Field parameterization and experimental test of the neutral theory of biodiversity

Ecologists would like to explain general patterns observed across multi-species communities, such as species-area and abundance-frequency relationships, in terms of the fundamental processes of birth, death and migration underlying the dynamics of all constituent species. The unified neutral theory of biodiversity and related theories based on these fundamental population processes have successfully recreated general species-abundance patterns without accounting for either the variation among species and individuals or resource-releasing processes such as predation and disturbance, long emphasized in ecological theory. If ecological communities can be described adequately without estimating variation in species and their interactions, our understanding of ecological community organization and the predicted consequences of reduced biodiversity and environmental change would shift markedly. Here, I introduce a strong method to test the neutral theory that combines field parameterization of the underlying population dynamics with a field experiment, and apply it to a rocky intertidal community. Although the observed abundance-frequency distribution of the system follows that predicted by the neutral theory, the neutral theory predicts poorly the field experimental results, indicating an essential role for variation in species interactions.     

Diversity of Plant Species of Alpine Grassland in Nakchu of Tibet, China

0Introduction Biologicaldiversityconcernedwiththesumofvariouslivingbeingsandtheirprocesses,aswellasthebasisofharmonious coexistencebetweenmanandnatureplaysanimportantroleinecology,economy,esthetics,ethics,etc.Duetodeteriorationofglobal environment,acceler…     

山地荒漠草原不同植物群落物种-多度关系分析

在群落样方调查的基础上,计算群落物种重要值,确定群落类型.对群落物种重要值采用分割线段模型(broken stick model)、对数级数分布(Log series distr ibution)、对数正态分布(Lognormal distribution)、几何级数分布(Geometric series distribution)等4个种-多度模型进行拟合.结果表明石质山坡(长芒草Stipa bungeana-冷蒿Artemisia frigida)群落对数级数拟合结果更好,土质山坡群落(短花针茅Stipa brevifora-长芒草Stipa bungeana)对数正态分布拟合更好,说明了2个群落结构是对2个样地环境特点与放牧干扰相互作用的响应.沙化草地(油蒿Artemisiaordosica-刺叶柄棘豆Oxytropis aciphlla)群落中油蒿处于极优势地位,占据整个群落的大多数生态空间.拟合检验表明该山地草地植被物种分布格局较符合随机生态位假说和生态位占领假说,严重的放牧干扰不仅降低了优势物种在群落中的优势程度,使次优势物种及其他物种也没能较好的发育,说明外部非生物环境对群落胁迫程度较大.     

长春市南湖公园鸟类群落季节动态的研究

自1997-2003年,对长春市南湖公园鸟类群落季节动态进行了研究．共记录鸟类96种,隶属13目34科．发现不同群落问鸟类季节动态有差异,迁徙鸟类占比例较大．秋季种类最多（57种）,生物量以冬季最高;春秋两季相似性最大（S=0．588）．食虫鸟类是季节变化的主要影响者,环境和食物是鸟类季节变化的主要因素,不同季节问鸟类群落多样性、均匀性差异较大．     

Productivity-biodiversity relationships depend on the history of community assembly

Identification of the causes of productivity-species diversity relationships remains a central topic of ecological research. Different relations have been attributed to the influence of disturbance, consumers, niche specialization and spatial scale. One unexplored cause is the history of community assembly, the partly stochastic sequential arrival of species from a regional pool of potential community members. The sequence of species arrival can greatly affect community structure. If assembly sequence interacts with productivity to influence diversity, different sequences can contribute to variation in productivity-diversity relationships. Here we report a test of this hypothesis by assembling aquatic microbial communities at five productivity levels using four assembly sequences. About 30 generations after assembly, productivity-diversity relationships took various forms, including a positive, a hump-shaped, a U-shaped and a non-significant pattern, depending on assembly sequence. This variation resulted from idiosyncratic joint effects of assembly sequence, productivity and species identity on species abundances. We suggest that the history of community assembly should be added to the growing list of factors that influence productivity-biodiversity patterns.     

