Impact Assessment - Box elder (Acer negundo) 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 Box elder
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 - 1026 KB)
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: Box elder
Scientific name: Acer negundo
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | This fast growing tree germinates on mass and can form dense thickets in riparian areas (Blood 2001). Therefore the species has the potential to be a major impediment in access to waterways and as a tree require significant works to remove. | H | MH |
| 2. Reduce tourism? | Unknown. | M | L |
| 3. Injurious to people? | People can have hypersensitivity to the species pollen (Shah & Lin 2004). | ML | MH |
| 4. Damage to cultural sites? | Has extensive root system which can invade piping in the search for water (Blood 2001). This could be damaging to infrastructure. | MH | MH |
| Abiotic | |||
| 5. Impact flow? | Saplings can establish in the stream bed, they are however killed if inundated for more than 85 days during the growing season or if broken under the stress of the water (Friedman & Auble 1999). Unknown to what extent this would impact on actual water flows. | M | L |
| 6. Impact water quality? | The species is a deciduous tree that is reported to occur in riparian habitats (Blood 2001). As a deciduous species alteration of seasonal light levels and changes to nutrient cycling could impact water quality, the impact this species has on water quality has not been reported however. | M | L |
| 7. Increase soil erosion? | Has an extensive root system (Blood 2001). Therefore there is a low probability of large scale soil movement occurring in association with this species. | L | MH |
| 8. Reduce biomass? | In open environments which are the species preferred habitat, establishment of the species especially in a thicket would increase biomass. In more heavily shaded environments where the species is more stunted its invasion is likely to cause a direct replacement of biomass (Mędrzycki 2007). | ML | MH |
| 9. Change fire regime? | Unknown impact on fire regime, considering the species preference for wetter environments it is unlikely to be significant. | M | L |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | EVC= Floodplain Riparian Woodland (E); CMA= Corangamite ; Bioreg= Otway Plain ; VH CLIMATE potential. Able to form thickets excluding all other species except winter growing bulb species (Blood 2001). Exclusion of all other species indicates a monoculture at least within a layer. | H | MH |
| (b) medium value EVC | EVC= Sedgy Riparian Woodland (D); CMA= Corangamite ; Bioreg= Otway Plain ; VH CLIMATE potential. Able to form thickets excluding all other species except winter growing bulb species (Blood 2001). Exclusion of all other species indicates a monoculture at least within a layer. | H | MH |
| (c) low value EVC | EVC= Riparian Scrub (LC); CMA= West Gippsland ; Bioreg= Wilsons Promontory; VH CLIMATE potential. Able to form thickets excluding all other species except winter growing bulb species (Blood 2001). Exclusion of all other species indicates a monoculture at least within a layer. | H | MH |
| 11. Impact on structure? | Able to form thickets excluding all other species except winter growing bulb species (Blood 2001). Therefore the species is capable of major displacement. | H | MH |
| 12. Effect on threatened flora? | Unknown; there is no evidence of this reported. | MH | L |
| Fauna | |||
| 13. Effect on threatened fauna? | Unknown; there is no evidence of this reported. | MH | L |
| 14. Effect on non-threatened fauna? | Significant alteration of habitat in terms of flora composition could have a significant impact on food supply for fauna species. The degree to which this species would impact on Australian fauna has not been quantified however. | M | L |
| 15. Benefits fauna? | Even in the species native range, it is generally avoided by foraging insectivorous birds (Gabbe et al 2002). As a moderate sized tree it may provide some shelter for species. | MH | M |
| 16. Injurious to fauna? | There is no evidence reported to support this. | L | M |
| Pest Animal | |||
| 17. Food source to pests? | Browsed by deer species (Rossell, Gorsira & Patch 2005). | ML | H |
| 18. Provides harbor? | Dense thickets of the species have been described as places of informal intimate social life (Mędrzycki 2007). This dense vegetation cover could provide shelter for pest species. | M | M |
| Agriculture | |||
| 19. Impact yield? | Not reported as a significant weed of agriculture. | L | M |
| 20. Impact quality? | Not reported as a significant weed of agriculture. | L | M |
| 21. Affect land value? | Not reported as a significant weed of agriculture. | L | M |
| 22. Change land use? | Not reported as a significant weed of agriculture. | L | M |
| 23. Increase harvest costs? | Not reported as a significant weed of agriculture. | L | M |
| 24. Disease host/vector? | The species is effected by die back caused by Fusarium solani and cankers caused by Eutypella parasitica and Inonotus rickii (Annesi, Coppola & Motta 2003; Demirci & Maden 2006; Ogris, Jurc & Jurc 2006). Fusarium solani can also damage soybeans (Roy et al 1989). Inonotus rickii is a wood decaying fungus of hardwoods and could have implications for forestry (Barnard 1993). | M | H |
This table can also be viewed as a PDF document (printer friendly).
Impact Assessment Record - Box Elder (PDF - 142KB)
Impact Assessment Record - Box Elder (DOC - 58KB)
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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