Tropical Rainforests in Kuching and Bintulu Area in Malaysia and Experimental Results of Their Restoration

The tropical rainforests in southeast Asia are classified into several types by Peter Ashton (1991). Their species composition is not yet clarified because of the high species richness. In this report several types of tropical rain forest were recorded based on phytosociology: 1. dipterocarp forests on mesic sites; 2. swamp forests on wet sites; 3. heath forests (kerangas) on dry sites; 4. secondary Macaranga forests. Very tall, developed tropical forests are now very few around Kuching and Bintulu. They were surveyed only in Similajau National Park and the experimental forest in Universiti Pertanian Malaysia (UPM), Bintulu Campus. These well developed tropical rainforests are Dryobalanops aromatica (kapur) and Cotylelobium burckii forest. When the tropical rainforests have an emergent tree layer, the cover values are similar to those of the tree crowns of the tree-1 layer. Forests without an emergent tree layer have about the same tree crown cover as the tree-1 and tree-2 layer. This is because of the selective cutting of big trees before. The various Macaranga secondary forests have similar species composition, number of layers and community height. The forest composition and site conditions are related to the growth of the seedlings to be planted in abandoned shifting-cultivated fields. The growth of these tropical forest species was compared with the growth of species in experimental plantation since 1990 at the abandoned shifting-cultivation area on the UPM campus. Seedlings of kerangas canopy species grow very well (1.5-2m/year) on the abandoned shifting-cultivation fields. The growth of kerangas species is better that of mesic and swamp species. Tropical species grow two times faster than warm-tempera especies in Japan which were planted as seedlings of native canopy species, in dense plantations (1-3 individuals/㎡).Contribution from the Department of Vegetation Science, Institute of Environmental Science & Technology, Yokohama Natlonal University, No.21