ABSTRACT
The Nakai-Nam Theun National Protected Area (NNT NPA) lies in east central Laos along the country’s border with Vietnam, and represents the country’s largest protected area. The reserve covers, with recent extensions, about 4,000 km2 of the Annamite Mountains and its foothills, which run NW–SE along the Lao–Vietnam border. The NNT NPA comprises a range of increasingly high forested hills and mountains that start from the Nakai Plateau on the western edge of the reserve and rise north-east towards the main spine of the Annamites, which defines the border between Laos and Vietnam. Elevation in the protected area ranges along a gradient of more than 1700 m, from 500 m to 2,288 m above sea level, although areas above 2,000 m are uncommon. Lowest elevations are on the Nakai Plateau and along interior river courses, and the highest are peaks along the Vietnam border. The area is drained by four roughly parallel tributaries of the Nam Theun, one of the largest tributaries of the Mekong. These water courses start in slopes near the Vietnam border and flow down through the reserve into the main stem of the Nam Theun on the Nakai Plateau, which as of 2008 has been substantially inundated by a dam on the Nam Theun river (see below).
