Yok Don Reserve (Khu Bao Ton Thien Yok Don)
IV (Managed Nature Reserve)
4.05.01 (Indochinese Rainforest)
Lies within the Easup District of Daklak Province in central southern Viet Nam. The western boundary is coincident with the international border with Kampuchea and is defined by the Prek Dak Dam River. The boundary is also defined by the Srepok River to the north and east and by the boundary between Daklak and Dakmil provinces to the south. 1230'-1301'N, 10730'-10750'E
DATE AND HISTORY OF ESTABLISHMENT
1988. The precise legal status is not clear (Laurie et al., 1989).
The general elevation is 200m, with only two hill formations rising above 300m, namely Yok Da (474m) and Yok R'Heng in the north-west and Yok Don (482m) in the south-east (Laurie et al., 1989)
Lies in the south-western part of the Central Highlands (Tay Nguyen) and is largely flat with meandering river valleys flowing generally north or east to the Srepok River. The main rivers are Dak Ken and Dak Na which both flow north into the Srepok River. There is a permanent lake at the western end of the Yok Don massif. The bedrock predominantly comprises Jurassic sediments, with an igneous intrusion of mainly diorite along the Srepok River west of Dak Ken. Soils are mainly grey or yellow-red, rich in sialite and ferralite. There are slabs of red clay near Yok Don and extensive silt deposits near the Srepok River and several areas are used by wild cattle and other animals as mineral licks (Laurie et al., 1989).
Yok Don has a tropical monsoon climate, with a well defined dry season from October to April. Mean annual rainfall is 1540mm and the annual rainfall during 1982-1985 ranged from 1,587mm to 2,037mm at Ban Don, located immediately beyond the north-east boundary, on the opposite bank of the Srepok River. Some 76% of rain falls between May and September, whilst only two or three days each month are likely to be wet during January and February. The mean monthly temperature at Ban Don varies between 24C and 26C, with a maximum in May and minimum in January. Mean annual relative humidity is about 60%, falling to 40% in March and increasing to about 75% in August and September. There is a mean of about 2,500 hours of sunshine annually, or about 84% of potential hours of sunshine. Cloud cover is at maximum between May and September, with 5/8 to 7/8 cover (Laurie et al., 1989).
- PHYSICAL FEATURES
The following account is drawn exclusively from Laurie et al., (1989). The dominant vegetation type is dry dipterocarp (deciduous) forest, in which the trees are widely spaced with extensive grass cover between them. This is interspersed with grassland, and tropical semi-evergreen forest along the rivers and on the higher ground. All these vegetation types, particularly the grassland and the open dipterocarp forest, have been heavily influenced by fire. The dominant trees in the open dipterocarp forest are Dipterocarpus obtusifolius (dau trabeng), D. intricatus (dau long), D. tuberculatus (dau dong), Shorea obtusa (ca cach) and Pentacme siamensis (cam lien). Dipterocarpus alatus (dau nuoc) and Terminalia tomentosa (chieu lieu den) (Combretaceae) are also common. All the above are valuable timber trees. Other trees include Dillenia spp., Syzgium spp. and Bombax sp. Tree heights rarely exceed 20m. Small bamboo Arundinaria falcata is common in the more densely shaded areas. Elsewhere the ground cover consists of grasses such as Arundinella setosa, Heteropogon contortus, Themeda triandra, Imperata cylindrica, Allopteropsis semialata and many others, and young dipterocarp saplings. Shrubs include Bauhinia malbaricum, Grewia asiatica and Zizyphus spp. In the open areas there is a wide variety of grasses (more than 60 species recorded) and sedges Cyperus spp. and Fimbristylis spp. These open areas often surround waterholes which are used by wild cattle for drinking and wallowing. On higher ground and along rivers the variety of tree species increases. Characteristic species on the hills include dipterocarps Hopea odorata (sao den) and Shorea siamensis (sen) and Terminalia belerica, T. tomontosa, Cassia siamea and Artocarpus spp. Cycads and tree ferns also occur in these forests. Along rivers are thickets of larger bamboos Bambusa arundinaceae and B. beecheyna. Typical tall riverine trees include Lagerstroemia calyculata and L. augustifolia (bang lang), Tetrameles nudiflora, Pahudia cochinchinensis (go do), Sindora cochinchinensis (gu mat) and Pterocarpus pedatus (giang huong) up to 30m tall. A total of 464 plant species, from 97 families, has been recorded, and a detailed description and classification of the vegetation is given in the management document (Sung and Huynh, 1986), and general information on Tay Nguyen (Central Highlands) vegetation is given by Loc (1983).
