Lawas Mangroves
Location:
4°51'-4°59'N, 115°23'-115°30'E; the lower reaches of Batang Lawas immediately downstream of Lawas town, at the northeastern tip of Sarawak, Fifth Division.
Area:
9,200 ha.
Altitude:
Sea level to 120m.
Biogeographical Province:
4.25.12
Wetland type:
02, 06, 07, 11 & 13.
Description of site:
The lower reaches and estuary of the Batang Lawns River with associated oxbow lakes, riverine nipa swamps, mangrove swamps and intertidal mudflats, and adjacent lowland mixed dipterocarp forest. The site is bounded by a high ridge on the southeastern side and low hills to the southwest. The northern edge of the site runs along the Sabah border up to the coast. Adjacent coastal mangroves and inshore islets are included in the site. The riverine areas are mostly under tidal influence, the major rivers being the Batang Lawas, Sungei Merapok, Sungei Kaingaran, Sungei Malusok, Sungei Sangkurum and Sungei Kuku Karu. The substrate is sandy clay loam. Salinities range from 28 p.p.t. at Kuala Lawas to 7 p.p.m. at Lawns; there is a major drop in salinity upriver from Tanjung Besar. The soils are very acidic (pH of dry substrate 2.9) and acid sulphate soil conditions prevail when the mudflats and mangroves are reclaimed. The median tidal range at Kuala Lawas is 1.5m.
Climatic conditions:
Humid tropical climate with an annual rainfall of 3,500-4,500 mm. The rainfall is more or less evenly distributed throughout the year, although there is a slight peak during the monsoon season (September-January).
Principal vegetation:
Mangrove forest with Sonneratia alba, Avicennia sp, Rhizophora apiculata, Bruguiera gyrnnorhiza and B. sexangula, and riverine nipa swamps (Nypa fruticans). The vegetation in surrounding areas includes lowland mixed dipterocarp forest (presumably heavily exploited), peat swamp forest (logged), kerangas "islands" dominated by Dacrydium elatum in peat swamps, rubber plantations, rice paddies and other cultivation.
Land tenure:
State owned (Sarawak State Government).
Conservation measures taken:
The mangroves are included in the Belansat Forest Reserve and Kayangeran Forest Reserve.
Conservation measures proposed:
It has been suggested that the Sabah and Sarawak State Governments (and possibly the Government of Brunei Darussalam) should collaborate to avoid the possible destruction of Sarawakian marine resources by the timber project at Sipitang, Sabah.
Land use:
Timber extraction under a long-term licence (1978-1988) for the production of poles for domestic consumption and cord-wood for export to Taiwan. The forest is harvested in blocks of six hectares (200m x 300m). Other activities include coastal and riverine fishing, and the occasional hunting of Cervus unicolor and Sus scrofa. Crops in nearby areas include rubber and rice. The town of Lawas is a provincial centre.
Possible Changes in Land use:
No information.
Disturbances and threats:
A large proportion of the mangrove forest has already been cleared and the remainder will be cleared by 1990 unless protected or brought under effective management for sustainable yield. The Sabah Timber Pulp and Paper Project at Sipitang threatens water quality in Brunei Bay and the survival of the Lawas mangroves and associated fisheries.
Economic and social values:
The mangroves support important fin fish and prawn fisheries in Brunei Bay, and protect the coastline from erosion and flooding, especially during the northeast monsoon. Under proper management, the forest could provide timber on a sustainable basis. According to the Department of Agriculture (l982c), the area has no agricultural potential.
Fauna:
The area is rich in fishes and crustaceans of economic importance. Little information is available on the other fauna. The area is known to be important for the endangered Proboscis Monkey Nasalis larvatus and the locally threatened Silvered Langur Presbytis cristata. Other mammals include Macaca fascicularis and Pteropus vampyrus. A monitor lizard Varanus sp has been reported.
Special floral values:
Nepenthes reinwardtiana occurs, and has been recommended for protection.
Research and facilities:
Studies have included a forest inventory (Marsden, 1972), a study of the mangrove vegetation (Chai, 1975), a soil survey (Department of Agriculture, l982c), and surveys of the Proboscis Monkey population (Salter & MacKenzie, 1981; Bennett, 1986).
References:
Bennett (1986); Chai (1975); Chai & Lai (1980); Department of Agriculture (1982c); DID Sarawak (1979/80); DUN Special Select Committee on Flora and Fauna (1986); Marsden (1982); Salter & MacKenzie (1981 & 1985); WWF Malaysia & State Planning Unit of Sarawak (1985).
Criteria for Inclusion:
1b. 1e, 2a, 2c.
Source:
National Parks and Wildlife Office (Sarawak Forest Department) and E.L. Bennett.