暖温带森林外生菌根树种优势和植物多样性对土壤氮素周转的影响  

Impact of ectomycorrhizal tree dominance and species richness on soil nitrogen turnover in a warm temperate forest

作　　者：何欣怡 潘玉梅 祝燕[4] 陈佳仪 张思榕 张乃莉 Xinyi He;Yumei Pan;Yan Zhu;Jiayi Chen;Sirong Zhang;Naili Zhang(State Key Laboratory of Efficient Production of Forest Resources,College of Forestry,Beijing Forestry University,Beijing 100083,China;Key Laboratory for Silviculture and Conservation of Ministry of Education,College of Forestry,Beijing Forestry University,Beijing 100083,China;Ecological Observation and Research Station of Heilongjiang Sanjiang Plain Wetlands,National Forestry and Grassland Administration,Shuangyashan,Heilongjiang 518000,China;State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,Chinese Academy of Sciences,Beijing 100093,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]北京林业大学林学院林木资源高效生产全国重点实验室,北京100083 [2]北京林业大学林学院森林培育与保护教育部重点实验室,北京100083 [3]国家林业和草原局黑龙江三江平原湿地生态观测研究站,黑龙江双鸭山518000 [4]中国科学院植物研究所植被与环境变化国家重点实验室,北京100093 [5]中国科学院大学,北京100049

出　　处：《生物多样性》2024年第9期77-90,共14页Biodiversity Science

基　　金：北京市自然科学基金(5222016);国家重点研发项目(2023YFF1304003-02)。

摘　　要：外生菌根(ectomycorrhizal,EcM)树种是温带森林植物群落的优势树种,是驱动包括土壤氮素周转在内的生态系统功能的主要植物类群;EcM树种在群落中的占比往往会影响植物多样性与生态系统功能的关系,但其生物学驱动机制尚不清楚。本项研究依托东灵山暖温带落叶阔叶林动态监测样地,通过分析土壤无机氮(NH_(4)^(+)-N和NO_(3)^(-)-N)含量、净氮矿化速率(R_(m))和硝化速率(R_(n)),以及氨氧化细菌(AOB)和氨氧化古菌(AOA)的绝对生物量,探索树种多样性和EcM树种比例以及其他生物、非生物因素对不同海拔和土层深度氮素周转及其有效性的影响。结果表明:(1)相比于树种多样性,EcM树种比例对土壤氮素周转及其有效性的影响更为强烈且表现出生境依赖性,即在低海拔缓坡、中海拔陡坡,尤其是中海拔陡坡,土壤R_(m)、R_(n)以及NH_(4)^(+)-N和NO_(3)^(-)-N的含量随着EcM树种比例增加而显著降低。此外,在低海拔缓坡土壤NH_(4)^(+)-N含量随着树种多样性的增加而显著降低,而R_(n)则显著增加;(2)相对于表土层,EcM树种比例更强烈地限制亚表土层和深层土壤的无机氮含量,即NH_(4)^(+)-N和NO_(3)^(-)-N含量均随着EcM树种比例增加而显著降低;(3)土壤R_(m)、R_(n)以及NH_(4)^(+)-N和NO_(3)^(-)-N含量与EcM树种、树种多样性、土壤含水量、AOA及AOB表现出较强的相关性。多元线性回归结果表明,土壤含水量、AOA和AOB对土壤R_(m)、R_(n)以及NH_(4)^(+)-N和NO_(3)^(-)-N含量的变差具有较高的解释量。综上所述,暖温带森林生态系统EcM树种和树种多样性对土壤氮素周转及其有效性的影响表现出较强的生境和土层差异,这些结果有助于提升暖温带森林树种多样性、菌根树种类群与生态系统功能关系的理论认知,对于温带森林生物多样性保护、可持续管理方面具有重要的科学意义。Aims:Ectomycorrhizal(EcM)trees are the dominant tree species in temperate forests and play a vital role in driving ecosystem functions,particularly soil nitrogen turnover.The proportion of EcM tree species within a community is believed to influence the relationship between plant diversity and ecosystem function;however,the underlying mechanisms remain unclear.In this study,we aim to investigate the effects of tree species richness,the proportion of EcM tree species,and various biotic and abiotic factors on nitrogen turnover and availability in soil collected from different habitats and depths within a warm-temperate forest ecosystem.Methods:Soil samples were collected over time from a 20-ha plot in the warm-temperate deciduous broad-leaved forest of Dongling Mountain.Each sample was analyzed to determine the net nitrogen mineralization rate(R_(m)),nitrification rate(R_(n)),and concentration of inorganic nitrogen(NH_(4)^(+)-N and NO_(3)^(-)-N).Soil nitrogen mineralization and nitrification are crucial ecological processes that indicate soil nitrogen availability.We also assessed the presence of ammonia-oxidizing archaea(AOA)and ammonia-oxidizing bacteria(AOB),which are key drivers of soil nitrogren processes.Result:The proportion of EcM tree species had a stronger,and habitat-dependent effect on soil nitrogen turnover and availability compared to tree species richness.Specifically,R_(m),R_(n),NH_(4)^(+)-N,and NO_(3)^(-)-N significantly decreased with increasing proportions of EcM tree species in low altitude areas with gentle slopes and mid altitude steep slopes.Additionally,while NH_(4)^(+)-N significantly decreased,R_(n) increased with greater tree species richness in low altitude areas with gentle slopes.Soil inorganic nitrogen was limited by the proportion of EcM tree species in subsoil and deep soil layers than in topsoil,with both NH_(4)^(+)-N and NO_(3)^(-)-N significantly decreasing as the proportion of EcM tree species increased.Further,R_(m),R_(n),NH_(4)^(+)-N,and NO_(3)^(-)-N showed stong correaltions

关 键 词：土壤无机氮 土壤净氮转化速率 外生菌根树种 树种多样性 暖温带森林生态系统 

分 类 号：S718.5[农业科学—林学]