土壤线虫对气候变化的响应研究进展

全球变化对陆地生态系统功能具有重要而深远的影响。陆地生态系统地下部分具有重要的生态功能,其组成及结构对气候变化的响应将进一步减缓或加剧全球化进程。土壤线虫在各类生态系统中分布十分广泛,是地下食物网的重要组分,在维持土壤生物多样性及营养物质循环过程中发挥重要作用,其组成及结构对不同气候变化驱动因子的响应机制与模式不尽相同。增温及降水格局变化主要是通过改变线虫生境而直接影响其种群密度与结构,两者通常表现为正效应且作用效果随处理时间的延长而增强。CO2与大气氮沉降主要是通过影响地上植被,凋落物质量,土壤理化性质等间接过程影响土壤线虫。同时,不同的全球变化因子之间存在着复杂的交互作用,深入理解这些因子之间交互作用对线虫群落的影响模式与机制对于探讨未来气候变化情景下生态统生物多样性及养分循环过程具有重要的理论指导意义。     

Complexity of multitrophic interactions in a grassland ecosystem depends on plant species diversity

1.?We studied the theoretical prediction that a loss of plant species richness has a strong impact on community interactions among all trophic levels and tested whether decreased plant species diversity results in a less complex structure and reduced interactions in ecological networks. 2.?Using plant species-specific biomass and arthropod abundance data from experimental grassland plots (Jena Experiment), we constructed multitrophic functional group interaction webs to compare communities based on 4 and 16 plant species. 427 insect and spider species were classified into 13 functional groups. These functional groups represent the nodes of ecological networks. Direct and indirect interactions among them were assessed using partial Mantel tests. Interaction web complexity was quantified using three measures of network structure: connectance, interaction diversity and interaction strength. 3.?Compared with high plant diversity plots, interaction webs based on low plant diversity plots showed reduced complexity in terms of total connectance, interaction diversity and mean interaction strength. Plant diversity effects obviously cascade up the food web and modify interactions across all trophic levels. The strongest effects occurred in interactions between adjacent trophic levels (i.e. predominantly trophic interactions), while significant interactions among plant and carnivore functional groups, as well as horizontal interactions (i.e. interactions between functional groups of the same trophic level), showed rather inconsistent responses and were generally rarer. 4.?Reduced interaction diversity has the potential to decrease and destabilize ecosystem processes. Therefore, we conclude that the loss of basal producer species leads to more simple structured, less and more loosely connected species assemblages, which in turn are very likely to decrease ecosystem functioning, community robustness and tolerance to disturbance. Our results suggest that the functioning of the entire ecological community is critically linked to the diversity of its component plants species.     

农田土壤食物网管理的原理与方法

土壤食物网在维持生态系统生产力和健康等方面起着重要作用,但现代农业中,化肥农药等外部投入已经改变或部分替代了土壤食物网的功能,由此也造成一系列的环境问题。为了协调作物高产与环境保护的利益,需要对土壤食物网进行管理,使土壤食物网符合作物生长的需要,即建立健康土壤食物网。管理土壤食物网有两种方式:(1)直接方式,即通过调节食物网各个功能群的组成来管理土壤食物网;(2)间接方式,即根据农田土壤食物网以自下而上调控方式为主、强调低营养阶层的资源限制的原理,通过调节碎屑的数量和质量来管理食物网。在这两种调控方式中,都需要对被管理的食物网进行监测,监测的方式也分两种,一种是直接测定食物网各功能群的数量和生物量,另外一种方式即以线虫为工具来反应土壤食物网的结构。     

