The Gulf of Tonkin has been existed by island with different larger, medium, small and very small sizes and under climate of tropical humid season monsoon, the temperature mode is toward as subtropical characteristics and different between islands that depend on the size or on the distance from the continent. The far islands were separated with continent about 8000 years ago at marine transgression while the islands that are near the continent were completely independent about 5000 years ago. The study of biodiversity and relationship between island floras has been meaningful both of scientific and reality. However, the previously studies were limited at statistics of number of taxa within each islands flora in purpose of supporting for planning of economical development and conservation.
This preliminary study reports the island floras in the Gulf of Tonkin comprise 1275 vascular plant species that belong to 179 families and 639 genera in 5 divisions. The most diverse are the Magnoliophyta and there is no representative of Psilotophyta. The island floras have 25 threatened species that include 2 CR, 8 EN, 14 VU and 1 LR species. There are 1040 useful species of this flora, including medicine plants (762 species), plants for firewood or materials for household goods (389 species), edible plants (269 species), and plants for timber and construction materials (244 species). The relationships among the island floras has been preliminary assessed, using the Sorenssen assessment method. The similarity index between limestone and non-limestone floras is 44%, which means the floras on limestone and non-limestone are not much different. Even the similarity index between floras of Tran islands and Ba Mun islands is 36%, the other indexes between islands floras are lower that indicates the individual floras are distinct. This can be explained by factors such as the size of islands, the distance from continent and the islands’ topography, soil, and microclimate.
Nguyen Huu Tu, Vu Anh Tai
Institute of Geography - VAST
(Proceedings of 4th National Scientific Conference on Ecology and Biological Resources, Hanoi 21st October 2011 - IEBR)