摘 要

我国已继欧美成为世界第三大氮沉降区，并且氮沉降量在未来一段时间内会继续增加。不断增强的氮沉降改变了氮和碳的转变模式，改变了森林土壤的理化性质和氮素供应，从而影响温室气体排放。为了准确评估增加氮沉降下的碳氮预算，有必要阐明氮沉降对温室气体排放和土壤碳氮的影响。本研究以福建戴云山毛竹林土壤为研究对象，通过野外模拟氮沉降控制实验，分析不同施氮水平（硝酸铵0、20、40、80 kg N·hm^-2·yr^-1）对亚热带森林土壤温室气体交换通及土壤碳、氮含量的影响。并初步探讨毛竹林土壤对外来氮素输入的响应机制。主要研究结论如下：

（1）氮沉降对森林土壤CO₂的排放具有明显的促进作用，施氮后一年内，中氮和低氮的施氮水平显著地改变了土壤CO₂的年排放量。

（2）氮沉降促进了土壤N₂O的排放，中氮和高氮处理的土壤N₂O的排放峰值显著高于对照组土壤和低氮处理的土壤。

（3）施氮对土壤有机碳和全氮没有产生显著影响，但提高了表层土壤无机氮含量。不同施氮水平处理下土壤有机碳和全氮之间呈现出显著的正相关关系。不同氮处理下土壤CO₂、N₂O气体通量间均达到了显著性相关关系。

关键词：温室气体（CO₂、N₂O）；氮素输入；氮沉降；土壤碳

Effects of Simulated Nitrogen Settlement on Nitrogen Oxidation and Carbon Dioxide Emissions in Soil of Bamboo Forest

Abstract

China has become the third largest nitrogen deposition area in the world after Europe and America, and the amount of nitrogen deposition will continue to increase in the future. Increasing nitrogen deposition alters the transformation patterns of nitrogen and carbon,changed the physical and chemical properties of forest soils and nitrogen supply, thus affecting greenhouse gas emissions. In order to accurately assess the carbon and nitrogen budget for increasing nitrogen deposition, it is necessary to clarify the impact of nitrogen deposition on greenhouse gas emissions and soil carbon and nitrogen. In this study, the soil of Phyllostachys pubescens Forest in Daiyun Mountain of Fujian Province was taken as the research object. The effects of different nitrogen application levels on greenhouse gas exchange and soil carbon and nitrogen content in subtropics forest soil were analyzed through field simulated nitrogen deposition control experiments. The response mechanism of soil to external nitrogen input in bamboo forest was preliminarily discussed. The main conclusions are as follows:

Nitrogen deposition has a significant promoting effect on CO₂ emissions from forest soils. Within one year after nitrogen application, the annual CO₂ emissions from forest soils were significantly changed by the levels of medium and low nitrogen application.

Nitrogen deposition promoted soil N₂O emission, and the peak value of N₂O emission in medium and high nitrogen treatments was significantly higher than that in control and low nitrogen treatments.

Nitrogen application had no significant effect on soil organic carbon and total nitrogen, but increased inorganic nitrogen content in surface soil. There was a significant positive correlation between soil organic carbon and total nitrogen under different nitrogen application levels. There was a significant correlation between soil CO₂ and N₂O fluxes under different nitrogen treatments.

Key words: Greenhouse gases(CO₂, N₂O); Nitrogen input; Nitrogen settlement; Soil carbon

目录

绪论…………………………………………………………………………………………………1

1.原位氮沉降模拟实验………………………………….…………………………………………4

1.1.实验地点……………………………………………………………………………………4

1.2.实验处理…………………………………………………… ...……………………………4

1.3.气体采样……………………………………………………………………………………4

1.4.土壤样品采样………………………………………………………………………………5

1.5.室内分析处理………………………………………………………………………………5

1.6.气体通量计算……………………………………………………………….………….…..5

1.7.数据分析……………………………………………………………….………….………..6

1. 实验结果………………………………….………………………………………………………7
   1. 氮沉降对土壤CO₂排放的影响………………………........…………………………......7
   2. 氮沉降对土壤N₂O排放的影响…………………………………………………..............8

2.3.全球增温潜势分析………………………………………………………………………..10

1. 讨论……………………………………………………………………………………...………11
2. 结论……………………………………………………………………………………...………12
3. 研究展望………………………………………………………………………………………13
4. 致谢…………………………………………………………………………………………......14

6.参考文献……………………………………………………........………………………...........15

绪论