In terms of plant biodiversity, the forest vegetation in Cao Bang Geopark is very rich and has many rare tropical species such as: ngũ gia bì gai (Eleutherococcus trifoliatus), mã đẩu linh (Aristolochia indica), đinh (Chukrasia tabularis), Indian mahogany (burretiodendron hsienmu), iron wood (Cinnamomum parthenoxylon), re hương (Codonopsis pilosula), campanula (Docynia indica), táo mèo (Fallopia multiflora), Multiflorous knootweed (fagraea), trai (Panax pseudoginseng), thủy (Amentotaxus yunnanensis), cẩm (Cupressus torulosa), tam thất (Drynaria fortunei). The high mountains, in particular the Phia Oac Mountain (Nguyen Binh district), are home to rare temperate species including yellow wood (Cupressus torulosa), pine power (Podocarpaceae), du sam (Keteleeria) etc. Moreover, Cao Bang Geopark has many common but characteristic species: evergreen bamboo (Bambusa multiplex), trúc sào (Phyllostachys edulis), star aniseed (Illicium verum), and dẻ ăn hạt (Vernicia montana) and some other medicinal plant species including tam thất (Panax pseudoginseng), hà thủ ô đỏ (Fallopia multiflora) and kim tiền thảo (Desmodium styracifolium), together with bitter tea tree.
Bitter Tea Tree (Ilexe kudincha C.J.T seng) is a rare plant species in Cao Bang. It grows naturally on rocky mountains. It is used as a drink, and for disease prevention and treatment. In the feudal age, it was considered a rare and valuable product to offer to the King. Today, bitter tea tree is one of the leading crops of the province. Bitter tea leaf has the following substances:
– Saponin group: Boost energy, strengthen the immune system for the body, stimulate nervous system, lower blood pressure, diuretic effects;
– Flavonid: Increase vascular endurance, reduce risks of strokes;
– Carotenoid: Support the treatment of benign and malignant tumors.
In terms of animal biodiversity, the forests in Cao Bang Geopark are habitats for many rare animal species: tigers, leopards, bears, monkeys, deer, black gibbons, wild boar, chamois, wolves, civet and many species of bird. Cao Bang Geopark has 58 animal species, 44 of which are rare and listed in the Vietnam Red Book: including Cao Vit gibbon, tiger, bear, deer, serow, musk incense, pheasant, red pheasants, and iguana. Some common reptile species are also found: python, snake, cobra in Thach An, Hoa An, Nguyen Binh, Bao Lac; yellow and black-ringed krait (Bungarus fasciatus), Black and white – ringed krait, Viperidae living in rocky areas; ba ba gai (Palea steindachneri), ba ba trơn (Pelodiscus sinensis) in rivers and streams; otter (Lutrinae) and other freshwater fish species.
Cao Vit Gibbon. The Northeast black gibbon species (Nomascus nasutus) or “the Eastern Black Crested Gibbon” used to exist in China and Vietnam. The species is now considered the rarest and most endangered primate in the world. Now they are classified into two groups.
Since the 1950s, the species was considered to be extinct in Vietnam. Now only 20 individuals of the Hainan gibbon group (Nomascus nasutus hainanus) are alive in Hainan Island. About 26 individuals of the Cao Vit gibbon group (Nomascus nasutus nasutus) were found in 2002 in Trung Khanh district, Cao Bang province in North Vietnam after their last appearance in the 1960s.
Cao Vit gibbons in Trung Khanh have no tail, long arms and weigh around 7-8 kilos when mature. The male gibbons have a black body with a crest on the head, while the adult females are yellow with a black patch and no crest. The baby gibbons are yellow. They live in groups on trees, moving quickly with help of their two arms. Their food is mainly fruits and leaves. Every early morning, they sing “cao vít”, “ka huýt”, and the sound lasts long, so the local people call them Cao Vít or Ka Huýt. According to the latest observation report, from 37 individuals found in 2004, the gibbon species now has 24 groups with 129 individuals.
In order to conserve the rarest primate of the world, in 2004 FFI Vietnam in cooperation with Cao Bang Provincial Authority developed the Cao Vit Gibbon Conservation Area. In 2011, FFI China and the Guangxi Provincial Authority undertook several trans-boundary cooperation activities to restore and expand the habitat for the species.
Cao Vit gibbon (Nomascus nasutus) in Trung Khanh
Cao Vit Gibbon Species/Habitat Conservation Area is located in Phong Nam, Ngoc Con and Ngoc Khe communes, Trung Khanh district, Cao Bang province covering a total area of 7,600ha, 1,600ha of which is the core area. The limestone area of the studied region is a small part of a vast limestone area at an altitude above 1,000m in two provinces Guangxi and Yunnan. The limestone area has typical terrain features (grand limestone blocks) of Northeast Vietnam. The central part is Carboniferous-Permian. Its main lithological composition is limestone, calcareous shale, or siliceous limestone with a thickness of 650-800m. The surrounding area is limestone of Na Quan Formation (D1-D2nq) with high content of siliceous material and a thickness of 300-320m. The area has a tropical monsoon climate with a cold winter, rainy summer and no dry season. The bio-climate is sub-tropical and rainy with an average temperature of 16-20°C. The cold season lasts more than four months. The annual average rainfall is moderate, i.e. 1,500-2,500mm. The dry season is short, lasting less than 2 months.
Limestone of Devonian to late Permian age occurs in most of the Ha Quang, Tra Linh, Trung Khanh, Quang Uyen, Phuc Hoa and Ha Lang districts, covering in total 60% of the area of Cao Bang Geopark. The karst landscape in Cao Bang is mostly mature to old age. Cao Bang Geopark can be regarded as a “land of caves”. Most of the caves are developed laterally and are of considerable size. An outstanding feature of the caves is the extensive and well-preserved system of speleothems decorating the cave ceilings and walls. Among the total of 400 caves surveyed throughout Vietnam, Cao Bang has 12 of the 30 longest caves (1km to 19km long) including: Nguom Sap (5379m), Ban Ngam (3600m), Nguom Nam Lao (3360m), Ki Lu (3353m), Pac Bo (3248m), Pac Lung (3109m) and Nguom Ngao (2769m).
Some 200 caves have been identified in Cao Bang by various Vietnamese expeditions and those of other countries such as France, Italy, UK, Romania, and the USA (Howard Limbert, 2003, 2005; Geokarst, 2012, 2015). Of these, 50 caves have potential for tourism development, such as Nguom Ngao, Ki Lu or Doi. However, most of them have not yet been opened to tourists, so there are many future possibilities. The only cave currently being exploited for tourism is Nguom Ngao, which was opened for tourists in 1996 and has become one of the main visitor sites in Cao Bang.