水热增加下黑土细菌群落共生网络特征

黑土是有机质含量高且肥沃的土壤类型之一,气候变化会显著改变黑土中微生物群落的结构,同时影响群落间的潜在相互作用关系。[目的] 揭示水热增加对黑土中的细菌群落结构及潜在互作关系的影响。[方法] 基于土壤移置试验,采用16S rRNA高通量测序解析农田黑土（原位黑土、水热增加1和水热增加2）中的细菌群落结构对水热增加的响应;使用CoNet构建微生物群落共生网络,识别共生网络中的枢纽微生物;利用结构方程模型、相关性分析探究水热条件变化下土壤性质、微生物交互作用、多样性之间的直接、间接关系。[结果] 黑土中的微生物以疣微菌、变形杆菌、酸性杆菌和放线菌为主。水热增加下土壤微生物共生网络的拓扑性质发生显著变化,网络中表征微生物潜在竞争关系的负连线随着水热增加而显著增加。气候因素通过改变微生物潜在相互作用影响了群落水平分类多样性。物种竞争增强可能直接导致了土壤有机碳含量的降低。[结论] 水热增加会显著改变黑土中微生物之间的潜在交互作用,枢纽微生物的响应更加敏感。     

十字花科作物根肿病对根际土壤微生物群落的影响

为探究根肿病对十字花科作物根际土壤微生物多样性的影响,以罹病大白菜和健康株根际土壤为研究对象,采用高通量测序技术对2组样本的细菌16S rDNA和真菌ITS基因进行序列测定,分析了样本间的微生物群落结构和组成差异,同时测定根际土壤理化性质,探讨根肿病、土壤微生物群落、土壤环境因子三者的相关性。研究表明:1)患病植株根际土壤pH和总磷、总钾、碱解氮、速效钾含量显著低于正常植株根际土,而交换性钙含量明显增加。2)根肿病的发生降低了根际土壤中细菌种群的丰富度和多样性程度,但对根际土壤中的真菌α-多样性无明显影响。3)变形菌门、拟杆菌门、放线菌门等是所测土壤样本的主要优势细菌种群,其中患病植株根际土壤中拟杆菌门丰度显著高于健康植株根际土壤,放线菌门丰度则显著降低(P0.05)。优势细菌纲为γ-变形菌纲、拟杆菌纲、α-变形菌纲、放线菌纲、酸杆菌纲等,2组土壤样本间多种优势细菌纲相对丰度差异显著。4)根际土壤优势真菌类群为子囊菌门、被孢霉门、担子菌门和壶菌门,其相对丰度在患病和健康株根际土壤样本中均有明显差异。主要真菌纲为散囊菌纲、被孢霉纲、锤舌菌纲等,并且土壤样本间的多种优势真菌纲相对丰度存在显著性差异。5)主坐标分析结果表明病株根际土壤与健康株根际土壤细菌和真菌群落结构差异明显,冗余分析结果显示速效钾和交换性钙是根际土壤微生物群落变化的主要影响因素。研究结果为揭示根肿病发生的根际微生态机制以及研发根肿病综合防控技术提供理论支撑。     

Land use and climatic factors structure regional patterns in soil microbial communities

Aim  Although patterns are emerging for macroorganisms, we have limited understanding of the factors determining soil microbial community composition and productivity at large spatial extents. The overall objective of this study was to discern the drivers of microbial community composition at the extent of biogeographical provinces and regions. We hypothesized that factors associated with land use and climate would drive soil microbial community composition and biomass.
Location  Great Basin Province, Desert Province and California Floristic Province, California, USA.
Methods  Using phospholipid fatty acid analysis, we compared microbial communities across eight land-use types sampled throughout the State of California, USA ( n = 1117).
Results  The main factor driving composition and microbial biomass was land-use type, especially as related to water availability and disturbance. Dry soils were more enriched in Gram-negative bacteria and fungi, and wetter soils were more enriched in Gram-positive, anaerobic and sulphate-reducing bacteria. Microbial biomass was lowest in ecosystems with the wettest and driest soils. Disturbed soils had less fungal and more Gram-positive bacterial biomass than wildland soils. However, some factors known to influence microbial communities, such as soil pH and specific plant taxa, were not important here.
Main conclusions  Distinct microbial communities were associated with land-use types and disturbance at the regional extent. Overall, soil water availability was an important determinant of soil microbial community composition. However, because of the inclusion of managed and irrigated agricultural ecosystems, the effect of precipitation was not significant. Effects of environmental and management factors, such as flooding, tillage and irrigation, suggest that agricultural management can have larger effects on soil microbial communities than elevation and precipitation gradients.     

