Cuc Phuong National Park lies at the south-eastern extent of a limestone range that runs north-west to Son La province. This limestone range predominantly comprises karst, marine in origin and perhaps 200 million years old. The section of the limestone range encompassed by the national park rises sharply out of the surrounding plain, to elevations of up to 636 m. This section is around 10 km wide and 25 km long, and has a central valley running along almost the entire length.
The karst topography exerts a dominant influence on drainage patterns in Cuc Phuong. Most of the water that the national park receives is quickly absorbed by a complex underground drainage system common to mature karst landscapes, often emerging from springs on the lower slopes flanking the national park. For this reason, there are no natural ponds or other standing bodies of water within the national park, and there is only one permanent watercourse, the Buoi river. This river bisects the western end of the national park from north to south, and feeds the Ma river, the major river in Thanh Hoa province.
The vegetation of Cuc Phuong National Park is dominated by limestone forest. In some places, the forest is stratified into as many as five layers, including an emergent layer up to 40 m in height. Due to the steep topography, however, the canopy is often broken and stratification is unclear. Many individual trees show well developed buttress roots in response to the generally shallow soils. The national park contains particularly large specimens of certain tree species, including Terminalia myriocarpa, Shorea sinensis, and Tetrameles nudiflora, which have been developed as tourist attractions. There is an abundance of timber trees and medicinal plants.
Cuc Phuong National Park has an extremely rich flora. To date, 1,980 vascular plant species in 887 genera and 221 families have been recorded at the national park. In terms of number of species, the best-represented families in the flora of Cuc Phuong are the Euphorbiaceae, Poaceae, Fabaceae, Rubiaceae, Asteraceae, Moraceae, Lauraceae, Cyperaceae, Orchidaceae and Acanthaceae. The flora of Cuc Phuong contains elements of the Sino-Himalayan, Indo-Burmese and Malesian floras. The high known floral diversity at Cuc Phuong can, however, be partly attributed to the high level of survey effort directed at the site.
Floral surveys have identified three vascular plant species known, to date, only from Cuc Phuong: Pistacia cucphuongensis, Melastoma trungii and Heritiera cucphuongensis. Cuc Phuong National Park is also considered to be one of seven globally significant Centres of Plant Diversity in Vietnam.
Cuc Phuong supports populations of several mammal species of conservation importance, including the globally critically endangered Delacour’s Leaf Monkey Trachypithecus delacouri and the globally vulnerable Owston’s Civet Hemigalus owstoni. In addition, the nationally threatened Leopard Panthera pardus has been recently recorded at the national park. Furthermore, over 40 bat species have been recorded at the national park, including 17 species from a single cave. Unfortunately, several large mammal species, including Tiger Panthera tigris and White-cheeked Crested Gibbon Hylobates leucogenys, are believed to have become extinct at Cuc Phuong in recent times, mainly due to high hunting pressure and the relatively small size of the national park.
To date, 313 species of bird have been recorded at Cuc Phuong National Park. Cuc Phuong is situated at the northern end of the Annamese Lowlands Endemic Bird Area (EBA). However, only one of the restricted-range bird species characteristic of this EBA, Short-tailed Scimitar Babbler Jabouilleia danjoui, has been recorded at the national park. Cuc Phuong qualifies as an Important Bird Area.
Other taxa that have been studied at Cuc Phuong include snails, 111 species of which were recorded during a recent survey, including 27 species endemic to the national park and its immediate surroundings. Subterranean cave-dwelling fish have also been studied, and at least one species recorded at Cuc Phuong is thought to be endemic to the limestone range: Cuc Phuong Cat Fish Pterocryptis (=Parasilurus) cucphuongensis; this species has subsequently been recorded at Pu Luong proposed nature reserve. There are currently 280 butterfly species known from the national park, seven of which were new records for Vietnam when they were first identified in 1998.
Cuc Phuong National Park is a popular tourist destination, and receives large numbers of visitors each year, mostly domestic tourists. Due to the large number of visitors, Cuc Phuong has high potential value for raising awareness of environmental issues among the general public. This potential has already been partly realised by, for example, the construction of a visitor centre at the national park, which opened in mid 2000.
Cuc Phuong National Park is an important site for biological research and for training scientists: many undergraduate and graduate students visit the national park on field courses.
Cuc Phuong has historical value as an archaeological site. Prehistoric human remains, up to 12,000 years old, have been found in caves in the national park. In addition, a fossilised marine reptile was recently found in the national park; this is the first discovery of its kind in Vietnam.
The forest at Cuc Phuong provides several essential hydrological services to local communities. For instance, the forest protects the watershed of the Yen Quang reservoir, which provides water for domestic and agricultural use.