Meyer, Jean-YvesMalet, Jean-Pierre2009-03-262009-03-261997-02Meyer JY, Malet JP. 1997. Study and management of the alien invasive tree Miconia calvescens DC. (Melastomataceae) in the Islands of Raiatea and Tahaa (Society Islands, French Polynesia): 1992-1996. Honolulu (HI): Cooperative National Park Resources Studies Unit, University of Hawaii at Manoa, Department of Botany. PCSU Technical Report, 111.http://hdl.handle.net/10125/7368Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in.Priorities for control of alien invasive plant species in natural areas are based on the severity of threat, the ecological value of the invaded area, management possibilities, and available human resources. Miconia calvescens DC. (Melastomataceae), a small tree native to Tropical America and introduced to Tahiti (Society Islands, Windward Group) as an ornamental in 1937, has escaped from cultivation and is presently established on over 65% of this island (ca. 70,000 ha) and about 10% of the neighboring island of Moorea (ca. 1,200 ha). This alien species forms dense stands which replace the native forests with dramatic reduction of biological diversity. M. calvescens was legally declared a "noxious species" in 1990 and is perceived as one of the most important ecological problems in French Polynesia. In 1992, its physical control on the islands of Raiatea and Tahaa (Society Islands, Leeward Group) which are in an early stage of invasion (242 ha and 2 ha respectively, & less than 2% of the surface invaded) appeared to be feasible. A total of ca. 645,000 plants including ca. 600 reproductive trees were removed on Raiatea during 4 years of extensive control efforts (manual removal and chemical treatment) coordinated by the Service du Developpement Rural, and with the help of thousands of volunteers (schoolchildren, conservation groups, religious groups) and the intervention of the French Army. A small population recently found on Tahaa (ca. 800 plants including one reproductive tree) was eliminated in 1995. Research studies on M. calvescens populations were conducted in 6 permanent plots set up on Raiatea in 1992: distribution and population structure were evaluated before the control; number of removed individuals per maturation class was counted during the control; recruitment from seeds and vegetative growth were studied after the control; age of first reproduction and soil seed bank dynamics were surveyed. Results of post-control monitoring give relevant information on the life cycle of M. calvescens, especially the beginning stage of invasion: massive recruitment of seedlings occurs for at least 6 months after the control; maximum growth rate under favorable conditions can reach 1.5 m/yr in height and 1.8 cm/yr in DBH; seeds in soil samples were still viable after 4 years, and age of first reproduction was not attained. These data are particularly useful for defining an appropriate control frequency until final eradication. Problems of reinvasion from isolated plants which escape control and fruit, and colonization by other alien species after control highlighted the necessity of a long-term monitoring program. Future success will depend on prevention, detection, early control, and last but not the least strong motivation.en-USInvasive plants -- French Polynesia -- Society Islands.Miconia calvescens -- Control -- French Polynesia -- Raiatea.Miconia calvescens -- Control -- French Polynesia -- Tahaa Island.Report