土壤管理措施及环境因素对土壤微生物多样性影响研究进展

本文综述了土壤管理措施及环境因素对土壤微生物多样性影响的研究进展,并介绍了土壤微生物多样性的研究方法,土壤微生物多样性包括微生物物种多样性、遗传多样性和生态多样性。传统上,土壤微生物群落的分析依赖于培养技术,但使用该技术只能培养和分离出一部分土壤微生物群落。现在国际上普遍使用Biolog分析、磷脂脂肪酸(PLFA)分析和核酸分析等多种现代技术研究和表征土壤微生物多样性。土壤微生物多样性受土壤管理措施和多种环境因素的影响。农药可能使土壤微生物多样性减少或改变其结构和功能;施有机肥有利于维持土壤微生物的多样性及活性;但在施用无机肥的影响上目前的报道有矛盾之处。农业土壤减少耕作可能增加微生物多样性和生物量;轮作可能比单一栽培耕作更有利于维持土壤微生物的多样性及活性。土壤微生物多样性也受土壤有机质、植被、季节变化等因素的影响,且通常遭受干旱、过度放牧、营养缺乏等的胁迫作用。     

黄顶菊对不同入侵地植物群落及土壤微生物群落的影响

为明确不同入侵地植物群落和土壤生态对黄顶菊入侵的反馈机制,选取天津静海(JH)、河北沧州(CZ)、河北衡水(HS)及河南安阳(AY)4个黄顶菊入侵典型区域,研究黄顶菊对不同入侵地植物群落多样性、土壤理化及土壤微生物群落结构的影响,并进一步揭示植物群落、土壤养分和土壤微生物之间的相关关系。结果表明,黄顶菊入侵显著降低了JH、CZ和HS的植物群落多样性指数(P0.05),改变了四个地区的土壤理化性质,显著升高了不同入侵地真菌PLFA的含量、总PLFA的含量、真菌/细菌和革兰氏阴性菌/革兰氏阳性菌(P0.05),降低了土壤微生物的Margalef丰富度指数(P0.05),但均存在地区间差异;RDA和相关分析的结果表明,硝态氮、全氮的含量对植物群落的影响较大,而铵态氮的含量对土壤微生物群落结构的影响较大,除丰富度指数外,植物群落与土壤微生物群落的多样性指数之间存在显著的负相关关系(P0.05)。总之,黄顶菊改变了入侵地植物群落多样性,并且对入侵地土壤理化性质和土壤微生物群落结构产生了显著影响,且存在地区差异。本研究将为更好的理解外来植物的入侵机制及制定相应的防控策略提供理论依据。     

水田改果园后土壤性质的变化及其特征

近年来,水田改作经济林地,在我国南方地区非常普遍。为深入了解这一转变对土壤质量的影响,以浙江省典型水稻土(青粉泥田)及其改果园不同年限的系列表层土壤(0—15 cm)为研究对象,应用磷脂脂肪酸生物标记等方法,研究了水田改果园后土壤理化性质和微生物群落结构等性质的变化以及它们之间的关系。结果表明,水田改果园后,土壤中大于0.25 mm水稳定性团聚体、盐基饱和度、p H值、有机质、全氮和碱解氮等随着改果园年限的延长而显著降低(P0.05)。土壤微生物生物量碳氮、微生物商和土壤呼吸强度随改果园年限增加而显著下降(P0.01)。土壤微生物群落结构也发生明显变化:磷脂脂肪酸总量显著降低(P0.01),微生物种类减少,原生动物在土壤微生物中所占比例增加,革兰氏阴性细菌与革兰氏阳性细菌比值降低(P0.01),好氧细菌/厌氧细菌和甲烷氧化菌/细菌增加(P0.01),表征养分胁迫的环丙基脂肪酸/前体物和异式脂肪酸/反异支链脂肪酸显著增加(P0.01)。冗余分析表明,土壤含水率、有机质和碱解氮是决定水田和果园土壤微生物群落结构差异的最重要因子(P0.01);改果园后,土壤微生物群落结构发生了阶段性变化,不同利用方式对微生物群落结构的影响程度要大于同一利用方式耕作不同年限对微生物群落结构的影响。研究表明,水田改果园后土壤理化性质以及生物学性质发生退化,土壤质量下降;而水田中微生物数量和种类都比较丰富,因而认为水田是土壤(地)可持续利用的一种有效方式。     

