以昆虫作为指示生物评估森林健康的生物学与生态学基础

昆虫是森林生物多样性的重要组成部分,在森林生态系统主体群落中,昆虫与植物密切关联.森林害虫胁迫及昆虫多样性变动,对于评估森林生态系统健康状况具有重要价值.昆虫多样性可用于对森林生态系统健康的快速评估,如基于昆虫指示生物评价森林生态系统的毒害水平、物种丰富度、多样性水平、靶标昆虫的地位和特有种水平等.针对影响森林环境健康的重要干扰因子,本文阐述了应用昆虫作为指示性生物监测与评估森林健康状况的生物与生态学依据,讨论了昆虫种群,特别是珍稀物种种群在生境破碎干扰下的种群波动,以及大气污染、干旱和二氧化碳浓度升高等对昆虫种群密度与分布的影响等.同时,分析了昆虫作为指示性生物监测与评估森林环境健康所存在的问题.     

农业景观异质性对生物多样性与生态系统服务的影响研究进展

农业景观是人类生活所需资料的最主要来源地,农业景观及其提供的生物多样性和生态系统服务是影响人类福祉的最主要因素之一。系统梳理了景观异质性变化对生物多样性和生态系统服务影响的相关研究,总结指出:(1)农业景观格局变化会强烈的影响着区域生物多样性和生态系统服务,但总体上更关注了空间异质性,对于时间和功能异质性的研究仍需加强;(2)尺度效应、大尺度上景观背景的差异、种间差异、营养级联效应等会对景观异质性和生物多样性、生态系统服务间的关系产生显著的、综合的、交互的影响效应。未来区域农业景观中如何通过景观构建和管理措施的施行来确保生物多样性与生态系统服务供给的持续稳定仍需进一步加强以下内容的研究:景观异质性变化在时间上和功能上的影响效应及其阈值的探讨;跨尺度、多因素、多物种类群与多生态系统服务的综合及其交互作用;不同生物类群和不同生态系统服务间的权衡;景观异质性提高与有效生境面积下降及其引起的生物随机丧失间的权衡等问题。     

青藏高原高寒草地生物多样性与生态系统功能的关系

生物多样性和生态系统功能(BEF)之间的关系是目前陆地生态系统生态学研究的热点, 对于生态系统的高效利用与管理意义重大, 而且对于退化生态系统功能的恢复及生物多样性的保护有重要的指导作用。高寒草地是青藏高原生态系统的主体, 近年来, 在气候变化与人为干扰等因素的驱动下, 高寒草地生态系统功能严重衰退。为此, 本文在综述物种多样性和生态系统功能及其相互关系研究进展的基础上, 首先从地下生态学过程研究、全球变化对生态系统多功能性的影响等方面解析了目前关于草地生物多样性和生态系统功能研究中存在的问题。继而, 从不同草地类型、草地退化程度、放牧、模拟气候变化、刈割、施肥、封育和补播等干扰利用方式对高寒草地物种多样性与生态系统功能的影响进行了全面的评述。并指出了高寒草地BEF研究中存在的不足, 今后应基于物种功能多样性开展高寒草地BEF研究, 全面且综合地考虑非生物因子(养分资源、外界干扰、环境波动等)对生物多样性与生态系统功能之间关系的影响, 关注尺度效应和要素耦合在全球气候变化对高寒草地BEF研究中的作用。最后, 以高寒草地BEF研究进展和结论为支撑依据, 综合提出了高寒草地资源利用和生物多样性保护的措施与建议: 加强放牧管理, 保护生物多样性; 治理退化草地, 维持生物多样性功能; 加强创新保护理念, 增强生态系统功能。     

