Biodiversity improves water quality through niche partitioning

Excessive nutrient loading of water bodies is a leading cause of water pollution worldwide, and controlling nutrient levels in watersheds is a primary objective of most environmental policy. Over the past two decades, much research has shown that ecosystems with more species are more efficient at removing nutrients from soil and water than are ecosystems with fewer species. This has led some to suggest that conservation of biodiversity might be a useful tool for managing nutrient uptake and storage, but this suggestion has been controversial, in part because the specific biological mechanisms by which species diversity influences nutrient uptake have not been identified. Here I use a model system of stream biofilms to show that niche partitioning among species of algae can increase the uptake and storage of nitrate, a nutrient pollutant of global concern. I manipulated the number of species of algae growing in the biofilms of 150 stream mesocosms that had been set up to mimic the variety of flow habitats and disturbance regimes that are typical of natural streams. Nitrogen uptake rates, as measured by using (15)N-labelled nitrate, increased linearly with species richness and were driven by niche differences among species. As different forms of algae came to dominate each unique habitat in a stream, the more diverse communities achieved a higher biomass and greater (15)N uptake. When these niche opportunities were experimentally removed by making all of the habitats in a stream uniform, diversity did not influence nitrogen uptake, and biofilms collapsed to a single dominant species. These results provide direct evidence that communities with more species take greater advantage of the niche opportunities in an environment, and this allows diverse systems to capture a greater proportion of biologically available resources such as nitrogen. One implication is that biodiversity may help to buffer natural ecosystems against the ecological impacts of nutrient pollution.     

南京典型城市道路植物多样性与土壤因子的耦合关系

目的 植物-土壤系统的作用机制复杂,揭示城市道路绿地植物群落正向演替的限制因子,筛选配置最优的植物群落类型,为城市道路绿化景观再设计提供数据支撑,也为城市道路绿化带土壤管护提供理论指导。方法 以南京市大气污染程度排名前列的3条城市道路(江北大道、诚信大道和仙林大道)为研究对象,选取典型的植物群落进行实地勘察和土壤采样分析,根据植物的生活型划分群落类别(单层群落、双层群落、3层群落和4层群落),采用灰色关联度分析方法测算不同类型群落的物种多样性与土壤因子的耦合关系。结果 随群落层次结构的增加,城市道路绿地的植物群落物种多样性水平呈现升高趋势。4层群落的土壤含水率普遍较高;土壤有机质、土壤全氮和土壤速效钾的含量随群落层次的增加呈现增大趋势。土壤因子更易影响植物的分布,而对植物种类的影响最小;土壤全钾、土壤容重、土壤有机质、土壤全氮、土壤全磷和土壤pH是植物生长的主要限制因子,平均关联系数均大于0.90,与物种多样性的关联度极强。随群落层次结构的增加,物种多样性与土壤因子的耦合度增大。结论 结构层次丰富的植物群落,其生态系统稳定性强,因此,城市道路绿化景观建设中,在考虑环境条件和交通需求的基础之上,植物群落的构建应首先推荐结构丰富的4层群落。     

Diversity of arbuscular mycorrhizal fungal spore communities and its relations to plants under increased temperature and precipitation in a natural grassland

Arbuscular mycorrhizal fungi(AMF)form mutualisms with most plant species,and therefore,understanding how AMF communities will respond to climate change is essential for predictions of changes in plant communities.To evaluate the impact of global climate change on AMFs and plant-AMF interactions in a natural grassland in Inner Mongolia,both artificial warming and watering treatments were assigned to experimental plots.Our results indicate that(1)warming and precipitation significantly affected the relative spore abundance of abundant sporulating AMF species;(2)the relative abundance of weak sporulating AMF species and AMF diversity decreased under experimental warming;(3)evidence was found that the composition of the AMF community in a given year might be correlated with plant community composition in the following year;and(4)grasses and forbs showing different preferences to Claroideoglomus etunicatum or Ambispora gerdemannii dominated plots.Our results imply that climate change appears to induce changes in AMF assemblages with knock-on effects on grassland plant communities.AMF communities may play a much more important role than we have thought in the responses of ecosystem to global climate changes.     