Microbial phylotype composition and diversity predicts plant productivity and plant–soil feedbacks

The relationship between ecological variation and microbial genetic composition is critical to understanding microbial influence on community and ecosystem function. In glasshouse trials using nine native legume species and 40 rhizobial strains, we find that bacterial rRNA phylotype accounts for 68% of amoung isolate variability in symbiotic effectiveness and 79% of host specificity in growth response. We also find that rhizobial phylotype diversity and composition of soils collected from a geographical breadth of sites explains the growth responses of two acacia species. Positive soil microbial feedback between the two acacia hosts was largely driven by changes in diversity of rhizobia. Greater rhizobial diversity accumulated in association with the less responsive host species, Acacia salicina, and negatively affected the growth of the more responsive Acacia stenophylla. Together, this work demonstrates correspondence of phylotype with microbial function, and demonstrates that the dynamics of rhizobia on host species can feed back on plant population performance.     

Differential sensitivity of total and active soil microbial communities to drought and forest management

Climate change will affect semiarid ecosystems through severe droughts that increase the competition for resources in plant and microbial communities. In these habitats, adaptations to climate change may consist of thinning—that reduces competition for resources through a decrease in tree density and the promotion of plant survival. We deciphered the functional and phylogenetic responses of the microbial community to 60 years of drought induced by rainfall exclusion and how forest management affects its resistance to drought, in a semiarid forest ecosystem dominated by Pinus halepensis Mill. A multiOMIC approach was applied to reveal novel, community‐based strategies in the face of climate change. The diversity and the composition of the total and active soil microbiome were evaluated by 16S rRNA gene (bacteria) and ITS (fungal) sequencing, and by metaproteomics. The microbial biomass was analyzed by phospholipid fatty acids (PLFAs), and the microbially mediated ecosystem multifunctionality was studied by the integration of soil enzyme activities related to the cycles of C, N, and P. The microbial biomass and ecosystem multifunctionality decreased in drought‐plots, as a consequence of the lower soil moisture and poorer plant development, but this decrease was more notable in unthinned plots. The structure and diversity of the total bacterial community was unaffected by drought at phylum and order level, but did so at genus level, and was influenced by seasonality. However, the total fungal community and the active microbial community were more sensitive to drought and were related to ecosystem multifunctionality. Thinning in plots without drought increased the active diversity while the total diversity was not affected. Thinning promoted the resistance of ecosystem multifunctionality to drought through changes in the active microbial community. The integration of total and active microbiome analyses avoids misinterpretations of the links between the soil microbial community and climate change.     

Rhododendron aureum Georgi formed a special soil microbial community and competed with above‐ground plants on the tundra of the Changbai Mountain,China

Rhododendron aureum Georgi is a perennial evergreen dwarf shrub that grows at all elevations within the alpine tundra of northern China. Previous research has investigated the plant communities of R. aureum; however, little information is available regarding interspecific competition and underground soil microbial community composition. The objective of our study was to determine whether the presence of R. aureum creates a unique soil microbiome and to investigate the relationship between R. aureum and other plant species. Our study site ranged from 1,800 to 2,600 m above sea level on the northern slope of the Changbai Mountain. The results show that the soil from sites with an R. aureum community had a higher abundance of nitrogen‐fixing bacteria and a higher resistance to pathogens than soils from sites without R. aureum. We emphasize that R. aureum promotes a unique soil microbial community structure that is distinct from those associated with other plants. Elevation and microbial biomass were the main influencing factors for plant community structure. Analysis of interspecific relationships reveals that R. aureum is negatively associated with most other dominant shrubs and herbs, suggesting interspecific competition. It is necessary to focus on other dominant species if protection and restoration of the R. aureum competition is to occur. In the future, more is needed to prove whether R. aureum decreases species diversity in the tundra ecosystems of Changbai Mountain.     

