Biotic communities cannot mitigate the negative effects of grazing on multiple ecosystem functions and services in an arid shrubland

Plant and Soil - Dryland biotic communities (plants and biocrusts) are known to maintain multiple functions (multifunctionality) and services (multiservices) that decline with overgrazing by...     

Seasonal effects of altered precipitation regimes on ecosystem-level CO2 fluxes and their drivers in a grassland from Eastern Australia

Plant and Soil - We evaluated the impacts of altered precipitation regimes on multiple aspects of the C cycle, including C fluxes, plant and soil microbial communities, and plant-soil interactions...     

Response to soil biota by native, introduced non-pest, and pest grass species: is responsiveness a mechanism for invasion?

Soil biota have been credited with helping to maintain native plant diversity in multiple systems. Recent evidence suggests that introduced species may be less responsive to soil communities than most native species. If response to soil communities is correlated with invasive ability, we predict that introduced pest species should be less responsive to soil communities than introduced non-pest species or natives. In this study we test whether response to soil biota from two diverse grassland communities differs between four introduced pest, six introduced non-pest, and five native species in grasses in Yolo County, California. We found no variation in plant size or response to soil biota between introduced pest and introduced non-pest species, and these were combined in subsequent analyses. Overall, all introduced species grew significantly faster than native species. Native species showed greater variation in response to soil communities than both groups of introduced species, and native species’ response varied with soil community. Variation among native species’ response to soil nutrients and biota through processes like soil feedbacks may be key to maintaining diversity across landscapes in uninvaded environments. Introduced species appear less responsive to landscape variability in soil communities, which may allow them to establish and dominate plant communities in multiple habitats.     

土壤动物群落空间格局和构建机制研究进展

群落空间格局和构建机制一直是生态学研究的核心内容。在生物多样性严重丧失的背景下, 揭示群落空间格局及其构建机制, 有助于深刻理解生物多样性丧失的原因, 更有助于应对生物多样性保护等重大生态环境问题。然而, 陆地生态系统的研究多集中于地上生物群落, 对地下生态系统, 尤其是土壤动物空间格局和构建机制的研究尚不充分。事实上, 土壤动物多样性是全球生物多样性的关键组成之一, 是地下生态系统结构和功能维持的重要部分。对土壤动物空间格局和构建机制的研究, 能明确不同空间尺度条件下土壤动物多样性的维持机制。土壤动物群落常在多种空间尺度形成复杂的空间分布格局, 因此, 本文首先介绍了不同空间尺度主要土壤动物群落的空间自相关性特征, 阐述了土壤动物群落斑块和孔隙镶嵌分布的复杂空间格局。继而阐明这种空间格局主要受生物间作用、环境过滤和随机扩散的调控, 并说明这三个过程对土壤动物群落的调控能力和作用方式。作者提出, 这三个过程仍是今后土壤动物群落空间格局和构建机制研究的重点内容, 需要进一步加强以土壤动物为研究对象的群落构建理论的验证和发展。我国土壤动物群落空间格局和构建机制起步较晚, 希望本文能够促进我国土壤动物生态学相关领域的研究。     

Erosion reduces soil microbial diversity,network complexity and multifunctionality

While soil erosion drives land degradation, the impact of erosion on soil microbial communities and multiple soil functions remains unclear. This hinders our ability to assess the true impact of erosion on soil ecosystem services and our ability to restore eroded environments. Here we examined the effect of erosion on microbial communities at two sites with contrasting soil texture and climates. Eroded plots had lower microbial network complexity, fewer microbial taxa, and fewer associations among microbial taxa, relative to non-eroded plots. Soil erosion also shifted microbial community composition, with decreased relative abundances of dominant phyla such as Proteobacteria, Bacteroidetes, and Gemmatimonadetes. In contrast, erosion led to an increase in the relative abundances of some bacterial families involved in N cycling, such as Acetobacteraceae and Beijerinckiaceae. Changes in microbiota characteristics were strongly related with erosion-induced changes in soil multifunctionality. Together, these results demonstrate that soil erosion has a significant negative impact on soil microbial diversity and functionality.Subject terms: Soil microbiology, Microbial ecology     

Plant community composition steers grassland vegetation via soil legacy effects

Soil legacy effects are commonly highlighted as drivers of plant community dynamics and species co‐existence. However, experimental evidence for soil legacy effects of conditioning plant communities on responding plant communities under natural conditions is lacking. We conditioned 192 grassland plots using six different plant communities with different ratios of grasses and forbs and for different durations. Soil microbial legacies were evident for soil fungi, but not for soil bacteria, while soil abiotic parameters did not significantly change in response to conditioning. The soil legacies affected the composition of the succeeding vegetation. Plant communities with different ratios of grasses and forbs left soil legacies that negatively affected succeeding plants of the same functional type. We conclude that fungal‐mediated soil legacy effects play a significant role in vegetation assembly of natural plant communities.     

