Phong Nha-Ke Bang National Park
Topography and hydrology
Phong Nha-Ke Bang National Park is located in western Bo Trach district, close to the international border with Laos. The national park is situated in one of the largest areas of contiguous limestone karst in Indochina, which also includes Hin Namno National Protected Area in Laos. The limestone massif is located in a transitional zone between the northern and central Annamite mountains.
The topography of the national park is characterised by precipitous karst ridges, which rise to elevations of around 400 m. Scattered among these ridges are narrow valleys and pockets of igneous rock formations. Because of the limestone topography, drainage is complex and there are few permanent water courses. There are, however, the Chay, Son and Trooc rivers, all of which are fed by underground streams, which emerge from the En, Vom, Toi and Phong Nha cave systems. All three rivers flow into the Gianh river, which empties into the East Sea.
Biodiversity values
The three most comprehensive biodiversity surveys of Phong Nha-Ke Bang National Park, together with the work of numerous other researchers, have recorded a high diversity of animal and plant species at the site, including a number endemic to the limestone karst massif.
The nature of the terrain at Phong Nha-Ke Bang National Park has restricted encroachment into limestone areas. As a result, the limestone karst is almost entirely forested, apart from steep cliff faces. The only clearance of forest has been in flat valleys within the limestone massif, and in lowland areas bordering it. Natural forest covers the majority of the national park. The most widespread forest type is limestone forest but there are also significant areas of lowland evergreen forest distributed on non-calcareous substrates in valleys among the limestone karst.
The limestone forest ecosystem at Phong Nha-Ke Bang supports a high diversity of plant and animal species. Of perhaps the greatest conservation significance are several species found at the site that are endemic to this part of central Vietnam and Laos. These include Sooty Babbler Stachyris herbeti, a globally near-threatened species that went unrecorded between its discovery in Laos in the 1920s and its rediscovery at the site in 1994. Phong Nha-Ke Bang also supports populations of two endemic primates, Annamese Leaf Monkey Trachypithecus hatinhensis, and an all-black form referred to as Black Leaf Monkey T. ebenus. Scientists recorded a number of globally threatened mammals in the area, including Owston's Civet Hemigalus owstoni and Southern Serow Naemorhedus sumatraensis. In addition, the globally endangered Red-shanked Douc Pygathrix nemaeus has been recorded at the site by a number of authors. Also, the recently described Annamite Striped Rabbit Nesolagus timminsi was recorded at Phong Nha-Ke Bang in 1998.
With regard to the avifauna of Phong Nha-Ke Bang National Park, scientists recorded several globally threatened and near-threatened species, including Crested Argus Rheinardia ocellata, Chestnut-necklaced Partridge Arborophila charltonii, Red-collared Woodpecker Picus rabieri and Short-tailed Scimitar Babbler Jabouilleia danjoui. On the basis of the occurrence of four restricted-range bird species, Phong Nha-Ke Bang lies within the Annamese Lowlands Endemic Bird Area. Researchers consider Phong Nha-Ke Bang to be of particular importance for bird conservation, because the populations of species of conservation concern are not at immediate risk of extirpation or major population declines. Both Phong Nha and the adjacent Ke Bang limestone area (including the portion in Minh Hoa district, outside of the national park) qualify as Important Bird Areas.
Other documented values
Phong Nha-Ke Bang has a spectacular limestone karst topography and extensive cave systems, which make it one of the most outstanding geological sites in the country. The centrepiece of the site is the Phong Nha cave, through which an underground river flows. The mouth of this cave is 30 m wide and 18 m high, and it is possible to enter up to 1.5 km into the cave. In addition to the Phong Nha cave, 16 other caves have been surveyed to date at the site, with a total length of over 60 km.
The Phong Nha cave system is an increasingly popular tourist destination, with recent investment in facilities and upgrade of access. Large numbers of tourists visit the caves daily, stretching the carrying capacity. A large area of the national park has been earmarked for potential tourism development, which could have negative impacts on the limestone forest ecosystem. There clearly exists, however, the potential for successful ecotourism development that brings widespread benefits to the national park and local communities alike.
The Phong Nha-Ke Bang area is home to members of the Ruc and Arem sub-groups of the Chut ethnic group. Until recently, these people lived in caves. They have now been settled in villages. The indigenous knowledge and customs of these people have yet to be adequately researched. Their existing or potential role in conservation needs to be assessed.