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Acacia mearnsii (tree, shrub)    |
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Management Information
Preventative measures: A Risk Assessment of Acacia mearnsii for Hawaii and other Pacific islands was prepared by Dr. Curtis Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived from Pheloung et al. (1999) with minor modifications for use in Pacific islands (Daehler et al. 2004). The result is a score of 15 and a recommendation of: "Likely to cause significant ecological or economic harm in Hawai‘i and on other Pacific Islands as determined by a high WRA score, which is based on published sources describing species biology and behaviour in Hawai‘i and/or other parts of the world."Integrated management: The Working for Water programme implemented by the South African Government is a collaborative program that aims to ameliorate the problems caused by Acacia species and other invasive plants. The program consists of more than 30 sub-projects in eight provinces in the country and consists of the clearing of weeds from water courses (by mechanical and chemical methods). Between 1995 and 2000 over $100 million of poverty-relief funds on the program which was labour intensive and provided job opportunities for local communities. After seven years of implementation of the project it became clear that rehabilitation of sites (following the removal of alien plant species) would sometimes be needed in order to prevent or reduce the soil erosion stimulated by the clearing of plants (Van Wilgen et al., 2002, Milton, Dean and Richardson, 2003). Richardson & Kluge (2008) observe that preventing the accumulation of seed banks by reducing seed production is critical to all successful management programmes and that biological control is the most effective and practical option. Please follow this link for more details on Chemical and Biological control options that have been found promising and effective.   
Location Specific Management InformationAustralia
Biological: Native bud, flower, fruit, and seed-feeding Cecidomyiidae gall midges have been found to occur naturally on A. mearnsii. Aveiro
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Beja
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Braga
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Coimbra
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Evora
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Faro
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Hawaii
A. mearnsii was listed as a noxious weed in Hawaii and targeted for eradication or control by the Hawaii Department of Agriculture (1992). Leiria
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Lisboa
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Madeira Is.
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Portalegre
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). Setubal (Setúbal)
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99). South Africa
Control involving manual removal or chemical control of weed species is labor intensive, expensive and usually needs to be applied indefinitely (is a short term solution). Sustainable long term solutions might be possible using biological control agents. A broad cost-benefit analysis taking into account the varied benefits and costs associated with A. mearnsii in South Africa concluded the most feasible and relatively cost-efficient management plan would be to combine biological control (using seed-feeding biocontrol agents) with physical control. The study took into consideration the preference of wattle growers for a biological control agent that would not affect vegetative growth of the plant. It also cited the labor intensiveness of the physical removal as an advantage, due to the creation of jobs in a country suffering from high levels of poverty and unemployment (ARC/LNR 1997, Zimmerman and Neser 1999; de Wit, Crookes and van Wilgen, 2001).
Preventative management: Wattle growers are currently testing a range of related Acacia species that are as invasive as A. mearnsii for commercial planting in South Africa; it would make sense to identify the responsibilities of associations benefiting from their release (Dunlop, 1998, de Wit, Crookes and van Wilgen, 2001).
Integrative management: The South African government developed a Working for Water program that aimed to ameliorate the problems caused by Acacia species and other invasive plants. Between 1995 and 2000 over $100 million of poverty-relief funds on the program, which focused on short term solutions and organised the physical and chemical clearing of invasive weed around water courses and water catchments. The program involved more than 30 projects in eight provinces, employed thousands of workers and empowered communities to care for their water and environment. After seven years of implementation of this project it became clear that the rehabilitation of sites (following the removal of alien plant species) would sometimes be needed in order to prevent or reduce the soil erosion stimulated by the clearing of plants (van Wilgen et al. 2002, Milton, Dean and Richardson, 2003; Hill, Gordon and Neser, 1999).
Biological: To date only one species-specific invertebrate has been used as a biological control agent of A. mearnsii; a seed-feeding weevil has been released in areas where the wattle is not grown commercially.
Another insect (a wasp, Bruchophagus acaciae) has been investigated for its use as a control agent for Acacia species. The wasp develops in the pods and feeds on the seeds of some Acacia species. The larvae over winter inside fallen seeds and the adults emerge as the pods reach full size (consequently laying eggs in the seeds of pods). Observations of the wasp in New Zealand (where the Australian-originating species was first described) suggest that the host-range of B. acaciae is restricted to Acacia species of Australian origin (but further investigation is needed). However B. acaciae does not infest the seed pods of A. mearnsii. This is presumably because A. mearnsii flowers in late summer, carries ""protopods"" throughout winter, and produces pods earlier in the following spring than those of Acacia that are susceptible to the wasp. In susceptible species pod formation occurs in synchrony with the appropriate developmental stage of the wasp (Hill, Gordon and Neser, 1999). Viana do Castelo
It is declared as invasive on the Portuguese Exotic Species List (Dec.lei 565/99).
