项目名称: 模拟氮沉降对森林有机质分解及其自有氮释放的影响和机理
项目编号: No.31200405
项目类型: 青年科学基金项目
立项/批准年度: 2013
项目学科: 生态学
项目作者: 熊燕梅
作者单位: 北京大学
项目金额: 24万元
中文摘要: 由于碳(C)、氮(N)循环过程在生态系统内密切相关,大气N沉降加剧作为一个全球问题很可能改变全球C循环过程。有机质分解是C循环的关键环节,然而,已有研究未能明确表明N沉降如何影响有机质的分解。此外,沉降输入的外源N对有机质分解过程中自有N释放的影响还鲜见报道。本项目从大量研究中提炼出三个决定加N影响有机质分解效应的方向和大小的主要因素:有机质类型(凋落物或土壤有机质)、有机质品质(针叶林、阔叶林和固氮树纯林内的有机质)和分解阶段,拟在广东鹤山森林生态站进行为期三年的野外分解实验,考察这三个因素如何影响加N对有机质分解的效应的方向和大小,并监测分解系统内相关微生物特性和化学特性对加N的响应,以明确加N对有机质分解过程的影响和机理。此外,设计稳定同位素15N野外施肥实验研究外源N对有机质分解过程中自有N释放的影响。研究结果将为预测N沉降对生态系统C、N循环的影响提供科学依据。
中文关键词: 氮沉降;全球变化;氮矿化;凋落物分解;氮固持
英文摘要: Enhanced atmospheric nitrogen (N) deposition as a global issue is expected to alter global cabon (C)cycling because C and N transformations are coupled in ecosystems. Decomposition of organic matter is a key process of C cycling. However, it is unclear how N deposition affects organic matter decomposition and how exogenous N from deposition affects the inherent N release in organic matter during decomposition. We designed a 3-year-long field decompopsition experiment to examine whether and how the effects of N addition on decomposition depend on organic matter type (litter or soil organic matter), quality (coniferous,broad-leaved and N-fixing tree plantations) and decomposition phase, three factors possibly at work based on our literature review. Microbial and chemical responses to N addition will be measured to investigate the mechanism of N addition effects on decomposition. In addition, field fertilization with stable isotope 15N will be applied to study the effects of exogenous N input on inherent N release during litter and soil organic matter decomposition. Results from this study are expected to help evaluate the effects of N deposition on ecosystem C and N cyclings.
英文关键词: nitrogen deposition;global change;decomposition;mineralization;N retention