氮添加对贝加尔针茅草原土壤细菌群落结构的影响

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刘红梅, 杨殿林, 张海芳, 赵建宁, 王慧, 张乃琴. 氮添加对贝加尔针茅草原土壤细菌群落结构的影响. 草业学报, 2019,28(9): 23-32
LIU Hong-mei, YANG Dian-lin, ZHANG Hai-fang, ZHAO Jian-ning, WANG Hui, ZHANG Nai-qin. Effects of nitrogen addition on the soil bacterial community structure of Stipa baicalensis steppe . Acta Prataculturae Sinica,2019,28(9): 23-32 复制到剪切板

Doi:10.11686/cyxb2019241
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氮添加对贝加尔针茅草原土壤细菌群落结构的影响

刘红梅¹, 杨殿林^1,^*, 张海芳¹, 赵建宁¹, 王慧¹, 张乃琴^2,^*

1.农业农村部环境保护科研监测所,农业农村部产地环境污染防控重点实验室,天津市农业环境与农产品安全重点实验室,天津300191

2.德州学院,生态与园林建筑学院,山东德州253023

*通信作者: E-mail:yangdianlin@caas.cn, nqzh67@126.com

作者简介:刘红梅(1976-),女,河北沧州人,副研究员,博士。E-mail: liuhongmei@caas.cn

收稿日期: 2019-04-10

基金项目:国家自然科学基金面上项目(41877343)资助

摘要

为揭示不同氮添加量对贝加尔针茅草原土壤细菌群落结构的影响,依托长期定位试验,采集8个氮添加水平(0、15、30、50、100、150、200、300 kg N·hm^-2·yr^-1)下0~10 cm土层土壤,利用高通量测序技术,分析不同氮添加水平下土壤细菌群落结构特征及其与土壤化学性质的关系。结果表明:随着氮添加水平增加,细菌Alpha多样性指数呈现先增加后降低的趋势,7个氮添加处理的Alpha多样性指数与对照相比无显著差异。在群落中占主导的细菌门类有酸杆菌门(19.01%~38.31%)、变形菌门(6.64%~17.11%)、放线菌门(5.07%~16.06%)、疣微菌门(3.57%~7.40%)、绿弯菌门(3.38%~8.42%)和芽单胞菌门(0.87%~1.81%)。随着氮添加水平的增加,占主导的细菌门类相对丰度表现出不同的变化趋势。氮添加改变了土壤细菌群落结构,且高氮添加对土壤细菌群落结构影响高于低氮添加。相关性分析表明,土壤pH、硝态氮、铵态氮和全磷含量是影响细菌群落结构的主要因素,其中土壤pH对细菌群落结构的影响最大。

关键词: 氮添加; 贝加尔针茅草原; 细菌群落; 多样性; 高通量测序

Effects of nitrogen addition on the soil bacterial community structure of Stipa baicalensis steppe

LIU Hong-mei¹, YANG Dian-lin^1,^*, ZHANG Hai-fang¹, ZHAO Jian-ning¹, WANG Hui¹, ZHANG Nai-qin^2,^*

1.Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, MARA, Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety, Tianjin 300191, China

2.Agronomy Department of Dezhou University, Department of Ecology and Landscape Architecture, Dezhou 253023, China

*Corresponding author: E-mail:yangdianlin@caas.cn, nqzh67@126.com

Abstract

This research evaluated the responses of the soil bacterial community structure and diversity to different nitrogen (N) addition levels in Stipa baicalensis steppe. High-throughput sequencing technology was used to study the changes in soil under different N treatments (0, 15, 30, 50, 100, 150, 200, 300 kg N·ha^-1·yr^-1). Soil samples were collected from the 0-10 cm soil layer of the eight different N treatments. The Alpha diversity index of the bacterial community was highest in the mid-range of tested N treatments and lower at low and high N rates. There was no significant difference in Alpha diversity index between the seven N treatments and the control. The dominant bacterial phyla were Acidobacteria (19.01%-38.31%), Proteobacteria (6.64%-17.11%), Actinobacteria (5.07%-16.06%), Verrucomicrobia (3.57%-7.40%), Chloroflexi (3.38%-8.42%), Gemmatimonadetes (0.87%-1.81%). The relative abundance of the dominant bacteria and the structure of the soil bacterial community were both affected by the N addition level. The effect of high N addition on the soil bacterial community structure was greater than that of low N addition. A correlation analysis showed that the bacterial community structure was mainly influenced by the pH, nitrate nitrogen, ammonium nitrogen and total phosphorus levels, with pH being the factor most influencing community structure.

Keyword: nitrogen addition; Stipa baicalensis steppe; bacterial community; diversity; high-throughput sequencing technology

文章图片

近几十年来, 由于化石燃料燃烧, 化肥施用等人类活动, 大气氮沉降呈现急剧增加趋势^[1], 导致了一系列生态环境问题。氮沉降增加会降低植物多样性^[2]、降低微生物生物量碳氮比^[3], 改变土壤微生物群落结构^{[4, 5]}, 影响微生物介导的碳氮循环过程^[6], 从而导致生态系统稳定性降低^[7]。我国草地面积占全国国土面积的41.7%, 在全球碳氮循环和气候变化响应中发挥重要作用。

氮元素是干旱和半干旱草原土壤微生物生长繁殖的主要限制因子之一^[8]。氮沉降增加会缓解草原生产中氮的限制, 提高土壤中有效态氮含量, 从而增加草原生产力。但过多的氮输入会增加土壤酸化和硝态氮淋溶的危险, 导致生态系统功能退化或丧失。氮沉降或氮添加引起北方温带草原地上植物群落组成、多样性、优势植物光合特征、叶片功能特性改变^{[9, 10]}, 影响土壤化学性质和微生物学特性^[11]以及增加温室气体排放^{[12, 13]}。土壤细菌是土壤微生物的重要组成部分, 在土壤有机质分解、养分转化等生态过程中有着不可或缺的地位^[14]。土壤细菌群落结构及多样性变化是表征土壤质量变化的重要指标^[15]。因此研究氮沉降增加对土壤细菌群落的影响具有重要意义。一些研究表明氮添加会影响土壤细菌优势菌群丰度, 改变土壤细菌群落结构^[16]。另一些研究表明, 短期施氮不会对土壤细菌群落产生显著影响, 但高氮处理会显著改变敏感菌群相对丰度, 富营养型细菌丰度增加, 而贫营养型类群丰度降低^{[17, 18, 19]}。由于氮添加量、氮添加时间和研究对象不同, 土壤细菌群落对氮沉降或氮添加响应不同。

贝加尔针茅(Stipa baicalensis)草原是亚洲中部草原区所特有的草原群系, 在我国畜牧业生产中占有重要地位。气候模拟研究表明, 中国北方草原氮沉降将会持续增加^[20]。本研究以贝加尔针茅草原为研究对象, 施氮模拟氮沉降增加, 利用Illumina Miseq高通量测序技术, 探讨不同氮添加水平下土壤细菌多样性、群落结构组成变化及其与土壤化学性质的关系, 为有效应对氮沉降增加并提高草原生态系统功能提供理论依据。

