生态系统稳定性及其与生物多样性的关系

在全球变化背景下, 生态系统能否长期有效地维持功能并提供服务, 有赖于其稳定性。生态系统稳定性及其与生物多样性的关系, 是生态学研究的核心问题, 生物多样性能否促进生态系统稳定性曾引起很多争论。该文在前期国内外综述和研究的基础上, 重点从以下三个方面对近期进展做了总结。第一, 介绍了近期理论研究在生态系统稳定性的内涵及不同稳定性指标间的内在关联方面取得的新认识。第二, 梳理了最近基于生物多样性实验开展的多项整合分析研究和理论探索, 以及在多维度框架下开展的多样性-稳定性关系研究。第三, 详细介绍了最近发展起来的多尺度稳定性理论框架, 对稳定性的尺度依赖、多样性-稳定性的多尺度关系等新议题做了探讨。最后, 提出了本领域有待进一步研究的关键问题和方向建议。     

生物多样性与生态系统功能:最新的进展与动向

生物多样性与生态系统功能的关系及其内在机制是当前生态学领域的重大科学问题。 2 0 0 2年以来人们不再过多地纠缠于“抽样 -互补之争” ,对这一世纪课题的认识又有了新的进展。 (1)人们开始运用已有的知识揭示更大时间和空间尺度上的物种多样性 -生态系统功能关系。多样性作用机制可能存在着动态变化———“抽样向互补转型” :群落建立初期 ,抽样效应是主要的多样性作用机制 ;随时间推移 ,生态位互补成为主要机制。理论研究则预测 :局域尺度上生态系统功能与物种多样性呈现单峰曲线关系 ,在区域尺度上为单调上升关系 ;(2 )非生物因素与多样性 -生产力的交互关系吸引了许多实验研究。人们发现 :物种多样性 -生产力关系可能会受到资源供给率和环境扰动的修正 ,环境因素可能是多样性 -生产力关系的幕后操纵者 ;(3)人们开始重视营养级相互作用对于多样性 -生态系统功能关系的影响 ,生态位互补和抽样假说开始被扩展运用到消费者营养级上 ;(4 )人们开始认真思考物种共存机制在多样性 -生态系统功能关系的形成中所扮演的角色。理论模型研究表明 ,不同的物种共存机制会导致不同的多样性 -生产力关系     

栖息地破碎化与鸟类生存

栖息地破碎化给野生动物带来的不良后果是全球生态学家和保护生物学家共同关心的问题.自从提出栖息地破碎化是导致生物多样性丧失的关键因素之一的论点后,近20年来,栖息地破碎化研究一直是生态学和保护生物学最活跃的前沿研究领域之一.栖息地破碎化是一动态过程,可在多尺度上发生并蕴涵着复杂的空间模式变化.栖息地破碎化对鸟类的生态学效应主要体现在面积效应、隔离效应和边缘效应等.这些效应影响着鸟类的分布、基因交流、种群动态、扩散行为、种间关系和生活史特征等,最终影响着鸟类的生存.介绍和总结了栖息地破碎化过程、研究的理论依据及栖息地破碎化对鸟类生存产生的诸多影响.     

集合种群的Allee效应研究进展

随着全球环境破坏的加剧,物种丧失的速度加快,人们日益关注生物多样性的保护。种群生物学和自然保护生物学的一些研究表明,如果一个局域种群受到Allee效应的影响,最终可能走向灭绝。从物种保护的角度考虑,分别介绍了集合种群水平上的Allee效应的和似Allee效应,比较了集合种群的Allee效应和似Allee效应产生的原因,以及集合种群的Allee效应和局域种群的Allee效应之间的关系、集合种群的似Allee效应和局域种群的Allee效应之间的关系,并提出集合种群的Allee效应还需要进一步的研究。     

