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1.
K.L. Steenwerth R.E. Drenovsky J.-J. Lambert D.A. Kluepfel K.M. Scow D.R. Smart 《Soil biology & biochemistry》2008,40(6):1330-1340
The composition of microbial communities responds to soil resource availability, and has been shown to vary with increasing depth in the soil profile. Soil microorganisms partly rely on root-derived carbon (C) for growth and activity. Roots in woody perennial systems like vineyards have a deeper vertical distribution than grasslands and annual agriculture. Thus, we hypothesized that vineyard soil microbial communities along a vertical soil profile would differ from those observed in grassland and annual agricultural systems. In a Pinot noir vineyard, soil pits were excavated to ca. 1.6–2.5 m, and microbial community composition in ‘bulk’ (i.e., no roots) and ‘root’ (i.e., roots present) soil was described by phospholipid ester-linked fatty acids (PLFA). Utilization of soil taxonomy aided in understanding relationships between soil microbial communities, soil resources and other physical and chemical characteristics. Soil microbial communities in the Ap horizon were similar to each other, but greater variation in microbial communities was observed among the lower horizons. Soil resources (i.e., total PLFA, or labile C, soil C and nitrogen, and exchangeable potassium) were enriched in the surface horizons and significantly explained the distribution of soil microbial communities with depth. Soil chemical properties represented the secondary gradient explaining the differentiation between microbial communities in the B-horizons from the C-horizons. Relative abundance of Gram-positive bacteria and actinomycetes did not vary with depth, but were enriched in ‘root’ vs. ‘bulk’ soils. Fungal biomarkers increased with increasing depth in ‘root’ soils, differing from previous studies in grasslands and annual agricultural systems. This was dependent on the deep distribution of roots in the vineyard soil profile, suggesting that the distinct pattern in PLFA biomarkers may have been strongly affected by C derived from the grapevine roots. Gram-negative bacteria did not increase in concert with fungal abundance, suggesting that acidic pHs in lower soil horizons may have discouraged their growth. These results emphasize the importance of considering soil morphology and associated soil characteristics when investigating effects of depth and roots on soil microorganisms, and suggest that vineyard management practices and deep grapevine root distribution combine to cultivate a unique microbial community in these soil profiles. 相似文献
2.
B. Mechri H. Chehab F. Attia F.B. Mariem M. Braham M. Hammami 《European Journal of Soil Biology》2010,46(5):312-318
The aim of this work was to study the effects of spreading olive mill wastewater (OMW) on the soil surface of an olive grove on the soil microbial communities. Analyses of ester-linked fatty acid methyl esters (EL-FAME) were used to assess variations in the soil microbial community structure following land spreading of OMW. Our data provide evidence that agronomic application of OMW has important effects on soil microbial community. Bacteria were relatively more reduced by these treatments than fungi and actinomycetes as revealed by an increased index of fungal/bacterial FAME and actinomycetes/bacterial FAME. Specific FAME markers indicated a significant reduction in the Gram-positive bacteria. However, the relative proportion of the Gram-negative bacteria was not significantly different after agronomic application of OMW. The ratios of cyclopropyl/monoenoic precursors decreased and the total monounsaturated/total saturated fatty acids increased in the OMW amended soils, suggesting that the microbes inhabiting the control soil are more carbon limited than the OMW amended soils. The changes in the FAME pattern of the soil organisms possibly were related (i) to an altered substrate quantity, that is the availability of substrates after the treatments, (ii) the complex nature of OMW which also contains high molecular-mass recalcitrant polyphenols. 相似文献
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4.
Soil profiles are often many meters deep, but with the majority of studies in soil microbiology focusing exclusively on the soil surface, we know very little about the nature of the microbial communities inhabiting the deeper soil horizons. We used phospholipid fatty acid (PLFA) analysis to examine the vertical distribution of specific microbial groups and to identify the patterns of microbial abundance and community-level diversity within the soil profile. Samples were collected from the soil surface down to 2 m in depth from two unsaturated Mollisol profiles located near Santa Barbara, CA, USA. While the densities of microorganisms were generally one to two orders of magnitude lower in the deeper horizons of both profiles than at the soil surface, approximately 35% of the total quantity of microbial biomass found in the top 2 m of soil is found below a depth of 25 cm. Principal components analysis of the PLFA signatures indicates that the composition of the soil microbial communities changes significantly with soil depth. The differentiation of microbial communities within the two profiles coincides with an overall decline in microbial diversity. The number of individual PLFAs detected in soil samples decreased by about a third from the soil surface down to 2 m. The ratios of cyclopropyl/monoenoic precursors and total saturated/total monounsaturated fatty acids increased with soil depth, suggesting that the microbes inhabiting the deeper soil horizons are more carbon limited than surface-dwelling microbes. Using PLFAs as biomarkers, we show that Gram-positive bacteria and actinomycetes tended to increase in proportional abundance with increasing soil depth, while the abundances of Gram-negative bacteria, fungi, and protozoa were highest at the soil surface and substantially lower in the subsurface. The vertical distribution of these specific microbial groups can largely be attributed to the decline in carbon availability with soil depth. 相似文献
5.