基于优势种的生物多样性保护价值空间异质性研究——以长白山生态功能区为例

生物多样性保护是生态系统的主导功能之一,对生物多样性空间异质性的研究有助于准确认识区域的保护价值及重要性,但目前可借鉴的生物多样性价值空间异质性评价方法和经验偏少。以长白山生态功能区核心区为研究区域,基于生物多样性丰富区域优势物种的分布及其环境因子,通过Maxent评估生物多样性保护价值,将研究区域分为生物多样性保护高价值区、中价值区和一般价值区,并开展景观分析与评估。研究结果表明:研究区域内生物多样性保护高价值区域占总面积的42.9%、主要分布于长白山保护区内,保护区内的高价值斑块也较保护区外完整、面积大;研究区域内生物多样性高价值斑块的平均面积和最大斑块面积远高于中价值区和一般价值区,其斑块景观较完整、破碎化水平相对较低,是研究区域生物多样性保护价值和生态系统稳定性的重要基础。植被是对研究区域生物多样性影响最大的环境因子,其次是土层厚度和海拔。从生态系统完整性和过程连续性保护的需要,保护区南部缓冲区可考虑调整为核心区,保护区外还有较大面积的生物多样性高价值和中价值区域也应纳入保护区进行保护;长白山西坡是生物多样性高价值斑块最破碎的区域,应在未来的保护工作中予以特别关注。本研究表明关联优势种空间分布及环境因子是认识生物多样性价值及空间异质性的有效手段,本研究方法可为生态红线划定和国家公园设计提供参考。     

气候变化与生物多样性之间的复杂关系和反馈机制

气候变化与生物多样性丧失是人类社会正在经历的两大变化。气候变化影响生物多样性的方方面面, 是导致生物多样性丧失的一个主要驱动因子; 反过来, 生物多样性丧失会加剧气候变化。因此, 阻止甚至扭转气候变化和生物多样性丧失是当前人类社会亟需解决的全球性问题,但我们对气候变化与生物多样性之间的复杂关系和反馈机制尚缺乏清晰认识。本文总结了近年气候变化与生物多样性变化的研究进展, 重点概述了不同组织层次、空间尺度和维度的生物多样性对气候变化的响应和反馈等相关领域的研究进展和存在的主要问题。结果发现多数研究关注气候变化对生物多样性的直接影响, 涉及到生物多样性的不同组织层次、维度和营养级, 但针对气候变化间接影响的研究仍然较少, 机理研究同样需要加强; 生物多样性对生态系统功能影响的环境依赖和尺度推演、生物多样性对生态系统多功能性的作用机理和量化方法是当前研究面临的挑战; 生物多样性对生态系统响应气候变化的作用机制尚无统一的认识; 生物多样性对气候变化的正、负反馈效应是国内外研究的盲点。最后, 本文展望了未来发展方向和需要解决的关键科学问题, 包括多因子气候变化对生物多样性的影响; 减缓和适应气候变化的措施如何惠益于生物多样性保护; 生物多样性与生态系统功能的理论如何应用到现实世界; 生物多样性保护对实现碳中和目标的贡献。     

基于植物多样性的生态系统恢复动力学原理

生态系统恢复动力学是生态学的重要问题.本研究利用岛屿生物地理学、植物群落演替、生物多样性维持机制及生态系统功能等有关理论,推导了生态系统恢复动力学模型,并用半湿润常绿阔叶林次生演替阶段数据作了初步验证.基于动力学模型讨论了动力学原理.结果表明,生态系统恢复的动力学过程决定于生态系统恢复力F1、干扰力F2和环境阻力F3的综合作用.植物多样性恢复速度的变率与植物种丰富度呈反比,与生态系统恢复总动力F呈正比.生态系统恢复力F1和环境阻力F3是初始物种丰富度s0、特定地理区域资源环境状况的函数.干扰力是干扰强度系数b和物种丰富度s的函数.当生态系统存在有害干扰的条件下,物种丰富度不能达到生态系统最高物种丰富度sm.动力学模型显示,初始物种丰富度s0越小,生态系统恢复过程越具有逻辑斯蒂性.建立了生态系统恢复力、环境阻力和干扰力的计算模型和植物多样性、干扰对生态系统恢复的作用模型.生态系统恢复动力模型显示,植物多样性能增加生态系统恢复力,促进生态系统稳定性.     