生物多样性与生态系统多功能性的关系研究进展

生物多样性与生态系统功能关系是生态学研究的热点之一,以往研究多关注生物多样性与单一生态系统功能之间的关系,然而生态系统能够同时提供多种功能和服务即生态系统多功能性(ecosystem multifunctionality, EMF),仅考虑单一生态系统功能会低估生物多样性的重要性。近年来,EMF研究的重要性受到更多重视,生物多样性与生态系统多功能性(biodiversity and ecosystem multifunctionality, BEMF)关系成为生态学研究新的热点。梳理近15年的研究发现,不同维度、不同尺度的单一或多营养级生物多样性均会对EMF产生显著的影响,并且在全球变化的背景下,自然干扰与人为干扰均会影响生物多样性与生态系统多功能性从而改变BEMF关系,EMF测度方法的差异也可能导致BEMF关系的不一致。生物多样性维度(尺度)选择的局限、不同EMF测度方法的认知差异、BEMF时空数据库的缺乏以及BEMF关系研究方法的单一等问题阻碍了BEMF关系的深入探究。未来研究应对现有测度方法进行深入比较并发展通用的新方法,深入探究多维度、多尺度生物多样性对EMF影响的综合作用。此...     

生物多样性与生态系统服务关系研究进展

生物多样性与生态系统服务关系是当前生态学研究的热点之一,2005年千年生态系统评估之后如何将两者关系应用到生态系统管理和政策制定中逐渐受到重视。然而,从理论上的两者关系认知到应用上的管理实践仍面临着严峻挑战,梳理已有研究成果有利于更好地指导管理实践。本文基于近年生物多样性与生态系统服务关系的主要研究成果,从生物多样性对生态系统单种服务、多种服务、生态系统服务权衡的影响以及环境变化如何影响这些关系等方面,总结了两者关系的主要研究进展,概述了两者关系在自然保护区管理、森林生态系统管理、退化生态系统恢复和农业生态系统改善等领域中的应用,分析了两者关系研究中依然存在的不足之处,强调未来需加强的研究方向主要包括: 生物多样性不同组分相互作用和多营养级生物多样性相互关系对生态系统服务的影响、环境耦合变化对两者关系的复合效应以及生物多样性改善生态系统服务的实践途径。     

多营养级生物多样性与陆地生态系统多功能性:研究现状与展望

生物多样性是人类赖以生存的基础,但由于受到人类活动以及全球变化的影响正加速丧失,这对全球生态系统造成巨大威胁.近年来,生物多样性与生态系统功能关系(biodiversity and ecosystem functioning, BEF)已经成为生物多样性保护和气候变化领域关注的热点问题之一,并由早期的单一营养级多样性与单个生态系统功能关系,发展到近年来的多营养级生物多样性与生态系统多功能性关系.本文介绍了多营养级生物多样性以及生态系统多功能性的基础概念,回顾了多营养级生物多样性与陆地生态系统多功能性研究的发展历程,并系统归纳了该领域近十年的重要研究进展.在此基础上,提出未来需要重点关注的3个方面:(ⅰ)基于控制实验的驱动机制研究;(ⅱ)地下多营养级生物多样性与生态系统多功能性的关系;(ⅲ)多营养级生物多样性与生态系统多功能性关系随时间尺度的变化.最后,本文呼吁不同研究方向的学者未来应加强合作并强调了开展整合性工作的必要性.     

高山生物多样性对气候变化响应的研究进展

高山带是指自然气候森林边界即林线到雪线之间的无林区域。受低温限制的高山生物对气候变化具有高度的敏感性, 因此高山带被视为监测气候变化的理想试验场所。气候变暖加速了高山冰雪消融, 也加剧了高山生物多样性的波动, 因而高山生物多样性变化对于指示全球气候变化具有十分重要的意义。目前, 高山生物多样性对气候变暖响应的研究主要集中在高山物种组成和群落结构的变化、物种的分布格局和适宜生境的变化、林线交错带的位移、种间关系的变化等方面。气候变化与人为干扰等因素的叠加效应为预测未来生物多样性的变化增加了很多不确定性, 从长期来看, 气候变化效应相对于其他因素会显得越来越重要。未来的重点研究领域包括高山带生物多样性对极端气候变化的响应、全球气候变化背景下生物多样性与生态系统过程的关系、高山带地上/地下生物多样性的相互作用关系及其对气候变化的响应与适应、全球气候变化与人类活动干扰的叠加效应对高山生物多样性格局的影响等。     