水分条件变化对土壤微生物的影响及其响应机制研究进展

土壤微生物在维持陆地生态系统服务中扮演着重要的角色.土壤水分条件是影响微生物活性与生态系统功能的重要因素之一,全球气候变化所引起的极端干旱与降雨必将加速土壤水分的剧烈变化.由于不同土壤微生物对干旱胁迫的耐受性不同及其对水分变化的响应差异,使得土壤水分条件变化直接改变了土壤微生物活性与群落结构,进而对微生物介导的关键过程与土壤生态系统功能造成深刻的影响.因此,全面深入地理解水分条件变化下土壤微生物群落的结构变化特征与响应机制具有重要意义.本文在总结土壤水分条件变化对土壤微生物活性(土壤呼吸与酶活性)和微生物群落结构的影响的基础上,进一步阐述了土壤微生物对干旱胁迫与水分条件变化的响应机制和生态学策略,包括: 1)积累胞内溶质、产生胞外聚合物、进入休眠状态等应对干旱胁迫的细胞生理策略;2)微生物之间、微生物与植物之间相关抗逆性基因的转移及土壤微生物群落的功能冗余等应对水分变化的微生物机制.研究水分条件变化下土壤微生物群落结构及生态系统功能之间的内在联系,不仅有助于进一步剖析微生物介导的土壤生态过程,而且能够为今后陆地生态系统对气候变化的响应研究和模型预测提供理论依据.     

Heat tolerance variation reveals vulnerability of tropical herbivore–parasitoid interactions to climate change

Assessing the heat tolerance (CTmax) of organisms is central to understand the impact of climate change on biodiversity. While both environment and evolutionary history affect CTmax, it remains unclear how these factors and their interplay influence ecological interactions, communities and ecosystems under climate change. We collected and reared caterpillars and parasitoids from canopy and ground layers in different seasons in a tropical rainforest. We tested the CTmax and Thermal Safety Margins (TSM) of these food webs with implications for how species interactions could shift under climate change. We identified strong influence of phylogeny in herbivore–parasitoid community heat tolerance. The TSM of all insects were narrower in the canopy and parasitoids had lower heat tolerance compared to their hosts. Our CTmax-based simulation showed higher herbivore–parasitoid food web instability under climate change than previously assumed, highlighting the vulnerability of parasitoids and related herbivore control in tropical rainforests, particularly in the forest canopy.     

土壤微食物网结构与生态功能

土壤微食物网是碎屑食物网中与土壤生态过程密切相关的一部分,通过取食资源基质直接或间接地参与养分循环过程,影响陆地生态系统功能.本文从土壤微食物网的组成、结构和生态功能等方面综述了近年来土壤微食物网的研究进展.通过对土壤微食物网的能量通道及营养级联效应的介绍,阐述了土壤微食物网在碳(C)、氮(N)转化、凋落物分解和植物生长等方面的重要作用.针对目前的研究现状,提出未来土壤生态学研究应与高通量测序及稳定同位素技术相结合;通过构建模型进一步加强对土壤食物网结构和功能的研究,从而深入揭示地下生态过程及其对地上植物生长的反馈作用机理.     

Forecasting fine‐scale changes in the food‐web structure of coastal marine communities under climate change

Climate change is inducing deep modifications in local communities worldwide as a consequence of individualistic species range shifts. Understanding how complex interaction networks will be reorganized under climate change represents a major challenge in the fields of ecology and biogeography. However, forecasting the potential effects of climate change on local communities, and more particularly on food‐web structure, requires the consideration of highly structuring processes, such as trophic interactions. A major breakthrough is therefore expected by combining predictive models integrating habitat selection processes, the physiological limits of marine species and their trophic interactions. In this study, we forecasted the potential impacts of climate change on the local food‐web structure of the highly threatened Gulf of Gabes ecosystem located in the south of the Mediterranean Sea. We coupled the climatic envelope and habitat models to an allometric niche food web model, hence taking into account the different processes acting at regional (climate) and local scales (habitat selection and trophic interactions). Our projections under the A2 climate change scenario showed that future food webs would be composed of smaller species with fewer links, resulting in a decrease of connectance, generality, vulnerability and mean trophic level of communities and an increase of the average path length, which may have large consequences on ecosystem functioning. The unified framework presented here, by connecting food‐web ecology, biogeography and seascape ecology, allows the exploration of spatial aspects of interspecific interactions under climate change and improves our current understanding of climate change impacts on local marine food webs.     