种、种的多样性及退化生态系统功能的恢复和维持研究

物种多样性是生态系统的重要特征并维持系统的功能支行,生物种和不同种类构成的群落为人类提供诸如营养物质循环、生物生产力、营养功能等形式的重要生态服务,特种多样性与生态系统抵御逆境和干扰的能力紧密相关,多样性的提高会增加系统的稳定性,与单个种和种类的数量相比,功能群和功能多样性对生态系统功能的影响效应要大得多,且易于被用来测度稳定性和预测群落变化,本文提出并探讨了种对生态系统功能作用的几种形式,理解物种多样性与生态系统的功能关系能指导退化生态系统恢复和维持其功能的实践活动,尤其为恢复的初始阶段进行群落的“种类组装”提供生态理论基础。     

河岸植被缓冲带主要生态服务功能研究的现状与展望

河岸植被缓冲带是河流生态系统和陆地生态系统之间的生态交错带,具有独特的生态系统结构和服务功能,也是近年来生态学和环境科学研究的热点之一.本文对河岸带的生态系统结构及其在生物多样性维持、非点源氮素污染防治等主要生态服务功能方面的研究进行了系统总结和分析.由于岸边缓冲带具有结构复杂、系统内外干扰因子多、时空异质性强等特征,要实现对河岸带生态系统的科学有效管理,还需要进行大量的理论和案例研究.从系统生态学和景观生态学的角度,展望了该领域的研究前景:(1)加强人类活动干扰如土地利用的时空变化对河岸区域生物多样性分布特征和生态环境效应的影响研究;(2)加强不同河岸植被缓冲带结构和区域环境特征对非点源氮素污染净化机理和控制过程的研究;(3)在小尺度长期定位观测和机理研究的基础上,综合运用数学方法、遥感(RS)和地理信息系统(GIS)等工具,开发适合我国地域特点和环境特征的生态系统管理模型,定量研究河岸带生态系统结构、过程与功能动态变化及其与人类活动干扰之间的相互关系和影响机制,为区域社会经济的可持续发展提供科学依据和管理对策.     

陆地植物群落物种多样性研究进展

生物多样性是当前生态学研究的热点之一,物种多样性层次是最直接、最易观察和最适合研究生物多样性的层次。总结了与群落动态、生境因子、取样尺度及生态系统相关的陆地植物物种多样性研究。同时,根据目前的趋势提出了多样性动态研究的发展动向。     

刈割、施肥对高寒草甸物种多样性与生态系统功能关系的影响及群落稳定性机制

植物群落中不同“功能身份”物种的多样性与特定生态系统功能之间具有何种关系及其作用机制尚不明确。通过在高寒矮嵩草(Kobresia humilis)草甸为期5年的刈割(不刈割、留茬3 cm、留茬1 cm)、施肥(施肥、不施肥)和浇水(浇水、不浇水)控制实验, 研究了刈割与土壤资源获得性梯度上不同“功能身份”物种(群落中所有物种、响应物种、作用物种和共有物种)的多样性变化与群落地上净初级生产力和稳定性的关系以及稳定性机制。研究结果显示: 群落中响应物种、作用物种和共有物种数分别占全部物种数的36.6%、18.3%和64.8%, 物种多样性对生态系统功能具有不同的效应, 净初级生产力主要受响应物种和作用物种的多样性变化影响, 而稳定性则主要由共有物种的多样性变化决定; 群落稳定性的维持主要依赖于共有物种的多样性增加, 其作用机制是投资组合效应, 而超产效应和异步性效应对稳定性并无作用; 刈割和施肥对物种多样性、稳定性和净初级生产力具有相反的影响, 前者能增加物种多样性和稳定性, 并降低净初级生产力, 而后者的作用正相反。这与群落中全部物种的多样性变化受刈割影响较大, 而作用物种的多样性变化受资源获得性影响较大有关。上述结果表明高寒草甸生态系统地上净初级生产力主要由少数影响生产力的作用物种的多样性决定, 而稳定性则由大量共有物种的多样性所掌控。投资组合效应是物种多样性导致稳定性的机制。由于群落中不同物种的多样性效应具有分异性, 对于特定的生态系统功能而言, 物种的“功能身份”可能比物种多样性本身更重要, 不加区别地笼统定义物种多样性与生态系统功能的关系可能欠妥。     

