Limbang Mangroves
Location:
4°47'-4°55'N, 114°55'-115°05'E; in Limbang District, Fifth Division, at the northeastern tip of Sarawak, on the border with Brunei Darussalam.
Area:
7,000 ha (including 800 ha of mudflats).
Altitude:
Sea level
Biogeographical Province:
4.25.12
Wetland type:
02, 06 & 07.
Description of site:
An estuarine complex dominated by the Limbang River, with associated mangrove and nipa swamps, and extensive intertidal mudflats and sand flats. The tidal range is 3.49m.
Climatic conditions:
Humid tropical climate with an average annual rainfall of 3,500 mm. The rainfall is more or less evenly distributed throughout the year, with a slight peak during the monsoon season from September to January (c.400 mm per month).
Principal vegetation:
Mangrove forest dominated by Rhizophora apiculata and swamps of Nypa fruzicans, with degraded swamp forest and lowland mixed dipterocarp forest in adjacent areas.
Land tenure:
Two areas of Pulau Limpaku Pinang and one area to the north of Sungei Jai Jai have been legally cleared for agriculture. All other areas are untitled state lands and all further clearance is illegal.
Conservation measures taken:
None. Adjacent areas in Brunei Darussalam (Pulau Berambang, Pulau Siarau and Sungei Brunei) are conservation areas.
Conservation measures proposed:
Salter and MacKenzie (1981) proposed that the Sungei Limbang mangroves be designated as a wildlife sanctuary for the protection of the Proboscis Monkey Nasalis larvatus. Howes and NPWO (1986) proposed that the mangroves and intertidal mudflats be made into a conservation area to link up with similar areas in adjacent Brunei Darussalam. The areas in Brunei are either fully protected or proposed for protection. The proposals could lead to the formation of an International Coastal Resource Conservation Area within Brunel Bay. In addition. Howes and NPWO recommended that the forests be managed on a sustainable yield basis and that illegal logging be terminated. Bennett and Gombek (1986) also proposed that the Limbang mangroves be protected for the following reasons: (a) the Limbang area is Sarawak's only major contribution to the Brunei Bay fishery; (b) Limbang links two protected sections of the mangroves in Brunei; thus destruction of the Limbang mangroves would isolate the Brunei reserves and result in faunal degradation; (c) the population of Nasalis larvatus in Brunei Bay is the only significant population of this species between Sandakan and the Rajang Delta; (d) Brunei Bay supports a population of the Silvered Langur Presbytis cristata, an endangered species in Sarawak.
Land use:
Fishing for fin fish and prawns, and forestry for "Bakau" (Rhizophora) poles and possibly for cord-wood for export to Taiwan. Most of the area is under licence for extensive logging; clear-felling began in 1977 and the first rotation was planned for completion in 1987. Two other logging licences have been issued for the production of charcoal and firewood. There are several settlements in the area, with domestic livestock and plantations of rubber, bananas and coconuts. The soils are, however, very saline and sulphidic, precluding the possibility of large-scale agriculture. The principal activities in surrounding areas are fishing, forestry (on a large scale), agriculture, hunting and river transport.
Possible Changes in Land use:
No information.
Disturbances and threats:
The principal threat is over-exploitation of the forestry resources. No measures have been taken to manage the forest on a sustainable yield basis, and as soon as the timber resources in the Lawas mangroves have been depleted, pressure on the Limbang mangroves will certainly increase. There is a considerable amount of illegal logging; patches of up to 50 ha in extent have been cleared for coconut plantations and aquaculture schemes along the Limbang River. Possible illegal immigration of families from Ulu Limbang into Kampong Rangau Jaya could result in further clearance. There were plans to clear the mangroves on the east bank of the Limbang River by the end of 1986, for the establishment of prawn ponds, and over 100 ha had already been cleared by April 1986. Other threats include the erosion of riverbanks by speed-boats and large barges, and a considerable amount of hunting of Nasalis larvatus and Presbytis cristata.
Economic and social values:
The mangrove swamps and mudflats are important for sustaining yields of penaid prawns within Brunei Bay. In 1973, 825.6 tons of prawns with a market value of M$3 million were caught in Brunei Bay. The mangroves also serve as an erosion barrier and protect towns such as Limbang against storms during the northeast monsoon (November-January). The area forms an important link between protected areas in the adjacent parts of Brunei, and would be an integral part of the proposed International Coastal Resource Conservation Area in Brunei Bay.
Fauna:
Over 100 species of fishes have been caught in the surrounding waters. Small concentrations of shorebirds have been recorded during the migration seasons, including Pluvialis dominica, P. squatarola, Charadrius mongolus, C. Ieschenaultif, Numenius phaeopus. N. madagascariensis, Tringa totanus, Xenus cinereus, Actitis hypoleucos, Heteroscelus brevipes, Arenaria interpres, Linmodromus semipalmatus, Calidris tenuirostris and C. ruficollis. Other waterfowl known to occur include Anhinga melanogaster, Egretta sacra, E. eulophotes, E. garzetta, E. alba, Ardea sumatrana, Leptoptilos javanicus and six species of terns (Laridae). Mammals include Nasalis larvatus, Presbytis cristata, Macaca fascicularis, Orcaella brevirostris and otters, and reptiles include the Estuarine Crocodile Crocodylus porosus and a monitor lizard Varanus sp.
Special floral values:
The area contains a good example of extensive Nypa fruticans forest with mature Heritiera littoralis.
Research and facilities:
Surveys have included a forest inventory in 1972 (Marsden, 1972), shorebird research in April and May 1986 (Howes & NPWO, 1986), a crocodile survey by the National Parks and Wildlife Office, and a study of the Proboscis Monkey (Bennett, 1986).
References:
Bennett (1986); Bennett & Gombek (1986); Cox & Gombek (1985); Department of Agriculture (1982c); Howes (in prep); Howes & NPWO (1986a); Marsden (1982); Salter & MacKenzie (1981).
Criteria for Inclusion:
1b, 1e, 2a, 2c, 3b.
Source:
John R. Howes, E.L. Bennett and National Parks and Wildlife Office (Sarawak Forest Department).