氮沉降对4个树种外生菌根群落结构和酶活性功能的影响  

Effects of nitrogen deposition on ectomycorrhizal structure and enzyme activity of four tree species

作　　者：宁晨 马伟[1,2] 唐盼婷 杨小婕 田雨洋 毛奥平 刘婷 雷志刚 NING Chen;MA Wei;TANG Panting;YANG Xiaojie;TIAN Yuyang;MAO Aoping;LIU Ting;LEI Zhigang(College of Life Science&Technology,Central South University of Forestry&Technology,Changsha 410004,Hunan,China;National Engineering Laboratory for Applied Technology of Forestry&Ecology in South China,Central South University of Forestry&Technology,Changsha 410004,Hunan,China;The Third Surveying&Mapping Institute of Hunan Province,Changsha 410018,Hunan,China)

机构地区：[1]中南林业科技大学生命科学与技术学院,湖南长沙410004 [2]中南林业科技大学南方林业生态应用技术国家工程实验室,湖南长沙410004 [3]湖南省第三测绘院,湖南长沙410018

出　　处：《中南林业科技大学学报》2024年第2期73-82,共10页Journal of Central South University of Forestry & Technology

基　　金：国家自然科学基金面上项目(32271731);国家自然科学基金青年基金(31901118);湖南省教育厅科研重点项目(21A0164);湖南省教育厅科学研究优秀青年项目(22B0241);长沙市杰出创新青年培养计划(kq2209018);长沙市自然科学基金(kq2208409)。

摘　　要：【目的】氮沉降水平不断上升对森林生态系统产生了不同程度的影响。过量的有效氮输入导致植物根系对养分获取策略发生变化,从而改变了土壤重要微生物,如树木根系外生菌根ECM群落的结构和生态功能。了解和确定森林主要树种根系微生物群落活动受氮沉降影响的变化阈值,对于研究森林养分循环特征和可持续经营管理具有重要的指导意义。【方法】采用室内盆栽试验,选取马尾松、华山松、湿地松和火炬松4个树种进行5个梯度的氮施加(0、15、30、60、150 kg·hm^(-2)·a^(-1)),通过检测树苗的养分含量、ECM根尖酶活性,以及提取鉴定DNA,分析不同松树在氮沉降水平下外生菌根群落结构和酶活性功能的动态变化。【结果】1)大多数松科树苗的菌根胞外酶活性在氮浓度30 kg·hm^(-2)·a^(-1)时达到了阈值;以分解纤维素为主的G酶在华山松、湿地松和火炬松中随着N浓度增加而持续提高,即便施氮水平达到当地氮沉降水平的10倍(150 kg·hm^(-2)·a^(-1)),酶活性仍未达到阈值;2)对菌根群落进行分析得出,棉革菌属Tomentella在4个树种中都为优势物种,而须腹菌属Rhizopogon、深色内隔菌Phialocephala会因宿主不同呈现不同的侵染丰度;3)华山松和火炬松的ECM菌根群落酶活性在不同氮浓度间无明显差异,即呈现生态冗余。【结论】在长期氮输入水平升高的情况下,ECM群落组成会因宿主植物和氮沉降水平的变化发生调整,而这一过程中会以变化阈值作为判断标准,该过程对于土壤养分循环中碳氮磷循环以及森林经营管理具有重要的指导意义。【Objective】The increasing levels of nitrogen deposition have varying impacts on forest ecosystems.Excessive input of available nitrogen leads to changes in plant root strategies for nutrient acquisition,consequently altering the structure and ecological functions of important soil microorganisms such as ectomycorrhizal(ECM)communities associated with tree roots.Understanding and determining the threshold of changes in root-associated microbial community activity in response to nitrogen deposition are of crucial importance for studying nutrient cycling characteristics and sustainable management practices in forests.【Method】The present experiment employed an indoor pot experiment,selecting four tree species,namely Pinus massoniana,Pinus armandii,Pinus elliottii and Pinus taeda.Five gradients of nitrogen addition(0,15,30,60,150 kg·hm^(-2)·a^(-1))were applied to study the dynamic changes in the structure and enzymatic activity of ECM communities under different nitrogen deposition levels.The nutrient content of seedlings and ECM root tip enzyme activity were analyzed to investigate the variations in the ECM community structure and enzymatic activity among the different pine species in response to nitrogen deposition levels.【Result】1)The extracellular enzyme activity of most pine seedlings reached a threshold at 30 kg·hm^(-2)·a^(-1).β-D-Glucosidase,mainly involved in cellulose decomposition,continues to increase with increasing N concentration in slash pine,loblolly pine,and China Armand pine.Even when N application reached 10 times the local N deposition level(150 kg·hm^(-2)·a^(-1)),the enzyme activity still did not reach the threshold;2)The analysis of the ECM community revealed that the genus Tomentella was a dominant species in all four tree species,while the abundance of the genera Rhizopogon and Phialocephala varies depending on the host species;3)There was no significant difference in the enzyme activities of ECM mycorrhizal communities of P.armandii and P.taeda at different N concentrations,

关 键 词：菌根 松科植物 氮沉降 胞外酶活性 生态冗余 

分 类 号：S718.554.2[农业科学—林学]