Interim profile, incomplete information
Management Information
Funding from the UK Foreign and Commonwealth Office allowed for an initial clearing and eradication programme on Inaccessible Island in September 2004. A team of four was deployed by helicopter to cut down as many large plants as possible (Ryan et al. 2007b). The follow-up for this project was planned for three to five years later and took place in October 2007 under the Managing Aliens on Outer Islands project. There was more re-growth of Phormium tenax than anticipated but only a few plants had flowered since the initial clearing in 2004. Follow-up operations are recommended.
Location Specific Management InformationInaccessible Is. (sub-Antarctic) (Saint Helena)
Inaccessible Island is a nature reserve and, although Tristan Islanders retain the right to collect driftwood and guano, other access is restricted (BirdLife International 2008b). Phormium tenax, which has the potential to exclude native vegetation communities, was spreading around the cliff north-west of the waterfall until control efforts in 2004 removed almost all plants. The island's management plan (Ryan & Glass 2001) identified the removal of flax as the island's highest conservation priority. Funding was obtained from the UK Foreign and Commonwealth Office to undertake an initial clearing programme. High-altitude experts trained through the highly-successful Working for Water programme in South Africa provided technical support and advice.
A team of four was deployed by helicopter for three weeks in September 2004 and a follow-up mission in Novemeber to tackle the invasive flax. An estimated 2000 to 3000 large flax plants were removed mainly from the area immediately west of the Waterfall centred on the old settlement site and every effort was made to remove all small plants and seedlings. For most plants, all leaves and rhizomes were removed, leaving only rootlets. Not all rhizomes were removed for some very large plants, but these were then sprayed with 5% glyphosate, an effective herbicide that should prevent any re-growth. The team recommended that a follow-up programme take place in 3 to 5 years to remove any plants missed during the current clearing effort as well as any new seedlings emerging from the seed bank. Subsequent checks at five-yearly intervals were thought to be sufficient to ensure eradication of flax from Inaccessible Island.
Eradication measures used appear to have successfully killed all plants. Cut leaf heads, even with rootlets attached, appeared to dry up within a few days, and showed no sign of regeneration over almost three weeks of observation. Plants where all rhizomes had been removed, and those where rhizomes had been cut back and sprayed with 5% glyphosate also showed no signs of re-growth. Working systematically up the cliffs to remove all flax plants proved to be a considerably harder task than initially estimated, due mainly to the larger number of plants. Team members had to spend up to 8 hours continuously working in harnesses on cliff faces to combat the flax. Outliers plants were especially difficult and at the last stages of the operation it took two people working solidly for 12 h to remove 7 plants! Overall the project ran smoothly.
The main notable points and lessons learned from the experience are as follows: hand axes were the most useful tools for tackling plants on steep terrain; sufficient amounts of ropes are essential in the process of clearing flax on the island; several pairs of tough leather gloves were required per person; the wooden-handled 2-kg hammers used to hammer in stakes were inadequate as the handles on both broke after being left on the summit for a few weeks (possibly through being soaked by rain); the solar system was extremely efficient to charge radio batteries; and about 5 litres of concentrated herbicide was utilised. Nightingale Is. (sub-Antarctic) (Saint Helena)
Control measures were initiated in the 1970s (Wace & Holdgate 1976, in Ryan et al. 2007b), but follow-ups were not conducted. By 2000 there were approximately 50 large plants on the island. These were tackled in 2004 to 2005 as part of the OTEP project: Conservation Management of Nightingale Island, OTEP (TDC002), a Tristan-based project administered by James Glass. Annual follow-up has been conducted to tackle any re-growth from these plants, but there has not been a systematic search for additional plants.
