	Terrestrial spp.		L
6. Impact water quality?	Terrestrial spp.		L
7. Increase soil erosion?	“…in heavily grazed pasture, [it leaves] bare ground when it dies back in summer.” Potential for erosion from both wind and water.	MLRAPCB1	ML
8. Reduce biomass?	It is primarily a weed of grazing land. Significant change to biomass unlikely. However, it competes “vigorously with smaller indigenous plants and impedes overstorey regeneration.” “The broad rosette leaves shade and smother most other species.”	Muyt (2001) P & C (2001)	MH
9. Change fire regime?	“…it seeds and dries off in spring leaving little residue.” Little or no change to fire regime.	Groves, et al. (1995)	L
Community Habitat
10. Impact on composition (a) high value EVC	EVC=Plains grassy woodland (E); CMA=West Gippsland; Bioreg=Gippsland Plain; VH CLIMATE potential. “Paterson’s curse can form very extensive, persistent populations in disturbed areas, competing vigorously with smaller indigenous plants and impeding overstorey regeneration.” Major impact on lower stratum, minor impact on mid strata.	Muyt (2001)	MH
(b) medium value EVC	EVC=Hillcrest herb-rich woodland (D); CMA=North Central; Bioreg=Goldfields; VH CLIMATE potential. Not as competitive in high quality, intact native vegetation. Minor impact on grasses/ forbs.	Muyt (2001)	ML
(c) low value EVC	EVC=Heathy woodland (LC); CMA=West Gippsland; Bioreg=Gippsland Plain; VH CLIMATE potential. Impact as in 10(b) above.	Muyt (2001)	ML
11. Impact on structure?	“Paterson’s curse can form very extensive, persistent populations in disturbed areas, competing vigorously with smaller indigenous plants and impeding overstorey regeneration.”	Muyt (2001)	MH
12. Effect on threatened flora?
Fauna
13. Effect on threatened fauna?
14. Effect on non-threatened fauna?	Changes to structure may limit suitable fodder for non-threatened fauna.		ML
15. Benefits fauna?	“The seed forms a large part of the diet of [Australian] crested pigeons (Ocyphaps lophotes) in summer and autumn.” Also a food source for two species of Australian ants (Iridomyrmex discors and Prolasius spp.)	Groves et al. (1995)	ML
16. Injurious to fauna?	“…presence of pyrrolizidine alkaloids contained in the plant cause cumulative chronic liver damage.” “Stiff bristles on all parts of mature plants irritate the udders of cows.” Potentially toxic and cause allergies in fauna. May not be grazed – No info on native spp. – Native spp more mobile unlikely to be grazing just on patto	P & C (2001)	MH
Pest Animal
17. Food source to pests?	Food source for introduced ant Pheidole megacephala. May be a food source for pest birds.	Groves et al. (1995)	ML
18. Provides harbour?	An annual. Unlikely to provide permanent harbour for pest animals.	P & C (2001)	L
Agriculture
19. Impact yield?	“…most graziers argue that the weed’s presence reduces both quantity and quality of useful fodder in pastures.” Cattle and horses tend to avoid the plant.	P & C (2001)	H
20. Impact quality?	The plant can dominate in pastures reducing the quality of fodder.	P & C (2001)	MH
21. Affect land value?	The cost of control and eradication would add to farm operating costs over several years. A significant seed bank with seeds that last for over five years. Land value would decrease.	P & C (2001) Groves et al. (1995) Blood (2001)	M
22. Change land use?	“Sheep find Paterson’s curse more palatable than do cattle and horses.” This may dictate a change in stock until the plant is controlled.	P & C (2001)	M
23. Increase harvest costs?	“The plant can occur, and make harvesting difficult, in crops if seed bed preparation is poor and sowing is early.”	Groves et al (1995)	M
24. Disease host/vector?	None evident		L