1 材料与方法

1.1 试验地概况

试验区域概况、试验开始前土壤理化性质及试验设计见参考文献[11]。试验地位于内蒙古自治区贝加尔针茅草原(48° 27'-48° 35' N, 119° 35'-119° 41' E)。海拔760~770 m, 年均降水量为328.7 mm, 年均气温-1.6 ℃。植被类型为贝加尔针茅草甸草原, 优势植物种类主要为贝加尔针茅和羊草(Leymus chinensis)。共有植物66种, 分属21科49属。土壤类型为暗栗钙土。

1.2 样地设置与样品采集

于2010年6月开始模拟氮沉降的氮添加试验。设8个外源氮添加处理水平, 依次为:对照N₀, 低氮添加(15、30、50 kg N· hm^-2· yr^-1)分别记为N₁₅、N₃₀和N₅₀, 高氮添加(100、150、200、300 kg N· hm^-2· yr^-1)分别记为N₁₀₀、N₁₅₀、N₂₀₀和N₃₀₀。于每年6月中旬和7月中旬分两次进行氮添加, 氮肥为NH₄NO₃, 将其溶于水后均匀喷洒在各小区内。小区面积8 m× 8 m, 小区间设2 m隔离带, 4次重复, 重复间设5 m隔离带。

于2015年8月中旬采集土壤样品。按照S型取样法在每个小区选取10个点, 用土钻取0~10 cm土层土壤样品混合均匀。去除植物根系、石砾等杂物, 装入无菌封口袋, 放入冰盒中带回实验室。过2 mm筛后, 将其分成两份, 一份于-20 ℃低温保存, 用于DNA提取和土壤速效养分分析, 另一份土样于室内自然风干后, 用于土壤化学指标测定。

1.3 土壤化学指标测定

采用玻璃电极法(土水质量比1.0∶ 2.5)测定土壤pH, 采用重铬酸钾外加热法测定土壤总有机碳(organic carbon), 采用凯氏定氮法测定土壤全氮(total nitrogen), 采用钼锑抗比色法测定土壤全磷(total phosphorus), 采用2 mol· L^-1氯化钾溶液提取-流动分析仪(AA3, 德国)测定土壤硝态氮(nitrage nitrogen, N ${O_{3}}^{-}$ -N)和铵态氮(ammonia nitrogen, N ${H_{4}}^{+}$ -N), 采用碳酸氢钠提取-钼锑抗比色法测定土壤速效磷(available phosphorus)。上述测定方法参照鲍士旦^[21]《土壤农化分析》第三版。

1.4 土壤细菌16S rDNA克隆文库构建和Illumina测序

采用Power Soil^®DNA Isolation Kit试剂盒提取土壤总DNA, 提取步骤按试剂盒说明书进行。提取后的土壤总DNA用1%琼脂糖凝胶电泳进行检测, 使用超微量分光光度计(NanoDrop2000, 德国)进行质检。采用Qubit 2.0 DNA检测试剂盒对提取的DNA进行精确定量, 以确定PCR反应加入的DNA量。选择细菌V3~V4区的16S rDNA序列进行PCR扩增。扩增引物序列为336F:5'-GTACTCCTACGGGAGGCAGCA-3'和806R:5'-GGACTACHVGGGTWTCTAAT-3'。使用带barcode的特异引物, 区分个体样本。PCR扩增体系为:10× Pyrobest Buffer 5 μ L, dNTPs (2.5 mmol· L^-1)4 μ L, 引物F(10 μ mol· L^-1)2 μ L, 引物R(10 μ mol· L^-1)2 μ L, Pyrobest DNA Polymerase(2.5 U· μ L^-1)0.3 μ L, DNA模板30 ng, 加去离子水到50 μ L。反应条件为:95 ℃预变性, 5 min; 95 ℃ 30 s, 56 ℃ 30 s, 72 ℃ 40 s进行25个循环; 72 ℃延长10 min。扩增反应完成后, 对PCR产物进行琼脂糖凝胶电泳, 采用上海生工琼脂糖回收试剂盒(cat:SK8131)进行DNA回收。使用Qubit2.0荧光定量系统测定回收产物浓度, 将等摩尔浓度的扩增子汇集到一起, 混合均匀后进行测序。测序由北京奥维森基因科技有限公司完成, 采用Illumina Miseq测序平台进行Paired-end高通量测序。每个土壤样品3个生物学重复。

1.5 数据分析

下机数据经过Trimmomatic、Readfq(vertion 6.0)和Flash(version 1.2.10)软件预处理, 去除低质量reads, 然后根据双末端测序读长(PE reads)之间的重叠(overlap)关系将成对的reads拼接成一条序列。去除tags两端的barcode序列及引物序列, 去除嵌合体及其短序列等后得到高质量的clean tags, 拼接过滤后的clean tags, 在0.97相似度下利用QIIME软件将其聚类为用于物种分类的操作分类单元(operational taxonomic units, OTU), 统计各样品OTU中的丰度信息。对比GreenGenes数据库, 对每个OTU进行物种注释。应用QIIME(version 1.7.0)计算样品的多样性指标。Alpha多样性是对单个样品物种多样性的分析, 基于OTU的结果, 计算Chao1指数、观测值指数(observed species)、谱系多样性指数(phylogenetic diversity, PD whole tree)和香农指数(Shannon)来进行生物多样性分析。Observed species、PD whole tree和Chao1指数反映样品中群落的丰度, 其值越大表明群落物种的丰富度越高。Shannon指数表示细菌群落多样性程度, 其值越大, 表明群落多样性越高。采用主成分分析(principal component analysis, PCA)和非度量多维尺度分析(nonmetric multidimensional scaling, NMDS)分析不同氮添加水平处理与对照间细菌群落组成的差异性。采用单因素方差分析(one-way ANOVA)分析不同氮添加处理之间的土壤化学性质、细菌丰度和多样性指数差异, 采用Pearson相关性分析土壤细菌多样性指数、优势类群与土壤化学因子之间的相关性。

2 结果与分析

2.1 土壤化学性质变化

连续6年不同氮添加处理条件下, 土壤化学性质变化见表1。低氮添加(N₁₅、N₃₀和N₅₀)处理下土壤有机碳、硝态氮含量与N₀相比无显著差异(P> 0.05); 高氮添加(N₁₅₀、N₂₀₀和N₃₀₀)处理下土壤有机碳含量显著高于N₀; 高氮添加(N₁₀₀、N₁₅₀、N₂₀₀和N₃₀₀)处理下土壤硝态氮和速效磷含量显著高于N₀。N₃₀、N₅₀、N₁₀₀、N₁₅₀、N₂₀₀和N₃₀₀的土壤pH均显著低于N₀(P< 0.05)。N₁₅、N₃₀、N₅₀、N₁₀₀、N₁₅₀和N₂₀₀处理的C/N与N₀相比无显著差异(P> 0.05), N₃₀₀则显著高于N₀(P< 0.05)。土壤全氮含量和N/P在不同氮添加处理间无显著差异(P> 0.05)。

表1 不同氮添加处理下土壤化学性质的变化 Table 1 Soil chemical properties in different nitrogen addition treatments