黄河三角洲刺槐根际与非根际细菌结构及多样性 总被引：4，自引：0，他引：4
为精确分析黄河三角洲刺槐根际与非根际土壤细菌群落定殖情况,本研究采用高通量测序方法对刺槐根际与非根际土壤细菌结构及多样性进行了研究。研究表明,根际土壤细菌共有36门214属,非根际土壤细菌共有33门153属。变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)细菌丰度超过15%,是根际与非根际土壤中的优势菌落。根际与非根际土壤中酸杆菌门、硝化螺旋菌门(Nitrospirae)丰度差异显著。根际土壤中红游动菌属(Rhodoplanes)、溶杆菌属(Lysobacter)、热单胞菌属(Thermomonas)、链霉菌属(Streptomyces)及非根际土壤中红游动菌属、溶杆菌属、链霉菌属、Kaistobacter细菌丰度超过4%。根际土壤中固氮菌丰度显著高于非根际土壤,解磷、解钾细菌丰度差异不显著。根际与非根际土壤细菌Chao丰富度分别为2 054、2 376,差异显著。根际与非根际土壤细菌之间的权重(Weighted Unifrac)距离在0.12~0.25之间。综上所述,黄河三角洲刺槐根际与非根际土壤细菌结构具有一定差异,多样性差异显著。 相似文献
6.
本文探讨了酰胺类除草剂苯噻草胺对水稻土微生物群落功能多样性的短期影响。本研究采用微生物群落基质利用潜力测定（Biolog法）评估生物群落。结果表明，苯噻草胺污染引起了水稻田微生物群落功能多样性的下降，降低了微生物对单-碳源底物的利用能力，但这种影响是短暂的，在试验最终没有导致土壤微生物群落功能多样性下降。多食鞘氨醇杆菌Y1（Sphingobacterium multiuorum）的添加有利于提高水稻土微生物群落的功能多样性。3个处理土壤的群落代谢剖面值与培养时间之间呈非线性关系，其变化过程符合微生物种群生长动态模型（S形）。模型模拟分析表明，动力学参数a和x0能更灵敏地表征苯噻草胺和Y1菌株处理对水稻土微生物群落功能多样性的影响。在本实验研究中，多样性指标指数Shannon（H）能灵敏而有效地指示污染环境的微生物学变化，但群落丰富度指标颜色变化孔数（S）提供的信息较片面。 相似文献
7.
在一年内棉花的四个生长时期（苗期,蕾期,花铃期,吐絮期）分别采集转Bt基因抗虫棉GK12和非转基因亲本棉花泗棉3号根际土壤,以及未种植棉花的背景土壤,利用末端标记限制性片段长度多态性（T-RFLP）分析技术,分析三种土壤中细菌和古菌的16S rRNA基因片段多态性,结合克隆文库建立和测序,研究了土壤中细菌和古菌群落结构的变化.结果表明：在棉花生长的各个时期,背景土壤中细菌群落结构发生了明显的变化,生物多样性指数明显降低,古菌群落结构也有一定的变化,说明季节性变化对土壤中微生物群落产生了明显的影响.与背景土壤相比,棉花种植后根际土壤中细菌和古菌群落发生显著的变化.转基因棉花与非转基因棉花相比,根际土壤细菌和古菌的种类和种群大小的分布也发生了明显的改变.克隆文库和测序结果表明土壤中主体微生物为目前未培养的、功能特性未知的细菌和古菌,转基因棉花种植对这些细菌和古菌影响的原因、环境危害和生态风险目前尚不清楚.与古菌群落相比,棉花种植对细菌群落结构的影响较小. 相似文献
8.
