Topography and hydrology

Phong Nha Nature Reserve is located in western Bo Trach district, close to the international border with Laos. The nature reserve is situated in one of the largest areas of contiguous limestone karst in Indochina, which also includes Hin Namno National Biodiversity Conservation Area in Laos, and the Ke Bang limestone area in Bo Trach and Minh Hoa districts, Vietnam. The limestone massif is located in a transition zone between the northern and central Annamite mountains. To the north and south of the limestone massif, the geology of the Annamite mountains is predominantly not limestone. The topography of the Phong Nha area 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, 40 km away at Ba Don town.

The three most comprehensive surveys of the wider Phong Nha-Ke Bang area are those of Le Xuan Canh et al. (1997), Kouznetsov et al. (1999) and Timmins et al. (1999). These surveys, 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 Nature Reserve has restricted encroachment into limestone areas (Timmins et al. 1999). 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. According to the investment plan, Phong Nha Nature Reserve supports 38,620 ha of natural forest, equivalent to 94% of the total area of the nature reserve. The most widespread forest type is limestone forest, which covers 24,861 ha, while lowland evergreen forest covers 13,617 ha and riparian forest covers 142 ha (Anon. 1992). The limestone forest ecosystem at Phong Nha 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 threatened species that went unrecorded between its discovery in Laos in the 1920s and its rediscovery at Phong Nha in 1994 (Eames et al. 1995). Phong Nha also supports populations of two endemic primates, Ha Tinh Leaf Monkey Semnopithecus francoisi hatinhensis, and an all-black form referred to as Black Leaf Monkey S. f. ebenus. Although Timmins et al. (1999) advise caution regarding the exact status and taxonomic identity of the all-black form at Phong Nha. Timmins et al. (1999) recorded a number of globally threatened mammals in the area, including Owston's Banded Civet Hemigalus owstoni and Southern Serow Naemorhedus sumatraensis.

In addition, the globally endangered Red-shanked Douc Langur Pygathrix nemaeus nemaeus has been recorded at Phong Nha by a number of authors, although the failure of Timmins et al. (1999) to record this species, led them to conclude that there may have been a major decline in the species at the site. Also at Phong Nha, a recently described rabbit species in the genus Nesolagus was recorded in 1998 (Surridge and Timmins 1999, Timmins et al. 1999).

Over 200 bird species have been recorded at Phong Nha-Ke Bang, with regard to the avifauna of Phong Nha Nature Reserve, Timmins et al. (1999) recorded several globally threatened species, including Crested Argus Rheinardia ocellata, Chestnut-necklaced Partridge Arborophila charltonii and Red-collared Woodpecker Picus rabieri, Short-tailed Scimitar Babbler Jabouilleia danjoui. On the basis of the occurrence of four restricted-range bird species, Phong Nha lies within the Annamese Lowlands Endemic Bird Area. Phong Nha area is considered 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.

Most highlights

Chestnut-necklaced Partridge, Red-collared Woodpecker, Brown Hornbill, Sooty Babbler and Short-tailed Scimitar Babbler.

Birding routes

Visitors can get the trail up to the grotto by boat to see Sooty Babbler.

There are several forest trails in the park for birding however foreigners need to have permission to entry.

Transportation

Car, motorbike. Phong Nha-Ke Bang is a major tourist attraction, and can be easily accessed by road from Dong Hoi city or from Hue.