Morphological and ecophysiological root and leaf traits in ectomycorrhizal,arbuscular-mycorrhizal and non-mycorrhizal Alnus incana seedlings

Plant and Soil - Green manuring can suppress crop diseases and change soil microbial communities, but the functional significances of changes in soil microbial communities are unclear. Effects of...     

Temperate forest understorey species performance is altered by local arbuscular mycorrhizal fungal communities from stands of different successional stages

Plant and Soil - Arbuscular mycorrhizal (AM) fungal communities in plant roots vary in space and time. However, the effect of different fungal communities on plant performance and growth is poorly...     

Response of Microbial Community Composition and Function to Soil Climate Change

Soil microbial communities mediate critical ecosystem carbon and nutrient cycles. How microbial communities will respond to changes in vegetation and climate, however, are not well understood. We reciprocally transplanted soil cores from under oak canopies and adjacent open grasslands in a California oak–grassland ecosystem to determine how microbial communities respond to changes in the soil environment and the potential consequences for the cycling of carbon. Every 3 months for up to 2 years, we monitored microbial community composition using phospholipid fatty acid analysis (PLFA), microbial biomass, respiration rates, microbial enzyme activities, and the activity of microbial groups by quantifying ¹³C uptake from a universal substrate (pyruvate) into PLFA biomarkers. Soil in the open grassland experienced higher maximum temperatures and lower soil water content than soil under the oak canopies. Soil microbial communities in soil under oak canopies were more sensitive to environmental change than those in adjacent soil from the open grassland. Oak canopy soil communities changed rapidly when cores were transplanted into the open grassland soil environment, but grassland soil communities did not change when transplanted into the oak canopy environment. Similarly, microbial biomass, enzyme activities, and microbial respiration decreased when microbial communities were transplanted from the oak canopy soils to the grassland environment, but not when the grassland communities were transplanted to the oak canopy environment. These data support the hypothesis that microbial community composition and function is altered when microbes are exposed to new extremes in environmental conditions; that is, environmental conditions outside of their “life history” envelopes.     

三江源地区不同建植期人工草地植被特征及其与土壤特征的关系

研究了三江源地区不同建植期人工草地群落生物量、物种组成、多样性指数和土壤理化特征,并用多元逐步回归分析法探讨了土壤理化特征对群落生物量、多样性变化的响应.结果表明:研究区不同建植期人工草地植物群落的种类组成、植物功能群组成和群落数量特征存在显著差异;土壤含水量随着物种多样性指数的增加而增加,土壤容重随着物种多样性的增加而减小;土壤微生物生物量碳与土壤含水量、土壤有机质呈极显著正相关,与土壤容重呈极显著负相关;土壤有机碳含量明显呈"V"字型变化,且与土壤含水量的变化趋势相一致,随土壤容重的增加而减少;群落生物量与土壤养分和土壤含水量之间呈显著正相关,群落地上、地下生物量的增加有利于提高土壤养分含量.     

Elevated CO2 increases fungal-based micro-foodwebs in soils of contrasting plant species

Plant and Soil - As different plant species support different soil communities, assessment of climate change impacts on soil communities must consider how these impacts depend on the vegetation. We...     

陕西洋县药用植物群落土壤种子库特性研究

采用种子萌发法对洋县药用植物群落土壤种子库物种组成、单位面积种子密度、物种丰富度及与地上群落结构的关系进行了研究。结果显示,研究区内共有种子植物50种(包括药用植物21种),隶属于28科47属,其中草本植物45种、乔木5种;不同药用植物群落间土壤种子库种子密度差异显著,从大到小依次为:2年生凹叶厚朴(Magnolia officinalis Rehd.et Wils.subsp.biloba(Rehd.et Wils.)Law)4年生凹叶厚朴7年生凹叶厚朴11年生凹叶厚朴杜仲-凹叶厚朴(Eucommia ulmoides Oliver-Magnolia officinalis Rehd.et Wils.subsp.biloba(Rehd.et Wils.)Law)7年生厚朴(Magnolia officinalis Rehd.et Wils.)杜仲山茱萸(Cornus officinalis Sieb.et Zucc.)山茱萸-凹叶厚朴;土壤种子库具有表聚性,土层深度与种子数量成负相关;药用植物群落土壤种子库与地上群落结构相似性普遍较低。低林龄群落的土壤种子库密度大于高林龄群落,因此低林龄群落有利于天然更新,它们在植被恢复和生物多样性保护中的潜在价值更大。本研究结果可为洋县药用植物群落天然更新提供理论指导。     

