中文摘要：

为探明热带季节雨林土壤溶解态有机碳（DOC）、溶解态氮（DN）的时空动态及与土壤温、湿度和土壤酸度的关系,本研究在西双版纳热带季节雨林开展了土壤剖面DOC和DN含量的研究,在同一自然年度,在雾凉季（1月）,干季（3月）,雨季前期（5月）,雨季中期（8月）,雨季后期（10月）,按0~20、20~40、40~60、60~80和80~100 cm分层采集土壤样品,测定土壤DOC和DN含量、土壤温、湿度和酸度。结果表明：西双版纳热带季节雨林土壤DOC和DN含量在0~60 cm随深度增加而逐层递减,在60~100 cm则随着深度增加而增加,总体表现为表层DOC和DN含量较深层土壤含量高的剖面特征。热带季节雨林各层土壤的DOC和DN的季节动态并不完全一致,呈雨季中后期高,干季低的季节特征。即DOC含量季节差异显著的土层为0~20和20~40 cm,而DN含量仅在0~20 cm土层季节差异显著;土壤温湿度与DOC和DN的关系存在着层间差异,即0~20和20~40 cm土壤DOC的含量与土壤湿度呈显著正相关关系;20~40 cm的DOC含量与土壤温度呈显著正相关关系;0~20和80~100 cm土层的DN含量与土壤湿度有显著的正相关关系;仅0~20 cm土层的土壤温度与DN含量呈显著正相关关系;热带季节雨林土壤DOC和DN的含量与土壤酸度的关系不显著。以上结果表明热带季节雨林各层土壤的DOC和DN对温、湿度和酸度的反馈不同。

英文摘要：

In order to clarify the seasonal and profile dynamics of soil dissolved organic carbon （DOC） and nitrogen （DN） contents, and to disclose the effects of soil temperature （T） , soil water content （SWC） and pH on DOC and DN dynamics, we carried out a one-year study in a tropical seasonal rainforest in Xishuangbanna, southwest China. We measured soil DOC and DN content, T, SWC, and pH variation at soil depths of 0 -20, 20 -40, 40 -80 and 80 - 100 cm in the fog-cool season （January） , dry hot season （ March）, the beginning of rainy season （ May）, the middle of the rainy season （August） and the end of the rainy season （October） of one year. The results showed： from surface to the 60 cm depth along the soil profile, DOC and DN concentrations decreased; to the contrast, from the 60 cm to 100 cm depth, DOC and DN concentrations increased. The soil DOC and DN concentrations in the surface soil layer （0 - 20 cm） were the highest along the soil profile in the tropical rainforest. The seasonal variations of soil DOC and DN concentrations showed a higher value in the middle/later rainy season than in the dry seasons. But significant seasonal dynamics only occurred in soil DOC concentration at soil layers of 0 -20 cm and 20 -40 cm and in DN concentration at soil layer of 0 -20 cm. The correlations between soil DOC/DN concentration and SWC and T were different among soil layers. There were significantly positive correlations between DOC concentration and SWC at soil layers of 0 -20 cm and 20 -40 cm, between DOC concentration and T at soil layers of 20 - 40 cm ; while, SWC at 0 - 20 cm and 80 - 100 cm, and T at 0 -20 cm had significantly positive correlations with DN concentration. Soil DOC and DN concentrations along the soil profile were not correlated with pH. The results indicated that the feedback of soil DOC and DN concentrations to SWC, T and pH at different soil layers along the profile varied.