Effect of habitat quality and phenotypic variation on abundance- and trait-based early warning signals of population collapses

Loss of resilience in population numbers in response to environmental perturbations may be predicted with statistical metrics called early warning signals (EWS) that are derived from abundance time series. These signals, however, have been shown to have limited success, leading to the development of trait-based EWS that are based on information collected from phenotypic traits such as body size. Experimental work assessing the efficacy of EWS under varying ecological and environmental factors are rare. In addition, disentangling how such warning signals are affected under varying ecological and environmental factors is key to their application in biological conservation. Here, we experimentally test how different rates of environmental forcing (i.e. warming) and varying ecological factors (i.e. habitat quality and phenotypic diversity) affected population stability and predictive power of early warning signals of population collapse. We analyzed population density and body size time series data from three phenotypically different populations of a protozoan ciliate Askenasia volvox in two levels of habitat quality subjected to three different treatments of warming (i.e. no warming, fast warming and slow warming). We then evaluated how well abundance- and trait-based EWS predicted population collapses under different levels of phenotypic diversity, habitat quality and warming treatments. Our results suggest that habitat quality and warming treatments had more profound effects than phenotypic diversity had on both population stability and on the performance of abundance-based signals of population collapse. In addition, trait-based EWS generally performed well, were reliable and more robust in forecasting population collapse than abundance-based EWS, regardless of variation in environmental and ecological factors. Our study points towards the development of a predictive framework that includes information from phenotypic traits such as body size as an indicator of loss of resilience of ecological systems in response to environmental perturbations.     

Effects of experimentally-enhanced precipitation and nitrogen on resistance,recovery and resilience of a semi-arid grassland after drought

Resistance, recovery and resilience are three important properties of ecological stability, but they have rarely been studied in semi-arid grasslands under global change. We analyzed data from a field experiment conducted in a native grassland in northern China to explore the effects of experimentally enhanced precipitation and N deposition on both absolute and relative measures of community resistance, recovery and resilience—calculated in terms of community cover—after a natural drought. For both absolute and relative measures, communities with precipitation enhancement showed higher resistance and lower recovery, but no change in resilience compared to communities with ambient precipitation in the semi-arid grassland. The manipulated increase in N deposition had little effect on these community stability metrics except for decreased community resistance. The response patterns of these stability metrics to alterations in precipitation and N are generally consistent at community, functional group and species levels. Contrary to our expectations, structural equation modeling revealed that water-driven community resistance and recovery result mainly from changes in community species asynchrony rather than species diversity in the semi-arid grassland. These findings suggest that changes in precipitation regimes may have significant impacts on the response of water-limited ecosystems to drought stress under global change scenarios.     

Species and genotype diversity drive community and ecosystem properties in experimental microcosms

Species diversity is important to ecosystems because of the increased probability of including species that are strong interactors and/or because multiple-species communities are more efficient at using resources due to synergisms and resource partitioning. Genetic diversity also contributes to ecosystem function through effects on primary productivity, community structure and resilience, and modulating energy and nutrient fluxes. Lacking are studies investigating the relationship between ecosystem function and diversity where hierarchical levels of biological diversity are systematically varied during experimentation. In this experiment, we manipulated both species and genotypic diversity of two Daphnia species in microcosms initially seeded with Chlamydomonas and measured community- and ecosystem-level properties to determine which level of diversity was most important for explaining variation in the property. Our results show that species diversity alters bacterial community composition while high genotypic diversity reduces bacterial richness and primary productivity. In addition, the highest levels of genotypic and species richness appear to increase community and ecosystem stability. These findings reveal that species and genotypic diversity are significant drivers of community and ecosystem properties and stability.     

Temporal stability of aquatic food webs: partitioning the effects of species diversity, species composition and enrichment

Theory predicts that species diversity can enhance stability of community‐level biomass while simultaneously decreasing population‐level stability. Enrichment can theoretically destabilize communities but effects may become weaker with increasing diversity because of the inclusion of consumer‐resistant prey. Few experiments using direct manipulations of species diversity have tested these predictions. We used laboratory‐based aquatic food webs to examine the effects of species composition, diversity and enrichment on temporal variability of population‐ and community‐level biomass. We found weak effects of enrichment on population‐ and community‐level stability. However, diversity enhanced community‐level stability while species composition had no influence. In contrast, composition effects outweighed diversity effects when stability was measured at the population level. We found no negative effects of diversity on population‐level stability, in opposition to theory. Our results indicate that diversity can enhance stability in multitrophic systems, but effects vary with the scale of biological organization at which stability is measured.     

