Record Details

Taylor, Jennifer;Harlow, Peter S;Niukula, Jone
Invasive-Plant Assessment and Weed Management Plan for the Fijian Crested Iguana Sanctuary Island of Yadua Taba, Bua.
2005
Report
65
Unpublished report to the National Trust of Fiji, Wildlife Conservation Society, and Zoological Parks Board of New South Wales
Brachylophus vitiensis
The Fijian Crested Iguana Sanctuary on the island of Yadua Taba is administered by the National Trust of Fiji Islands and contains the only viable wild population of Fijian crested iguanas in the world. This makes it the most important wildlife sanctuary in Fiji and of high international significance. A recent vegetation survey identified several invasive plant species of concern and suggested immediate action is required to eradicate and control these species that have the potential to degrade the natural vegetation on Yadua Taba (Olson et al., 2002). In July 2003 we investigated the status of invasive plants on Yadua Taba, and identified a small number of exotic species of concern. We initially prioritized five species that require physical methods of management. Early detection and control may prevent the spread of these species and provides the soundest long-term management strategy. Only one species appears to have the ability to dominate undisturbed native plant communities (rain tree, Samanea saman). The other species requiring management currently do not appear to actively invade undisturbed sites (vaivai, Leucaena leucocephala; Wedelia, Wedelia trilobata; guava, Psidium guajava; and Lantana, Lantana camara). Trial control methods of hand removal, cutting and poisoning were used on experimental sites for the above five invasive species in July 2003. Rain trees were ringbarked and poisoned (with diesel or Glyphosate 360). Vaivai, Lantana and guava were cut off at 20-80 cm above the ground and poisoned. Small Lantana plants were removed by hand. Wedelia was removed by hand and burnt. An assessment of the effectiveness of these techniques was made in May and November 2004, along with further control measures. Our final recommendations for long-term management of invasive weeds on Yadua Taba identify four species that require continued active removal and/or poisoning (rain tree, Wedelia, guava and Lantana) until 2010, when a reassessment should be made. We recommend that two other invasive plants should not be disturbed as we feel that natural forest regeneration will eventually displace and minimise the impact of these species (vaivai and mile-a-minute vine, Mikania micrantha). The importance of raising local awareness of the potential for invasive plants to degrade native vegetation was addressed by a series of meetings and lectures in the village of Denimanu on Yadua. The need to prevent future introductions of unwanted plant species to Yadua (and thus Yadua Taba) was stressed. The National Trust of Fiji Islands is fortunate to have all necessary resources already in place (i.e., a full-time ranger and sanctuary boat) to coordinate and carry out a weed management plan at minimal expense.