土壤化学性质 Soil chemical properties	处理 Treatments
土壤化学性质 Soil chemical properties	N₀	N₁₅	N₃₀	N₅₀	N₁₀₀	N₁₅₀	N₂₀₀	N₃₀₀
pH	6.98± 0.16a								6.85± 0.03a	6.54± 0.01b	6.43± 0.03b	5.99± 0.12c	5.77± 0.09d	5.70± 0.06d	5.19± 0.05e
有机碳Organic C (g· kg^-1)	39.43± 0.47cd								38.79± 0.22d	35.70± 0.77d	39.75± 0.58cd	40.04± 0.41c	44.57± 0.43b	44.87± 0.50b	61.42± 0.50a
全氮Total N (g· kg^-1)	2.31± 0.21a								2.41± 0.39a	2.26± 0.22a	2.27± 0.20a	2.50± 0.38a	2.56± 0.09a	2.33± 0.13a	2.39± 0.56a
全磷Total P (g· kg^-1)	0.43± 0.02a								0.42± 0.01a	0.39± 0.00b	0.39± 0.01b	0.43± 0.02a	0.41± 0.02ab	0.38± 0.01b	0.39± 0.01b
硝态氮N ${O_{3}}^{-}$ -N (mg· kg^-1)	1.82± 0.04e								1.92± 0.23e	2.93± 0.24e	2.82± 0.07e	9.90± 0.13d	37.67± 0.48c	48.09± 1.46b	66.21± 0.98a
铵态氮N ${H_{4}}^{+}$ -N (mg· kg^-1)	27.42± 1.28c								21.11± 0.43d	30.97± 2.24c	66.26± 2.06a	61.16± 3.88b	27.60± 0.85c	29.25± 1.05c	30.32± 0.80c
速效磷Available P (mg· kg^-1)	4.58± 0.14c								3.89± 0.28d	4.03± 0.14c	3.89± 0.28d	5.69± 0.14b	6.94± 0.28a	5.28± 0.56b	5.83± 0.48b
碳氮比C/N	17.15± 1.36b								16.38± 2.59b	15.87± 1.21b	17.59± 1.30b	16.25± 2.33b	17.40± 0.41b	19.32± 0.84b	26.66± 6.21a
氮磷比N/P	5.41± 0.22a								5.72± 0.78a	5.75± 0.47a	5.80± 0.37a	5.80± 0.67a	6.31± 0.12a	6.07± 0.15a	6.07± 1.33a

Note: Different small letters in the same line mean significant difference at 0.05 level among treatments.

注:同行不同字母表示处理间差异显著(P< 0.05)。

表1 不同氮添加处理下土壤化学性质的变化 Table 1 Soil chemical properties in different nitrogen addition treatments

2.2 不同氮添加处理对Alpha多样性指数的影响

通过Miseq高通量测序共得到有效序列1036564条, 质量控制后得到优质序列919775条, 每个处理OTU数为18264~27426。不同氮添加处理下土壤细菌Alpha多样性指数变化见表2。7个氮添加处理的Chao1、Observed species、PD whole tree和Shannon指数与对照相比无显著差异。N₁₅、N₅₀、N₁₀₀和N₁₅₀处理的Chao1和Observed species指数显著高于N₃₀₀。

表2 不同氮添加处理条件下土壤细菌群落Alpha多样性指数 Table 2 Alpha diversity index of soil bacterial community under different nitrogen addition treatments

土壤细菌Alpha多样性与土壤化学因子的相关性分析结果见表3。Observed species与土壤有机碳含量呈显著负相关关系(P< 0.05)。Chao1、Observed species、PD whole tree和Shannon指数均与全氮含量呈极显著正相关关系(P< 0.01); Chao1与全磷含量呈显著正相关关系(P< 0.05), Observed species、PD whole tree和Shannon指数与全磷含量呈极显著正相关关系(P< 0.01)。表明影响土壤Alpha多样性指数的主要土壤环境因子是土壤全氮和全磷含量。

表3 土壤Alpha多样性指数与土壤化学因子的相关性 Table 3 Correlation analysis between soil bacterial Alpha diversity index and soil chemical properties

多样性指数Diversity index	N输入量 N input	pH	有机碳 Organic C	全氮 Total N	全磷 Total P	硝态氮 N ${O_{3}}^{-}$ -N	铵态氮 N ${H_{4}}^{+}$ -N	速效磷 Available P
Chao1指数Chao1 index	-	-	-	0.637^{* *}	0.482^*	-	-	-
观测值指数Observed species	-	-	-0.407^*	0.626^{* *}	0.558^{* *}	-	-	-
谱系多样性PD whole tree	-	-	-	0.669^{* *}	0.581^{* *}	-	-	-
香农指数Shannon index	-	-	-	0.602^{* *}	0.578^{* *}	-	-	-

Note:* indicates correlation is significant at 0.05 level, * * indicates correlation is significant at 0.01 level, “ -” indicates no significant correlation. The same below.

注:“ * ” 表示显著相关(P< 0.05), “ * * ” 表示极显著相关(P< 0.01), “ -” 表示无显著相关(P≥ 0.05)。下同。

表3 土壤Alpha多样性指数与土壤化学因子的相关性 Table 3 Correlation analysis between soil bacterial Alpha diversity index and soil chemical properties

2.3 不同氮添加处理土壤细菌群落结构和组成

各个样品在门分类水平上具有较高的多样性, 在群落中占主导的细菌门类有酸杆菌门(Acidobacteria)(19.01%~38.31%), 变形菌门(Proteobacteria)(6.64%~17.11%), 放线菌门(Actinobacteria)(5.07%~16.06%), 疣微菌门(Verrucomicrobia)(3.57%~7.40%), 绿弯菌门(Chloroflexi)(3.38%~8.42%)和芽单胞菌门(Gemmatimonadetes)(0.87%~1.81%)(图1)。N₅₀、N₁₀₀和N₃₀₀的酸杆菌门相对丰度显著低于N₀。N₃₀、N₅₀、N₁₀₀、N₁₅₀、N₂₀₀和N₃₀₀的疣微菌门相对丰度显著低于N₀。N₃₀、N₅₀、N₁₀₀和N₁₅₀的芽单胞菌门相对丰度显著高于N₀。7个氮添加处理的绿弯菌门相对丰度均显著低于N₀。

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	图1 不同氮添加处理下土壤细菌门类相对丰度变化Fig.1 Relative abundances of the dominant bacterial phylum for different nitrogen addition treatments

不同氮添加处理之间有显著差异的OTUs丰度的PCA如图2所示, 前两个主成分分别占细菌群落变异的36.97%和12.52%。高氮添加(N₁₅₀、N₂₀₀、N₃₀₀)位于主成分1右侧, 而N₀、N₁₀₀与低氮添加(N₁₅、N₃₀和N₅₀)位于主成分1左侧。说明高氮添加有显著差异OTUs丰度组成相似, 而N₀、N₁₅、N₃₀、N₅₀与N₁₀₀有显著差异OUTs丰度组成相似。非度量多维尺度分析常用于比较不同样本组之间的差异, 样品点的分布代表了样本与样本之间的相似度程度。基于各氮添加处理差异OTUs丰度的NMDS结果, 可以发现7个氮添加处理差异OTUs与对照处理差别显著, 且高氮添加处理与低氮添加、对照和N₁₀₀处理处于不同排序区(图3)。表明高氮添加对土壤细菌群落产生了显著影响。

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	图2 不同氮添加处理之间有显著差异的细菌OTUs丰度的PCA分析Fig.2 Principal component analysis (PCA) of pyrosequencing bacterial OTUs abundance with significant differences among different nitrogen addition treatments

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	图3 基于差异OTUs丰度的NMDS分析Fig.3 Nonmetric multidimensional scaling (NMDS) analysis based on the major different OTUs abundance