Indicators and mechanisms of stability and resilience to climatic and landscape changes in a remnant calcareous grassland

When considering the development of conservation strategies for threatened plant communities it is crucial to understand their resilience to environmental change, taking into account current decline and the occurrence of further habitat fragmentation and climatic changes. Many recent works describe resilience character and elements, but there is little focus on the metrics and indices that describe elements of stability and specific resistance or resilience over the community composition matrix. Communities with strong niche selection might be restricted to specific resistance strategies to cope with environmental changes. This would result in a community at greater risk from increasing fragmentation and climatic changes.In a 35 years survey of relic calcareous grasslands, we looked at measures to identify the resilience mechanisms for stability in the presence and abundance of species. We used techniques of partitioning of temporal beta diversity in nestedness and turnover components, analysis of functional strategy changes and dissimilarity analysis to detect changes in between⿿plot diversity and exchanges.Contrary to expectations, we observe strong resilience with different stabilizing mechanisms both at plot level and exchanges between plots. At the scale of our grassland complex, response diversity and environmental stochasticity allow for the maintenance of high biodiversity under natural perturbations and gradual human-induced environmental changes. This highlights the importance of dispersal, recruitment dynamics and microsite diversity.Community resilience is more than just the sum of species resilience strategies; adaptive management strategies need more emphasis on the variability of conditions, as this can enable or disrupt important community resilience mechanisms.     

Two approaches using traits to assess ecological resilience: A case study on earthworm communities

The relation between biological diversity and ecosystem functioning is a central theme in ecology. Ecological traits of species are often regarded as a link between structure and function, and trait distributions in a community may change in response to environmental stressors. Likewise, resilience in a community may be derived from the diversity in traits and trait values relevant to a particular stressor. We combine two approaches to test this: a novel trait frequency analysis and a multivariate ordination approach. The two methods are applied on a case study of an earthworm community in a frequently flooded floodplain in the Netherlands. Periodic flooding in floodplains restricts population growth and recolonization of earthworms. The strategies employed by different earthworm species for coping with this stress can be described by a combination of ecological traits. From the literature we compiled 10 ecological traits for the earthworm species encountered along an inundation gradient in the Duursche Waarden floodplain area flanking the river IJssel. Trait frequency analysis showed a greater diversity at low elevation sites of traits considered to be associated to flood tolerance, suggesting greater community resilience to flooding. The ordination analysis using trait composition provided information on which trait classes in the community were related with the inundation stress. Results from both analyses showed that important traits in species to deal with flooding are active dispersal, high hydrophily, diapause and parthenogenetic reproduction. Thus, a further understanding of community resilience was gained by combining traditional ordination analysis with trait diversity analysis.     

Contrasting resistance and resilience to light variation of the coupled oxic and anoxic components of an experimental microbial ecosystem

Understanding how microbial communities of aquatic ecosystems respond to environmental change remains a critical challenge in microbial ecology. In this study, we used light‐dependent oxic–anoxic micro‐ecosystems to understand how the functioning and diversity of aerobic and anaerobic lake analog communities are affected by a pulse light deprivation. Continuous measurements of oxygen concentration were made and a time series of full‐length 16S rRNA sequencing was used to quantify changes in alpha‐ and beta diversity. In the upper oxic layer, oxygen concentration decreased significantly under light reduction, but showed resilience in daily mean, minimum, and maximum after light conditions were restored to control level. Only the amplitude of diurnal fluctuations in oxygen concentrations did not recover fully, and instead tended to remain lower in treated ecosystems. Alpha diversity of the upper oxic layer communities showed a delayed increase after light conditions were restored, and was not resilient in the longer term. In contrast, alpha diversity of the anoxic lower layer communities increased during the light reduction, but was resilient in the longer term. Community composition changed significantly during light reduction, and showed resilience in the oxic layer and lack of resilience in the anoxic layer. Alpha diversity and the amplitude of daily oxygen fluctuations within and among treatments were strongly correlated, suggesting that higher diversity could lead to less variable oxygen concentrations, or vice versa. Our experiment showed that light deprivation induces multifaceted responses of community function (oxygen respiration) and structure, hence focusing on a single stability component could potentially be misleading.     