Monomethyl-mercury is one of the most toxic compounds. Methylation of Hg usually appears under anoxic conditions. In Swiss forest soils, methyl-Hg concentrations of up to 3 μg kg−1 soil dw have been observed, but the impact of methyl-Hg on soil microorganisms have rarely been examined so far. In this study, we investigated the effect of increasing concentrations of methyl-Hg (0, 5, 20, 90 μg kg−1 soil dw) on the microbial communities in various forest soils differing in their physico-chemical properties. Experiments were conducted in microcosms under controlled conditions and the basal respiration (BR), the microbial biomass carbon (MBC) and the bacterial and fungal community structures using T-RFLP-profiling were investigated. BR was significantly affected by methyl-Hg. In general, the BR increased with increasing methyl-Hg concentrations, whereas the MBC was significantly reduced. Bacterial communities were more sensitive to methyl-Hg than fungal communities. In five out of seven soils, the bacterial community structures differed significantly between the treatments whereas the fungal communities did not. The impact of methyl-Hg on the soil bacterial communities was site specific. In one soil, a methyl-Hg concentration of already 5 μg kg−1 soil dw significantly affected the relative abundance of 13% bacterial operational taxonomic units (OTU), whereas in other soils concentrations of even 90 μg kg−1 soil dw rarely affected the abundance of OTUs. In this study, for the first time, the impact of methyl-Hg on soil bacterial and fungal communities in forest soils was assessed. We showed that its impact strongly depends on the physico-chemical conditions of the soil and that bacterial communities were more sensitive to methyl-Hg than fungi. 相似文献
9.
Na+和K+共存对A2/O工艺脱氮除磷效果及污泥性质的影响 总被引：1，自引：1，他引：0
为了揭示多种金属离子共存的含盐废水生物处理系统污染物的去除机制和污泥特性,考察Na~+、K~+共存对A~2/O工艺污染物去除率、污泥性质和微生物群落的影响,采用高通量测序技术分析了厌氧区、缺氧区和好氧区的微生物群落结构,结合脱氮除磷效果和污泥性质的变化,探讨不同Na~+/K~+摩尔比下A~2/O工艺优势种群的演替规律,以期从微生物角度明确Na~+、K~+共存对含盐废水污染物去除率的影响。结果表明:当进水Na~+/K~+摩尔比分别为2、1和0.5时,A~2/O工艺的COD去除率分别为80%、84%和86%,TN去除率分别为73%、77%和80%,K~+浓度的提高缓解了Na~+对COD和TN去除率的抑制作用;厌氧区释磷率分别为70%、73%和74%,缺氧区吸磷率分别为53%、55%和58%,好氧区吸磷率分别为70%、72%和75%。随着进水Na~+/K~+摩尔比的降低,厌氧区、缺氧区和好氧区微生物群落的丰富度和多样性降低,微生物群落差异显著,变形菌门的相对丰度均升高约30%,拟杆菌门和绿弯菌门相对丰度逐渐降低。陶氏菌属和固氮弧菌属作为优势菌属,其相对丰度逐渐增大,有利于氮磷污染物的去除。通过增加K~+的浓度有利于提高氮、磷去除率,增强污泥的生物絮凝性和反硝化聚磷菌的活性。 相似文献
10.
Effects of straw amendment and moisture on microbial communities in Chinese fluvo-aquic soil 总被引：2，自引：0，他引：2
Lin Chen Jiabao Zhang Bingzi Zhao Pei Yan Guixiang Zhou Xiuli Xin 《Journal of Soils and Sediments》2014,14(11):1829-1840
Purpose
Returning crop straw into fields is a typical agricultural practice to resolve an oversupply of straw and improve soil fertility. Soil microorganisms, especially eukaryotic microorganisms, play a critical role in straw decomposition. To date, microbial communities in response to straw amendment at different moisture levels in Chinese fluvo-aquic soil are poorly understood. The aim of this study was to explore the effects of straw amendment and moisture on microbial communities in Chinese fluvo-aquic soil.Materials and methods
Two soils (one was applied with organic manure, and the other was not applied with any fertilizer) from a long-term field experiment in the North China Plain were collected. Soils with and without straw amendment at 25 and 55 % of the average water-holding capacities of the two soils were incubated at 25 °C for 80 days. All treatments were sampled 20 and 80 days after the start of incubation. Microbial biomass and community structure were analyzed by phospholipid fatty acids (PLFA) assay, and the eukaryotic diversity and community composition were assessed via barcoded pyrosequencing of the 18S ribosomal RNA (rRNA) gene amplicons.Results and discussion
PLFA analysis showed that straw amendment increased the biomass of Gram-positive bacteria, Gram-negative bacteria, actinobacteria, and fungi and shifted microbial community structure. The varied straw availability resulted in a large variation in microbial community structure. In the presence of straw, actinobacterial and fungal biomass both decreased under high moisture content. 18S rRNA gene pyrosequencing indicated that straw amendment decreased eukaryotic diversity and richness and probably restructured the eukaryotic community. Under identical moisture content, long-term organic manure-fertilized soil had higher eukaryotic diversity and richness than the unfertilized soil. In the amended soils under high moisture content, the relative abundance of dominant fungal taxa (Dikarya subkingdom, Ascomycota phylum, and Pezizomycotina subphylum) decreased.Conclusions
Straw amendment increases microbial biomass, shifts microbial community structure, and decreases eukaryotic diversity and richness. High moisture content probably has a negative effect on fungal growth in the amended soils. In conclusion, microbial communities in Chinese fluvo-aquic soil are significantly affected by straw amendment at different moisture levels. 相似文献11.
