中文摘要：

通过对1988年和2006年西双版纳补蚌地区望天树林样方资料的比较研究，探讨了望天树林群落近20a来在物种多样性方面的变化．研究结果表明，在2006年的样方中，望天树仍然具有最大的优势度，该群落仍然是以望天树为优势种的单优群落．在群落自身演替以及外界环境干扰的影响下，幼树、灌木和藤本植物种类和数量明显增加，而草本植物和附生植物减少．分析乔木层的物种多样性变化发现，尽管2006年样方在植物种类和数量上都要高于1988年样方，但辛普森指数和均匀度指数并未增加，很可能是样方中形成了林窗的结果．另外，乔木层中物种优势度变化非常明显，少数优势种衰退了，少数变得更优势．1988年的两个样方中分别有50％和40％的物种被后来的物种所取代，物种替换现象特别显著，外界环境的干扰可能是导致物种成分替换的主要原因．

英文摘要：

Based on a comparison of the sampling data between 1988 and 2006 obtained from Parashorea forest in Bubeng, Xishuangbanna in southwest of China, the changes in the structure, species composition, life form, plant abundance and species diversity of the forest in the past 20 years were analyzed. Parashorea chinensis was still the most dominant species in the forest. The species number and individuals of young trees, shrubs and lianas increased obviously, but herbs and epiphytes were found decreasing. Both the species number and individuals of trees in the sampling plots in 2006 increased compared to those in the plots in 1988, but the Simpson＇s and Pielous indiees were found no inerease. The changes in the tree species dominance were obvious. Some speeies deelined in their abundance, while some increased. In two plots of 1988, 50% and 40% of tree species were replaeed by new migrants respeetively, whieh were caused mainly by the inereasing disturbances, ineluding human aetivities.