大气沉降氮在土壤-植物系统中的留存机制  

Retention mechanisms of atmospheric deposited nitrogen in soil-plant systems

作　　者：王斌 王汝振 李甜 张玉革 姜勇[1] WANG Bin;WANG Ruzhen;LI Tian;ZHANG Yu-ge;JIANG Yong(Institute of Applied Ecology,Chinese Academy of Sciences,Shenyang 110016,China;College of Environment,Shenyang University,Shenyang 110044,China;University of Chinese Academyof Sciences,Beijing 100049,China)

机构地区：[1]中国科学院沈阳应用生态研究所,沈阳110016 [2]中国科学院大学,沈阳110044 [3]沈阳大学环境学院,北京100049

出　　处：《生态学杂志》2023年第2期463-470,共8页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(32071563,31870441);国家重点研发计划课题(2016YFC0500707)资助。

摘　　要：大气沉降氮在土壤和植物中的留存特征,是陆地生态系统氮截获和持续供应的关键。采用稳定性氮同位素技术标记15NO3-和15NH4+,可以量化两种形态沉降氮的归趋动态。国内外氮同位素示踪试验的主要特点是氮添加量小(多小于250 mg15N·m^(-2)),运行时间短(少于48个月),15NO3-和15NH4+归趋的对比研究少。大气沉降氮中NO3-和NH4+在生态系统中的留存,会因植物吸收偏好、微生物-植物氮竞争状况和生物-非生物固定过程的差异而不同。已有的研究表明,持续周转的微生物生物量氮是外源氮转化和固持的主要场所之一,土壤微生物偏好吸收利用NH4+,而非NO3-;多数植物物种偏好吸收NO3-,且能更快地转移到根表而被固定;团聚体组成对植物-土壤的氮留存量和土壤氮饱和过程具有重要的调节作用。大气活性氮在生态系统各组分分布与稳定的时空格局,不同粒径土壤团聚体对沉降氮的留存机制方面尚需要系统研究。相关研究可为完善生态系统氮循环理论,优化氮循环模型提供科学依据和数据支持。The retention of atmospheric N in plant and soil is a key pathway of ecosystem nitrogen(N) sequestration and sustainable supply. Stable isotope tracing techniques with15NO3-and15NH4+can be used to quantify the fate of the two inorganic forms of deposited N. Globally, the main characteristics of isotopic N tracing studies are applying trace amount of15N(mostly lower than 250 mg15N·m^(-2)), short experimental duration(mostly shorter than 48 months), and scarcely comparing the fate of NO3-and NH4+. The retention of atmospheric-deposited NO3-and NH4+in ecosystems may depend on plant N uptake preference, N competition between soil microbes and plants, and differences in abiotic versus biotic fixations. Several studies demonstrate that continuously cycling microbial biomass N is the main place for the turnover and fixation of exogenous N, that microbes preferentially take up NH4+rather than NO3-, that most plant species prefer to absorb NO3-of which being transferred to root surface and assimilated more quickly, and that soil aggregation can substantially modulate N retention in plant-soil systems and soil N saturation process. Future studies should be strengthened in systematically investigating the spatial and temporal patterns of atmospheric-deposited reactive N distributing and stabilizing in various ecosystem components and the retention mechanisms of deposited N in different soil aggregates. These studies would provide scientific evidence and supportive data sets for improving ecosystem N-cycling theory and optimizing N-cycling models.

关 键 词：自然生态系统 土壤团聚体 氮吸收 氮添加形态 氮稳定性同位素 

分 类 号：S154.4[农业科学—土壤学]