氮添加对中国陆地植被地上-地下生物量分配的影响  

Effects of nitrogen addition on plant above⁃and below⁃ground biomass allocation in terrestrial ecosystems in China

作　　者：陆啸飞 郭洁芸 王斌 乐旭 LU Xiaofei;GUO Jieyun;WANG Bin;YUE Xu(Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control,Collaborative Innovation Center of Atmospheric Environment and Equipment Technology,School of Environmental Science and Engineering,Nanjing University of Information Science&Technology,Nanjing 210044,China;Department of Ecology,School of Life Science,Nanjing University,Nanjing 210023,China;Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems,Chinese Academy of Sciences,Guangzhou 510650,China)

机构地区：[1]南京信息工程大学环境科学与工程学院,江苏省大气环境监测与污染控制高技术研究重点实验室,大气环境与装备技术协同创新中心,南京210044 [2]南京大学生命科学学院生态学系,南京210023 [3]中国科学院退化生态系统植被恢复与管理院重点实验室,广州510650

出　　处：《生态学报》2024年第4期1313-1323,共11页Acta Ecologica Sinica

基　　金：国家自然科学基金(42275128);中国科学院退化生态系统植被恢复与管理院重点实验室开放基金(VRMDE2203)。

摘　　要：大气氮沉降水平持续升高导致的外源氮输入增加,强烈影响了陆地生态系统的碳循环。目前,已有大量报道证实了氮沉降升高对全球陆地植被固碳的积极影响。虽然之前大部分研究将这一结果归因于光合作用增强导致的地上生物量增加,但最近的研究发现长期氮添加对植物地下根系的影响也同样重要。归纳整理了181篇公开发表的我国野外模拟氮沉降试验结果,采用整合分析(Meta-analysis)方法,定量评估了氮添加对我国陆地植被地上-地下生物量分配的影响特征和不同生态系统类型及施氮方式之间的影响差异。通过分析地上-地下生物量分配对氮添加的响应差异来探究植被碳增益对长期大气氮沉降增加的潜在响应机制。结果表明,氮添加显著增强了我国陆地植被的光合作用及碳固存,且植物碳增益在不同生态系统类型及施氮制度间有所差异。植物叶片的氮含量显著增加,使得叶片碳氮比及凋落物碳氮比显著降低,但并未显著影响细根的碳氮比。氮添加总体上显著提高了植物的净光合速率,但降低了光合利用效率。地上生物量,凋落物产量和根生物量平均分别显著增加了38%,17%和18%,总体上植物地上部分对氮添加的响应程度比地下部分更高。然而,不同生态系统类型的地上-地下生物量分配对氮添加的响应并不一致。在受氮限制的温带森林及草地生态系统,地上生物量显著增加而根生物量的变化并不显著,但是在富氮的亚热带森林则相反,氮添加显著增加了根生物量而地上生物量增长不显著。回归分析表明,地上生物量并不随着根生物量的增加而线性增加,反而呈现先增加后降低的趋势。此外,植物的净光合速率和光合氮利用效率随着叶片氮含量的增加,也呈现先增加后降低的趋势。这暗示着大气氮沉降增加下的植物的碳分配策略是变化的,随着外源氮添加的持续输�Increasing exogenous nitrogen(N)input due to(C)cycle of terrestrial ecosystems.Nowadays,a large number of studies have demonstrated the positive effects of increasing N deposition on globally terrestrial vegetation C storage.While most of previous studies attributed it to the increased plant above-ground biomass due to the enhanced photosynthesis,recent studies have found that the effects of long-term N addition on below-ground biomass were also important for terrestrial C sinks.This study synthesized data from 181 available published papers across the Chinese major terrestrial ecosystems,and performed a meta-analysis to quantitatively evaluate the impact of the elevated N inputs on the biomass allocation of above-and below-ground in the Chinses terrestrial vegetation,as well as the differences between ecosystem types and fertilization regimes.We analyzed the different responses of plant biomass allocation to N enrichment to investigate the potential mechanisms of vegetation C gain response to chronically elevated atmospheric N deposition.Our results showed that N addition significantly enhanced the net photosynthetic rate and C storage in the Chinese terrestrial vegetation,and the responses of plant biomass allocation to N addition differed considerably between the different ecosystem types or fertilization regimes.The N concentration in the leaves of terrestrial plants significantly increased,and hence significantly reduced the C/N ratios in the leaves and litter,but did not significantly affect the C/N ratio in fine roots.N addition significantly increased plant net photosynthetic rate,but decreased photosynthetic nitrogen-use efficiency.On average,the above-ground biomass,litter mass,as well as root biomass increased significantly by 38%,17%,and 18%,respectively.The magnitude of response of shoot to N addition was higher than that of the root in general.However,the responses of above-and below-ground biomass allocation to N addition were inconsistent in different ecosystem types.We found that the N addition s

关 键 词：生物量 整合分析 大气氮沉降 陆地生态系统 碳分配策略 

分 类 号：Q948[生物学—植物学]