北京市湿地植物多样性及旱生植物入侵对生物多样性的影响

通过研究北京市湿地植物群落的结构,群落植物物种的组成、分布等情况,对湿地植物物种的重要值和湿地的生物多样性进行了分析。结果表明北京市主要湿地的物种组成和群落结构存在很大的差异,湿地内主要物种的重要值有季节性的变化。决定湿地群落中植物组成的主要因素是：旱生植物入侵、人为活动的干扰强度和湿地的水资源状况。因为连年降雨的减少导致了北京市湿地面积的下降和旱生植物的入侵问题日益加重。如汉石桥湿地保护区,捧草等入侵植物的群落盖度达到90％以上,有些形成单优势的群落,抑制了芦苇等湿地植物的生长。使湿地在整体上呈退化的趋势,湿地的景观价值、生态价值、湿地功能和湿地的生物多样性均严重损坏。因此,必须采取措施解决北京市湿地的水资源短缺问题,减少人类活动干扰,以恢复北京市郊县湿地和城市建成区湿地的活力,保护湿地的生物多样性。     

Effects of biodiversity on the functioning of trophic groups and ecosystems

Over the past decade, accelerating rates of species extinction have prompted an increasing number of studies to reduce species diversity experimentally and examine how this alters the efficiency by which communities capture resources and convert those into biomass. So far, the generality of patterns and processes observed in individual studies have been the subjects of considerable debate. Here we present a formal meta-analysis of studies that have experimentally manipulated species diversity to examine how it affects the functioning of numerous trophic groups in multiple types of ecosystem. We show that the average effect of decreasing species richness is to decrease the abundance or biomass of the focal trophic group, leading to less complete depletion of resources used by that group. At the same time, analyses reveal that the standing stock of, and resource depletion by, the most species-rich polyculture tends to be no different from that of the single most productive species used in an experiment. Of the known mechanisms that might explain these trends, results are most consistent with what is called the 'sampling effect', which occurs when diverse communities are more likely to contain and become dominated by the most productive species. Whether this mechanism is widespread in natural communities is currently controversial. Patterns we report are remarkably consistent for four different trophic groups (producers, herbivores, detritivores and predators) and two major ecosystem types (aquatic and terrestrial). Collectively, our analyses suggest that the average species loss does indeed affect the functioning of a wide variety of organisms and ecosystems, but the magnitude of these effects is ultimately determined by the identity of species that are going extinct.     

General patterns of taxonomic and biomass partitioning in extant and fossil plant communities

A central goal of evolutionary ecology is to identify the general features maintaining the diversity of species assemblages. Understanding the taxonomic and ecological characteristics of ecological communities provides a means to develop and test theories about the processes that regulate species coexistence and diversity. Here, using data from woody plant communities from different biogeographic regions, continents and geologic time periods, we show that the number of higher taxa is a general power-function of species richness that is significantly different from randomized assemblages. In general, we find that local communities are characterized by fewer higher taxa than would be expected by chance. The degree of taxonomic diversity is influenced by modes of dispersal and potential biotic interactions. Further, changes in local diversity are accompanied by regular changes in the partitioning of community biomass between taxa that are also described by a power function. Our results indicate that local and regional processes have consistently regulated community diversity and biomass partitioning for millions of years.     

