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1.
Ecological theory predicts that a complex community formed by a number of species is inherently unstable, guiding ecologists to identify what maintains species diversity in nature. Earlier studies often assumed a community with only one interaction type, either an antagonistic, competitive, or mutualistic interaction, leaving open the question of what the diversity of interaction types contributes to the community maintenance. We show theoretically that the multiple interaction types might hold the key to understanding community dynamics. A moderate mixture of antagonistic and mutualistic interactions can stabilize population dynamics. Furthermore, increasing complexity leads to increased stability in a "hybrid" community. We hypothesize that the diversity of species and interaction types may be the essential element of biodiversity that maintains ecological communities. 相似文献
2.
The loss of interactions from mutualistic networks could foreshadow both plant and animal species extinctions. Yet, the characteristics of interactions that predispose them to disruption are largely unknown. We analyzed 12 pollination webs from isolated hills ("sierras"), in Argentina, ranging from tens to thousands of hectares. We found evidence of nonrandom loss of interactions with decreasing sierra size. Low interaction frequency and high specialization between interacting partners contributed additively to increase the vulnerability of interactions to disruption. Interactions between generalists in the largest sierras were ubiquitous across sierras, but many of them lost their central structural role in the smallest sierras. Thus, particular configurations of interaction networks, along with unique ecological relations and evolutionary pathways, could be lost forever after habitat reduction. 相似文献
3.
Palmer TM Stanton ML Young TP Goheen JR Pringle RM Karban R 《Science (New York, N.Y.)》2008,319(5860):192-195
Mutualisms are key components of biodiversity and ecosystem function, yet the forces maintaining them are poorly understood. We investigated the effects of removing large mammals on an ant-Acacia mutualism in an African savanna. Ten years of large-herbivore exclusion reduced the nectar and housing provided by plants to ants, increasing antagonistic behavior by a mutualistic ant associate and shifting competitive dominance within the plant-ant community from this nectar-dependent mutualist to an antagonistic species that does not depend on plant rewards. Trees occupied by this antagonist suffered increased attack by stem-boring beetles, grew more slowly, and experienced doubled mortality relative to trees occupied by the mutualistic ant. These results show that large mammals maintain cooperation within a widespread symbiosis and suggest complex cascading effects of megafaunal extinction. 相似文献
4.
Mechanisms of recognition are essential to the evolution of mutualistic and parasitic interactions between species. One such example is the larval mimicry that Maculinea butterfly caterpillars use to parasitize Myrmica ant colonies. We found that the greater the match between the surface chemistry of Maculinea alcon and two of its host Myrmica species, the more easily ant colonies were exploited. The geographic patterns of surface chemistry indicate an ongoing coevolutionary arms race between the butterflies and Myrmica rubra, which has significant genetic differentiation between populations, but not between the butterflies and a second, sympatric host, Myrmica ruginodis, which has panmictic populations. Alternative hosts may therefore provide an evolutionary refuge for a parasite during periods of counteradaptation by their preferred hosts. 相似文献
5.
Understanding species' interactions and the robustness of interaction networks to species loss is essential to understand the effects of species' declines and extinctions. In most studies, different types of networks (such as food webs, parasitoid webs, seed dispersal networks, and pollination networks) have been studied separately. We sampled such multiple networks simultaneously in an agroecosystem. We show that the networks varied in their robustness; networks including pollinators appeared to be particularly fragile. We show that, overall, networks did not strongly covary in their robustness, which suggests that ecological restoration (for example, through agri-environment schemes) benefitting one functional group will not inevitably benefit others. Some individual plant species were disproportionately well linked to many other species. This type of information can be used in restoration management, because it identifies the plant taxa that can potentially lead to disproportionate gains in biodiversity. 相似文献
6.
城市生物多样性分布格局由自然生态环境和城市化过程所决定;其动态和机理与自然生态系统迥然不同.城市生物多样性为城市生态系统提供了诸多生态系统功能和服务,对改善城市环境、维持城市可持续发展有着重要的意义和作用.城市化过程深刻改变了城市的生物多样性分布格局,导致了诸如本地物种多样性降低、外来物种多样性增加、物种同质化等一系列问题.近年来,城市生物多样性受到学界高度关注,大量研究结果既回答了一些关键性问题,又提出了诸多新的论题和挑战.分析了当前城市生物多样性分布格局研究的若干热点问题,总结了影响城市生物多样性格局的主要因素,探讨了城市生物多样性格局研究方法的关键问题,指出了未来城市生物多样性研究的发展方向,特别强调了城市生物多样性的生态系统功能研究在未来城市生物多样性研究中的重要地位. 相似文献
7.