施用生物质炭和羊粪对宿根连作茶园根际土壤微生物的影响

茶树长期宿根连作会导致土壤酸化严重、土壤营养不平衡、根际土壤微生态结构恶化.研究生物质炭、羊粪对宿根连作茶树生长以及土壤微生物群落结构和功能的影响,探讨其对宿根连作茶树土壤环境的调节效果,可为宿根连作茶园土壤微生态的改善提供理论依据.本研究以宿根连作20年的茶园土壤为对象,利用Biolog技术和磷脂脂肪酸(PLFA)方法,研究施用生物质炭(40 t·hm^-2)和羊粪替代部分化肥对连作茶树产量和品质、土壤化学性质、根际土壤微生物群落功能和结构的影响.结果表明:施用生物质炭、羊粪1年后酸化茶园土壤的p H和土壤养分显著提高,并提高了茶叶产量.与常规施肥相比,施用生物质炭、羊粪替代部分化肥处理显著提高了茶树根际土壤微生物的碳源代谢活性和微生物多样性,对胺类、碳水化合物和聚合物的相对利用有所增加.生物质炭和羊粪处理的根际土壤总PLFA含量分别比常规施肥处理提高了20.9%和47.5%,羊粪处理还显著降低了总饱和/总单一不饱和脂肪酸比例.生物质炭和羊粪可改善茶园土壤酸化状况和土壤肥力,对宿根连作茶树的生长具有促进作用,两种措施均不同程度地增加了土壤微生物的代谢活性和微生物量、提高了多样性指数、改善了微生物群落结构.施用生物质炭和羊粪可作为调节宿根连作茶园根际土壤微生态的有效措施.     

土壤微生物对气候变暖和大气N沉降的响应

气候变暖和大气N沉降是近一、二十年来人们非常关注的全球变化现象,它们所带来的一系列生态问题已成为全球变化研究的重要议题。它们不仅影响地上植被生长和群落组成,还直接或间接地影响土壤微生物过程,而土壤微生物对此做出的响应正是生态系统反馈过程中非常重要的环节。该文分别从气候变化对土壤微生物的影响(土壤微生物量、微生物活动和微生物群落结构)和土壤微生物对气候变化的响应(凋落物分解、养分利用与循环以及养分的固持与流失)两个角度,综述近期土壤微生物对气候变暖和大气N沉降响应与适应的研究进展。气候变暖和大气N沉降对土壤微生物的影响更多地反映在微生物群落的结构和功能上,而土壤微生物量、微生物活动和群落结构的变化又会通过改变凋落物分解、养分利用和C、N循环等重要的土壤生态系统功能和过程做出响应,形成正向或负向反馈,加强或削弱气候变化给整个陆地生态系统带来的影响。然而,到目前为止土壤微生物的响应对陆地生态系统产生的最终结果仍是未决的关键性问题。     

羊草基因型数目与氮添加对土壤微生物群落的交互影响

物种多样性(或同一物种遗传多样性)减少和氮富集都是影响陆地生态系统进程的主要因素,它们之间的交互作用是否对土壤微生物群落产生显著影响已成为研究者关心的主要科学问题。研究羊草基因型数目(1、2、4三种基因型数目组合)和氮添加(无氮添加、低氮添加和高氮添加3种水平)对土壤微生物群落的总磷脂脂肪酸(PLFA,Phospholipid Fatty Acid)含量、细菌PLFA生物标记含量、真菌PLFA生物标记含量、真菌/细菌比、以及基于每个PLFA生物标记相对含量百分比所得微生物群落的Shannon-Wiener多样性指数和Simpson优势度指数的影响。结果表明:氮添加对细菌PLFA生物标记含量,以及土壤微生物PLFA生物标记的Shannon-Wiener多样性指数和Simpson优势度指数具有显著影响(P0.05);基因型数目对所测变量无显著影响(P0.05),但基因型数目和氮添加的交互作用对细菌PLFA生物标记含量和真菌/细菌比具有显著影响(P0.05)。研究结果为全球变化背景下氮沉降及重要物种种群数量减少对土壤微生物群落的影响提供了科学数据,为合理解释群落动态变化提供了数据支持。     

Microbial communities of ultramafic soils in maquis and rainforest at Mont Do,New Caledonia

We analysed variation in microbial community richness and function in soils associated with a fire‐induced vegetation successional gradient from low maquis (shrubland) through tall maquis to rainforest on metal‐rich ultramafic soils at Mt Do, New Caledonia. Random amplified polymorphic DNA fingerprinting was used to determine the extent of genetic relatedness among the microbial communities and indicated that the open and tall maquis microbial communities were more similar to each other than they were to the rainforest community. Sole‐source carbon utilization indicated variation in the microbial communities, again with greater diversity in rainforest soils. Plate counts showed that both rainforest and maquis soils contained bacteria that can grow in the presence of up to 20 mmol L^?1 nickel and 10 mmol L^?1 chromium. Understanding microbial community composition and dynamics in these ultramafic soils may lead to a better understanding of the processes facilitating vegetation succession from shrubland to forest on these high‐metal substrates, and of approaches to successful revegetation following mining for metals including nickel, chromium and cobalt.     