Comparison of soil microbial communities from two distinct karst areas in Hungary

Karst areas belong to the most exposed terrestrial ecosystems, therefore their study have a priority task in Hungary, as well. The aim of this study was to compare the structure, activity and diversity of soil microbial communities from two distinct Hungarian karst areas (Aggtelek NP and Tapolca-basin). Soil samples were taken three times from 6 distinct sites, from different depths. Soil microbial biomass C (MBC), microbial biomass N (MBN), basal respiration (BRESP) and substrate induced respiration (SIR) were measured. The phylogenetic diversity of bacterial communities was compared by Denaturing Gradient Gel Electrophoresis (DGGE). The highest MBC, MBN, BRESP and SIR values were measured in the rendzina soil from Aggtelek. On the basis of biomass and respiration measurements, microbial communities differentiated mainly according to soil depths whereas DGGE profiles of bacterial communities resulted in groups mainly according to sampling sites.     

典型黑土区农田土壤线虫群落的纬度分布格局及其驱动机制

东北黑土区是保障我国粮食安全的重要土壤资源, 了解该区域内农田土壤线虫的群落组成及其对环境驱动因子的响应机制, 对于研究黑土区农田土壤生态系统的生物多样性分布格局具有重要意义。2018年9月, 我们在42°50°‒49°08° N的典型黑土区采集了93个农田土壤样品, 利用形态学鉴定技术分析了土壤线虫群落的组成与结构。共鉴定出47个线虫属(相对丰度 > 1%), 其中食细菌线虫中的拟丽突属(Acrobeloides)是典型黑土区农田土壤中的优势属(相对丰度 > 5%)。土壤线虫总丰富度和总多度均随纬度增加而显著增加, 然而类似的变化趋势只出现在食细菌和杂食/捕食线虫中。土壤有机碳是影响土壤线虫丰富度和多度最为重要的环境因子, 其次是月平均温度。典型黑土区农田土壤线虫群落结构以47° N为分界线分为南部和北部两类, 主要归因于线虫群落中植物寄生和杂食/捕食线虫的相对多度在南、北特征属中存在差异。土壤pH值和容重分别是影响南部与北部黑土区线虫群落最重要的环境因子。本研究明确了典型黑土区农田土壤线虫群落的纬度分布格局及其与环境因素的关系, 可为揭示农业活动干扰下土壤生物对环境因子的响应机制提供基础数据和理论参考。     

Biogeographic patterns in below-ground diversity in New York City's Central Park are similar to those observed globally

Soil biota play key roles in the functioning of terrestrial ecosystems, however, compared to our knowledge of above-ground plant and animal diversity, the biodiversity found in soils remains largely uncharacterized. Here, we present an assessment of soil biodiversity and biogeographic patterns across Central Park in New York City that spanned all three domains of life, demonstrating that even an urban, managed system harbours large amounts of undescribed soil biodiversity. Despite high variability across the Park, below-ground diversity patterns were predictable based on soil characteristics, with prokaryotic and eukaryotic communities exhibiting overlapping biogeographic patterns. Further, Central Park soils harboured nearly as many distinct soil microbial phylotypes and types of soil communities as we found in biomes across the globe (including arctic, tropical and desert soils). This integrated cross-domain investigation highlights that the amount and patterning of novel and uncharacterized diversity at a single urban location matches that observed across natural ecosystems spanning multiple biomes and continents.     

