中文摘要：

地温是森林气候重要的环境因素之一，与植物生长密切相关，且是影响土壤呼吸的关键因素，适宜的地温能够促进土壤微生物活动，加速凋落物分解，提高土壤肥力，对地温的深入研究有利于正确把握森林碳通量的变化规律。本文利用西双版纳热带季节雨林2003-2006年的地温数据，分析不同深度地温的日变化、季节变化及年际变化规律。结果表明：近地层地温呈现正弦变化趋势；深层地温相对稳定，随深度增加地温日变幅减小；地温峰值出现时刻随深度增加而呈现滞后现象，相位变化明显；地温季节差异明显，平均地温在雨季（5—10月）较高，雾凉季（11月-翌年2月）较低，干热季（3—4月）居中，地温垂直变化季节差异显著；地温年变化呈现单峰分布，最低值在1月，最高值出现在7月；总体来看，热带季节雨林的地温变化强度为地温年较差〉地温年间变幅〉不同深度间地温变幅〉地温日较差。

英文摘要：

Soil temperature is an important environmental factor in forest, which not only closely relates with plant growth, but also influences soil respiration. An optimal soil temperature can improve soil fertility via promoting soil microbial activity and litter decomposition. Therefore, the study on soil temperature will be helpful to understand the changes of carbon flux in forest ecosystem. Based on the data from 2003 to 2006 in a tropical seasonal rain forest in Xishuangbanna, the diurnal, seasonal, and inter-annual variations of soil temperature at different depths were analyzed, and the results indicated that the diurnal variation of soil temperature in near-surface soil layer demonstrated a sine trend, while that in deeper soil layers was relatively stable. With the increase of soil depth, the variation magnitude of soil temperature decreased, the peak of soil temperature lagged behind, and the phase change was obvious. The seasonal variation of soil temperature was obvious too, with the highest value in rainy season （May to October）, lowest value in foggy-cool season （November to the next February） , and intermediate value in dry-hot season （ March to April）. Different soil layers were different in the seasonal variation of soil temperature. The inter-annual variation of soil temperature was a single-peak curve, with the lowest temperature in January and the highest temperature in July. Generally speaking, the variation range of soil temperature was decreased in the order of yearly soil temperature 〉 inter-annual soil temperalure 〉 soil temperature among different soil layers 〉 diurnal soil temperature.