Forest structure and biomass of a tropical seasonal rain forest in Xishuangbanna, Southwest China

Xishuangbanna is a region located at the northern edge of tropical Asia. Biomass estimates of its tropical rain forest have not been published in English literature. We estimated forest biomass and its allocation patterns in five 0.185-1.0 ha plots in tropical seasonal rain forests of Xishuangbanna. Forest biomass ranged from 362.1 to 692.6 Mg/ha. Biomass of trees with diameter at 1.3 m breast height (DBH) >= 5 cm accounted for 98.2 percent of the rain forest biomass, followed by shrubs (0.9%), woody lianas (0.8%), and herbs (0.2%). Biomass allocation to different tree components was 68.4-70.0 percent to stems, 19.8-21.8 percent to roots, 7.4-10.6 percent to branches, and 0.7-1.3 percent to leaves. Biomass allocation to the tree sublayers was 55.3-62.2 percent to the A layer (upper layer), 30.6-37.1 percent to the B layer (middle), and 2.7-7.6 percent to the C layer (lower). Biomass of Pometia tomentosa, a dominant species, accounted for 19.7-21.1 percent of the total tree biomass. The average density of large trees (DBH >= 100 cm) was 9.4 stems/ha on two small plots and 3.5 stems/ha on two large plots, illustrating the potential to overestimate biomass on a landscape scale if only small plots are sampled. Biomass estimations are similar to typical tropical rain forests in Southeast Asia and the Neotropics.