2.4 土壤细菌主要类群相对丰度与土壤化学性质的相关性

优势细菌门和土壤环境因子相关性分析结果见表4。酸杆菌门与氮输入量和硝态氮含量呈显著负相关(P< 0.05), 与铵态氮含量呈极显著负相关(P< 0.01), 与土壤pH值呈极显著正相关(P< 0.01)。变形菌门与土壤pH和全磷含量呈显著负相关(P< 0.05)。疣微菌门与氮输入量、有机碳和硝态氮含量呈极显著负相关(P< 0.01), 与土壤C/N呈显著负相关(P< 0.05), 与土壤pH和全磷含量呈极显著正相关(P< 0.01)。绿弯菌门与土壤pH和全磷含量呈极显著正相关(P< 0.01), 与氮输入量和硝态氮含量呈极显著负相关(P< 0.01), 与土壤有机碳、速效磷和N/P呈显著负相关(P< 0.05)。土壤pH与酸杆菌门、疣微菌门和绿弯菌门呈极显著正相关(P< 0.01), 与变形菌门呈显著负相关(P< 0.05)(图4), 说明氮添加通过改变土壤pH而影响了土壤细菌群落结构。

表4 土壤细菌主要类群相对丰度与土壤化学性质的相关性 Table 4 Correlation analysis between the relative abundance of soil bacterial groups and soil chemical properties

细菌类群 Bacterial groups	N输入量 N input	pH	有机碳 Organic C	全氮 Total N	全磷 Total P	硝态氮 N ${O_{3}}^{-}$ -N	铵态氮 N ${H_{4}}^{+}$ -N	速效磷 Available P	碳氮比 C/N	氮磷比 N/P
酸杆菌门Acidobacteria	-0.515^*	0.609^{* *}	-	-	-	-0.415^*	-0.534^{* *}	-	-	-
变形菌门Proteobacteria	-	-0.426^*	-	-	-0.514^*	-	-	-	-	-
放线菌门Actinobacteria	-	-	-	-	-	-	0.467^*	-	-	-
疣微菌门Verrucomicrobia	-0.734^{* *}	0.733^{* *}	-0.575^{* *}	-	0.606^{* *}	-0.678^{* *}	-	-	-0.492^*	-
绿弯菌门Chloroflexi	-0.620^{* *}	0.639^{* *}	-0.467^*	-	0.642^{* *}	-0.580^{* *}	-	-0.441^*	-	-0.493^*
芽单胞菌门Gemnatimonadetes	-	-	-	-	-	-	0.542^{* *}	-	-	-

表4 土壤细菌主要类群相对丰度与土壤化学性质的相关性 Table 4 Correlation analysis between the relative abundance of soil bacterial groups and soil chemical properties

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	图4 土壤细菌主要类群相对丰度与土壤pH的相关性Fig.4 Correlations between soil dominant bacterial phylum and soil pH

3 讨论

3.1 土壤细菌多样性对氮添加响应的综合分析

多样性指数是表征土壤微生物群落丰富度和多样性的重要指标, 多样性指数越高表明土壤微生物群落丰富度和多样性越高^[22]。杨山等^[23]对我国北方温带典型草原和郝亚群等^[17]对中亚热带杉木林(Cunninghamia lanceolata)氮添加试验表明, 短期氮添加对土壤细菌丰富度指数和多样性指数未产生显著影响。本研究表明, 随着氮添加水平的升高, 细菌丰富度指数和多样性指数总体上表现为先升高后降低的趋势, 但与对照相比无显著差异。连续6年氮添加对细菌Alpha多样性指数未产生显著性影响。高氮添加处理(300 kg N· hm^-2· yr^-1)时土壤细菌Alpha多样性指数均低于对照, 有降低趋势。Freitag等^[24]研究表明, 过量无机氮素添加不利于提高草地土壤细菌α 多样性。前人研究认为, 低氮添加缓解了细菌生长的氮限制, 细菌丰度和种类增加, 而高浓度氮添加反而会抑制土壤细菌多样性^{[25, 26]}。本研究结果与这一研究结论一致。这可能是因为本研究模拟氮沉降所用肥料为NH₄NO₃, N ${H_{4}}^{+}$ 在氧化成亚硝酸盐过程中释放出H⁺, 引起土壤酸化, 从而使不耐酸细菌物种繁殖缓慢, 物种多样性下降; 也有可能是高氮添加导致土壤中可利用性氮素含量增多, 导致喜氮微生物生长迅速^[27]。本研究中, 土壤细菌Alpha多样性与土壤化学因子的相关性分析结果表明, 土壤全氮和全磷含量是影响土壤细菌群落Alpha多样性重要因素。

3.2 土壤细菌群落结构对氮添加响应的综合分析

氮素是干旱和半干旱草原生态系统限制因子之一, 氮沉降增加会影响土壤微生物生长和繁殖以及细菌丰度和多样性变化。本研究对细菌群落种群的相对丰度分析表明, 随着氮添加水平的升高, 细菌门类相对丰度表现出不同的变化趋势。高氮添加提高了放线菌门和变形菌门相对丰度, 前人研究认为放线菌和变形菌门属于富营养型细菌, 在高氮环境中生长繁殖速度快^{[25, 28]}, 本研究结果与此一致。酸杆菌门和疣微菌门相对丰度随着氮添加量增加而降低。其可能原因是其属于寡营养类群, 这类微生物类群具有较低的生长速度和较难降解物质能力。Fierer等^[28]研究表明, 疣微菌门更适合养分含量较低的土壤条件, 这符合微生物氮矿化假说, 即在高氮环境中微生物利用较难降解碳源的能力降低^[29]。高氮添加处理中, 寡营养类群微生物与富营养类群相比有较低的竞争力。氮添加对土壤细菌群落结构的影响与氮添加水平有关。Zeng等^[25]对温带草原氮添加试验发现, 氮添加大于120 kg N· hm^-2· yr^-1显著影响土壤细菌群落结构。本研究中, 氮添加大于150 kg N· hm^-2· yr^-1显著影响贝加尔针茅草原土壤细菌群落结构。

土壤细菌生长受土壤环境因子的影响^[30], 其中土壤酸碱程度对土壤细菌群落的影响最为显著^[31]。本研究优势菌群与土壤化学性质相关分析表明(表4), 土壤pH值是影响土壤细菌群落的主要因素, 这与前人研究一致^{[25, 32, 33]}。Wang等^[34]在亚热带森林氮添加试验表明, 氮添加150 kg N· hm^-2· yr^-1显著降低土壤pH, 且土壤细菌群落组成与土壤pH呈负相关。前人研究认为, 土壤酸化对细菌群落的生态选择和不同细菌群落在酸性条件下压力下的适应性进化, 是土壤酸化导致土壤细菌群落改变的机制^[35]。疣微菌门在高氮添加处理中具有较低相对丰度, 且该类群相对丰度与土壤有机碳、硝态氮和C/N呈显著负相关。土壤硝态氮含量与酸杆菌门、疣微菌门和绿弯菌门呈显著负相关。土壤铵态氮含量与放线菌门、芽单胞菌门和酸杆菌门均有显著相关性。推测在本研究区细菌优势菌群的相对丰度变化也受到了养分有效性的驱动。Yang等^[36]研究也表明土壤化学性质包括土壤pH、无机氮含量等是影响土壤细菌群落结构的土壤环境因素。原因可能是氮添加导致草地植物群落组成发生变化^[9], 而植物凋落物分解和根系分泌物影响土壤细菌生长条件, 如土壤pH、容重、速效氮、可溶性碳等土壤理化因子不同, 导致土壤细菌可获取的营养物质和所处的环境不同, 土壤中适宜生长的细菌群落也不同。