植物遗传多样性与生态系统功能关系的研究进展

全球变化和人类活动导致物种生境的萎缩, 造成很多植物种群数量缩减, 遗传多样性快速丧失。对于物种多样性低的生态系统, 优势种的遗传多样性可能比物种多样性对生态系统功能产生更大的影响。因此, 了解遗传多样性和生态系统功能的关系(GD-EF)及其机制对生物多样性保护、应对环境变化和生态修复具有指导意义。该文综述了植物遗传多样性对生态系统结构(高营养级生物群落结构)和生态系统功能(初级生产力、养分循环和稳定性)的影响及机制、功能多样性对GD-EF的影响、遗传多样性效应和物种多样性效应的比较, 以及GD-EF在生态修复等实际应用的研究进展。最后指出当前研究的不足之处, 以期为后续研究提供参考: 1)还需深入研究GD-EF机制; 2)未评估遗传多样性对生态系统多功能性的影响; 3)不同遗传多样性测度对生态系统功能的影响不明确; 4)缺少长期的和多空间尺度结合的GD-EF实验; 5)遗传多样性效应相对于其他因子的作用不清楚。     

生物多样性与生态系统功能:进展与争论

生物多样性与生态系统功能的关系已成为当前人类社会面临的一个重大科学问题,生物多样性的空前丧失,促使人们开展了大量研究工作来描述物种多样性-生态系统功能关系,并试图揭示多样性与系统功能关系的内在机制,本文将多样性对生态系统功能作用机制的有关假说分为统计学与生物学两大类：前者是从统计学角度来解释观察到的多样性-系统功能模式,包括抽样效应,统计均衡效应等;而后者是基于多样性的生物学效应给出的,包括生态位互补,种间正相互作用,保险效应等,本文较为详细地介绍了该领域内有代表性的实验工作,包括“生态箱”实验,Cedar Creek草地多样性实验,微宇宙实验,欧洲草地实验,以及在这些实验结果解释上的激烈争论。     

Does alteration in biodiversity really affect disease outcome? – A debate is brewing

How changes in biodiversity alter the transmission of infectious diseases is presently under debate. Epidemiologists and ecologists have put a lot of effort to understand the mechanism behind biodiversity–disease relationship. Two important mechanisms, i.e. dilution and amplification theories have in some manner made it clear that biodiversity and disease outcome have an intimate relationship. The dilution effect theory seems to answer some overarching questions, but paucity of information about many disease systems is a real obstacle for its acceptance. Also, there is hardly any agreement on host population threshold and critical community size vis-à-vis wild life diseases. We suggest a multidimensional approach whereby the same disease system needs to be studied in different ecological zones and then the effect of biodiversity on disease outcome needs to be ascertained. Nonetheless, caution is to be taken while jumping to any conclusion as biodiversity–disease relationship is a multifactorial process.Abbreviations: CEM, Classical Epidemiological Model; DEH, dilution effect; MNV, Murine Norovirus     

Dilution effect in bovine tuberculosis: risk factors for regional disease occurrence in Africa

Changes in host diversity have been postulated to influence the risk of infectious diseases, including both dilution and amplification effects. The dilution effect refers to a negative relationship between biodiversity and disease risk, whereas the amplification effect occurs when biodiversity increases disease risk. We tested these effects with an influential disease, bovine tuberculosis (BTB), which is widespread in many countries, causing severe economic losses. Based on the BTB outbreak data in cattle from 2005 to 2010, we also tested, using generalized linear mixed models, which other factors were associated with the regional BTB presence in cattle in Africa. The interdependencies of predictors and their correlations with BTB presence were examined using path analysis. Our results suggested a dilution effect, where increased mammal species richness was associated with reduced probability of BTB presence after adjustment for cattle density. In addition, our results also suggested that areas with BTB infection in the preceding year, higher cattle density and larger percentage of area occupied by African buffalo were more likely to report BTB outbreaks. Climatic variables only indirectly influenced the risk of BTB presence through their effects on cattle density and wildlife distribution. Since most studies investigating the role of wildlife species on BTB transmission only involve single-species analysis, more efforts are needed to better understand the effect of the structure of wildlife communities on BTB dynamics.     