Efforts are now underway by staff of the Tristan Natural Resources Department, with OTEP funding (which also allows for the monitoring of seabirds and the production of an island management plan), to eradicate flax from around one of the ponds on the island. In late 2005 a number of large plants was uprooted with the aid of axes, brush cutters and a 25kg winch and then treated with herbicide. This ongoing project has been facilitated by the appointment in September 2005 of a full-time Conservation Officer with in the Tristan Natural Resources Department. Under the Managing Aliens on Outer Islands project Phormium tenax eradication efforts in the Inaccessible and Nightingale Islands were followed-up. A team of five was deployed on Inaccessible Island October 2007 to check on the status of Flax cleared there in September 2004. The large plants pulled out with a winch on Nightingale were mostly completely dead. A few stumps showed signs of limited re-growth; these were broken open and either crushed or allowed to dry out. Systematic searches of the affected area found ca 20 new plants, most of which were small or medium-sized plants, although one large plant had been overlooked among dense rocks and tussock along the ridge on the path to First Pond. All these plants were chopped apart and crushed, as done on Inaccessible Island. Saint Helena
Specific Protected Area legislation and management plans have not yet been developed or implemented for the conservation of Wahlenbergia angustifolia - a species currently threatened by the spread of New Zealand flax - and there is currently no specific conservation action for this species. A Draft Recovery Action Plan for W. linifolia - also under threat from New Zealand flax has been developed (Cairns-Wicks 2003a; 2003b).
In 1997 the total population size of the Endangered (IUCN Redlist category) Saint Helena endemic Nesohedyotis arborea (dogwood) - a species negatively impacted by the spread of New Zealand flax - was estimated as about 132. Since then consistent alien plant species control has been carried out (as part of the management plan for Diana’s Peak National Park) as well as the planting of endemic species including dogwood. Survival rates are not known but Dogwood does less well when planted in open ground (cleared of alien plants such as Phormium tenax) than he cabbage and whitewood (Cairns-Wicks 2003c). The he cabbage tree Pladaroxylon leucadendron and The black cabbage tree Melanodendron integrifolium are negatively impacted by the spread of New Zealand flax. Since 1995 consistent alien plant control has been carried out (as part of a management plan for Diana’s Peak National Park) and endemic trees including the he cabbage tree have been planted in the wild. Survival rates have not been quantified but observation show that planted stocks do establish and produce healthy growth. Regeneration has been successful where invasive plants, such as New Zealand flax, have been cleared (Cairns-Wicks 2003d; Cairns-Wicks 2003e). Tristan da Cunha Is. (sub-Antarctic) (Saint Helena)
With funding from the UK Foreign & Commonwealth Office, two visits were made to Inaccessible in late 2004 by plant eradication experts from South Africa to eradicate New Zealand Flax Phormium tenax. All large plants (an estimated 2,000-3,000) were successfully removed from the coastal cliffs, which necessitated the eradication team using ropes to reach the plants in safety. Plants were cut off at their bases using axes and a brush cutter. Herbicide was used on some very large plants to prevent regrowth. Not all seedlings could be removed so follow-up visits are planned at threeto five-year intervals to ensure that flax is finally eradicated from the island.
Management Resources/Links
2. de Villiers, Marienne S., John Cooper, Noel Carmichael, James P. Glass, Gordon M. Liddle, Ewan McIvor, Thierry Micol and Andy Roberts., 2006. Conservation Management at Southern Ocean Islands: towards the Development of Best-Practice Guidelines. Polarforschung 75 (2–3), 113 – 131, 2005 (erschienen 2006)
Summary: Available from: http://epic.awi.de/Publications/Polarforsch2005_2-3_6.pdf [Accessed 25 October 2009] 3. ICES. 2006. Working Group on Introductions and Transfers of Marine Organisms (WGITMO), 16–17 March 2006, Oostende, Belgium. ICES CM 2006/ACME:05. 334 pp. 6. Ryan, P.G., Barendse, J., Chiloane, L.A. & Moreku, G.L., 2004. Clearing invasive flax Phormium tenax on Inaccessible Island: reporting on clearing clearing activities, September-November 2004.- Unpubl. Report, Percy Fitzpatrick Institute, Cape Town, South Africa, 1-25. 7. Ryan, Peter G., Erica Sommer, Eugene Breytenbach, Warren Glass & Clifton Repetto. 2007b. Managing alien plants on the outer islands of Tristan da Cunha: follow-up of Flax eradication efforts. Report on activities, October-November 2007 Results Page: 1
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