Species-diversified plant cover enhances orchard ecosystem resistance to climatic stress and soil erosion in subtropical hillside

Naturally occurring plants in agroecosystem evidently play an important role in ecosystem stability. Field studies on the ecological effects of native plants conserved in orchard and their resistance to adverse climatic stress, and soil erosion were conducted from 1998 to 2001 in a newly developed Changshan-huyou (Citrus changshan-huyou Y.B. Chang) orchard. The experimental area covered 150 ha in typical red soil hilly region in southeastern China. The experimental design was a randomized complete block with six combinations of twelve plant species with four replications. All species used were native in the orchard. Plots were 15 x 8 m2 and separated by 2 m buffer strips. Precipitation, soil erosion in rainstorm days and aboveground biomass of plant community when rainstorm days ended, soil temperature and moisture under various plant covers during seasonal megathermal drought period, antiscourability of soil with different root density under various simulated rainfalls were measured. Plant cover significantly decreased the daily highest and mean soil temperature and its daily variation in hot-drought season, but there was no significant difference of the alleviation among various plant covers. Plant covers significantly increased the soil moisture in seasonal megathermal drought period. Better moisture maintenance and soil erosion reduction was found when the plant species numbers in cover plant communities increased from one to eight. Higher root density in plant communities with higher species richness increased significantly the antiscourability of the soil. It was suggested that conserving plant communities with diversified native species could produce the best positive ecological effects on citrus orchard ecosystem stability.     

Invasion sequence affects predator-prey dynamics in a multi-species interaction

Ecologists seek to understand the rules that govern the assembly, coexistence and persistence of communities of interacting species. There is, however, a variety of sequences in which a multi-species community can be assembled--unlike more familiar one- and two-species systems. Ecological systems can exhibit contrasting dynamics depending on initial conditions, but studies have been focused on simple communities initiated at different densities, not on multi-species communities constructed in different sequences. Investigations of permanence and convergence in ecological communities have been concerned with the flux of whole species (presence or absence) but have not addressed the central issues concerning the dynamics exhibited by individual species in particular interactions. Here we examine data for replicated three-species systems and demonstrate that the dynamic trajectories of both a predator and its prey within the system are determined by the sequence in which it is constructed, and that for one construction-sequence alternative dynamic patterns are possible.     

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.     

土壤因素对羊草群落构成与种群生物量的影响

对不同程度盐碱生境下羊草群落的生态分布及地上生物量作了研究，得出：影响羊草群落生态分布和生物量的主导因素是土壤含盐量和酸碱度（ｐＨ值），其中土壤含盐量是影响生物量的主要因素，并且以７月份最为显著，盐碱对羊草群落生物量影响还表现在不同盐碱生境下地上生物量季节动态存在差异。     

北美CHIHUAHUAN荒漠17种啮齿动物的日耗能动态比较

利用时间序列分析方法，季节性指标和主分量分析比较了北美Ｃｈｉｈｕａｈｕａｎ荒漠１７种啮齿动物的日耗能动态，结果显示：（１）各物种种群日耗能一般随环境改变有相似年变化，但季节变化呈多样化；（２）只有盘尼西拉特斯更格卢鼠有明显的季节性；（３）各物种种群日耗能的对数与体重的对数成正相关关系，与种群密度的对数也成正相关关系，与扩菜距离的对数成负相关关系；（４）１７个物种可划分为４个日耗能类型，即优势型，季     

福建省三沙湾饵料浮游动物生态特征研究

饵料浮游动物是海洋经济水产动物直接或者间接的饵料,对它的研究有着重要的理论意义和实用价值.根据2007年2、5、8、11月福建省三沙湾4个航次的调查资料,分析三沙湾饵料浮游动物的生态特征.共鉴定饵料浮游动物82种(类);饵料浮游动物生物量均值为94.52 mg/m~3,占浮游动物总生物量的90.21%,生物量季节分布呈典型双峰型:春、秋两季高于夏、冬两季,且随着季节的变化,呈现不同的平面分布特点;丰度的季节变化和平面分布特点与生物量的季节变化趋势一致;分析结果显示,水温和不同流系是影响三沙湾饵料浮游动物季节变化与平面分布的主要因素.三沙湾饵料浮游动物群落多样性丰富,均匀度均较高,表现出较高的稳定性;小拟哲水蚤(Paracalanus parvus)是三沙湾的主要优势种类.     

Cultures in chimpanzees.