4 结论

1)连续6年氮添加未显著改变贝加尔针茅草原土壤细菌Alpha多样性。土壤全氮和全磷含量是影响土壤细菌群落Alpha多样性的重要因素。

2)细菌群落结构与组成受氮添加水平的影响。15~100 kg N· hm^-2· yr^-1氮添加未显著改变贝加尔针茅草原土壤细菌群落结构, 150 kg N· hm^-2· yr^-1以上氮添加显著改变土壤细菌群落结构。

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[32]	Bartram A, Jiang X, Lynch M D J, et al. Exploring links between pH and bacterial community composition in soils from the craibstone experiment farm. FEMS Microbiology Ecology, 2014, 87(2): 403-415. [本文引用:1]
[33]	Lauber C L, Hamady M, Knight R, et al. Pyrosequencing-based assessment of soil pH as a predictor of soil bacterial community structure at the continental scale. Applied and Environmental Microbiology, 2009, 75(15): 5111-5120. [本文引用:1]
[34]	Wang H, Liu S R, Zhang X, et al. Nitrogen addition reduces soil bacterial richness, while phosphorus addition alters community composition in an old-growth N-rich tropical forest in southern China. Soil Biology and Biochemistry, 2018, 127: 22-30. [本文引用:1]
[35]	Zhang X M, Liu W, Zhang G M, et al. Mechanisms of soil acidification reducing bacterial diversity. Soil Biology and Biochemistry, 2015, 81: 275-281. [本文引用:1]
[36]	Yang F, Wu J W, Zhang D D, et al. Soil bacterial community composition and diversity in relation to edaphic properties and plant traits in grassland s of Southern China. Applied Soil Ecology, 2018, 128: 43-53. [本文引用:1]

2013

0.0

... 近几十年来,由于化石燃料燃烧,化肥施用等人类活动,大气氮沉降呈现急剧增加趋势^[1],导致了一系列生态环境问题 ...

2018

0.0

... 氮沉降增加会降低植物多样性^[2]、降低微生物生物量碳氮比^[3],改变土壤微生物群落结构^[4,5],影响微生物介导的碳氮循环过程^[6],从而导致生态系统稳定性降低^[7] ...

2017

0.0

2016

0.0

2014

0.0

2010

0.0

2015

0.0

2010

0.0

... 氮元素是干旱和半干旱草原土壤微生物生长繁殖的主要限制因子之一^[8] ...

2015

0.0

. 2015, 35(19):6460-6469 DOI:10.5846/stxb201403180471

Effects of nitrogen and water addition on plant species diversity and biomass of common species in the Stipa baicalensis steppe, Inner Mongolia, China

氮素和水分添加对贝加尔针茅草原植物多样性及生物量的影响

Li W J , Liu H M , Zhao J N

李文娇, 刘红梅, 赵建宁

Increases in atmospheric nitrogen deposition and changes in precipitation patterns are important phenomena related to changes in the global environment. These changes have created a series of increasingly serious ecological problems affecting the structure and function of grassland ecosystems. Therefore, grasslands have become a focus of ecological research in China and around the world in recent years. High nitrogen deposition can acidify grassland soils and lead to nutritional imbalances, decreases in biodiversity and productivity, and grassland degradation, all of which are serious threats to the function of grassland ecosystems. Precipitation can increase the efficiency of nitrogen fertilizer used by plants, and climate warming is accompanied by changes in precipitation. Studies of the interactive effects of nitrogen deposition and variation in rainfall on natural grassland ecosystems can help to increase our understanding of the responses of such ecosystems to changes in the global climate. In China, the Stipa baicalensis steppe, a type of meadow steppe, is mainly distributed in the forest steppe zone of the Songliao Plain and the east Inner Mongolian Plateau. In Inner Mongolia, farmers mainly use S. baicalensis steppe as natural pasture;therefore, it has an important role in livestock production. The aim of this study was to evaluate the responses of grassland plant community species diversity and the aboveground biomass of several common plant species to nitrogen deposition and irrigation.We set up a factorial experiment to test the interactive effects of eight nitrogen treatments and water addition in S. baicalensis steppe in Inner Mongolia in June 2010. This involved nitrogen (NH 4 NO 3 ) application levels of 0 (the control treatment, CK), 15, 30, 50, 100, 150, 200, 300 kg N hm -2 a -1 (referred to as N0, N15, N30, N50, N100, N150, N200, N300, respectively) and simulated 100 mm summer rainfall. In mid-August 2013, we established 96 1 m×1 m sample plots. The vegetation was harvested from each plot and the biomass of each species was measured to determine the effects of nitrogen and water addition on species diversity and the aboveground biomass of several common plants. Nitrogen and water application reduced plant species diversity in the steppe community, and there was a significant interaction effect between nitrogen and moisture. When water was added, increasing nitrogen application levels resulted in decreases in plant species richness, Shannon-Wiener index, and Pielou evenness index. When water was not added, increasing nitrogen application levels resulted in changes in species richness, Shannon-Wiener index, and Pielou evenness index that showed a "single-peak", but overall downward trend. Plant species differed in their responses to nitrogen and water addition. With increasing nitrogen application levels, the aboveground biomass of Leymus chinensis increased significantly, reaching a maximum at N300;the aboveground biomass of S. baicalensis , Achnatherum sibiricum , Cleistogenes squarrosa , Carex duriuscula, and Artemisia frigida first increased and then decreased, showing a "single-peak" trend;and the aboveground biomass of Potentilla acaulis , Thermopsis lanceolata , Melilotoides ruthenica , and Filifolium sibiricum decreased gradually. There was a significant interaction effect between water and nitrogen application level on the biomass of S. baicalensis , A. sibiricum, and M. ruthenica . We concluded that the changes in plant species diversity and aboveground biomass were related to nutrient application levels, water availability, their own characteristics, and interspecific and intraspecific competition.

为了解草原植物群落物种多样性和植物地上生物量对氮沉降增加和降水变化的响应,在内蒙古贝加尔针茅( Stipa baicalensis )草原,分别设置对照(N0)、1.5 g/m 2 (N15)、3.0 g/m 2 (N30)、5.0 g/m 2 (N50)、10.0 g/m 2 (N100)、15.0 g/m 2 (N150)、20.0 g/m 2 (N200)和30.0 g/m 2 (N300)(不包括大气沉降的氮量)8个氮素(NH 4 NO 3 )添加梯度和模拟夏季增加降水100mm的水分添加交互试验,研究氮素和水分添加对草原群落植物物种多样性和几种常见植物地上生物量的影响。结果表明:(1)氮素和水分的添加降低了草原群落植物物种多样性,且氮素和水分有显著的互作效应。在水分添加的条件下,随着施氮水平的增加,群落植物物种多样性减小;在无水分添加的条件下,随着施氮水平的增加,群落植物物种多样性呈先增加后减小的"单峰"变化趋势。(2)不同植物对氮素和水分添加的响应不同,随着施氮水平的增加,羊草地上生物量显著增加;贝加尔针茅、羽茅、糙隐子草、寸草苔和冷蒿先增加后减少,呈单峰曲线;星毛委陵菜、牧马豆、扁蓄豆和线叶菊地上生物量则逐渐减少。而且氮素和水分对贝加尔针茅、羽茅、扁蓄豆地上生物量有显著的交互作用。

... 氮沉降或氮添加引起北方温带草原地上植物群落组成、多样性、优势植物光合特征、叶片功能特性改变^[9,10],影响土壤化学性质和微生物学特性^[11]以及增加温室气体排放^[12,13] ...

