Impact Criteria

Criteria	Intensity Ratings
Criteria	Lowest Threat (L)	Medium Low (ML)	Medium High (MH)	Highest Threat (H)
Social – Tourism, Visual Aesthetics, Experience, Cultural sites
1.To what extent does the weed restrict human access?	Minimal or negligible impact (ie. can go anywhere).	Low nuisance value. Impedes individual access; unable to walk to waterways.	High nuisance value. People and/or vehicles access with difficulty.	Major impediment to access waterways or machinery. Significant works required to provide reasonable access, tracks closed or impassable.
2. To what level does this weed reduce the ‘tourism / aesthetics/ recreational use of the land?	Weeds not obvious to the ‘average’ visitor.	Minor effects to aesthetics and/or recreational uses (ie. aware but not bothered or activity inhibited).	Some recreational uses affected.	Major impact on recreation. Weeds obvious to most visitors, with visitor response complaints and a major reduction in visitors.
3. To what level is the plant injurious, toxic, or spines affect people?	No effect, no prickles, no injuries.	Mildly toxic, may cause some physiological issues (eg. hayfever, minor rashes, minor damage from spines and burrs at certain times of year).	Spines, burrs or toxic properties at most times of the year, or may be a major component in allergies, hayfever and/or asthma.	Large spines or burrs, extremely toxic, and/or cause serious allergies to humans throughout year.
4. How much damage is done to indigenous or european cultural sites?	Little or negligible effect on aesthetics or structure of site.	Moderate visual effect.	Moderate structural effect.	Major structural damage to site, and/or obliteration of the historic/cultural feature.
Natural Resources – Soil, Water & Processes
5. To what extent does this weed impact on water flow within watercourses or waterbodies?	Little or negligible affect on water flow.	Minor impact on surface or subsurface flow either by roots or free floating aquatics.	Major impact on either surface or subsurface flow (eg. major root obstructions, submergent aquatics).	Serious impacts both to surface and subsurface water flow (eg. attached emergent aquatics).
6. To what extent does the weed impact on water quality (ie. dissolved 02, water temperature)?	No noticeable effect on dissolved 02 or light levels.	Noticeable but minor effects in either dissolved 02 or light levels.	Noticeable but moderate effects in both dissolved 02 and light; causing increased algal growth.	High effects in either dissolved 02 and/or light; causing eutrophication.
7. To what extent does the weed increase soil erosion?	Low probability of large scale soil movement.	Moderate probability of large scale soil movement.	High probability of large scale soil movement with minor off-site implications.	High probability of large scale soil movement with major off-site implications.
8. To what extent does this weed reduce the biomass of the community? (nb. biomass acting as a carbon sink).	Biomass may increase.	Direct replacement of biomass by invader.	Biomass slightly decreased.	Biomass significantly decreased (eg. trees replaced by more open community).
9. To what extent does the weed change the frequency or intensity of fires?	Small or negligible effect on fire risk.	Minor change to either frequency or intensity of fire risk.	Moderate change to both frequency and intensity of fire risk.	Greatly changes the frequency and/or intensity of fire risk.
Fauna and flora / vegetation & EVCs
10. To what extent does this weed impact on the vegetation composition on the following:
a. High value EVCs	Very little displacement of any indigenous spp. Sparse/ scattered infestations.	Minor displacement of some dominant or indicator spp. within any one strata/layer (eg. ground cover, forbs, shrubs & trees).	Major displacement of some dominant spp. within a strata/layer (or some dominant spp. within different layers).	Monoculture within a specific layer; displaces all spp. within a strata/layer.
b. Medium value EVCs	(as above)	(as above)	(as above)	(as above)
c. Low value EVCs	(as above)	(as above)	(as above)	(as above)
11. To what extent does this weed effect the structure of a vegetation community?	Minor or negligible effect on <20% of the floral strata/layers present; usually only affecting one of the strata.	Minor effect on 20-60% of the floral strata.	Minor effect on >60% of the layers or major effect on < 60% of the floral strata.	Major effects on all layers. Forms monoculture; no other strata/layers present.
