Types and Categories of Sarawak's Forests

There are about 80% or almost 10 million hectares of Sarawak's total land area of 12.3 million hectares covered with forest (including natural as well as secondary forests). The remaining 2.3 million hectares are under settlements, towns, agricultural crop cultivation and native customary rights land.
Secondary forests refer to ecological systems deriving from clearing of natural forests for shifting cultivation. These forests have been established through a long fallow period of natural regeneration and now contain minimum crown covers of trees and are associated with wild flora, fauna and natural soil conditions. Secondary forests are established after abandonment of 10 years or more by shifting cultivators. Secondary forest formations in Sarawak are closed forests.
Six million hectares of the State's forests are zoned as the Permanent Forest Estate which is meant for sustainable forest management and about 1 million hectares are designated as Totally Protected Areas.
Although five types of natural forest are recognized in Sarawak, three main types predominate. These are Hill Mixed Dipterocarp Forest (covering about 7 million hectares), Peat Swamp Forest (comprising about 1 million hectares) and Mangrove Forest (occupying slightly more than 0.1 million hectares). The other two types, the Kerangas and the Montane Forests, are minimal in size.
Where each of the forest types is found depends on the altitude, soil conditions and water availability. Hill Mixed Dipterocarp Forest is found in the interior, upriver areas, extending from coastal peat swamps up to heights of 1,500 meters. Montane Forest takes over beyond this altitude. The domain of the Peat Swamp Forest is lowlying coastal plains with a high water table reaching inland along the lower reaches of major river systems. The Rejang delta and the Batang Baram are fine examples of Peat Swamp Forest. Mangrove Forest, on the other hand, is found in tidal and estuarine stretches extending from mud flats to where the saline waters start while Kerangas Forest occurs on poor, sandy soil and terrain.