辣椒青枯病罹病与健康植株根际土壤微生物群落多样性研究

系统研究和分析辣椒青枯病常发地发病与健康植株土壤微生物群落结构特征,为辣椒青枯病的绿色防治提供理论依据.基于16SrDNA基因高通量测序技术,对辣椒青枯病发病和健康植株根际土壤微生物群落结构和组成进行分析,同时采用biologyeco平板培养技术研究其土壤微生物群落代谢多样性和功能多样性的特征.结果表明,辣椒青枯病发病和健康植株根际土壤微生物群落组成之间存在显著差异,辣椒青枯病发病土壤的OTU为4566个,辣椒青枯病健康土壤的OTU为4167个.依据OTU所属细菌物种信息对土壤细菌群落结构进行分析,变形菌门在发病和健康土壤中均为优势细菌类群,其次为放线菌门类群.其中健康植株根际土壤中芽单胞菌门(Gemmatimonadetes)、装甲菌门(Armatimonadetes)的相对丰度比发病植株的分别高出了4.37,3.87倍,而发病植株根际土壤中厚壁菌门(Firmicutes)的相对丰度比健康植株的高出了3.87倍.辣椒青枯病发病土壤和健康土壤的土壤微生物代谢多样性也存在显著差异,同时,健康土壤中其微生物群落代谢得到显著增强,特别是对酚类化合物的利用显著增多,对辣椒抗病性存在显著的影响.研究表明,辣椒青枯病发病和健康植株根际土壤微生物群落组成和结构之间存在显著差异,并且健康土壤的微生物群落对酚类化合物的利用显著增强.     

Fertilisation practice changes rhizosphere microbial community structure in the agroecosystem

Rhizosphere microbial community is important for the acquisition of soil nutrients and closely related to plant species. Fertilisation practice changed soil quality. With the hypothesis of stronger rhizosphere effect of plant on rhizosphere microbial community than fertilisation management, we designed this research based on a long‐term field experiment (1982–present). This study consists of no fertilisation (NF), mineral fertilisers (NPK), mineral fertilisers plus 7,500 kg/ha of wheat straw addition (WS) and mineral fertilisers plus 30,000 kg/ha of cow manure (CM). After analysing, we found that fertilisation management not only elevated crop yield but also affected crop rhizosphere microbial community structure. The influence of fertilisation practice on wheat rhizosphere microbial structure was stronger than that of wheat. For wheat rhizosphere bacterial community, it was significantly affected by soil water content (SWC), nitrogen (TN), phosphorus (TP), pH, available phosphorus (AVP) and nitrogen (AVN), dissolved organic nitrogen (DON) and carbon (DOC). Besides SWC, pH, AVP, AVN, TN, TP and DOC, the wheat rhizosphere fungi community was also significantly affected by soil organic matter (SOM) and available potassium (AVK). Moreover, compared to rhizosphere bacterial community, the influences of soil physiochemical properties on rhizosphere fungal community was stronger. In conclusion, fertilisation practice was the primary factor structuring rhizosphere microbial community by changing soil nutrients availabilities in the agroecosystem.     

Effect of long‐term mineral fertilisation on soil microbial abundance,community structure and diversity in a Typic Hapludoll under intensive farming systems

Fertiliser application can not only influence plant communities, but also the soil microbial community dynamics, and consequently soil quality. Specifically, mineral fertilisation can directly or indirectly affect soil chemical properties, microbial abundance and, the structure and diversity of soil microbial communities. We investigated the impact of six different mineral fertiliser regimes in a maize/soybean rotation system: control (CK, without fertilisation), PS (application of phosphorus plus sulphur), NS (application of nitrogen plus S), NP (application of N plus P), NPS (application of N, P plus S) and NPSm (application of N, P, S plus micronutrients). Soil samples were collected at the physiological maturity stage of maize and soybean in March of 2013 and 2014, respectively. Overall, mineral fertilisation resulted in significantly decreased soil pH and increased total organic carbon compared with the control (CK). The analysis of terminal restriction fragment length polymorphism (T‐RFLP) revealed that mineral fertilisers caused a shift in the composition of both bacterial and fungal communities. In 2013, the highest value of Shannon diversity of bacterial terminal restriction fragments (TRFs) was found in control soils. In 2014, NPSm treated soils showed the lowest values of diversity for both bacterial and fungal TRFs. In both crop growing seasons, the analysis of phospholipid fatty acid (PLFA) detected the lowest value of total microbial biomass under CK. As PLFA analysis can be used to evaluate total microbial community, this result suggests that fertilisation increased total microbial biomass. When the bacterial and fungal abundance were examined using real time polymerase chain reaction, the results revealed that mineral fertilisation led to decreased bacterial abundance (16S rRNA), while fungal abundance (18S rRNA) was found to be increased in both crop growing seasons. Our results show that mineral fertiliser application has a significant impact on soil properties, bacterial and fungal abundance and microbial diversity. However, further studies are needed to better understand the mechanisms involved in the changes to microbial communities as a consequence of mineral fertilisation.     