As an increasing number of field studies of chimpanzees (Pan troglodytes) have achieved long-term status across Africa, differences in the behavioural repertoires described have become apparent that suggest there is significant cultural variation. Here we present a systematic synthesis of this information from the seven most long-term studies, which together have accumulated 151 years of chimpanzee observation. This comprehensive analysis reveals patterns of variation that are far more extensive than have previously been documented for any animal species except humans. We find that 39 different behaviour patterns, including tool usage, grooming and courtship behaviours, are customary or habitual in some communities but are absent in others where ecological explanations have been discounted. Among mammalian and avian species, cultural variation has previously been identified only for single behaviour patterns, such as the local dialects of song-birds. The extensive, multiple variations now documented for chimpanzees are thus without parallel. Moreover, the combined repertoire of these behaviour patterns in each chimpanzee community is itself highly distinctive, a phenomenon characteristic of human cultures but previously unrecognised in non-human species.     

贵州茂兰退化喀斯特森林群落的数量特征

对不同演替阶段30个群落样地的数量特征进行研究。结果表明:(1)在自然恢复过程中,灌木林阶段物种丰富度和物种多样性均高于乔木林阶段,前者均匀度也稍高于后者,而乔木林阶段生态优势度有所增加;(2)退化喀斯特森林群落具有较为明显的优势种,通常为1~2种;(3)退化喀斯特森林群落的生物量随自然恢复演替的进程不断增大,群落生物量构成也随自然恢复演替的进程而发生变化,灌木林的草本层和灌木层平均生物量都远高于乔木林的相应值,分别是乔木林的5.4倍和3.5倍;(4)群落的连续带指数分析反映了不同群落类型在群落演替中所处的地位。     

岷江上游退化植被恢复演替过程中优势种群空间分布格局研究

采用扩散系数、T检验、聚集指数、平均拥挤度、聚块性指数、Green指数和聚集强度等7 项指标对岷江上游滇榛、杭子梢和辽东栎3个优势种群在不同恢复演替阶段的空间格局进行了分析. 结果表明: 3 个优势种群在不同恢复群落内都呈较强的聚集分布, 聚集强度和聚集面积都随恢复时间的延长而增加, 人工恢复16 年群落具有较高的聚集强度, 自然恢复群落具有较高的聚集面积. 优势种群的格局类型、聚集强度以及分布格局的动态变化都表明有效的恢复措施使群落向着稳定的方向发展.     

典型草原7种植物的放牧退化敏感度的比较研究

研究了大针茅 羊草草原三个不同退化强度群落中7个植物种-大针茅、羊草、羽茅、糙隐子草、洽草、冷蒿、星毛委陵菜的地上生物量的差异及其季节变化特点.研究结果表明随着退化强度的增加,大针茅、羽茅地上生物量明显降低,糙隐子草、星毛委陵菜的地上生物量持续地增加,变化规律比较明显.根据距离系数和相对敏感度的特点,可把7种植物分为两种类型,一种类型包括羽茅、洽草、冷蒿、大针茅四种植物,当草原从无退化阶段发展到中度退化阶段时,它们的退化敏感度较大,其退化敏感度大小依次是:羽茅≥洽草>冷蒿>大针茅;可把它们作为草原发生中度退化的指示植物,其中羽茅、洽草具有相对较强的指示意义.另一类型包括羊草、星毛委陵菜、糙隐子草三种植物,当草原从中度退化阶段发展到重度退化阶段时,它们的退化敏感度较大,其敏感度大小依次是:羊草>星毛委陵菜>糙隐子草,它们可被作为草原从中度退化向重度退化发展的指示种,以羊草的指示价值最高.     