12. What effect does the weed have on threatened flora spp.?	Minor/negligible effects on any Bioregional Priority or VROT spp.	Any population of a VROT spp is reduced.	Any population of Bioregional Priority 1A spp is reduced, or any population of a VROT spp is replaced.	Any population of Bioregional Priority 1A spp is replaced.
Flora & Fauna/ Fauna
13. What effect does the weed have on threatened fauna spp.?	No threatened fauna affected due to fauna not co-existing within infested area or strata.	Minor effects on threatened spp.; minor hazard or reduction in habitat/food/ shelter.	Reduction in habitat for threatened spp, leading to reduction in numbers of individuals of 9 spp. but not to local extinction.	Habitat changed dramatically, leading to the possible extinction (extirpation) of a VROT or Bioregional Priority spp.
14. What effect does the weed have on non-threatened fauna spp.?	No fauna affected due to fauna not co-existing within weed area or strata.	Minor effects on fauna spp.; minor hazard or reduction in habitat/food/ shelter.	Reduction in habitat for fauna spp., leading to reduction in numbers of individuals of spp 9 but not to local extinction.	Habitat changed dramatically, leading to the possible extinction (extirpation) of non-threatened fauna.
15. To what extent does this weed provide benefits or facilitates the establishment of indigenous fauna?	Provides vital food, shelter or assists the recolonisation of desirable species.	Provides an important alternative food source and/or harbor to desirable species.	Provides some assistance in either food or shelter to desirable species.	Provides very little support to desirable species.
16. To what extent is the plant toxic, its burrs or spines affect indigenous fauna?	No effect.	Mildly toxic, may cause fauna to lose condition.	Spines, burrs or toxic properties to fauna at certain times of the year.	Large spines or burrs dangerous to fauna. Toxic, and/or causes allergies.
Flora and Fauna/ Fauna / Pest Animal
17. To what extent does this weed provide a food source to assist in success of pest animals?	Provides minimal food for pest animals.	Supplies food for one or more minor pest spp. (eg. blackbirds or environmental insect pests).	Supplies food serious pest (eg. rabbits and foxes), but at low levels (eg. foliage).	Supplies food for > 1 major pest spp at crucial times of the year (eg. heavy berry load or continual food throughout the year).
18. To what extent does this weed provide important habitat or harbor for serious pests (eg. foxes, rabbits)?	No harbour for pest spp.	Doesn’t provide harbor for serious pest spp, but may provide for minor pest spp.	Capacity to harbor rabbits or foxes at low densities or as overnight cover.	Capacity to provide harbor and permanent warrens for foxes and rabbits throughout the year.
Agriculture – Quality, Quantity, Cost to Production, Effect on land use and value
19. To what extent does this weed impact on the quantity or yield of agricultural produce?	Little or negligible affect on quantity of yield.	Minor impact on quantity of produce (eg < 5% reduction).	Major impact on quantity of produce (eg 5-20%).	Serious impacts on quantity (eg >20% reduction) – Unviable to harvest crop/ stock.
20. To what extent does the weed impact on agricultural quality (eg contamination – lower price)?	Little or negligible affect on quality of yield.	Minor impact on quality of produce (eg < 5% reduction).	Major impact on quality of produce (eg 5-20%).	Serious impacts on quality (eg >20% reduction) – Produce rejected for sale or export.
21. To what extent does this weed affect land value?	Little or none.		Decreases in land value <10%	Major significance > 10%
22. To what extent does this weed cause a change in priority of land use?	Little or no change	Some change, but no serious alteration of either agricultural return. Affects more the visual rather than intrinsic agricultural value	Downgrading of the priority land use, to one with either less agricultural return.	Major detrimental change and significant loss for agricultural usage (eg complete change to different ag use eg farm forestry.)
23. To what extent the presence of the weed increases the cost of harvest?	Little or none.		Minor increase in cost of harvesting – eg slightly more time or labour is required.	Major increase in time or labour, or machinery in harvesting.
24. To what extent does this weed act as an alternative host or vector for diseases of agriculture?	Little or no host		Provides host to minor (or common) pests or diseases	Host to major and severe disease or pest of important agricultural produce.

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