... 原因可能是氮添加导致草地植物群落组成发生变化^[9],而植物凋落物分解和根系分泌物影响土壤细菌生长条件,如土壤pH、容重、速效氮、可溶性碳等土壤理化因子不同,导致土壤细菌可获取的营养物质和所处的环境不同,土壤中适宜生长的细菌群落也不同 ...

2016

0.0

. 2016, 25(11):76-85 DOI:10.11686/cyxb2016110

Effects of long-term nitrogen addition on photosynthetic characteristics and leaf traits of Stipa baicalensis in Inner Mongolia, China

贝加尔针茅光合特征与叶片功能特性对长期氮添加的响应

Liu H M , Li J , Huangfu C H

刘红梅, 李洁, 皇甫超河

Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China

Atmospheric nitrogen deposition is an important component phenomenon of global change, and induces a series of ecological problems. We conducted a field manipulation experiment to study the photosynthetic response and change in leaf functional traits after long-term nitrogen addition in an S.baicalensis grassland in Inner Mongolia. This study was conducted from 2010-2015. Five treatments including N 0 (0 kg N/ha), N 30 (30 kg N/ha), N 50 (50 kg N/ha), N 100 (100 kg N/ha) and N 150 (150 kg N/ha) were set up and forty-eight plots, sized 8 m×8 m, were established with 2 m strips between each plot. The objective was to determine how photosynthetic characteristics and leaf traits vary with nitrogen addition and what causes these differences. Photosynthetic traits and leaf traits differed among different nitrogen addition treatments. Net photosynthetic rate ( P n ), stomatal conductance ( G s ), transpiration rate ( T r ), photosynthetic nitrogen use efficiency (PNUE), photosynthetic energy use efficiency (PEUE) under N 30 , N 50 , N 100 , and N 150 treatments were lower or significantly lower than those under N 0 . Specific leaf area (SLA), leaf N content ( N mass ), leaf construction cost ( CC mass ), leaf N∶P under N 30 , N 50 , N 100 , N 150 treatments tended to be higher or were significantly higher than those under N 0 . Correlation analysis showed that P n was positively correlated with G s , T r , PNUE, PEUE, leaf P content ( P mass ), N mass and soil N, P while P n was negatively correlated with SLA, N mass , CC mass , soil water content and soil pH; N mass was positively correlated with SLA, CC mass and soil N, P, and N mass was negatively correlated with PNUE, PEUE, P mass , soil water content and soil pH. In conclusion, long-term nitrogen addition induced decreases in P n and nutrient use efficiency of S. baicalensis , and increases in leaf CC mass and N∶P. Soil water content and pH decreased with nitrogen addition. This suggests that water content and soil pH are two important factors affecting photosynthetic characteristics and leaf traits of S.baicalensis under different nitrogen addition regimes.

以贝加尔针茅草甸草原建群种贝加尔针茅为研究对象,通过一个连续6年氮添加野外控制试验,设置5个氮素处理:N 0 (0 kg N/hm 2 )、N 30 (30 kg N/hm 2 )、N 50 (50 kg N/hm 2 )、N 100 (100 kg N/hm 2 )、N 150 (150 kg N/hm 2 ),探讨氮沉降变化对贝加尔针茅种群光合特性与叶片功能特性变化规律及其影响因子。结果表明,氮素添加变化显著影响贝加尔针茅的净光合速率等光合特性,氮素添加处理净光合速率(net photosynthetic rate, P n )、气孔导度(stomatal conductance, G s )、蒸腾速率(transpiration rate, T r )、光合氮利用效率(photosynthetic nitrogen use efficiency, PNUE)和光合能量利用效率(photosynthetic energy use efficiency, PEUE)均低于或显著低于无氮素添加处理。氮素添加处理叶片比叶面积(specific leaf area, SLA)、叶片N含量(leaf N content, N mass )、建成成本(leaf construction cost, CC mass )、叶片N∶P均高于或显著高于无氮素添加处理。相关分析表明,5个氮素处理的 P n 与 G s 、 T r 、PNUE、PEUE、叶片P含量(leaf P content, P mass )、土壤N∶P呈显著正相关,与叶片比叶面积(SLA)、 N mass 、 CC mass 、土壤含水量、土壤pH值呈极显著负相关;叶片 N mass 与SLA、 CC mass 、土壤N∶P呈显著正相关,与PNUE、PEUE、 P mass 、土壤含水量、土壤pH值呈显著负相关。综合以上研究表明,长期氮添加会降低贝加尔针茅净光合速率、养分利用效率,提高叶片建成成本和叶片N∶P,土壤含水量和土壤pH值是引起这种改变发生的主要因子。

2017

0.0

... 1 试验地概况试验区域概况、试验开始前土壤理化性质及试验设计见参考文献[11] ...

2017

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2017

0.0

2013

0.0

... 土壤细菌是土壤微生物的重要组成部分,在土壤有机质分解、养分转化等生态过程中有着不可或缺的地位^[14] ...

2014

0.0

... 土壤细菌群落结构及多样性变化是表征土壤质量变化的重要指标^[15] ...

2018

0.0

. 2018, 38(1):244-253 DOI:10.5846/stxb201612092539

Effects of simulated nitrogen deposition and precipitation change on soil bacterial community structure in a Stipa baicalensis steppe

模拟氮沉降和降雨变化对贝加尔针茅草原土壤细菌群落结构的影响

Zhang H F , Liu H M , Zhao J N

张海芳, 刘红梅, 赵建宁

Nitrogen (N) deposition and precipitation change are important phenomena in global climate change and they can strongly influence grassland ecology. There have been many studies on the response of plant and soil microbial communities to N addition. However, the interactive effects of N addition and irrigation on soil microbial communities are still largely unknown. Studying the effects of nitrogen (N) deposition and precipitation change on soil microbial community structure is of great significance for predicting the interactive effects of multiple climate factors on grassland ecosystems in the future. Here, we simulated N deposition and precipitation change by N addition (0, 15, 30, 50, 100, 150, 200, 300 kg N hm -2 a -1 ) and irrigation (no irrigation and irrigation equivalent to 100 mm extra summer rainfall) at a test area on the Stipa baicalensis steppe. A split-plot design was adopted. Soil samples were collected with a soil probe after four years of experimental treatments. Using high-throughput sequencing technology, we evaluated the interactive effects of N addition and irrigation on the soil bacterial community structures. Statistical analyses showed that N addition and irrigation significantly ( P P < 0.05), but the relative abundance of Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes increased with high N addition levels. However, the relative abundance of Firmicutes did not significantly change. When water was added with N, the relative abundance of Verrucomicrobia increased following the increase of N addition rates and significantly increased in N200-N300, but the relative abundance of Acidobacteria, Firmicutes and Actinobacteria decreased after N addition. The relative abundance of Proteobacteria and Bacteroidetes did not significantly change under N addition combined with irrigation. The ANOVA of the split-plot design showed that N addition and irrigation interactively affected the structure of the soil bacterial community. The results of the Linear Discriminant Analysis (LDA) showed that the relative abundance of 19 bacterial phyla significantly shifted under different N and water addition rates. The changes in soil bacterial community structure were mainly related to changes in the relative abundance of the phyla Verrucomicrobia and Acidobacteria. Hence, phyla Verrucomicrobia and Acidobacteria could be used as indicator species for changes in soil bacterial community structure. In all, N addition and irrigation significantly changed the structure of the soil bacterial community. N and water addition interactively affected the relative abundance of different soil bacterial phyla.