亚热带3个地点青钱柳群落特征比较

【目的】以亚热带3个区域青钱柳天然群落为研究对象,通过调查其物种组成、结构特征、种群结构以及更新状况,探究影响青钱柳种群更新的主要原因,为青钱柳野生资源的保护和可持续利用提供科学依据和技术支撑。【方法】采用典型样方调查的方法,对3个青钱柳群落[四川沐川(群落M)、广西金钟山(群落J)和湖北鹤峰(群落H)]进行样方调查,分析其物种组成、物种多样性特征和区系特征,并评价群落间的相似性。以径级代替年龄的方式分析种群结构和更新情况。【结果】四川沐川群落(群落M)、广西金钟山群落(群落J)和湖北鹤峰群落(群落H)分别有维管植物32科50属70种、50科79属96种和59科100属126种;3个群落区系特征差异不显著,均以亚热带和温带成分为主;物种多样性和物种丰富度变化趋势较为一致,表现为乔木层>灌木层>草本层。3个群落的物种多样性和丰富度总体表现为群落H>群落J>群落M;群落结构为中等不相似,相似度表现为群落M与群落J的较高,群落M与群落H的次之,群落J与群落H的较小。【结论】整体来看,不同地理分布的青钱柳群落物种组成差异明显,相似性水平低,但其结构特征具有一定的相似性;乔木层树种优势显著,导致林分郁闭,林下光照减少,影响种群更新;灌木层植物种类较多,分布较为均匀;草本层占据较少空间,以蕨类植物为主;青钱柳种群天然更新在径级结构上出现不同程度的残缺现象,导致更新不连续。从天然更新的角度看,适当开辟林窗,有利于促进林下青钱柳幼苗幼树的生长及均匀分布,完成种群更新,使群落向着长久稳定的方向发展。     

雾灵山东大石沟核桃楸群落特征研究

采用样地调查法对雾灵山东大石沟核桃楸群落的结构特征、群落间相关性及群落内物种类型做了调查.结果表明：（1）该群落共有维管束植物51科80属94种;（2）群落整体郁闭度较高,草本层植被较为丰富;（3）群落物种数随海拔升高先减小后增加;多样性随海拔变化明显,海拔越高,物种多样性越小,海拔差越小,群落种类组成越相似;（4）群落内植物分布主要以温带为主.     

太湖西区公路两侧植物物种多样性的研究

按植物群落的乔木层、灌木层、草本层和藤本层,运用物种丰富度指数(S)、Shannon-Wiener指数、Simpson指数和Pielou均匀度指数,研究无锡马山国家旅游度假区公路两侧主要植物群落的物种多样性。结果表明:(1)各植物群落乔木层和灌木层的4种生物多样性指数变化具有相关一致性,草本层则差异较大;(2)公路边坡经人工植被修复后,植物物种多样性比未经修复的显著增加,起到防护边坡和改善景观的作用;(3)修复的湖滩地植物群落盖度大,但种类单一,故物种多样性较低;(4)原生植物群落的物种多样性最大;合理的人工修复可促进受损植物群落生物多样性增加;(5)通过物种多样性计算方法的比较,可以更客观地反映一个地区的物种多样性状况。     

内蒙古羊草草原退化系列上群落生物量组成特征的研究

通过对羊草草原退化系列上四个退化梯度植物种类组成、不同生活型和水分生态型的绝对和相对生物量以及群落的多样性指数的比较发现,随着退化程度的增强,物种的数量逐渐减少.禾本科在群落中的作用逐渐下降,而其它科,尤其是菊科的作用逐渐增大.群落科组成的多样性随着群落的退化先降后增,水分生态类型的多样性则逐渐下降.旱生植物的生物量逐渐增加,其作用随着群落的退化也逐渐增强,整个群落逐渐向旱生方向发展.多年生根茎禾草在群落中的生物量逐渐降低.群落生活型组成的多样性先降后增.在重度退化群落,多年生根茎禾草和多年生丛生禾草的相对生物量均有所下降,小半灌木和多年生草本的相对生物量有所升高,四种植物在群落中优势度较为平均,打破了原生群落中多年生丛生禾草和多年生根茎禾草占优势的局面.     

四川丘陵地区鸟类群落结构的研究

对四川省丘陵地区的鸟类资源进行初步调查，报道的110种鸟类中，以阔叶林最多，占67种，针叶林最少，占17种。分析其生境状况，多样性指数和丰富度指数以阔叶林最大，农田灌丛荒地最小。同时，分析了各群落的相似性，讨论了影响鸟类群落结构的各种因素和鸟类的经济意义。     

岩溶地区森林自然恢复过程中植物和土壤微生物多样性的关联分析

本研究以岩溶地区森林自然恢复过程中的草丛(HL)、灌丛(SL)、灌乔林(SAF)、次顶极乔林(SCAF)和顶极乔林(CAF)为研究对象,对植物多样性与土壤微生物群落多样性进行关联分析,探究森林恢复能否促进整个生态系统的恢复,为岩溶森林生态保护修复和科学管理提供理论依据.结果表明:(1)随着森林的恢复,植物群落的物种丰富...     