Effect of swine and dairy manure amendments on microbial communities in three soils as influenced by environmental conditions 总被引：2，自引：0，他引：2
Robert P. Larkin C. Wayne Honeycutt Timothy S. Griffin 《Biology and Fertility of Soils》2006,43(1):51-61
Understanding the impacts of manure amendments on soil microorganisms can provide valuable insight into nutrient availability and potential crop and environmental effects. Soil microbial community characteristics, including microbial populations and activity, substrate utilization (SU) profiles, and fatty acid methyl ester (FAME) profiles, were compared in three soils amended or not amended with dairy or swine manure at two temperatures (18 and 25°C) and two soil water regimes (constant and fluctuating) in laboratory incubation assays. Soil type was the dominant factor determining microbial community characteristics, resulting in distinct differences among all three soil types and some differing effects of manure amendments. Both dairy and swine manures generally increased bacterial populations, substrate diversity, and FAME biomarkers for gram-negative organisms in all soils. Microbial activity was increased by both manures in an Illinois soil but only by dairy manure in two Maine soils. Dairy manure had greater effects than swine manure on SU and FAME parameters such as increased activity, utilization of carbohydrates and amino acids, substrate richness and diversity, and fungal FAME biomarkers. Temperature and water regime effects were relatively minor compared with soil type and amendment, but both significantly affected some microbial responses to manure amendments. Overall, microbial characteristics were more highly correlated with soil physical factors and soil and amendment C content than with N levels. These results indicate the importance of soil type, developmental history, and environmental factors on microbial community characteristics, which may effect nutrient availability from manure amendments and should be considered in amendment evaluations.Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture 相似文献
12.
基于高通量测序的两种植被恢复类型根际土壤细菌多样性研究 总被引：21，自引：1，他引：20
为研究库布齐沙地生态恢复过程中不同植被恢复类型土壤微生物细菌群落结构、多样性的变化特征,以流动沙地为对照,运用高通量测序技术,对自然恢复的油蒿群落、人工种植的中间锦鸡儿群落根际和非根际土壤细菌多样性进行了研究,并分析了土壤理化性质对其分布的影响。结果表明:(1)与流沙对照相比,两种植被恢复类型对细菌多样性产生了正效应,细菌群落丰度、多样性和均匀度明显增加。其中,自然恢复的油蒿群落土壤细菌丰度高于人工种植的中间锦鸡儿群落;(2)变形菌门、酸杆菌门和放线菌门为研究区土壤中的优势细菌类群,其中变形菌门在各样地丰度比例最高,变形菌的4个亚群变化趋势一致,α-变形菌相对含量在油蒿和中间锦鸡儿群落根际土壤中明显增加,尤其是自然恢复的油蒿群落根际土壤中α-变形菌得到了很好的恢复;(3)土壤有机质、全氮、速效氮、速效钾含量和土壤含水量是影响土壤细菌群落丰度和多样性的主要土壤因子,典型相关分析表明土壤有机质、全氮、全钾、速效钾、速效氮含量对于研究区土壤细菌群落遗传多样性的变化起着重要作用。 相似文献
13.