重庆主城区屋顶绿化乡土植物资源调查及其应用分析 总被引：2，自引：1，他引：1
植物多样性是生物多样性的组成部分, 而园林植物则是城市生态系统的主体, 城市生物多样性的维持依赖于多样化的城市植物, 乡土植物恰恰是城市植物的重要组成部分, 更是城市植物景观特色构建的必要条件。为了丰富重庆主城区屋顶植物多样性, 本文采用抽样调查的方法, 以重庆主城区31处不同屋顶绿化作为样方, 进行实地调查并从植物类型、配置方式、观赏特性3个层面进行研究分析, 从而判断导致重庆地区屋顶绿化中乡土植物应用频度低的薄弱环节。调查显示样方中应用的植物共有110种, 隶属47科76属, 但乡土植物仅占13.64%, 隶属14科15属。从以上3个层面进行数据统计, 均存在乡土植物种类少、应用频度低的现象。因此加强园林工作者对乡土植物的重视, 开发利用这些乡土植物是当务之急。结合以上研究及对相关资料的收集、整理, 针对在重庆野外均生长良好、对城市环境适应力相对较强、可供近期开发的乡土植物进行了统计, 并初步筛选出观赏价值较高, 且适合应用于重庆地区屋顶绿化的乡土植物, 其中着重增加了草本及观果、观花乡土植物, 在准确掌握其生物学特性及观赏特点、生态习性及适生范围等方面的前提下, 可以逐步应用于屋顶绿化, 从而为重庆地区屋顶绿化及乡土植物发展提供科学依据。 相似文献
8.
Obligate Acacia ant plants house mutualistic ants as a defense mechanism and provide them with extrafloral nectar (EFN). Ant/plant mutualisms are widespread, but little is known about the biochemical basis of their species specificity. Despite its importance in these and other plant/animal interactions, little attention has been paid to the control of the chemical composition of nectar. We found high invertase (sucrose-cleaving) activity in Acacia EFN, which thus contained no sucrose. Sucrose, a disaccharide common in other EFNs, usually attracts nonsymbiotic ants. The EFN of the ant acacias was therefore unattractive to such ants. The Pseudomyrmex ants that are specialized to live on Acacia had almost no invertase activity in their digestive tracts and preferred sucrose-free EFN. Our results demonstrate postsecretory regulation of the carbohydrate composition of nectar. 相似文献
9.
茂兰自然保护区生物物种多样性及其保护 总被引：11，自引：0，他引：11
茂兰自然保护区动、植物资源丰富;在1023余种植物中有国家保护种类24科35种;特有种42个;动物2028余种中有国家保护种类18科53种;特有种171个;以茂兰为模式标本建立的模式种13个、新种150个.笔者从物种多样性水平上对茂兰保护区生物物种作了分析和研究;对珍稀、濒危物种及特有种资源面临威胁的原因作相关分析,并提出了生物多样性保护对策. 相似文献
10.
抚育采伐对山杨次生林植物多样性影响的研究 总被引：27，自引：1，他引：26
研究森林经营措施对森林群落物种多样性的影响动态是当前森林经营实践面临的急需解决的问题 ,也是建立多样性评价指标体系的基础与关键 .通过对冀北山地次生山杨中龄林不同强度抚育后 1 ,2 ,5a的山杨林群落物种多样性变化的调查研究 ,结果表明 :弱度、中度抚育提高了群落物种多样性 ,强度抚育降低了群落物种多样性 ;传统的抚育方式需要改进 .合理保留非目的树种可提高乔木层的多样性 ,保留林下植被对维持群落的多样性及减少抚育间伐对群落生境的负影响有极其重要的生态学意义 相似文献
11.
野生动植物是我国珍贵的自然资源与宝贵财富,只有对其加强保护,维护物种安全才
能实现自然的可持续发展。目前,野生动植物资源濒临灭绝,如果不能对其加以保护,就会影响
生态平衡。要实现生物多样性,就要了解野生动植物资源利用存在的问题,并采取有效的保护
对策。 相似文献
12.
13.
森林资源连续清查是为掌握宏观森林资源现状和动态而开展的重要工作。为了使森林资源清查工作更贴近自然保护区的日常管理需求,本文结合我国自然保护区特点,对保护区内森林资源清查工作的调查因子、调查方法和记录表格等进行了优化,修订并增加了所有动植物名称、植物多度和生活力、动物活体、痕迹和巢穴数量等调查因子;改进了下木、植被和天然更新等的野外调查和统计方法,并优化了其野外调查记录表。并于2015年78月份对北京市6个自然保护区内的森林资源连续清查固定样地进行了调查测试,改进后生物多样性信息量明显增加,调查记录的灌木种类平均每块样地增加了150%,草本种类平均每块样地增加了700%。采用改进的调查方法所调查样地结果能够更好地体现自然保护区内生物多样性的现状,以期能为自然保护区的森林资源连续清查工作的完善提供借鉴和参考。 相似文献
14.