Diversity-dependent stability under mowing and nutrient addition: evidence from a 7-year grassland experiment

Anthropogenic perturbations may affect biodiversity and ecological stability as well as their relationships. However, diversity-stability patterns and associated mechanisms under human disturbances have rarely been explored. We conducted a 7-year field experiment examining the effects of mowing and nutrient addition on the diversity and temporal stability of herbaceous plant communities in a temperate steppe in northern China. Mowing increased population and community stability, whereas nutrient addition had the opposite effects. Stability exhibited positive relationships with species richness at population, functional group and community levels. Treatments did not alter these positive diversity-stability relationships, which were associated with the stabilising effect of species richness on component populations, species asynchrony and portfolio effects. Despite the difficulty of pinpointing causal mechanisms of diversity-stability patterns observed in nature, our results suggest that diversity may still be a useful predictor of the stability of ecosystems confronted with anthropogenic disturbances.     

Ecological and evolutionary implications of food subsidies from humans

Human activities are the main current driver of global change. From hunter‐gatherers through to Neolithic societies–and particularly in contemporary industrialised countries–humans have (voluntarily or involuntarily) provided other animals with food, often with a high spatio‐temporal predictability. Nowadays, as much as 30–40% of all food produced in Earth is wasted. We argue here that predictable anthropogenic food subsidies (PAFS) provided historically by humans to animals has shaped many communities and ecosystems as we see them nowadays. PAFS improve individual fitness triggering population increases of opportunistic species, which may affect communities, food webs and ecosystems by altering processes such as competition, predator–prey interactions and nutrient transfer between biotopes and ecosystems. We also show that PAFS decrease temporal population variability, increase resilience of opportunistic species and reduce community diversity. Recent environmental policies, such as the regulation of dumps or the ban of fishing discards, constitute natural experiments that should improve our understanding of the role of food supply in a range of ecological and evolutionary processes at the ecosystem level. Comparison of subsidised and non‐subsidised ecosystems can help predict changes in diversity and the related ecosystem services that have suffered the impact of other global change agents.     

Macrofaunal Functional Diversity Provides Resilience to Nutrient Enrichment in Coastal Sediments

The degradation of ecosystems is often associated with losses of large organisms and the concomitant losses of the ecological functions they mediate. Conversely, the resilience of ecosystems to stress is strongly influenced by faunal communities and their impacts on processes. Denitrification in coastal sediments is a process that may provide ecosystem resilience to eutrophication by removing excess bioavailable nitrogen. Here, we conducted a large-scale field experiment to test the effect of macrofaunal community composition on denitrification in response to two levels of nutrient enrichment at 28 sites across a biologically heterogeneous sandflat. After 7 weeks of enrichment, we measured denitrification enzyme activity (DEA) along with benthic macrofaunal community composition and environmental variables. We normalised treatment site specific DEA values by those in ambient sediments (DEA_CN) to reveal the underlying response across the heterogeneous landscape. Nutrient enrichment caused reductions in DEA_CN as well as functional changes in the community; these were both more pronounced under the highest level of nutrient loading (on average DEA_CN was reduced by 34%). The degree of suppression of DEA_CN following moderate nitrogen loading was mitigated by a key bioturbating species, but following high nitrogen loading (which reduced the key species density) the abundance and diversity of other nutrient processing species were the most important factors alleviating negative effects. This study provides a prime example of the context-dependent role of biodiversity in maintaining ecosystem functioning, underlining that different elements of biodiversity can become important as stress levels increase. Our results emphasise that management and conservation strategies require a real-world understanding of the community attributes that facilitate nutrient processing and maintain resilience in coastal ecosystems.