模拟氮沉降对高山森林土壤碳积累与稳定性影响

项目名称： 模拟氮沉降对高山森林土壤碳积累与稳定性影响

项目编号： No.41301219

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 天文学、地球科学

项目作者： 常瑞英

作者单位： 中国科学院水利部成都山地灾害与环境研究所

项目金额： 26万元

中文摘要： 高山森林土壤碳对大气氮沉降的响应是当前全球变化研究的重要方向。本项目利用15N标记的增氮实验（8 kg N/ha/y和50 kg N/ha/y两个水平）模拟氮沉降增加，首先测算15N在高山森林土壤中的积累量与分配比例，并结合土壤C:N，估算N添加下土壤碳变化。同时利用传统的配对样地方法（对比对照样方和施氮样方土壤碳储量）和连续观测方法（比较施氮前后土壤碳储量）评估土壤碳对N添加的响应。此外，通过土壤有机碳分组（易变碳和稳定性碳），分析其13C和14C组成（δ13C和Δ14C），研究不同有机碳组分的稳定性对N添加的差异性响应。最后，利用土壤淋溶实验，研究土壤碳、氮淋溶对N添加的响应，并结合15N研究，分析淋溶碳对土壤碳积累的作用。本研究为深入研究高山森林土壤碳氮循环提供重要基础，并对于认知森林土壤在N沉降下的碳汇作用具有重要价值。

中文关键词： 全球变化；碳循环；同位素技术；淋溶；土壤碳分组

英文摘要： The responses of alpine forest soil carbon(C) changes and stability to nitrogen(N) deposition are being paid more attention to. In this study, two 15N labeled N additions treatments with 8 kg N/ha/y and 50 kg N/ha/y respectively,were used to study the effects of N addition on alpine forest soil C. First,the 15N enrichments and proportion of 15N tracer recovered in the soil pools were calculated based on N mass and amount of 15N applied. The soil carbon changes due to N additions were estimated multiplied by soil C:N ratio by N enrichments in the soil. Moreover, two traditional methods, paired sites comparison method (comparison of soil carbon between the reference site and the fertilization sites at a point in time) and retrospective method (detection in soil carbon at the different points in time in the same fertilization site), were also used to estimate the changes in soil carbon.Second, the soil organic carbon (SOC) of each treatment was separated into labile and recalcitrant SOC, and the 13C and 14C fractionation (δ13C andΔ14C)were detected in these two fractions and the aboveground litter. The analysis of 13C and 14C was used to investigate the responses of stability of labile and recalcitrant SOC to N additions. Third, the soil leaching solution was collected to estimate the solution volume, dissolved org

英文关键词： global change；carbon cycle；isotope technique；leaching；soil carbon fractionation