研究氮沉降和降雨变化对土壤细菌群落结构的影响，对未来预测多个气候变化因子对草地生态系统影响的交互作用具有重要意义。以施氮和灌溉分别模拟氮沉降和降雨增加，采用高通量测序技术，研究8个氮添加水平（0、15、30、50、100、150、200、300kg N hm -2 a -1 ）和2个水分添加水平（不灌溉、模拟夏季增雨100 mm灌溉）对土壤细菌群落结构的影响。结果表明，氮素和水分输入增加后，土壤细菌群落组成、丰度均显著变化（ P 1%）表现出不同的变化趋势。疣微菌门相对丰度在常规降雨N100-N300条件下显著降低，但在氮素和水分同时添加条件下随氮添加水平升高而逐渐升高，在N200-N300时显著升高。变形菌门和拟杆菌门相对丰度在常规降雨高氮添加条件下呈升高趋势，但在水分添加时却无明显变化。酸杆菌门相对丰度在常规降雨高氮添加条件下升高，但在水分添加后呈明显下降趋势。放线菌门Actinobacteria相对丰度在常规降雨N100-N300条件下显著升高，但在水分添加后高氮添加时显著降低。厚壁菌门Firmicutes相对丰度在常规降雨条件下无显著变化，但在水分和高氮添加条件下降低。浮霉菌门Planctomycetes相对丰度在两种不同的水分添加条件下均呈先升高后降低的趋势。氮素和水分添加对土壤细菌群落结构的变化存在明显的互作效应（ P < 0.0001）。在不同氮素和水分输入条件下共有19个土壤细菌门类相对丰度有显著差异。土壤细菌群落结构的变化主要来自于疣微菌门和酸杆菌门的相对丰度变化，两者可作为土壤细菌群落结构变化的指示种。综上，氮素和水分添加显著改变了土壤细菌群落结构，氮素和水分对土壤细菌不同门类相对丰度变化存在明显的互作效应。

... 一些研究表明氮添加会影响土壤细菌优势菌群丰度,改变土壤细菌群落结构^[16] ...

2018

0.0

... 另一些研究表明,短期施氮不会对土壤细菌群落产生显著影响,但高氮处理会显著改变敏感菌群相对丰度,富营养型细菌丰度增加,而贫营养型类群丰度降低^[17,18,19] ...

... 杨山等^[23]对我国北方温带典型草原和郝亚群等^[17]对中亚热带杉木林(Cunninghamia lanceolata)氮添加试验表明,短期氮添加对土壤细菌丰富度指数和多样性指数未产生显著影响 ...

2014

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2016

0.0

2008

0.0

... 气候模拟研究表明,中国北方草原氮沉降将会持续增加^[20] ...

2000

0.0

... 上述测定方法参照鲍士旦^[21]《土壤农化分析》第三版 ...

2013

0.0

. 2013, 22(6):21-30 DOI:10.11686/cyxb20130603

Effect of rest-grazing on soil microbial community functional diversity in Stipa baicalensis steppe

休牧对贝加尔针茅草原土壤微生物群落功能多样性的影响

Li Y J , Li G , Song X L

李玉洁, 李刚, 宋晓龙

采用ＢｉｏｌｏｇＥｃｏ微平板技术和氯仿熏蒸浸提法，以自由放牧地（ｚｅｒｏｒｅｓｔｇｒａｚｉｎｇ，ＲＧ０）为对照，研究了休牧不同年限（ＲＧ３ａ、ＲＧ６ａ和ＲＧ９ａ）贝加尔针茅草原土壤微生物群落功能多样性及土壤微生物量的变化。结果表明，休牧后贝加尔针茅草原土壤微生物群落代谢活性显著升高。反映土壤微生物活性的平均颜色变化率（ AWCD ）呈以下变化趋势：ＲＧ６ａ＞ＲＧ９ａ＞ＲＧ３ａ＞ＲＧ０。ＲＧ６ａ和ＲＧ９ａ样地 AWCD 值差异不显著（ P ＞０．０５），但均显著高于ＲＧ０样地（ P ＜０．０５），ＲＧ３ａ与ＲＧ０样地差异不显著（ P ＞０．０５）。休牧不同年限贝加尔针茅草原土壤微生物群落Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ物种丰富度指数（ H ）、Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ物种均匀度指数（ E ）和Ｓｉｍｐｓｏｎ优势度指数（ D ）均为ＲＧ９ａ最高，其中ＲＧ９ａ样地犎值与其他样地差异显著（ P ＜０．０５）；不同处理 E 值差异不显著（ P ＞０．０５），ＲＧ９ａ样地 D 值与ＲＧ０差异显著（ P ＜０．０５）。主成分分析结果表明，ＲＧ０，ＲＧ３ａ和ＲＧ６ａ样地土壤微生物群落碳源利用方式及代谢功能相似，而ＲＧ９ａ样地土壤微生物群落具有不同的碳源利用方式和代谢功能。对不同碳源的分析结果表明，糖类、氨基酸类、脂类为土壤微生物利用的主要碳源。随休牧年限的增加，土壤微生物量呈增加趋势。ＲＧ９ａ土壤微生物量碳、微生物量氮（ｓｏｉｌｍｉｃｒｏｂｉａｌｂｉｏｍａｓｓＣ，Ｎ）含量均最高，分别为５９０．２０和７２．８６ｍｇ／ｋｇ。相关分析表明， AWCD 值与土壤微生物 H 值呈显著正相关（ P ＜０．０５），与 D 值呈极显著正相关（ P ＜０．０１）； H 值与 D 值呈极显著正相关（ P ＜０．０１）。 H 值、 D 值均与土壤微生物量碳（ＳＭＢＣ）呈显著正相关（ P ＜０．０５）； H 值与土壤微生物量氮（ＳＭＢＮ）呈显著正相关（ P ＜０．０５）。由此可知，休牧使草原土壤微生物代谢功能增强，土壤微生物繁殖快、数量大，从而促进土壤微生物量碳、氮含量的增加。

... 1 土壤细菌多样性对氮添加响应的综合分析多样性指数是表征土壤微生物群落丰富度和多样性的重要指标,多样性指数越高表明土壤微生物群落丰富度和多样性越高^[22] ...

