The orchids (Orchidaceae) everywhere in the world represent most vulnerable and sensitive element of native indigenous floras. Most species of this family extinct very fast under worldwide processes of deforestation and antropogenous transformation of landscapes. Organization of protection areas for conservation of primary natural habitats is living important for salvation of global orchid diversity. In this connection inventory of orchids in local floras has a primary significance for delineation of areas with highest level of orchid endemism desirable for timely protection Area of Rao An watershed in Huong Son District of Ha Tinh Province up to now keeps primary evergreen broadleaved lowland forests which extinct in most other regions of Vietnam many years ago. At the same time these forests have very high level of plant diversity and local endemism, which represents great interest for scientific studies and exploration.
Preliminary inventory of the orchid flora in Rao An watershed during short exploration trip in April 2002 and studies of herbarium materials at the Herbarium of the Institute of Ecology and Biological Resources (HN) reveal distinct diversity of orchids in this area. During laboratory and fieldwork were observed and documented 35 species of the family collected in the belt of warm loving primary closed evergreen tropical broad-leaved forests spreading at elevations 200-400 m a.s.l. (Table 1). Among them the folowing species are local Vietnamese endemics: Biermannia calcarata Aver., Dendrobium ochraceum De Wild., Eria calcarea Aver. & V.N. Long, Habenaria tonkinensis Seidenf., Micropera poilanei (Guillaum.) Garay and Pholidota guibertiae Finet. All these plants have very restricted distribution and represent most significant indigenous element of pristine Vietnamese flora. Besides mentioned strict Vietnamese endemics some orchids observed in Rao An area belong to the group of endemic species to Indochinese Peninsula. They are Dendrobium faulhaberianum Schltr., Liparis balansae Gagnep., Liparis chapaensis Gagnep., Liparis stricklandiana Rchb.f. and Pholidota chinensis Lindl.
All listed strict endemic to Vietnam and endemic to Indochina orchids, as well as other more widespread orchid species observed and documentary reported for Rao An area represent typical integral element of lowland evergreen broadleaved forest flora of lowlands of the northern Vietnam. Noteworthy mention that primary forests on low elevations extinct now in northern Vietnam in most territories of their original distribution. In this connection forests of Rao An area desires urgent and effective protection as one of the last refugiums of very rich pristine flora typical in the past for wide lowlands of the country. Special protection of these plants in the country is very important goal in national politics of nature protection of highest priority.
Leonid V. Averyanov
Komarov Botanical Istitute, RUSSIA
Phan Ke Loc
College of Science-VNU, Institute of Ecology & Biological Resources
Nguyen Tien Hiep
Institute of Ecology & Biological Resources