Floristic structure and biomass distribution of a tropical seasonal rain forest in Xishuangbanna, southwest China

The aim of this research was to study the forest community structure, tree species diversity and biomass production of a tropical seasonal rain forest in Xishuangbanna, southwest China. The community structure showed a divers ified species composition and supported many species of economic significan ce. This tropical rain forest is closely related to Malaysian forests. The biomass and its distribution were, studied using standard regression analys is and the clear-cut method for shrubs and herbs. The total biomass was 360 .9 t/ha and its allocation in different layers was: tree layer 352.5 t/ha, shrub layer 4.7 t/ha, liana 3.1 t/ha and herb layer 0.5 t/ha. Most of the b iomass was concentrated in the trees: stem 241.2 t/ha, root 69.6 t/ha, bran ch 37.2 t/ha. and leaves 4.3 t/ha; The DBH class allocation of the tree bio mass was concentrated in the middle DBH class. The biomass of six DBH class es from 20 to 80 cm was 255.4 t/ha. There are twenty-six species with bioma ss over 0.5% of the total biomass of the tree layer, and three species with biomass over 5%, i.e., Pometia tomentosa, Barringtonia macrostachya (5.4%) and Terminalia myriocarpa (5.2%). Data on stem, branch, leaves and root of the individual tree species were used to develop regression models. (DH)-H -2 was found to be the best estimator of the biomass in this tropical rain forest. However, higher biomass figures have been reported from tropical forests el sewhere e.g., 415-520 t/ha in the tropical forests of Cambodia, the tropica l moist mixed dipterocarp forests, and the tropical moist logged moist ever green-high, medium, and low yield forests of SriLanka. In some forests, low er accumulation of biomass was reported, e.g., 10-295 t/ha in the tropical moist forests of Bangladesh, the tropical moist dense forest of Cambodia, t he tropical dry forests of India, the tropical moist forests of Penninsular -Malaysia, the tropical moist mixed dipterocarps forests of Sarawak-Malaysi a, the tropical evergreen forests of Myanmar and the tropical moist ever-gr een logged forests of SriLanka. (C) 2001 Published by Elsevier Science Ltd.