The Middle Reaches of the Sugut River
Location:
6°14'-6°20'N, 117°20'-111°38'E; in the Sugut River system inland from the tidal delta area, in northeastern Sabah.
Area:
c.40,000 ha.
Altitude:
0-30m.
Biogeographical Province:
4.25.12.
Wetland type:
11, 13, 14, 15 & 21.
Description of site:
The middle river area of the Sugut flood plain is characterized by about fifteen oxbow lakes averaging a few hectares in size. The river is sluggish, meandering through fiat country vegetated with riverine forest, logged lowland dipterocarp forest and freshwater swamp forest. The river water is fresh, but tidal influence extends a considerable distance upstream from the delta. There are short-term and seasonal variations in water level according to local run-off and rainfall in the upper reaches of the Sugut east of Mount Kinabalu.
Climatic conditions:
Humid tropical climate with an average annual rainfall of about 3,000 mm.
Principal vegetation:
Freshwater swamp forest, riverine forest and logged lowland dipterocarp forest. Mangrove and nipa swamp downstream in the delta, and some shifting cultivation in adjacent areas.
Land tenure:
Mostly state owned (Commercial Forest Reserve).
Conservation measures taken:
Most of the area is included in the Sugut Forest Reserve (Class II).
Conservation measures proposed:
IWhitaker (1984) has recommended that six deep perennial lakes be protected as crocodile breeding areas. These are as follows: Sabahpola Lake (6°l9'N, 1l7°33 E), Usu Lake (6°19'N, 117°35'E), Kambawan Lake (6°17'N, 117°35'E), and three unnamed lakes at 6°22'N, 1 l7°37'E, 6°20'N, 117°35'E, and 6°17'30°N, 117°34'30"E, respectively.
Land use:
Fishing and shifting cultivation. The least disturbed large riverine flood plain in Sabah; although heavily logged in the past, the forest has been left to regenerate. There are few human settlements, no plantations and no permanent roads.
Possible Changes in Land use:
There are plans to drain an extensive portion of the Bird Sanctuary in the Kerah Swamp area. Under the Fifth Malaysia Plan (starting in 1986/87), a pumping station is to be installed to reduce surface water, and under the Sixth Plan (1990/95), more drainage canals are to be constructed. The Aquabio Prawn Farm is to be expanded from its existing 40 ha to 4,000 ha, at the expense of open grazing land.
Disturbances and threats:
Shifting cultivation. There appears to have been little or no hunting pressure on the crocodiles in recent years, although according to villagers, hunting for skins in the l960s and l970s caused a decline in the local population.
Economic and social values:
The area is important for its commercial timber and local fishery resources.
Fauna:
Anhinga melanogaster is known to occur, but no other information on the waterfowl is available. Mammals recorded in the area since 1978 include Dicerorhinus sumatrensis, Bos javanicus (common), Helarctos malayanus, Neofelis nebulosa, Pongo pygmaeus, Hylobates muelleri and Nasalis larvatus.
The region is particularly important for its population of the Estuarine Crocodile Crocodylus porosus. During a survey of 151 km of river and seven oxbow lakes in 1983, 24 C. porosus were observed, including several young. Many of the oxbow lakes are prime habitat for crocodiles, and from the evidence gathered in the 1983 survey, it seems that these small lakes are the most important areas for breeding crocodiles and their young.
Special floral values:
None known.
Research and facilities:
Davies and Payne (1982) conducted an extensive faunal survey of the lower Sugut in October 1981, and Whitaker (1984) carried out a crocodile survey in 1983.
References:
Davies & Payne (1982); Whitaker (1984).
Criteria for Inclusion:
1b. 2a, 2b.
Source:
See references.