Management Resources/Links
1. Adair, R. J., Neser, S., Kolesik, P. 2000. Australian seed-preventing gall midges (Diptera: Cecidomyiidae) as potential biological control agents for inavsive Acacia spp. on South Africa. Proceedings of the X International Symposium on Biological Control of Weeds. 4-14 July, Montana State University, Bozemann, Montana, USA.
Summary: Information on the effects of A. mearnsii in South Africa and possible biological control agents. 2. Champion, P. D., S. M. Beadel, and T. M. Dugdale. 2001. Turf communities of Lake Whangape and some potential management techniques. Department of Conservation: Wellington, New Zealand. Science for Conservation 186. 3. Daehler, C.C; Denslow, J.S; Ansari, S and Huang-Chi, K., 2004. A Risk-Assessment System for Screening Out Invasive Pest Plants from Hawaii and Other Pacific Islands. Conservation Biology Volume 18 Issue 2 Page 360.
Summary: A study on the use of a screening system to assess proposed plant introductions to Hawaii or other Pacific Islands and to identify high-risk species used in horticulture and forestry which would greatly reduce future pest-plant problems and allow entry of most nonpests. 4. De Wit, M.P., Crookes, D.J. and Van Wilgen, B.W. 2001. Conflicts of Interest in Environmental Management: Estimating the Costs and Benefits of a Tree Invasion, Biological Invasions: 3 167 - 178.
Summary: A good overview of the associated uses and negative impacts of A. mearnsii in South Africa, as well 5. Dye, P. and Jarmain, C. 2004. Water use by Black Wattle (Acacia mearnsii): Implications for the Link Between Removal of Invading Trees and Catchment Streamflow Response, South African Journal of Science: 100 40 - 44.
Summary: A study on the evaporation rates from areas infested with A. mearnsii in Western Cape and KwaZulu-Natal in South Africa. 7. Goodman, P.S. 2003. Assessing Management
Effectiveness and Setting Priorities in Protected Areas in KwaZulu-Natal, BioScience53 (9): 843 - 850.
Summary: The threats to conservation faced in the KwaZulu-Natal province of South Africa. 8. Hill, R.L., Gordon, A.J. and Neser, S. 1999. The Potential Role of Bruchophagus acaciae (Cameron) (Hymenoptern: Eurytomidae) in the Integrated Control of Acacia Species in South Africa. In Spencer, N.R. (ed.) Proceedings of the X International Symposium on Biological Control of Weeds. Montana State University: Montana. 919 - 929.
Summary: The paper discusses the appropriateness of the wasp Bruchophagus acaciae for use as a biological control agent for Australian Acacia species. 9. Impson, F. A. C.; Kleinjan, C. A.; Hoffmann, J. H.; Post, J. A., 2008. Dasineura rubiformis (Diptera: Cecidomyiidae), a new biological control agent for Acacia mearnsii in South Africa. South African Journal of Science. 104(7-8). JUL-AUG 2008. 247-249. 10. IUCN/SSC Invasive Species Specialist Group (ISSG)., 2010. A Compilation of Information Sources for Conservation Managers.
Summary: This compilation of information sources can be sorted on keywords for example: Baits & Lures, Non Target Species, Eradication, Monitoring, Risk Assessment, Weeds, Herbicides etc. This compilation is at present in Excel format, this will be web-enabled as a searchable database shortly. This version of the database has been developed by the IUCN SSC ISSG as part of an Overseas Territories Environmental Programme funded project XOT603 in partnership with the Cayman Islands Government - Department of Environment. The compilation is a work under progress, the ISSG will manage, maintain and enhance the database with current and newly published information, reports, journal articles etc. 13. Richardson, David M.; Kluge, Robert L., 2008. Seed banks of invasive Australian Acacia species in South Africa: Role in invasiveness and options for management. Perspectives in Plant Ecology Evolution & Systematics. 10(3). 2008. 161-177. 14. Swaziland's Alien Plants Database., Undated. Acacia mearnsii
Summary: A database of Swaziland's alien plant species. 16. Viljoen, B. D.; Stoltsz, C. W. Control of black wattle (Acacia mearnsii De Wild.) seedlings with Garlon herbicide applied by backpack mistblower. South African Journal of Plant & Soil. 25(4). 2008. 242-244 Results Page: 1
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