NaCl盐度对A2/O工艺去除废水污染物和系统微生物的影响 总被引：2，自引：2，他引：0
为了提高含盐废水的有机物去除率和脱氮效率,考察NaCl盐度对A~2/O工艺污染物去除和微生物群落的影响,采用高通量测序技术分析了厌氧区、缺氧区和好氧区的微生物群落结构,结合有机物去除和脱氮效率的变化探讨不同盐度下A~2/O工艺优势种群的演替规律,以期揭示含盐废水生物脱氮机理。结果表明:1)随着NaCl盐度的增大,A~2/O工艺污染物去除率下降,当盐度由0增大至40 g/L时,A~2/O反应器厌氧、缺氧和好氧区域COD去除率分别由52%、80%和56%下降至30%、50%和40%;厌氧区和好氧区NH4+-N去除率分别由33%和61%下降至11%和39%;缺氧区NO3--N去除率由63%下降至47%。2)与无NaCl废水相比,加入NaCl后,微生物的多样性降低;高盐度(40 g/L)与低盐度(0、10 g/L)处理的微生物群落结构差异较大;缺氧区陶氏菌属和副球菌属、好氧区梭菌属和硝化螺旋菌相对丰度的降低是导致A~2/O工艺脱氮效率下降的主要原因;厚壁菌门中的部分菌属(如Lactobacillus、Streptococcus、Tepidibacterium、Veillonella、Lachnoclostridium、Zoogloea)相对丰度增大,具有较强的耐盐性;随着盐度的增大,与脱氮相关的微生物(如变形菌门、拟杆菌门、厚壁菌门等)一直是A~2/O工艺厌氧区、缺氧区和好氧区的优势菌门,保证了不同盐度下A~2/O工艺始终具有一定的脱氮效能。 相似文献
14.
Land-use conversion affects the soil community and microbial abundance, which are essential dynamic indicators of soil quality and sustainability. However, little to no work has been performed to analyse the impact from different land-use histories (i.e. fallow, tea, rice, banana, and maize) on the microbial abundance and diversity in the soil of sacha inchi (Plukenetia volubilis L.). Real-time quantitative PCR (qPCR) was performed to quantify soil bacterial and fungal abundance. Denaturing gradient gel electrophoresis (DGGE) combined with cloning and sequencing was used to assess the microbial communities. Our results showed that the bacterial and fungal abundance in fallow land-use conversion soils was significantly lower than that in the other four land-use conversion soils (tea, rice, banana, and maize). Moreover, the highest abundance of bacteria and fungi was detected in the soils converted from maize to sacha inchicultivation. In addition, canonical correspondence analysis (CCA) showed that the total N and pH were significantly related to bacterial and fungal community structures. These results suggest that land-use conversion from maize fields to sacha inchi farms is an effective way to maintain the soil microbial quantity and hence the sustainability of the soil. 相似文献
15.
Arctic soil microorganisms remain active at ecologically relevant rates in frozen soils. We used bromodeoxyuridine (BrdU) labeling and terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA gene amplicons to examine active bacterial communities in two Alaskan tundra soils collected in summer and winter of 2005. Active community T-RFLP profiles were compared to total community profiles to determine if active bacteria were a subset of the total community. In shrub soils, active bacteria communities differed in composition between summer and winter, and winter-active bacterial taxa were not detected in the total community, suggesting that they are likely rare within the overall community. In contrast, tussock tundra soil contained more bacterial taxa that were active in both summer and winter and also represented a large portion of the total community. Using in silico digest of a sequence library from this site, we attempted to identify the dominant organisms in our samples. Our previous research suggested that the total microbial community was stable throughout the year, but this new study suggests that the active community is more dynamic seasonally. In general, only a subset of the total community was growing at a given time. This temporal niche partitioning may contribute to the high diversity of microbial communities in soils. Understanding which taxa contribute to microbial function under different conditions is the next frontier in microbial ecology and linking composition to biogeochemical cycling. 相似文献
16.
《Communications in Soil Science and Plant Analysis》2012,43(9):1008-1026
The aims of this study were to investigate soil microbial community characteristics and their interrelationships with soil geochemistry under different farmlands in Shouguang, China. The traditional dilution plate counts, BIOLOG system, and fatty acid methyl ester (FAME) analyses were used to assess microbial populations, substrate utilization, and fatty acid profiles. The number of aerobic heterotrophic bacteria varied significantly among untilled land, maize, and mungbean fields. The amounts of actinomycetes, fungal fatty acids, and Gram-positive/Gram-negative bacteria ratios varied greatly among celery, tomato, and aubergine fields. In the tomato field, the soil microbial community characteristics were significantly different from other fields. Principal component analysis of BIOLOG and FAME data revealed differences in the catabolic capability and fatty acid profiles of soil microbial communities among different farmlands. Spearman correlation analyses showed that in these sand clay soils of Shouguang, microbial communities in different farmlands were closely correlated with soil geochemical elements, moisture, and organic matter. 相似文献
17.
