中文摘要：

林下树种幼苗是森林生态系统的一个重要组成部分,在森林的自然更新过程中发挥着重要作用.为了解树种幼苗的海拔分布格局以及森林群落林下幼苗对季节性气候的响应,本研究调查了云南省哀牢山（亚热带）和玉龙雪山（亚高山）两个地区的林下树种幼苗物种组成及个体数量的海拔分布格局及其季节动态.结果表明：随着海拔的升高,两个山体的树种幼苗物种丰富度均先增加后下降,优势种也呈现明显的变化;雨季末期的幼苗物种丰富度明显大于旱季末期,其中,占据优势地位的物种具有较明显的季节性差异;不同海拔带树种幼苗优势种也具有显著差异.

英文摘要：

Tree seedlings under forests serve as an important part of forest ecosystem and play a role in the natural regeneration of forests. To understand the altitudinal distribution patterns of tree seed- lings and the response to seasonal variation, we investigated the species composition and individual numbers of tree seedlings, and their seasonal dynamics in Ailao Mountain （ subtropical region） and Yulong Mountain （subalpine region） in Yunnan Province. The results showed that the species rich- ness of tree seedlings increased with altitude, peaked in the middle of the mountains, and followed a decline at higher altitudes, and the dominant species also changed significantly. Species richness of tree seedlings was significantly higher at the end of rainy season than that at the end of dry sea- son, and the dominant species had obvious seasonal difference.