Tasek Bera is an alluvial blackwater swamp lake located in the southern part of Malay Peninsula at uppermost reach of the southern branch of River Pahang. It occupies an area of about 25 km x 35 km on the forest-covered peneplain that stretches over the low east-west watershed of the peninsula. A narrow channel drains its water northward to River Pahang and eventually eastward into South China Sea.

The lake is a complex dendritic system consisting of extensive swamp forests that account for nearly two-thirds of its area, littoral swamps overgrown by Pandanus shrub or sedges (mostly Lepironia), network of flowing channels and scattered small open waters. The open water area constitutes less than 1.5% of the whole system. The water is poor in calcium and magnesium contents, and is acidic and brown-colored due to dissolved humic substances. The decomposition of plant detritus is thus remarkably inhibited resulting in the accumulation of peat several meters thick on the lake bottom. The vigorous growth of insectivorous Utricularia in open waters and the occurrence of the other insectivores, Nepenthes spp., along the lake shore suggest oligotrophic nature of the habitats. However, the nitrogen and phosphorus contents of lake water and the biological productivity are not very low.

The catchment area has been inhabited for centuries by a Malayan aboriginal tribe, Semalai. Their subsistence depended on the shifting cultivation of upland rice and cassava, fishery in the lake and gathering forest and swamp products. The slash.and-burn agriculture has turned an extensive area of original vegetation of mixed rain forest into low secondary forest in the northern half of the catchment. In recent years, they were given a chance to go beyond their traditional subsistence economy by growing rubber trees and wetland rice, which may gradually affect the lake environment.

An integrated ecosystem research on Tasek Bera was carried out during 1970- 1974 at Pos (Fort) Iskander, within the framework of the International Biological Program by the Joint Malaysian-Japanese Team of 19 scientists. The program contributed much to the knowledge of the swamp ecosystem of this type, which once widely occurred throughout the lowlands of equatorial Southeast Asia but has almost disappeared. As its valuable relics that escaped exploitation, it is desirable to preserve the peculiar biota and natural physiognomy of Tasek Bera as a nature reserve (Editor).