Global change and species interactions in terrestrial ecosystems

The main drivers of global environmental change (CO₂ enrichment, nitrogen deposition, climate, biotic invasions and land use) cause extinctions and alter species distributions, and recent evidence shows that they exert pervasive impacts on various antagonistic and mutualistic interactions among species. In this review, we synthesize data from 688 published studies to show that these drivers often alter competitive interactions among plants and animals, exert multitrophic effects on the decomposer food web, increase intensity of pathogen infection, weaken mutualisms involving plants, and enhance herbivory while having variable effects on predation. A recurrent finding is that there is substantial variability among studies in both the magnitude and direction of effects of any given GEC driver on any given type of biotic interaction. Further, we show that higher order effects among multiple drivers acting simultaneously create challenges in predicting future responses to global environmental change, and that extrapolating these complex impacts across entire networks of species interactions yields unanticipated effects on ecosystems. Finally, we conclude that in order to reliably predict the effects of GEC on community and ecosystem processes, the greatest single challenge will be to determine how biotic and abiotic context alters the direction and magnitude of GEC effects on biotic interactions.     

重金属污染土壤中生物间相互作用及其协同修复应用

土壤是人类赖以生存的物质基础。我国土壤重金属污染状况不容乐观,给人类健康构成严重威胁。生物修复重金属污染土壤被广泛认为是可持续的修复技术,但当前仍存在修复效率不高的科学瓶颈问题。土壤中生活着丰富的微生物、植物和动物,且这些生物之间存在着复杂的相互作用,并且通过物质循环和能量传递形成了错综复杂的食物网联系。土壤生物间的相互作用能深刻影响土壤中污染物的迁移转化和生物修复的效率,多元生物协同的修复技术集合了单一生物修复方法的优势,具有强化生物修复效果的巨大潜力。文中综述了土壤中微生物-植物-动物之间的相互作用,及其对土壤重金属迁移转化和生物修复效果的影响,并对定向调控土壤食物网结构、提高重金属污染土壤的生物修复效果、建立基于食物网的多元生物协同修复技术进行了展望。     

Climate change–contaminant interactions in marine food webs: Toward a conceptual framework

Climate change is reshaping the way in which contaminants move through the global environment, in large part by changing the chemistry of the oceans and affecting the physiology, health, and feeding ecology of marine biota. Climate change‐associated impacts on structure and function of marine food webs, with consequent changes in contaminant transport, fate, and effects, are likely to have significant repercussions to those human populations that rely on fisheries resources for food, recreation, or culture. Published studies on climate change–contaminant interactions with a focus on food web bioaccumulation were systematically reviewed to explore how climate change and ocean acidification may impact contaminant levels in marine food webs. We propose here a conceptual framework to illustrate the impacts of climate change on contaminant accumulation in marine food webs, as well as the downstream consequences for ecosystem goods and services. The potential impacts on social and economic security for coastal communities that depend on fisheries for food are discussed. Climate change–contaminant interactions may alter the bioaccumulation of two priority contaminant classes: the fat‐soluble persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), as well as the protein‐binding methylmercury (MeHg). These interactions include phenomena deemed to be either climate change dominant (i.e., climate change leads to an increase in contaminant exposure) or contaminant dominant (i.e., contamination leads to an increase in climate change susceptibility). We illustrate the pathways of climate change–contaminant interactions using case studies in the Northeastern Pacific Ocean. The important role of ecological and food web modeling to inform decision‐making in managing ecological and human health risks of chemical pollutants contamination under climate change is also highlighted. Finally, we identify the need to develop integrated policies that manage the ecological and socioeconomic risk of greenhouse gases and marine pollutants.     

