Labuk-Sugut Deltas
Location:
5°50'-6°31'N, 117°27'-117°45'E; on the northeast coast of Sabah, northwest of Sandakan.
Area:
c.150,000 ha.
Altitude:
Sea level.
Biogeographical Province:
4.25.12.
Wetland type:
02, 03, 06, 07, 08, 11, 13, 14, 15 & 21.
Description of site:
A large stretch of coastal mangrove and nipa swamp distributed over two delta systems, backed by freshwater marshes, some of the best swamp forest in Sabah and two large river systems with associated oxbow lakes. The main source of water is freshwater run-off from the northern part of the Crocker Range on the Labuk and Sugut river systems. The water regime is partly tidal, partly free-flowing and partly stagnant. The mangroves are subject to tidal inundation, the swamps are permanent, and the freshwater areas may be semi-permanent to permanent. The tidal range is about 1-2.5m.
Climatic conditions:
Humid tropical climate; one of the wetter areas of Sabah with the average annual rainfall exceeding 3,500 mm. The greater part of the rain falls during the northeast monsoon from December to February. The driest period of the year is probably in April and May, but evaporation is unlikely to exceed rainfall except in exceptional droughts which may be expected once every 10-15 years.
Principal vegetation:
In the Sugut Delta, the mangrove forest is dominated by Rhizophora mucronata, R. apiculata and species of Ceriops, Excoecaria, Sonneratia, Bruguiera and Avicennia. The swamp forests are often characterized by the family Myristicaceae, with local dominance of Aistonia spathulata, Nauclea spp, Terminalia spp, Campnosperma spp, Lophopetalum multinervum and Octomeles sumatrana. Surrounding areas are under logged lowland dipterocarp forest with patches of shifting cultivation and riverine forest.
Land tenure:
The wetland and surrounding areas are state owned (Sabah State Government).
Conservation measures taken:
Large portions of the area are included in forest reserves. Some 56,912 ha of mangrove forest are included in the Kuala Bonggaya and Kuala Labuk Forest Reserves (Class V), and much of the mangrove forest in the Sugut Delta is included in the Sungei Sugut Forest Reserve (Class V). Much of the remaining swamp forest is in the Sugut Forest Reserve (Class II), a commercial forest reserve of 32,000 ha. Paitan Forest Reserve lies to the northwest of the Sugut Delta.
Conservation measures proposed:
Several areas of importance for Estuarine Crocodiles Crocodylus porosus have been proposed for special protection.
Land use:
Forestry in the mangrove forest reserves and commercial forest reserves, particularly logging for commercial timber. Large areas of the Sugut Delta have been selectively logged for timber and this may continue periodically. There is extensive fishing and some subsistence agriculture in the area.
Possible Changes in Land use:
No information.
Disturbances and threats:
Crocodile habitat in the mangroves of the Sugut Delta is apparently subject to heavy disturbance, and the crocodiles have now almost disappeared from the estuarine zone. Hunting undoubtedly occurs, and may be threatening populations of the larger mammals. A hydro-electric power dam has been proposed for the upper reaches of the Labuk River, and the Sabah Electricity Board has commissioned a study including environmental impact assessment. If the project goes ahead, it may affect the lower Labuk.
Economic and social values:
The swamp forest and mangroves provide a valuable source of timber and other forest products, and the mangrove swamps and oxbow lakes support a major commercial fishery. Some 1,143 tons of prawns were taken from the adjacent sea in 1974, comprising 29% of the total catch in Sabah in that year.
Fauna:
A very poorly known area, but probably of great importance for wildlife in view of its size, remoteness and lack of land alienation. Wildlife appears to be abundant and is probably representative of the coastal lowlands of eastern Sabah. The very rare pheasant Polyplectron malacense has been reported in the Sugut Delta area. The Estuarine Crocodile Crocodylus porosus still occurs quite commonly upriver, but has now become very rare in the coastal zone.
Special floral values:
No information.
Research and facilities:
A crocodile survey was carried out in 1983 (Whitaker, 1984).
References:
Davies & Payne (1982); Simpson & Chin (1978); Whitaker (1984).
Criteria for Inclusion:
1b. 1e, 2a, 2b, 2c.
Source:
C. Phillipps.