Soil microorganisms are influenced by various abiotic and biotic factors at the field plot scale. Little is known, however, about the factors that determine soil microbial community functional diversity at a larger spatial scale. Here we conducted a regional scale study to assess the driving forces governing soil microbial community functional diversity in a temperate steppe of Hulunbeir, Inner Mongolia, northern China. Redundancy analysis and regression analysis were used to examine the relationships between soil microbial community properties and environmental variables. The results showed that the functional diversity of soil microbial communities was correlated with aboveground plant biomass, root biomass, soil water content and soil N: P ratio, suggesting that plant biomass, soil water availability and soil N availability were major determinants of soil microbial community functional diversity. Since plant biomass can indicate resource availability, which is mainly constrained by soil water availability and N availability in temperate steppes, we consider that soil microbial community functional diversity was mainly controlled by resource availability in temperate steppes at a regional scale. 相似文献
18.
Jens Dyckmans Heiner Flessa Andr Lipski Martin Potthoff Friedrich Beese 《植物养料与土壤学杂志》2006,169(1):108-115
Soil microbial activity, biomass, and community structure were examined during the transition from oxic to anoxic conditions after the addition of glucose and with or without nitrate addition. In two sets of treatments, samples were incubated for up to 35 d in closed ampoules either aerobically until oxygen was depleted or anoxically throughout the experiment. Heat‐flow rate was monitored to indicate microbial activity. Microbial biomass and community structure were measured by adenylate and phospholipid fatty acid (PFLA) content, and adenylate energy charge (AEC) was used to monitor the physiological status of the microbial biomass. Microbial activity was highest under oxic conditions and abruptly decreased under anoxic conditions. Activity peaks were observed after about 9 d of anoxic conditions probably triggered by increased nutrient availability from dying microbial biomass, but these peaks were smaller after initial oxic incubation or nitrate addition. Microbial biomass was unchanged under oxic conditions but decreased under anoxic conditions. Most surviving microbes switched into dormancy. Changes in the microbial‐population structure were small and occurred only after 9 d of anoxic incubation. The results show that the nutrient status and the availability of electron acceptors such as nitrate were important factors ruling the direction and the extent of shifts in the microbial activity and community structures due to anoxic conditions. 相似文献
19.
Zachary T. Aanderud Michal I. Shuldman Rebecca E. Drenovsky James H. Richards 《Soil biology & biochemistry》2008,40(9):2206-2216
In desert ecosystems, belowground characteristics are influenced chiefly by the formation and persistence of “shrub-islands of fertility” in contrast to barren plant interspaces. If soil microbial communities are exclusively compared between these two biogeochemically distinct soil types, the impact of characteristics altered by shrub species, especially soil C and N, are likely to be overemphasized and overshadow the role of other characteristics in structuring microbial composition. To determine how belowground characteristics influence microbial community composition, and if the relative importance of these characteristics shifts across the landscape (i.e., between and within shrub and interspace soils), changes in microbial communities across a 3000-year cold desert chronosequence were related to 27 belowground characteristics in surface and subsurface soils. When shrub and interspace communities in surface and subsurface soils were combined across the entire chronosequence, communities differed and were primarily influenced by soil C, NO3− concentrations, bulk density, pH, and root presence. Within shrub soils, microbial communities were shrub species-specific, especially in surface soils, highlighting differences in soil characteristics created by specific shrub species and/or similarity in stresses structuring shrub species and microbial communities alike. Microbial communities in shrub soils were not influenced by soil C, but by NO3− and NH4+ concentrations, pH, and silt in surface soils; and Cl, P, soil N, and NO3− concentrations in subsurface soils. Interspace soil communities were distinct across the chronosequence at both depths and were strongly influenced by dune development. Interspace communities were primarily associated with soil stresses (i.e., high B and Cl concentrations), which decreased with dune development. The distribution of Gram-positive bacteria, Actinobacteria, and fungi highlighted community differences between and within shrub and interspace soils, while Gram-negative bacteria were common in all soils across the chronosequence. Of the 27 belowground characteristics investigated, 13 separated shrub from interspace communities, and of those, only five emerged as factors influencing community composition within shrub and interspace soils. As dunes develop across this cold desert chronosequence, microbial community composition was not regulated primarily by soil C, but by N and P availability and soil stresses in shrub soils, and exclusively by soil stresses in interspace soils. 相似文献
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