A meta‐analysis suggesting that the relationship between biodiversity and risk of zoonotic pathogen transmission is idiosyncratic

Zoonotic pathogens are significant burdens on global public health. Because they are transmitted to humans from non‐human animals, the transmission dynamics of zoonoses are necessarily influenced by the ecology of their animal hosts and vectors. The ‘dilution effect’ proposes that increased species diversity reduces disease risk, suggesting that conservation and public health initiatives can work synergistically to improve human health and wildlife biodiversity. However, the meta‐analysis that we present here indicates a weak and highly heterogeneous relationship between host biodiversity and disease. Our results suggest that disease risk is more likely a local phenomenon that relies on the specific composition of reservoir hosts and vectors, and their ecology, rather than patterns of species biodiversity.     

The Effects of Host Diversity on Vector-Borne Disease: The Conditions under Which Diversity Will Amplify or Dilute the Disease Risk

Multihost vector-borne infectious diseases form a significant fraction of the global infectious disease burden. In this study we explore the relationship between host diversity, vector behavior, and disease risk. To this end, we have developed a new dynamic model which includes two distinct host species and one vector species with variable preferences. With the aid of the model we were able to compute the basic reproductive rate, R ₀, a well-established measure of disease risk that serves as a threshold parameter for disease outbreak. The model analysis reveals that the system has two different qualitative behaviors: (i) the well-known dilution effect, where the maximal R₀ is obtained in a community which consists a single host (ii) a new amplification effect, denoted by us as diversity amplification, where the maximal R₀ is attained in a community which consists both hosts. The model analysis extends on previous results by underlining the mechanism of both, diversity amplification and the dilution, and specifies the exact conditions for their occurrence. We have found that diversity amplification occurs where the vector prefers the host with the highest transmission ability, and dilution is obtained when the vector does not show any preference, or it prefers to bite the host with the lower transmission ability. The mechanisms of dilution and diversity amplification are able to account for the different and contradictory patterns often observed in nature (i.e., in some cases disease risk is increased while in other is decreased when the diversity is increased). Implication of the diversity amplification mechanism also challenges current premises about the interaction between biodiversity, climate change, and disease risk and calls for retrospective thinking in planning intervention policies aimed at protecting the preferred host species.     

No Observed Effect of Landscape Fragmentation on Pathogen Infection Prevalence in Blacklegged Ticks (Ixodes scapularis) in the Northeastern United States

Pathogen prevalence within blacklegged ticks (Ixodes scapularis Say, 1821) tends to vary across sites and geographic regions, but the underlying causes of this variation are not well understood. Efforts to understand the ecology of Lyme disease have led to the proposition that sites with higher host diversity will result in lower disease risk due to an increase in the abundance of inefficient reservoir species relative to the abundance of species that are highly competent reservoirs. Although the Lyme disease transmission cycle is often cited as a model for this “dilution effect hypothesis”, little empirical evidence exists to support that claim. Here we tested the dilution effect hypothesis for two pathogens transmitted by the blacklegged tick along an urban-to-rural gradient in the northeastern United States using landscape fragmentation as a proxy for host biodiversity. Percent impervious surface and habitat fragment size around each site were determined to assess the effect of landscape fragmentation on nymphal blacklegged tick infection with Borrelia burgdorferi and Anaplasma phagocytophilum. Our results do not support the dilution effect hypothesis for either pathogen and are in agreement with the few studies to date that have tested this idea using either a landscape proxy or direct measures of host biodiversity.     

