氮添加对杨树地上和地下生物量增加的直接和间接效应  

Direct and indirect effects of nitrogen addition on the increase of above- and below-ground biomass of poplar

作　　者：闫香如 李品 吴贤杰 孙语倩 YAN Xiangru;LI Pin;WU Xianjie;SUN Yuqian(State Key Laboratory of Efficient Production of Forest Resources,The Key Laboratory for Silviculture and Conservation of Ministry of Education,Key Laboratory for Silviculture and Forest Ecosystem of State Forestry and Grassland Administration,Beijing Forestry University,Beijing 100083,China)

机构地区：[1]林木资源高效生产全国重点实验室,森林培育与保护教育部重点实验室,干旱半干旱地区森林培育及生态系统研究国家林草局重点实验室,北京林业大学,北京100083

出　　处：《生态学杂志》2025年第1期56-64,共9页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(32271673)资助。

摘　　要：氮(N)添加引起的植物生物量增加效应,是促进植物固碳潜力的重要因素之一。目前,N添加下植物、土壤和微生物之间的直接和间接相互作用对森林地上和地下生物固碳(C)功能的影响尚不清楚。本研究设置4个N水平(不加N、加50、100和200 kg·hm^(-2)·a^(-1)尿素),利用结构方程模型解析短期外源N输入下欧美杨107(Populus euramericana cv.‘74/76’)幼树叶和细根化学性状、土壤微生物群落和土壤理化因子对地上和地下生物量增加的直接和间接效应。结果表明,随着外源N输入的增加,地上生物量的增加幅度大于地下生物量,导致根冠比随之下降;N输入增加显著增加叶N浓度,降低叶C浓度,导致叶C∶N降低,而对细根化学性状的影响有限;N输入增加未对根际土壤微生物群落产生显著影响;结构方程模型显示,影响地上和地下生物量的直接和间接因子是一致的:外源N输入、叶C和叶N有直接影响,NH_(4)^(+)-N、NO_(3)^(-)-N含量和叶N通过外源N输入的促进效应产生间接影响。本研究解析了植物、土壤和微生物之间的直接或间接相互作用,为评估N添加对杨树人工林地上和地下固碳功能的影响提供科学依据。The increase of plant biomass caused by nitrogen(N) addition is one of the important factors to enhance carbon sequestration potential of plants. At present, the effects of direct and indirect interactions between plants, soil, and microorganisms under N addition on the above-and below-ground carbon sequestration(C) function of forests are unclear. We used structural equation models to analyze the direct and indirect effects of leaf and fine root chemical traits, soil microbial community and soil physicochemical factors on above-and below-ground biomass increase of poplar 107(Populus euramericana cv. ‘74/76') saplings under four N input levels(no N addition, additions of 50, 100, and 200 kg·hm^(-2)·a^(-1) urea). The results showed that with the increases of exogenous N input, the increase of aboveground biomass was greater than that of belowground biomass, resulting in a decrease of root-shoot ratio. The increase of N input significantly increased leaf N concentration and decreased leaf C concentration, resulting in the decrease of leaf C∶N, but the effect on the chemical traits of fine roots was limited. The increase of N input did not affect rhizosphere soil microbial community. The structural equation modeling showed that the direct and indirect factors affecting above-and below-ground biomass were consistent, i.e., exogenous N input, leaf C and leaf N had direct effects, while NH_(4)^(+)-N, NO_(3)^(-)-N content, and leaf N had indirect effects. Our results clarified the direct or indirect interactions among plants, soil and microorganisms, providing a scientific basis for evaluating the effects of N addition on the above-and below-ground carbon sequestration of poplar plantations.

关 键 词：氮添加 杨树 植物性状 生物量 结构方程模型 效应 

分 类 号：S792.11[农业科学—林木遗传育种]