2015

0.0

. 2015, 26(3):739-746

Effects of nitrogen and water addition on soil bacterial diversity and community structure in temperate grasslands in Northern China

氮水添加对中国北方草原土壤细菌多样性和群落结构的影响

Yang S , Li X B , Wang R Z

杨山, 李小彬, 王汝振

( 1 College of Environmental Science, Shenyang University, Shenyang 110044, China;  2 State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China)

In this study, we measured the responses of soil bacterial diversity and community structure to nitrogen (N) and water addition in the typical temperate grassland in northern China. Results showed that N addition significantly reduced microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) under regular precipitation treatment. Similar declined trends of MBC and MBN caused by N addition were also found under increased precipitation condition. Nevertheless, water addition alleviated the inhibition by N addition. N addition exerted no significant effects on bacterial α-diversity indices, including richness, Shannon diversity and evenness index under regular precipitation condition. Precipitation increment tended to increase bacterial α-diversity, and the diversity indices of each N gradient under regular precipitation were much lower than that of the corresponding N addition rate under increased precipitation. Correlation analysis showed that soil moisture, nitrate (NO 3 - -N) and ammonium (NH 4 + -N) were significantly negatively correlated with bacterial evenness index, and MBC and MBN had a significant positive correlation with bacterial richness and evenness. Nonmetric multidimensional scaling (NMDS) ordination illustrated that the bacterial communities were significantly separated by N addition rates, under both water ambient and water addition treatments. Redundancy analysis (RDA) revealed that soil MBC, MBN, pH and NH 4 + -N were the key environmental factors for shaping bacterial communities.

研究了我国北方典型温带草原土壤细菌多样性和群落结构对氮水添加及环境因素的响应. 结果表明: 在常规降水条件下，土壤微生物生物量碳(MBC)和微生物生物量氮(MBN)均随氮(N)梯度增加而逐渐降低；在增加降水条件下，MBC和MBN也随N梯度增加而降低，但降水增加削弱了N的抑制效应.在常规降水条件下，土壤细菌丰富度、Shannon多样性和均匀度等α-多样性指数随N梯度没有明显变化；增加降水条件下，各N梯度处理的土壤细菌α多样性指数都显著高于常规降水条件下相应的N处理梯度. 相关分析显示，土壤含水量、硝态氮(NO 3 - -N)和铵态氮(NH 4 + -N)与土壤细菌均匀度指数呈显著负相关关系；MBC和MBN与Shannon丰富度指数和均匀度指数呈显著正相关关系.土壤细菌群落非度量多维标度排序(NMDS)显示，在常规降水和增加降水处理下，土壤细菌群落结构均随N梯度增加发生明显改变.冗余分析(RDA)表明，MBC、MBN、pH和NH 4 + -N是影响土壤细菌群落结构的重要环境因子.

2005

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... Freitag等^[24]研究表明,过量无机氮素添加不利于提高草地土壤细菌#cod#x003b1 ...

2016

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... 前人研究认为,低氮添加缓解了细菌生长的氮限制,细菌丰度和种类增加,而高浓度氮添加反而会抑制土壤细菌多样性^[25,26] ...

... 高氮添加提高了放线菌门和变形菌门相对丰度,前人研究认为放线菌和变形菌门属于富营养型细菌,在高氮环境中生长繁殖速度快^[25,28],本研究结果与此一致 ...

... Zeng等^[25]对温带草原氮添加试验发现,氮添加大于120 kg N#cod#x000b7 ...

... 本研究优势菌群与土壤化学性质相关分析表明(表4),土壤pH值是影响土壤细菌群落的主要因素,这与前人研究一致^{[25, 32,33]} ...

2018

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... 前人研究认为,低氮添加缓解了细菌生长的氮限制,细菌丰度和种类增加,而高浓度氮添加反而会抑制土壤细菌多样性^[25,26] ...

2018

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... 也有可能是高氮添加导致土壤中可利用性氮素含量增多,导致喜氮微生物生长迅速^[27] ...

2012

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... Fierer等^[28]研究表明,疣微菌门更适合养分含量较低的土壤条件,这符合微生物氮矿化假说,即在高氮环境中微生物利用较难降解碳源的能力降低^[29] ...

2007

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... Fierer等^[28]研究表明,疣微菌门更适合养分含量较低的土壤条件,这符合微生物氮矿化假说,即在高氮环境中微生物利用较难降解碳源的能力降低^[29] ...

2016

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... 土壤细菌生长受土壤环境因子的影响^[30],其中土壤酸碱程度对土壤细菌群落的影响最为显著^[31] ...

2007

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. 2007, 47(5):751-756

Soil microbial diversity of artificial peashrub plantation on North Loess Plateau of China

西北黄土高原柠条种植区土壤微生物多样性分析

Zhang W , Hu Y G , Huang G H

张薇, 胡跃高, 黄国和

Peashrub ( Caragana korshinskii Kom) is a kind of excellent shrub used for dune-fixation in Loess Plateau of China. In order to explore relationship between peashrub and soil microorganisms，microbial communities diversity associated with rhizoplane，rhizosphere and bulk soil of peashrub in Loess Plateau of China were characterized based on a culture-independent approach. Three 16S rDNA gene libraries were constructed，respectively，and each different profile was used to define an operational taxonomic unit (OTU). The numbers of microorganisms decreased as root proximity decreased and a few OTUs became dominant. Phylogenetic analyses indicated that Proteobacteria was the predominant group in rhizoplane，which included many α-Proteobacteria，partially consisted of rhizobia，and γ-Proteobacteria beneficial to plant growth. In bulk soil，the most frequent OTUs were closely related to Archaea，while Acidobacteria was the dominant group in rhizosphere of peashrub. The diversity index (H′) was higher in rhizosphere than in rhizoplane and bulk soil，whereas microbial populations in rhizoplane and bulk soil had the greater dominance indices (D). It was shown that there was a significant change in microbial species composition along the root gradient，shifting from complex plant-associated bacterial community in the root habitats to a simple bacterial community in the bulk soil. These results showed that plant roots and soil conditions created a selective environment for microbial populations.

柠条锦鸡儿( Caragana korshinskii )是我国黄土高原区重要的饲用豆科灌木植物。为揭示土壤微生物与柠条种植之间的关系,采用未培养技术提取样品宏基因组DNA,分别构建柠条根表、根际和自然土16SrDNA文库,分析各文库微生物群落的变化。结果显示,随距离柠条根部渐远,微生物数量呈现递减趋势。聚类分析发现,变形杆菌纲是根表土壤区系中的优势微生物种群(70.3%),尤其存在大量α- Proteobacteria 类的能诱使植物形成根瘤的根瘤菌和对植物有促生作用的 γ-Proteobacteria 类微生物;而在根际和自然土中,酸杆菌属( Acidobacteria )和古菌(Archaea)数量较多。柠条根际的多样性指数最高,而根表和自然土微生物类群具有较高的优势度,表现出从根表、根际植物相关微生物到自然土单一简单微生物类群的过渡。说明植物根系和土壤环境与微生物类群具有相互选择性。

... 土壤细菌生长受土壤环境因子的影响^[30],其中土壤酸碱程度对土壤细菌群落的影响最为显著^[31] ...

2014

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... 本研究优势菌群与土壤化学性质相关分析表明(表4),土壤pH值是影响土壤细菌群落的主要因素,这与前人研究一致^{[25, 32,33]} ...

2009

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... 本研究优势菌群与土壤化学性质相关分析表明(表4),土壤pH值是影响土壤细菌群落的主要因素,这与前人研究一致^{[25, 32,33]} ...

2018

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... Wang等^[34]在亚热带森林氮添加试验表明,氮添加150 kg N#cod#x000b7 ...

2015

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... 前人研究认为,土壤酸化对细菌群落的生态选择和不同细菌群落在酸性条件下压力下的适应性进化,是土壤酸化导致土壤细菌群落改变的机制^[35] ...

2018

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... Yang等^[36]研究也表明土壤化学性质包括土壤pH、无机氮含量等是影响土壤细菌群落结构的土壤环境因素 ...