Kakadu National Park Landscape Symposia Series 2007–2009
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The Paper8.1 IntroductionThe management and control of exotic weeds is a difficult and resource-hungry process. However it can be cost effective and feasible to completely eradicate potentially invasive species whilst their distributions are still limited to less than one hectare (Rejmánek & Pitcairn 2001). There are currently 55 introduced species known to occur in the township of Jabiru, in the World Heritage listed Kakadu National Park. Amongst these 55 species are a number of known invasive species including lantana, rubber vine, blue thunbergia, salvinia and ivy gourd that have the potential to escape and become established outside of the township (NB Salvinia is already established in some wetlands within Kakadu National Park, but not in waterways in the immediate vicinity of Jabiru). The land tenure in Jabiru, and hence who is responsible for the strategic management of weeds in the town is complicated. The Mirrar people are the recognised Aboriginal traditional owners of the area. The Commonwealth, through the Director of National Parks currently holds the title for the land and has leased it to the Northern Territory through the Jabiru Town Development Authority (JTDA). The current lease is due to expire in 2026. There is no free-hold title in Jabiru and all housing, commercial and recreation facilities are sub-let to various organisations (including Telstra, Northern Territory Government (NTG) departments, Jabiru Town Council (JTC), Energy Resources of Australia (ERA) and Parks Australia North (PAN)). ERA, the largest sub-lease holder, has made a commitment to rehabilitate the land at the cessation of it’s mining operations in the area, but the future of the town of Jabiru is still not clear. In the meantime, plants are escaping from household gardens to open spaces in the town and into the surrounding landscape. It has been difficult to determine which organisation should fund a pro-active project aimed at controlling some of these supposedly innocuous garden plants before they become a larger problem. This is despite the fact that the cost-savings and environmental benefits of achieving such control are obvious and substantial. The Weedy Time Bomb Project was established in 2007 and was endorsed by the major stakeholders in the town including ERA, JTC, JTDA, PAN, NTG, the Environmental Research Institute of the Supervising Scientist (eriss), and Gundjeihmi Aboriginal Corporation (GAC). Funding was sought from Envirofund and a grant of nearly $50 000 was subsequently received to support the project, which actively commenced in the 2008–09 financial year. 8.2 The Weedy Time Bomb Project: background and project designThe aim of the Weedy Time Bomb Project is to completely eradicate at least 10 known invasive plant species whose current regional distribution is limited to houses within the township of Jabiru before they escape and become established in the surrounding landscape. The project has the potential to contribute to the prevention of serious and irreversible environmental and/or economic harm in the surrounding landscapes of Kakadu National Park. The project partners identified seven distinct stages of the project: 1 Community consultationThe 1200 residents of Jabiru will be informed about the importance of these potentially invasive species and requested to participate in the project. 2 Mapping of introduced speciesA residential survey of gardens in Jabiru was undertaken in the early 1990s. This will be updated and expanded by experts to include all of the Jabiru Lease (1333 ha). All species locations will be spatially mapped using GIS. 3 Prioritisation of target speciesThe 10 target species will be determined with the help of the NT Government Weeds Branch using their Weed Risk Assessment tool, the extent of species distributions and local expert opinion. 4 Target species controlTarget species will be controlled using the most appropriate methods, including registered herbicide and hand pulling. Repeat weed control will be undertaken when initial kill is not 100%. Since all sub-leases are under institutional control it was considered that that any disputes arising about plant removal in the town would be far easier to negotiate. 5 Monitoring and evaluationThe Envirofund project will go for 18 months in which time the bulk of the on-ground work will be carried out. Monitoring of eradicated success will be undertaken 2 and 12 months respectively after control work. A final report will be given to Envirofund, partners and the community. However, no species can be declared eradicated until there has been zero observed recruitment from the seed bank in three years. The project partners will commit to undertake this post-project monitoring. 6 EducationEducation to prevent reintroduction and communication of success: a crucial component to the long-term success of the program is to prevent reintroduction of target species. This will be done by developing community education/quarantine programs, an updated permitted species list, and increasing the availability of local native plant species for gardening. The current and future works will be incorporated into the Jabiru Weed Management Plan (a separate project). 7 Supply of alternative garden plantsA nursery supplying indigenous plants has been recently established in Jabiru and this has provided a valuable source of suitable alternative plant species for gardens in the town. The nursery is entirely operated and staffed by indigenous people. The bulk of the on-ground work and initial monitoring of eradication success will be undertaken within the 18 month Envirofund project but project partners are currently committed to undertake monitoring and control activities of target species for a further three years and to develop and implement strategies to prevent the re-establishment of these species. In addition all key regional stakeholders have existing weed management programs which have the capacity to detect target species outside of the project area. |