黄土高原四种人工植物群落土壤呼吸季节变化及其影响因子

以黄土高原侧柏、柠条、沙棘和油松人工植物群落为对象,土壤呼吸日动态和季节变化及其与环境因子之间的关系,结果表明:4种植物群落土壤呼吸速率具有典型的日变化和季节变化模式, 4种群落中,以侧柏6月土壤呼吸日变幅最大,沙棘6月土壤呼吸日变幅最小,大部分群落不同月份最大土壤呼吸与最小土壤呼吸倍数在1.1～1.6之间.4种群落中,以柠条土壤呼吸季节变幅最大,侧柏最小,最大土壤呼吸与最小土壤呼吸的倍数为1.5～2.2倍之间.同一植物类型土壤呼吸具有明显的季节变化特征,其具体变化趋势因植物类型而异.4种植物群落土壤呼吸速率与土壤和大气温度以及土壤含水量的关系在不同季节表现为不同的关系,其中侧柏和柠条土壤呼吸与土壤温度均呈乘幂关系,与大气温度为指数关系.沙棘土壤呼吸与土壤温度和大气温度均为乘幂关系,油松土壤呼吸与土壤温度和大气温度均为线性关系.这表明土壤呼吸与土壤和大气温度之间的关系及其紧密程度因植被类型而异.综合分析表明,同一气候区相同环境因子对不同植物群落土壤呼吸的影响作用不同,且因其自身具有明显的季节变化,从而导致对土壤呼吸的调控作用也具有明显的季节变异模式.     

紫茎泽兰与非洲狗尾草单、混种群落土壤酶活性和土壤养分的比较

 植物对土壤有效养分的影响是植物竞争取胜的重要生态策略之一, 土壤酶活性对土壤有效养分的变化具有重要作用。该文研究了紫茎 泽兰(Ageratina adenophora)单种(A)、非洲狗尾草(Setaria sphacelata)单种(S)和两物种混种(A+S)群落4种重要的土壤酶活性和土壤养分的 变化及其规律, 并对土壤酶活性与土壤养分进行了相关分析。结果表明: 1)群落S土壤有效氮(NH₄⁺-N和NO₃^--N)含量高于群落A对应养分含量, 而与群落A＋S该养分含量没有显著差异; 群落S土壤有效磷和有效钾含量低于群落A对应指标, 而群落A＋S其含量最低。2)群落S、A+S和A土壤蛋 白酶和脲酶活性的高低次序分别为S>A＋S>A、A＋S>S>A; 群落A+S、S和A磷酸酶活性依次升高; 群落A+S、A和S蔗糖酶活性依次降低。3)在生长 过程中, 3类群落土壤NO₃^--N、有效磷和有效钾含量在生长初期(5月)最高, 随后逐渐降低; 土壤NH₄⁺-N含量呈现单峰趋势, 在生长后期(9月)最 高。3类群落土壤蛋白酶和蔗糖酶活性随生长时间推移而升高, 在生长末期(11月)最高; 土壤磷酸酶和脲酶酶活性在生长过程中呈现单峰趋势, 在生长旺盛期(7月)最高。3类群落间土壤酶活性与土壤肥力具有较一致的相关性。由此推断, 非洲狗尾草对土壤含氮化合物的活化能力比紫茎 泽兰强, 且在种间竞争中能够强烈抑制紫茎泽兰对土壤含磷、含钾化合物的活化能力是其竞争取胜的可能原因; 不同植物群落土壤酶活性的差 异是引起土壤有效养分变化的重要驱动机制之一。     

Litter decomposition in Mediterranean pine forests is enhanced by reduced canopy cover

Plant and Soil - Compare bacterial communities in non-vegetated soils and in the rhizosphere of Ni-hyperaccumulating or Ni-excluding plants from four serpentine sites of the Iberian Peninsula....     

Soil microbial activity in a Mediterranean garrigue responds more to changing shrub community than to reduced rainfall

Plant and Soil - The functioning of soil microbial communities is co-determined by plant community composition and environmental factors. Decreased precipitation predicted in the Mediterranean area...     

Linking soil biodiversity and vegetation: implications for a changing planet

Soil biota are intimately tied to plant communities through herbivory and symbiosis and indirectly by the decomposition of dead organic plant material. Through both roots and aboveground organic material (e.g., leaves and wood), plants provide substantial inputs of organic matter to soil systems. Plants are the basis for most biotic soil food webs that comprise an enormous diversity of species whose multiple interactions function to help regulate nutrient cycling, which in turn influences plant growth. Many factors govern the biogeography of soil biota, including the physical and chemical properties of soil, climate, the composition and type of vegetation, and interactions with other soil biota. Despite awareness of factors influencing soil communities, no single factor allows predictions of soil animal diversity or distribution. However, research is showing that plants can have unique soil biotic communities. Degradation of soil, which removes predators and biotic regulation that occurs in less managed ecosystems, can result in increased pathogens and pests that affect humans, other animals and plants. Global changes such as land use, desertification, and soil pollution all have been shown to alter soil animal diversity and abundance. Because of our dependence on soils and plant production, studies linking soil biotic communities to primary productivity are needed to assure long-term soil sustainability.