Biotechnology, environmental forcing, and unintended trophic cascades

A long ongoing discussion between scientists and policy decision-makers seems to have entered recently into a new phase. The consequences of release of transgenic crops into the environment are being discussed not only by scientists but also by farmers, environmental groups and politicians, while an increasing amount of data is becoming available at all biological scales, including the field level. However, data still rely on experiments designed to capture direct consumer–resource interactions. Here we argue that we should attempt to concentrate on the ecosystem functioning of soil biota under genetically-modified (GM) plants, because functional and mechanistic analysis of the multitrophic effects of GM plants on soil biota is still lacking. It is our opinion that we should avoid addressing taxa and soil communities separately, but link them at their functional level. We shall explain why, using examples from ecosystem services, allometric scaling, and soil food webs. The energy flow of any food web under stress incorporates several factors and pooled information on ecosystem services and on the different responses of soil invertebrates to induced perturbations in other trophic levels. Therefore, we will systematically focus on the complementarities of these approaches. Handling editor: Sam Cook     

Local and non-local soil microbiota impede germination of the endangered Acacia whibleyana

Inoculating soils with microbiota that benefit the germination and growth of endangered plant species could improve their revegetation success and conservation status. While ecosystem degradation can disrupt beneficial plant–soil-microbial interactions, the prospect of reintroducing native plant-associated soil microbiota during revegetation could help to restore these important ecological links and assist the recovery of key species. We address the role of soil microbiota on germination and seedling fitness traits of the endangered Acacia whibleyana (Fabaceae) through a 17-week greenhouse experiment. Soil treatments included local soil, potting medium, three inoculation ratios (3:1, 1:1, 1:3 local soil: potting medium), sterilized local soil and sterilized potting medium. Soil sterilization reduced the time to first seed germination, indicating a role of soil microbiota on germination. The 1:1 whole soil inoculation saw reduced germination rates compared with either pure local or potting-medium treatments, and the slower germination times observed in live soils confirmed the strong influence of soil microbiota on the timing of germination. We report evidence that poor inoculation strategies can adversely impact germination of this endangered Acacia. Furthermore, our findings suggest that careful assessment of microbiota associated with A. whibleyana could help to improve germination and recruitment during its revegetation and conservation management.     

农田土壤线虫多样性研究现状及展望

目前土壤生物多样性已成为土壤生态学研究的热点问题之一。土壤生物以不同的方式改变着土壤的物理、化学和生物学特性。在农田生态系统中, 土壤动物是分解作用和养分矿化作用等生态过程的主要调节者。线虫作为土壤中数量最丰富的后生动物, 其生活史和取食类型多样, 在生态系统中发挥着重要作用。本文介绍了农田生态系统中影响线虫多样性的主要因素; 回顾了土壤线虫的物种多样性、营养类群多样性、生活史多样性和功能多样性的研究现状; 并提出了今后农田生态系统线虫多样性研究的重点。建议通过综合土壤线虫的生活史策略和营养类群等信息, 深入了解其生物多样性和土壤生态系统功能, 从而更好地发挥土壤线虫对农田生态系统变化的生物指示作用。     

干旱半干旱草地生态系统与土壤水分关系研究进展

研究干旱半干旱草地生态系统与土壤水分关系和相互作用机理对于揭示草地生态系统稳定性及其水土关键要素的变化过程具有重要意义。从不同界面、不同尺度综述了草地生态系统对土壤水分的影响及草地生态系统的响应与适应机制,总结了草地生态系统与土壤水分关系模型研究的相关进展,并分析了气候变化对草地生态系统和土壤水分关系的影响。草地生态系统通过影响水文过程和生态过程来影响土壤水分,土壤水分在植物生长发育、形态、生理生态过程、种间关系、群落组成和结构以及草地生态系统功能等方面对草地生态系统产生影响;充分揭示草地生态系统-土壤水分相互作用机理是模型研究的关键;气候变化对草地生态系统植物与土壤水分关系具有重要影响。今后应加强以下研究:1)开展草地不同优势种和植物功能型与土壤水分关系的研究,找出能反映植物对土壤水分响应的性状指标,阈值响应点及适应机制;2)注重对不同时间和空间尺度上的转换和比较;3)加强个体、群体和生态系统尺度草地植物生长模型的研究及其与土壤-植被-大气水分传输模型的耦合;4)加强草地生态系统与土壤水分关系对气候变化响应的研究。     

