A Decade Dynamics of Equatorial Rain Forest System in Sumatra

本研究在印度尼西亚西苏门答腊省巴塘市附近的Gunung（Mount）Gadut地区建立了约10年的永久样地，并分析了那里物种极其丰富的植物群落的10年动态。六个永久性地块覆盖海拔和演替梯度，包括两个主要的1公顷地块，即槟榔屿槟榔屿地块和Gajabuih地块在山麓雨林约。两个主要样地分别有310和250种胸径大于8 cm（胸径）的树种，这是热带雨林物种丰富度的最高记录。极端潮湿的气候被假设为导致这一记录。丰富度与森林的层次有关。用一种新的剖面网格照相技术定量描述了植物叶片的分层。山地森林表现出较少的分层结构，同时更多样化的树木植物群比日本暖温带雨林。主要分布在林隙和次生林中的先锋树种在不同的干扰条件下也有明显的差异，两个主要样地中由于存活木的生长和幼树的补充而增加的生物量与由于树木死亡而损失的生物量基本平衡，其周转率约为0.02/a。树种的生态性状可以用胸径生长率进行分类。林下树种的相对生长率普遍较低，约为100%。林隙的形成影响了后继树的生长速率。树木的空间分布分析表明，小树的补充频繁的死树周围。母树与成苗幼树的空间分布呈负相关，而冠下树种与母树的空间分布不相关。

This research completed about ten-year censuses in permanent plots established in Gunung (Mount) Gadut area near Padang City of West Sumatra Province, Indonesia, and analyzed ten-year dynamics of extremely species-rich plant communities there. Six permanent plots cover altitudinal and successional gradients, including two main 1-ha plots namely Pinang Pinang Plot and Gajabuih Plot in foothill rain forests at ca. 600 m above sea level.The two main plots contained 310 and 250 tree species above 8 cm dbh (trunk diameter at breast height), which is the maximum record of species richness in tropical rain forests. Extremely wet climate was hypothesized to cause this record. The richness was related to the stratification of the forest. Foliage leaf stratification was quantitatively described by a new profile grid-photograph technique. Montane forests showed less stratified structure, meanwhile more diverse tree flora than Japanese warm-temperate rain forests. Pioneer tree species occurring mainly in treefall gaps and secondary stands were also differentiated in their habitats in terms of disturbance regime.The biomass increment due to growth of survived trees and recruitment of small trees was balanced with the biomass loss due to tree death in two main plots, and its turnover rate was about 0.02 per annum. Ecological traits of tree species could be classified by dbh growth rate. Subcanopy tree species had generally low relative growth rates, ca. 0.005 per annum.Gap formation affected growth rate of successor trees. Analysis of spatial distribution of trees suggested that recruitment of small trees was frequent around dead trees. Emergent and canopy tree species showed negative correlation in spatial distribution between mother trees and established saplings, while not for subcanopy tree species.