Lists of 58 mammal species, 136 bird species, 35 reptile species and 12 amphibian species recorded in the reserve are given in the management plan (Sung and Huynh, 1986). Large carnivores include tiger Panthera tigris (E), leopard P. pardus (T), sun bear Helarctos malayanus and wild dog Cuon alpinus (V). The most common large ungulates include banteng Bos javanicus (V), barking deer Muntiacus muntjak, sambar Cervus unicolor and wild pig Sus scrofa. The status of kouprey Bos sauveli (E), Eld's deer Cervus eldi and hog deer Axis porcinus is unclear. Amongst the birds, green peafowl Pavo muticus (V) is of particular interest, and appears to be relatively common. Silver pheasant Lophura nycthemera, Siamese fireback L. diardi (K) and Germain's peacock pheasant Polyplectron germanii (K) also occur. Other noteworthy birds include red-headed vulture Sarcogyps calvus, woolly-necked stork Ciconia episcopus, lesser adjutant stork Leptoptilus javanicus, green imperial pigeon Ducula aenea, Aleaxandrine parakeet Psittacula eupatria and racket-tailed treepie Temnurus temnurus. The most common reptiles appear to be agamid lizards of the genera Calotes and scincids of the genus Mabuya. Flying lizards Draco sp. and monitor lizards Varanus salvator are present. Siamese crocodile Crocodylus siamensis (E) still occur in the Srepok River, but are now rare (Laurie et al., 1989). A partial species list is given in Laurie et al. (1989).
LOCAL HUMAN POPULATION
There about 1,500 villagers of Ede, Muong, Giarai and Lao origins at or near Ban Don, and about 500 employees of the Forestry stations at Ban Don and Bon Drang Phok, to the immediate north, making 2,000 altogether. Approximately 1,000 buffalo, 300 cattle and 20 domestic elephants are kept. Considerable numbers of people are engaged in farming in the east of the reserve and there is widespread collection of resin from dipterocarp trees, as well as collection of honey, bamboo shoots and a wide variety of medicinal plants. Areas have also been cleared along the banks of the Dak Ken River in the south by hunters and resin collectors, for the cultivation of tobacco and taro. These are then harvested on subsequent visits (Laurie et al., 1989).
VISITORS AND VISITOR FACILITIES
The principal means of access to the reserve is by road from Buan Ma Thuot to Ban Don. There are no motorable roads within the reserve, although it is possible to travel by small boat along the Srepok River, and there is a motorable road from Ban Don via Bon Drang Phok to the Kampuchean border. The most convenient means of transport within the reserve is by elephant (Laurie et al., 1989). Although there are at present no tourists, the development of various facilities to accommodate up to 10,000 visitors annually has been envisaged in the 1986 management plan (Sung and Huynh, 1986)
- CULTURAL HERITAGE
As part of an international effort to save the kouprey from extinction (MacKinnon and Stuart, 1989), an initial survey for the species was made in the reserve during April 1989. Results of the survey suggested that there are few if any kouprey present, although individuals may migrate into the reserve from Kampuchea during the wet season (Laurie et al., 1989).
- SCIENTIFIC RESEARCH AND FACILITIES
There has been a hunting ban in Easup District since 1984 and commercial logging ceased in the present reserve area in 1986. The reserve headquarters lie on the west bank of the Srepok River opposite Buon Jeng Lan in the extreme east. There is also a reserve building on the bank of the Srepok River, opposite Ban Don. The management document (Sung and Huynh, 1986) suggests various development projects, the main priority being placed on office development. The proposals include: construction of the reserve headquarters and recruitment of an office staff of 45; construction of three guard posts at Jeng, Dak S'sot and on the border with Kampuchea; establishment of a zonation system; provision for sport hunting of game species; construction of footpaths and tree hides for tourists and 'development' of Yok Don Lake; provision of tourist activities such as boating and elephant riding; construction of a dam on Dak Na and Dak Nor rivers to provide water during the dry season; provision of controlled harvesting of medicinal plants, bamboo shoots and resin; research on local ecology and medicinal plants; and a fire prevention and control programme. This programme is likely to be revised in late 1989 to more fully accommodate conservation priorities (Laurie et al., 1989).
- CONSERVATION MANAGEMENT
There is widespread hunting, although it does not appear to be very intense, and elephants are still captured within the reserve (Laurie et al., 1989).
Comprises one full time employee, who acts as Director, and a further 21 who are either temporarily employed or shortly to be employed. The Director is employed by the Easup District Forestry, Agriculture and Industry Union (Laurie et al., 1989).
Easup District Forestry, Agriculture and Industry Union
- MANAGEMENT PROBLEMS
- Survey for kouprey (Bos Sauveli) in Western Daklak Province, Vietnam. The Kouprey Conservation Trust. Unpublished. 34 pp.
- Laurie, A, Duc, H.A. and Anh, P.T. (1989).
- The kouprey: an action plan for its conservation. Prepared by the IUCN Species Survival Commission and WWF. IUCN, Gland, Switzerland. 20 pp.
- MacKinnon, J.R. and Stuart, S.N. (Eds). (1989).
- The plant world in the Tay Nguyen Region. In: Tap, B.B. (Ed.) Research on nature and people of Tay Nguyen. University of Hanoi. (Unseen)
- Loc, P.K. (1983).
- Report of survey and proposals for management of Yok Don. Prepared by a team from the Centre for Ecology and Biological Resources of Vietnam, Hanoi. (Unseen)
- Sung, C.V. and Huynh, D.H. (Eds). (1986).