Identifying orchid hotspots for biodiversity conservation in Laos: the limestone karst vegetation of Vang Vieng District, Vientiane Province

<p><span class="char-style-override-20">A project to study the phytodiversity of the Indo-Burma Biodiversity Hotspot (IBBH) was initiated by Kadoorie Farm and Botanic Garden, Hong Kong, in 2011, with the aim of surveying primary forest fragments and identifying conservation priorities within this expansive but highly threatened ecoregion. Vang Vieng District of Vientiane Province, northern Laos, was chosen as a focus for a pilot expedition, since it features an extensive karst landscape that has barely been explored. Together with officials from the Ministry of Science and Technology, Government of Lao PDR, surveys of three sites were conducted in April 2012, at the end of the dry northeast monsoon season. Emphasis was placed on Orchidaceae because it is among the most species-rich and commercially exploited flowering plant families in the region. A total of 179 specimens were collected, of which approximately 135 were unique taxa accounting for 29.6% of the orchids found in Laos and 5.8% of those found in IBBH as a whole, and equivalent to 0.27 species/hectare within the area surveyed, substantially higher than published figures for other limestone areas in the region, such as Cuc Phuong National Park in Vietnam (0.0055 species/hectare) and Perlis S</span><span class="char-style-override-20" xml:lang="it-IT">tate in Peninsular Malaysia (</span><span class="char-style-override-20" xml:lang="fr-FR">0.0036 species/hectare). </span><span class="char-style-override-20">At least one is a species new to science, nine represent new distributional records for Laos and a further nine are new records for Vientiane Province. A list of the species encountered during the study is presented and the significance of the findings is discussed. Major threats to the natural environment in northern Laos are highlighted.</span>