内陆河流域浮床植物根际微生物群落特征与比较

为研究内陆河流域不同浮床植物的根际微生物群落结构、多样性、潜在生态功能及其差异,采集了位于沱江二级支流赤水河生态浮床上的风车草（Cyperus involucratus）、黄菖蒲（Iris pseudacorus）、再力花（Thalia dealbata）、鸢尾（Iris tectorum）、美人蕉（Canna indica）、梭鱼草（Pontederia cordata）6种植物生长旺盛时期的根系样本,通过细菌16sRNA片段高通量测序和生物信息学手段,分析了微生物群落结构组成、生物多样性以及潜在的生态功能。结果表明,变形菌门（Proteobacteria）在6种浮床植物根际细菌中占绝对优势,丰度达47.5% - 72.2%,在植物生长环境较为相似且空间距离较近的情况下,不同浮床植物根际微生物属水平优势种群丰度差异仍较大。微生物群落多样性由大到小依次为鸢尾、美人蕉、黄菖蒲、风车草、再力花、梭鱼草,同科同属的黄菖蒲和鸢尾根际细菌组成相对较为相似。风车草根际硝化/反硝化功能菌群丰度更高,梭鱼草根际芳香族化合物降解功能菌群丰度显著高于另外5种植物。根长、株高和生物量更大的植物根际微生物中芽殖杆菌属丰度显著更高,植物生长指标与部分根际细菌氮转化存在正相关关系。研究结果可为浮床植物根际微生物群落研究和生态浮床的建设优化提供参考。     

鄱阳湖底栖动物生态研究及其底层鱼产力的估算

研究了鄱阳湖底栖动物种类组成，数量分布、季节变化及其与环境因子的关系等生态特点并估算了底层鱼类的生产潜力。结果表明，鄱阳湖底栖动物种类丰富，平均总生物量为２４６．４２６ｇ／ｍ＾２，平均栖息密度为７２１个／ｍ＾２。生物量和栖息密度的分布极不均匀，呈Ｅ＝Ｐ核心分布，局部区域的水动力特点、水生植被类型、不同沉积物类型都影响底栖动物种群和数量的分布。     

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.     

滇池浮游植物群落结构的时空变化及与环境因子的关系

在滇池外海选取8个样点, 调查分析主要的环境因子和浮游植物群落的季节和年际变化, 并识别其相关关系。在滇池共检测出浮游植物6门49 属84种, 其中绿藻门的种类数最多, 占59.2%, 其次是蓝藻门, 占16.67%, 硅藻门占5.95%; 全年蓝藻门占优势, 春季隐球藻(Aphanocapsa sp.)占优势, 其他季节微囊藻(Microcystis sp.)占绝对优势。研究结果表明: 1) 藻密度和生物量的季节变化不一致, 与藻类组成的季节演替以及不同藻类的生物量大小存在较大差异有关; 2) Shannon-Wiener物种多样性指数(H)较小, 季节变化不显著; 3) 藻密度和生物量与TP正相关, 与 NO₃^-和N:P负相关; 而H与TP负相关, 与NO₃^-和N:P正相关; 4) 营养盐是影响浮游植物群落分布的关键因子, 滇池最重要的优势种微囊藻的密度和生物量与pH、NH₄⁺和TP浓度正相关, 与NO₃^-、N:P、TN、DOC和TOC的浓度负相关。推测除环境因子外, 绿藻、硅藻等优势度较小的藻类受其他生物因素的影响较大(如种间竞争和捕食等), 掩盖了环境因子对藻类的真实影响。     

内蒙古灌木群落物种丰富度与气候的关系

为了验证几种重要的物种多样性地理格局假说(水分能量动态假说、生产力假说、寒冷忍耐假说、生态学代谢假说)在干旱、半干旱地区灌木群落中的适用性, 对内蒙古中西部地区1100 km样线内的灌木群落进行调查, 结合气候数据、植被归一化指数研究不同气候或生产力因子对群落物种丰富度的解释能力。同时研究了不同功能型的植物在物种多样性?气候关系方面的差异, 包括不同的生活型(木本、草本)、水分生态型(旱生、中旱生、中生)。结果表明: 1) 水分能量动态假说能较好地解释本研究区灌木群落多样性的地理格局, 植物能获得的有效水分是影响物种丰富度的主要因素; 2) 研究结果与代谢假说的预测相反, 该假说无法解释干旱、半干旱区的群落多样性格局, 结果不支持寒冷忍耐假说在研究区的适用性, 而生产力也只能解释部分功能型的物种丰富度; 3) 不同功能型的植物对气候、 生产力梯度的响应表现出很大的差异, 物种的生态特性以及种间相互作用对物种丰富度格局有着重要的影响, 深入理解群落的构建机制可能是理解生物多样性的地理格局所必需的。