准噶尔盆地植被与土壤盐渍化关联性变化趋势分析

准噶尔盆地作为北疆地区主要的气候单元其环境变化会影响北疆地区整体的的生态环境变化。植被作为衡量区域生态环境的重要指标直接反映了准噶尔盆地的生态状况,近年来受到全球气候变化的影响准噶尔盆地地区气候格局发生改变,盆地相比于往年降水和气温明显升高,这种改变影响了盆地的植被变化同时也会在部分地区诱发土壤盐渍化灾害。土壤盐渍化是我国西北地区常见的导致植被退化的因素,其生成原因与地形和气候因素有关。为了探究准噶尔盆地植被变化与土壤盐渍化的关联性,基于2002-2019年生长季MOD09A1遥感影像数据,利用最大值合成法、Mann-Kendall趋势分析,Hurst趋势分析法、相关性分析等方法对准噶尔盆地植被和土壤盐渍化变化趋势以及两者的关联性进行了分析。结果表明,受区域降水和气温升高的影响,近20年来准噶尔盆地生长季植被整体呈增加趋势,各季节增加区域面积占比为63.50%-90.93%,平均为77.98%。土壤盐渍化呈减少趋势,各季减少区域面积占比为46.50%-86.78%,平均为70.68%。在地形低洼、排水不畅的区域土壤盐渍化程度加重,植被因盐分胁迫导致衰退,植被减少及巨大的蒸发降水比使得该地区土壤进一步变干,湿度降低。关联性分析结果表明各季植被与土壤盐渍化的变化中呈显著负相关的区域面积占比为37.36%-57.83%,平均为51.75%。Hurst趋势预测结果表明,当前植被和土壤盐渍化两者呈显著性变化的区域未来预测与当前变化方向相同,两者呈一般性变化的区域未来预测与当前相反。研究有助于在全球气候变化背景下了解准噶尔盆地近年来生态环境变化,结果为区域生态环境的可持续发展提供参考。     

Soils in warmer and less developed countries have less micronutrients globally

Soil micronutrients are capital for the delivery of ecosystem functioning and food provision worldwide. Yet, despite their importance, the global biogeography and ecological drivers of soil micronutrients remain virtually unknown, limiting our capacity to anticipate abrupt unexpected changes in soil micronutrients in the face of climate change. Here, we analyzed >1300 topsoil samples to examine the global distribution of six metallic micronutrients (Cu, Fe, Mn, Zn, Co and Ni) across all continents, climates and vegetation types. We found that warmer arid and tropical ecosystems, present in the least developed countries, sustain the lowest contents of multiple soil micronutrients. We further provide evidence that temperature increases may potentially result in abrupt and simultaneous reductions in the content of multiple soil micronutrients when a temperature threshold of 12–14°C is crossed, which may be occurring on 3% of the planet over the next century. Altogether, our findings provide fundamental understanding of the global distribution of soil micronutrients, with direct implications for the maintenance of ecosystem functioning, rangeland management and food production in the warmest and poorest regions of the planet.     

Plant metabolomics for plant chemical responses to belowground community change by climate change

General circulation models on global climate change predict increase in surface air temperature and changes in precipitation. Increases in air temperature (thus soil temperature) and altered precipitation are known to affect the species composition and function of soil microbial communities. Plant roots interact with diverse soil organisms such as bacteria, protozoa, fungi, nematodes, annelids and insects. Soil organisms show diverse interactions with plants (eg. competition, mutualism and parasitism) that may alter plant metabolism. Besides plant roots, various soil microbes such as bacteria and fungi can produce volatile organic compounds (VOCs), which can serve as infochemicals among soil organisms and plant roots. While the effects of climate change are likely to alter both soil communities and plant metabolism, it is equally probable that these changes will have cascading consequnces for grazers and subsequent food web components aboveground. Advances in plant metabolomics have made it possibile to track changes in plant metabolomes as they respond to biotic and abiotic environmental changes. Recent developments in analytical instrumentation and bioinformatics software have established metabolomics as an important research tool for studying ecological interactions between plants and other organisms. In this review, we will first summarize recent progress in plant metabolomics methodology and subsequently review recent studies of interactions between plants and soil organisms in relation to climate change issues.     

