Impact Assessment - Pond apple (Annona glabra) 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.
| 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 Pond apple.
A more detailed description of the methodology of the Victorian Weed Risk Assessment (WRA) method can be viewed below:
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: Pond apple
Scientific name: Annona glabra
| Question | Comments | Rating | Confidence |
| Recreation | |||
| 1. Restrict human access? | A semi-deciduous tree 12 – 15 metres tall, occurring on creek banks, wetlands, mangrove communities & high tide litter zones on beaches (NRM 2001). ‘Thickets of pond apple restrict access’ (ARMCANZ 2000). | MH | MH |
| 2. Reduce tourism? | ‘Thickets of pond apple restrict access and impair outlooks and the general variety of the coastal recreational experience’ (ARMCANZ 2000). | H | MH |
| 3. Injurious to people? | “…pond apple was introduced to Australia as grafting stock for custard apple. In its native America pond apple fruit has some commercial use” (NRM 2001). No toxic principle or physical properties likely to cause injury. | L | M |
| 4. Damage to cultural sites? | Occurs mostly in riparian or wetland areas subjected to regular natural disturbance. Not documented to occur in areas of cultural significance (WTMT 2004). Where it may occur, dense infestations (approaching a monoculture) it would present a moderate negative visual impact. | ML | MH |
| Abiotic | |||
| 5. Impact flow? | Terrestrial species. “It grows in fresh, brackish and even saline waters. The plant will not survive, however, in areas that are permanently inundated” (ARMCANZ 2000). Due to its dependence on a high water supply, it is found in riparian areas, floodplains and the margins of wetland areas. In such areas a dense infestation may affect the watercourse by narrowing the channel or reducing the size of the waterbody (WTMT 2004). | ML | MH |
| 6. Impact water quality? | Not documented to affect water quality. Does not withstand permanent inundation (ARMCANZ 2000). | L | MH |
| 7. Increase soil erosion? | A semi-deciduous tree that in open areas forms dense stands (NRM 2001). Unlikely to contribute to soil erosion. | L | M |
| 8. Reduce biomass? | “Pond apple can establish as a dense understorey that suppresses other growth and under favourable conditions can replace mature stands of paperbark with a monoculture forest of pond apple” (NRM 2001). Suppression of other species may result in slight reduction of biomass. | MH | M |
| 9. Change fire regime? | “Time between fires is lengthened due to the reduction in understorey in infested areas” (ARMCANZ 2000). Does not contribute to an increase in fire risk. | L | MH |
| Community Habitat | |||
| 10. Impact on composition (a) high value EVC | Basin=South Gippsland (ISC=very poor-moderate); CMA=West Gippsland; CLIMATE potential=L. Therefore no high value EVC exists. | L | H |
| (b) medium value EVC | All Victorian waterbodies are presumed to be high value EVCs. | L | H |
| (c) low value EVC | All Victorian waterbodies are presumed to be high value EVCs. | L | H |
| 11. Impact on structure? | “Pond apple forms a dense understorey/sub-canopy, replacing ferns, grasses, shrubs and sedges and prevents tree regeneration” (ARMCANZ 2000). “Creeks may become muddy monocultures” (NRM 2001). Major effect on all strata in some situations. | H | MH |
| 12. Effect on threatened flora? | This species is not documented as posing an additional risk to threatened flora. | MH | L |
| Fauna | |||
| 13. Effect on threatened fauna? | This species is not documented as posing an additional risk to threatened fauna. | MH | L |
| 14. Effect on non-threatened fauna? | Dense infestations would alter the habitat for native fauna. The plant may provide suitable shelter/nesting sites, but food source is radically altered due to impacts on plant diversity (NRM 2001). Possible serious reduction in local faunal populations. | MH | M |
| 15. Benefits fauna? | The fruit is a food source to some fruit-eating animals such as the cassowary and flying foxes (ARMCANZ 2000). | MH | MH |
| 16. Injurious to fauna? | Not known to be harmful. | L | MH |
| Pest Animal | |||
| 17. Food source to pests? | The fruit is known as a food source to native fauna. In Queensland feral pigs spread the seed (ARMCANZ 2000). | MH | MH |
| 18. Provides harbor? | May provide harbour to minor pest species such as birds (NRM 2001). | ML | M |
| Agriculture | |||
| 19. Impact yield? | Not known as a weed of agriculture (ARMCANZ 2000). | L | MH |
| 20. Impact quality? | Not known as a weed of agriculture (ARMCANZ 2000). | L | MH |
| 21. Affect land value? | Not known as a weed of agriculture (ARMCANZ 2000). | L | MH |
| 22. Change land use? | Not known as a weed of agriculture (ARMCANZ 2000). | L | MH |
| 23. Increase harvest costs? | Not known as a weed of agriculture (ARMCANZ 2000). | L | MH |
| 24. Disease host/vector? | Not known to be a host or vector of disease for agriculture (ARMCANZ 2000). | L | MH |
Impact Assessment Record - Pond apple (PDF - 71KB)
Impact Assessment Record - Pond apple (DOC - 63KB)
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