不同药用植物根际土壤原核微生物多样性研究

为研究不同药用植物根际土壤中的原核微生物多样性,分别采集白术(Atractylodes macrocephala)、白芍(Paeonia sterniana)、牡丹(Paeonia suffruticosa)、玄参(Scrophularia ningpoensis)四种药用植物的根际土壤以及非种植区的土壤,针对16S rRNA基因的V3～V4区进行测序,分析土壤细菌群落的组成。结果表明,药用植物根际土壤中的细菌群落多样性指数显著高于非种植区土壤。五组样本的优势类群差异不大,总体相对丰度较高的有变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)、芽单胞菌门(Gemmatimonadetes)、绿弯菌门(Chloroflexi)等,药用植物根际中的放线菌相对丰度高于非种植区。属水平上四种药用植物根际细菌和非种植区的群落结构有较大差异,四种中药材的根际土壤中各自富集了特异性的有益细菌属。药用植物根际土壤中的NMD1、Dongia、Gaiella、Streptomyces等相对丰度高于非种植区,而非种植区土壤中Lysoba...     

Molecular and Functional Assessment of Bacterial Community Convergence in Metal-Amended Soils

Species diversity and the structure of microbial communities in soils are thought to be a function of the cumulative selective pressures within the local environment. Shifts in microbial community structure, as a result of metal stress, may have lasting negative effects on soil ecosystem dynamics if critical microbial community functions are compromised. Three soils in the vicinity of a copper smelter, previously contaminated with background, low and high levels of aerially deposited metals, were amended with metal-salts to determine the potential for metal contamination to shape the structural and functional diversity of microbial communities in soils. We hypothesized that the microbial communities native to the three soils would initially be unique to each site, but would converge on a microbial community with similar structure and function, as a result of metal stress. Initially, the three different sites supported microbial communities with unique structural and functional diversity, and the nonimpacted site supported inherently higher levels of microbial activity and biomass, relative to the metal-contaminated sites. Amendment of the soils with metal-salts resulted in a decrease in microbial activity and biomass, as well as shifts in microbial community structure and function at each site. Soil microbial communities from each site were also observed to be sensitive to changes in soil pH as a result of metal-salt amendment; however, the magnitude of these pH-associated effects varied between soils. Microbial communities from each site did not converge on a structurally or functionally similar community following metal-salt amendment, indicating that other factors may be equally important in shaping microbial communities in soils. Among these factors, soil physiochemical parameters like organic matter and soil pH, which can both influence the bioavailability and toxicity of metals in soils, may be critical.     

Feedbacks of plant identity and diversity on the diversity and community composition of rhizosphere microbiomes from a long‐term biodiversity experiment

Soil microbes are known to be key drivers of several essential ecosystem processes such as nutrient cycling, plant productivity and the maintenance of plant species diversity. However, how plant species diversity and identity affect soil microbial diversity and community composition in the rhizosphere is largely unknown. We tested whether, over the course of 11 years, distinct soil bacterial communities developed under plant monocultures and mixtures, and if over this time frame plants with a monoculture or mixture history changed in the bacterial communities they associated with. For eight species, we grew offspring of plants that had been grown for 11 years in the same field monocultures or mixtures (plant history in monoculture vs. mixture) in pots inoculated with microbes extracted from the field monoculture and mixture soils attached to the roots of the host plants (soil legacy). After 5 months of growth in the glasshouse, we collected rhizosphere soil from each plant and used 16S rRNA gene sequencing to determine the community composition and diversity of the bacterial communities. Bacterial community structure in the plant rhizosphere was primarily determined by soil legacy and by plant species identity, but not by plant history. In seven of the eight plant species the number of individual operational taxonomic units with increased abundance was larger when inoculated with microbes from mixture soil. We conclude that plant species richness can affect below‐ground community composition and diversity, feeding back to the assemblage of rhizosphere bacterial communities in newly establishing plants via the legacy in soil.