FLORISTIC AND STRUCTURAL DIVERSITY OF MIXED DIPTEROCARP FOREST IN LAMBIR HILLS NATIONAL PARK, SARAWAK, MALAYSIA

Abstract

A 52-ha permanent forest plot was established in Lambir Hills National Park Sarawak, Malaysia to begin the long-term study of factors controlling the origin and maintenance of tree diversity. Stand structure and floristic composition of the plot are described. Lambirwas found to have the highest diversity of trees anywhere on earth. In the 52-ha plot there were 356501 trees with a total basal area of 2252 m², comprising 1173 tree species in 286 genera and 81 families. The Euphorbiaceae (125 species) and the Dipterocarpaceae (87 species) were the mostspecies-rich families. The Dipterocarpaceae dominated the forest with 42% of the basal area and 16% of the trees. The Burseraceae, Anacardiaceae and Euphorbiaceae were the next most important large trees in the plot. Shorea was the most important genus with 53 species and the highest basal area and stem number. As with other Asian tropical forests there were many speciose
genera in the plot; 21 genera had > 12 species. In addition to Shorea, Dipterocarpus and Dryobalanops were important basal area contributors and Dryobalanops was the second most abundant genus. Dryobalanops aromatica and Dipterocarpus globosus were the most important canopy trees. Fordia splendidissima was the most abundant understorey tree in the 52 ha. An important finding is the change in floristic composition and stand structure across the 52-ha plot in relation to soil and topographic variation.