Frontiers in research on biodiversity and disease

Global losses of biodiversity have galvanised efforts to understand how changes to communities affect ecological processes, including transmission of infectious pathogens. Here, we review recent research on diversity–disease relationships and identify future priorities. Growing evidence from experimental, observational and modelling studies indicates that biodiversity changes alter infection for a range of pathogens and through diverse mechanisms. Drawing upon lessons from the community ecology of free‐living organisms, we illustrate how recent advances from biodiversity research generally can provide necessary theoretical foundations, inform experimental designs, and guide future research at the interface between infectious disease risk and changing ecological communities. Dilution effects are expected when ecological communities are nested and interactions between the pathogen and the most competent host group(s) persist or increase as biodiversity declines. To move beyond polarising debates about the generality of diversity effects and develop a predictive framework, we emphasise the need to identify how the effects of diversity vary with temporal and spatial scale, to explore how realistic patterns of community assembly affect transmission, and to use experimental studies to consider mechanisms beyond simple changes in host richness, including shifts in trophic structure, functional diversity and symbiont composition.     

Grasshopper （Orthoptera： Acrididae） biodiversity and grassland ecosystems

Interesting results may arise by combining studies on the structure and function of ecosystems with that of biodiversity for certain species. Grasshopper biodiversity is the result of the evolution of grassland ecosystems; however, it also impacts on the structure and the function of those ecosystems. We consider there to be a close relationship between the health of grassland ecosystems and grasshopper biodiversity. The main problems involved in this relationship are likely to include： （i） grasshopper biodiversity and its spatial pattern; （ii） the effect of grasshopper biodiversity on the ecological processes of grassland ecosystems; （iii） the biodiversity threshold of grasshopper population explosions; （iv） the relationship between grasshopper biodiversity and the natural and human factors that affect grassland ecosystems; and （v） grasshopper biodiversity and the health of grassland ecosystems. The solutions to these problems may provide sound bases for controlling disasters caused by grasshoppers and managing grassland ecosystems in the west of China. In this paper, we introduced two concepts for grasshopper biodiversity, that is, ＂spatial pattern＂ and ＂biodiversity threshold＂. It is helpful to understand the action of the spatial pattern of grasshopper biodiversity on the ecological processes of grassland ecosystems and the effect of this spatial pattern on the health of those ecosystems, owing to the fact that, in the west of China, grasslands are vast and grasshoppers are widely distributed. Moreover, we inferred that the change in the level of component richness at each type of grasshopper biodiversity can make an impact on grassland ecosystems, and therefore, there is likely to be a threshold to grasshopper biodiversity for the stability and the sustainability of those ecosystems.     

Effect of Biodiversity Changes in Disease Risk: Exploring Disease Emergence in a Plant-Virus System

The effect of biodiversity on the ability of parasites to infect their host and cause disease (i.e. disease risk) is a major question in pathology, which is central to understand the emergence of infectious diseases, and to develop strategies for their management. Two hypotheses, which can be considered as extremes of a continuum, relate biodiversity to disease risk: One states that biodiversity is positively correlated with disease risk (Amplification Effect), and the second predicts a negative correlation between biodiversity and disease risk (Dilution Effect). Which of them applies better to different host-parasite systems is still a source of debate, due to limited experimental or empirical data. This is especially the case for viral diseases of plants. To address this subject, we have monitored for three years the prevalence of several viruses, and virus-associated symptoms, in populations of wild pepper (chiltepin) under different levels of human management. For each population, we also measured the habitat species diversity, host plant genetic diversity and host plant density. Results indicate that disease and infection risk increased with the level of human management, which was associated with decreased species diversity and host genetic diversity, and with increased host plant density. Importantly, species diversity of the habitat was the primary predictor of disease risk for wild chiltepin populations. This changed in managed populations where host genetic diversity was the primary predictor. Host density was generally a poorer predictor of disease and infection risk. These results support the dilution effect hypothesis, and underline the relevance of different ecological factors in determining disease/infection risk in host plant populations under different levels of anthropic influence. These results are relevant for managing plant diseases and for establishing conservation policies for endangered plant species.