Studies of ecological networks (the web of interactions between species in a community) demonstrate an intricate link between a community's structure and its long-term viability. It remains unclear, however, how much a community's persistence depends on the identities of the species present, or how much the role played by each species varies as a function of the community in which it is found. We measured species' roles by studying how species are embedded within the overall network and the subsequent dynamic implications. Using data from 32 empirical food webs, we find that species' roles and dynamic importance are inherent species attributes and can be extrapolated across communities on the basis of taxonomic classification alone. Our results illustrate the variability of roles across species and communities and the relative importance of distinct species groups when attempting to conserve ecological communities. 相似文献
15.
Solan M Cardinale BJ Downing AL Engelhardt KA Ruesink JL Srivastava DS 《Science (New York, N.Y.)》2004,306(5699):1177-1180
Rapid changes in biodiversity are occurring globally, yet the ecological impacts of diversity loss are poorly understood. Here we use data from marine invertebrate communities to parameterize models that predict how extinctions will affect sediment bioturbation, a process vital to the persistence of aquatic communities. We show that species extinction is generally expected to reduce bioturbation, but the magnitude of reduction depends on how the functional traits of individual species covary with their risk of extinction. As a result, the particular cause of extinction and the order in which species are lost ultimately govern the ecosystem-level consequences of biodiversity loss. 相似文献
16.
The diversity and complexity of food webs (the networks of feeding relationships within an ecological community) are considered to be important factors determining ecosystem function and stability. However, the biological processes driving these factors are poorly understood. Resource quality affects species interactions by limiting energy transfer to consumers and their predators, affecting life history and morphological traits. We show that differences in plant traits affect the structure of an entire food web through a series of direct and indirect effects. Three trophic levels of consumers were influenced by plant quality, as shown by quantitative herbivore-parasitoid-secondary parasitoid food webs. We conclude, on the basis of our data, that changes in the food web are dependent on both trait- and density-mediated interactions among species. 相似文献
17.
缀花草坪具有较强的景观与生态作用,可利用其品种多样、色彩丰富、成本低、养护简单、适应性强等特点,合理地运用到高速公路绿化景观中,通过栽培和养护,增加植物群落的层次和色彩,丰富高速公路的生物多样性,营造特色景观效果。 相似文献
18.
生物多样性对气候变化的响应是研究区域生态环境演变的重要部分。为了分析甘肃安西极旱荒漠国家级自然保护区生物多样性对气候变化的响应趋势,笔者等选择保护区建区25年来温度和降水的变化情况及动植物资源的演变趋势,通过调查区域内动植物资源现状和总结区域25年以来年均温度和降水的变化趋势,与建区时保护区动植物资源概况进行对比。结果显示:保护区近25年来年均气温以升高趋势为主,21世纪初较20世纪80年代末升高0.989℃;年降水量整体上呈现下降趋势,21世纪初较20世纪80年代末减少3.3 mm。保护区荒漠植被出现群落面积减少、局部覆盖度下降、群落类型减少趋势;动物出现珍稀濒危数种减少、区系演变和动物种类数量减少的趋势。为掌握和应对气候变化对安西自然保护区生物多样性的影响提供了科学依据。 相似文献
19.
Climate change, urbanization, and population increase limit food availability. To sustain human existence, there is the need to increase food and agricultural production to mitigate the impact of these factors. Scientists have been working for years on ways to increase food production. From plant breeding techniques to soil science, scientists have made tremendous progress. The rhizobiome has been proven to be important to crop production, and the impact of the rhizobiome on plant health cannot be overemphasized. Being rich in diverse complex microbial interactions, the rhizosphere has become a major force in recent plant growth promotion studies. The upsurge in next-generation sequencing applications with the various “omics” technologies is helping to unearth information relating to rhizosphere impact on plant growth. Explaining the complex interactions between and across microbial species present in the rhizosphere is important to further enhance our understanding of their mechanistic and mutualistic functions. Knowledge from this can be used in rhizosphere biome engineering for improved plant growth and yield in the face of the various biotic and abiotic challenges. 相似文献
20.
Corridors increase plant species richness at large scales 总被引：1，自引：0，他引：1
Damschen EI Haddad NM Orrock JL Tewksbury JJ Levey DJ 《Science (New York, N.Y.)》2006,313(5791):1284-1286
Habitat fragmentation is one of the largest threats to biodiversity. Landscape corridors, which are hypothesized to reduce the negative consequences of fragmentation, have become common features of ecological management plans worldwide. Despite their popularity, there is little evidence documenting the effectiveness of corridors in preserving biodiversity at large scales. Using a large-scale replicated experiment, we showed that habitat patches connected by corridors retain more native plant species than do isolated patches, that this difference increases over time, and that corridors do not promote invasion by exotic species. Our results support the use of corridors in biodiversity conservation. 相似文献