西藏濒危植物桃儿七群落结构及其环境因子

通过样地调查和数据统计,分析了三个桃儿七生长的典型群落的物种组成、物种重要值和群落多样性指数,应用主成分分析法分析了环境因子对群落的影响.结果表明:三个群落中桃儿七重要值均较高,在草本层具有一定优势;物种丰富度指数和多样性指数均为群落C的最大,均匀度指数为群落A的最大;主成分分析表明环境因子中土壤肥沃和光照强度对桃儿七是有利的,而人为干扰为不利因素.林缘、林窗和灌木林均为桃儿七群落的适生环境,但需要肥沃的土壤和一定的光照条件,避免人为干扰.在林缘的半阳坡地带或较为平缓的林间空地,散射光丰富,空气湿度和土壤肥力较高,人为干扰少的区域是野生桃儿七的适生区,可通过建立保护区进行保护;人工种植时,应充分考虑土壤、光照和温度等环境因子,提高人工种植的成功率.     

辽宁铁岭莲花湖湿地植物群落研究

铁岭莲花湖湿地中生长着大量的自然群落和人工种植群落,它们都对莲花湖湿地的生态环境有着重要的影响作用。通过对辽宁铁岭莲花湖湿地的36个样方进行了湿地植物资源和植物群落的调查研究,进行了群落分类,并在BioDiversityPro等软件的支持下,进行了物种多样性分析。结果表明：铁岭莲花湖湿地共有12种植物群落类型,其中陆生植物群落8种,水生植物群落4种。植物物种多样性在辽河大堤上自然群落中最大,在水中的人工群落中最小,自然群落在大堤上生长最为集中。对莲花湖湿地的生物多样性保护提出了对策建议,为今后莲花湖及类似湿地的研究提供了基础资料。     

Parasitic plants indirectly regulate below-ground properties in grassland ecosystems

Parasitic plants are one of the most ubiquitous groups of generalist parasites in both natural and managed ecosystems, with over 3,000 known species worldwide. Although much is known about how parasitic plants influence host performance, their role as drivers of community- and ecosystem-level properties remains largely unexplored. Parasitic plants have the potential to influence directly the productivity and structure of plant communities because they cause harm to particular host plants, indirectly increasing the competitive status of non-host species. Such parasite-driven above-ground effects might also have important indirect consequences through altering the quantity and quality of resources that enter soil, thereby affecting the activity of decomposer organisms. Here we show in model grassland communities that the parasitic plant Rhinanthus minor, which occurs widely throughout Europe and North America, has strong direct effects on above-ground community properties, increasing plant diversity and reducing productivity. We also show that these direct effects of R. minor on the plant community have marked indirect effects on below-ground properties, ultimately increasing rates of nitrogen cycling. Our study provides evidence that parasitic plants act as a major driver of both above-ground and below-ground properties of grassland ecosystems.     

Competition and phylogeny determine community structure in Müllerian co-mimics

Until recently, the study of negative and antagonistic interactions (for example, competition and predation) has dominated our understanding of community structure, maintenance and assembly. Nevertheless, a recent theoretical model suggests that positive interactions (for example, mutualisms) may counterbalance competition, facilitating long-term coexistence even among ecologically undifferentiated species. Müllerian mimics are mutualists that share the costs of predator education and are therefore ideally suited for the investigation of positive and negative interactions in community dynamics. The sole empirical test of this model in a Müllerian mimetic community supports the prediction that positive interactions outweigh the negative effects of spatial overlap (without quantifying resource acquisition). Understanding the role of trophic niche partitioning in facilitating the evolution and stability of Müllerian mimetic communities is now of critical importance, but has yet to be formally investigated. Here we show that resource partitioning and phylogeny determine community structure and outweigh the positive effects of Müllerian mimicry in a species-rich group of neotropical catfishes. From multiple, independent reproductively isolated allopatric communities displaying convergently evolved colour patterns, 92% consist of species that do not compete for resources. Significant differences in phylogenetically conserved traits (snout morphology and body size) were consistently linked to trait-specific resource acquisition. Thus, we report the first evidence, to our knowledge, that competition for trophic resources and phylogeny are pivotal factors in the stable evolution of Müllerian mimicry rings. More generally, our work demonstrates that competition for resources is likely to have a dominant role in the structuring of communities that are simultaneously subject to the effects of both positive and negative interactions.     