Soil multitrophic network complexity enhances the link between biodiversity and multifunctionality in agricultural systems

Belowground biodiversity supports multiple ecosystem functions and services that humans rely on. However, there is a dearth of studies exploring the determinants of the biodiversity–ecosystem function (BEF) relationships, particularly in intensely managed agricultural ecosystems. Here, we reported significant and positive relationships between soil biodiversity of multiple organism groups and multiple ecosystem functions in 228 agricultural fields, relating to crop yield, nutrient provisioning, element cycling, and pathogen control. The relationships were influenced by the types of organisms that soil phylotypes with larger sizes or at higher trophic levels, for example, invertebrates or protist predators, appeared to exhibit weaker or no BEF relationships when compared to those with smaller sizes or at lower trophic levels, for example, archaea, bacteria, fungi, and protist phototrophs. Particularly, we highlighted the role of soil network complexity, reflected by co-occurrence patterns among multitrophic-level organisms, in enhancing the link between soil biodiversity and ecosystem functions. Our results represent a significant advance in forecasting the impacts of belowground multitrophic organisms on ecosystem functions in agricultural systems, and suggest that soil multitrophic network complexity should be considered a key factor in enhancing ecosystem productivity and sustainability under land-use intensification.     

帽儿山3种森林生态系统土壤动物与土壤呼吸及其相互关系研究

土壤呼吸是森林生态系统碳循环的关键过程,土壤动物可通过自身代谢及影响微生物活动调控土壤呼吸,因此研究土壤动物与土壤呼吸的相互关系对进一步揭示生态系统碳循环的规律和机理具有重要意义。通过野外定点,以帽儿山3种森林生态系统的土壤呼吸及土壤动物为研究对象,探讨不同森林生态系统的土壤呼吸、土壤动物个体密度和生物量的时间变化规律及二者相互关系。结果表明:(1)3种森林生态系统土壤总呼吸速率与土壤异养呼吸速率均呈现先增强后减弱的时间动态变化(P<0.05),且不同森林生态系统土壤异养呼吸速率差异显著(P<0.05),表现为硬阔叶林最高,红松人工林最低;(2)3种森林生态系统土壤动物生物量也具有显著的时间动态变化(P<0.05),均在9月份达到最大,且不同森林生态系统土壤动物个体密度显著不同(P<0.05),蒙古栎林土壤动物个体密度显著小于红松人工林与硬阔叶林;(3)通过回归分析可得,土壤动物数量及生物量的增加抑制了土壤呼吸速率,尤其在生长季初期、末期。研究表明土壤动物可通过抑制微生物生命活动和降低根系呼吸从而对土壤总呼吸及异养呼吸产生负反馈作用,三者是不可分割的整体,与土壤温度、水分等环境因子共同调控着土壤呼吸。     

喀斯特地区土壤异质性及其与植物相互作用

喀斯特地区复杂生境造成该地区土壤高度异质性,植被为适应特殊环境形成一定形态和生理结构特征,导致较高功能性状多样性。同时,植被又通过一系列生命活动改善了土壤的物理化学结构特征。植物与土壤之间的相互作用对研究生态系统的结构和功能及其对全球气候变化的响应具有重要作用。本文总结了喀斯特地区土壤异质性特征,概述了植物功能性状对异质土壤的响应及植物对土壤的反馈过程,揭示了喀斯特生态系统中植物-土壤耦合机制,并根据目前研究现状对该领域未来的研究内容和方向进行了展望,以期为喀斯特脆弱生态系统结构和功能稳定性维系提供科学参考。