岷江干旱河谷主要草本种群生态位研究

在对岷江干旱河谷植被及其环境因子系统取样调查的基础上,研究了20种主要草本种群在土壤水分、全N、速效P、速效K和pH 5个资源维上的生态位特征。绵枣儿、铁扫帚、翻白委陵菜、黄背草、密生苔草的生态位宽度较高,对环境有较强的适应能力,形成了该地区的优势种群;猪毛莱、紫花野茅,歧茎蒿、虱子草等种群的生态位宽度较小。生态位宽度较小的物种并非就不是群落的优势种,取决于种群分布的范围和分布的均匀程度。种群在各个资源维上的生态位宽度表明对不同资源空间的利用能力和适应性不尽相同。各个资源维上所有种群生态位宽度和的大小依次为土壤含水量〉pH〉速效K〉全N〉速效P,表明物种对速效P资源的利用能力较低,对土壤含水量的利用能力较高,草本物种对水分资源的利用能力高于灌木物种。     

呼伦贝尔草原群落生产力与物种多样性关系分析

在呼伦贝草原选取5种代表性草原群落类型,采用取样调查的方法,探讨自然状况下草原植被群落生产力与物种多样性的关系,旨在为草原生态系统功能的恢复和草原有效管理提供理论依据.研究结果表明:大针茅+糙隐子草群落、羊草+克氏针茅群落、克氏针茅+羊草群落和贝加尔针茅+羊草群落多样性指数(物种丰富度指数、Simpson指数和Shannon-Winner指数)与生产力均呈显著正相关关系,但是羊草+寸草苔草甸草原物种多样性指数与生产力没有显著性相关关系.群落生产力受物种多样性、物种组成和环境因子等多因素共同影响,不仅仅是由物种多样性决定.     

荆州城市公园植物群落多样性研究

目的分析荆州城市公园植物群落物种多样性,为荆州及周边地区城市公园绿地规划和植物多样性保护提供参考依据.方法采用典型样方法,对荆州市7个城市公园选取235个样方开展植物多样性现状调查,分析其群落特征.结果荆州城市公园植物物种丰富,共有植物96科248属351种,植物群落优势种明显,植物多样性总体趋势依次为:灌木层,乔木层,草本层,但各公园之间又有差异,以中山公园和荆襄河湿地公园为最高;植物多样性指数大小依次为:综合公园,带状公园,专类公园.结论荆州城市公园植物群落物种组成较为丰富,物种多样性较高,但专类公园植物单一性较高,故选择适宜的植物品种,增加乡土植物的运用,提高群落的稳定性.     

Partitioning selection and complementarity in biodiversity experiments.

The impact of biodiversity loss on the functioning of ecosystems and their ability to provide ecological services has become a central issue in ecology. Several experiments have provided evidence that reduced species diversity may impair ecosystem processes such as plant biomass production. The interpretation of these experiments, however, has been controversial because two types of mechanism may operate in combination. In the 'selection effect', dominance by species with particular traits affects ecosystem processes. In the 'complementarity effect', resource partitioning or positive interactions lead to increased total resource use. Here we present a new approach to separate the two effects on the basis of an additive partitioning analogous to the Price equation in evolutionary genetics. Applying this method to data from the pan-European BIODEPTH experiment reveals that the selection effect is zero on average and varies from negative to positive in different localities, depending on whether species with lower- or higher-than-average biomass dominate communities. In contrast, the complementarity effect is positive overall, supporting the hypothesis that plant diversity influences primary production in European grasslands through niche differentiation or facilitation.