Regularities in the variability of species structure of costal littoral kelp: the model analysis

The model describes species structure of competitive community, inhabiting stochastically variable environment. Species list of this community, rearranged accordingly decreasing species abundance, can be described by decreasing geometrical series. According to the model, the value of coefficient of this progression q should be q = exp(-1) = 0.368. The actual data do not contradict statistically to this model constant. Seasonal variability of species structure in biotopes is observed. These biotopes differ one from another by the stability and heterogeneity levels of environmental conditions, estimated with the help of expert evaluation. Total community biomass shows two seasonal peaks; at winter and at spring - summer. Maximal values of total biomass are observed in the biotope with intermediate level of environment stability. The number of species is increased simultaneously with the growth of environmental stability. The level of species abundance equitability grows up too in these conditions. The model of geometric series describes the species structure of the macroalgae community quite adequately. At the same time, the positive correlation between sample's species richness and equitability of species structure results in the outcome that after all samples averaging the biomass distribution of species is approximately more accurately not by geometrical series but by power model. The new statistical method is offered in the application to this work. It allows the expose of statistically significant not monotone essential non-linear relations of nonquantitative (order-type) arguments.     

不同演替阶段鼢鼠土丘群落植物多样性变化研究

用空间序列代替时间序列的方法对高寒草甸不同演替阶段高原鼢鼠土丘植物群落的物种组成和多样性变化进行了研究．结果表明,不同演替阶段鼠丘植物群落的物种组成及外貌特征与原生植被(对照)之间存在较大差异．在演替的早期阶段,r对策者如萼果香薷、灰绿藜、鹅绒委陵菜、细叶亚菊等演替先锋种在群落中占相对重要地位．随着演替的进展,k对策者如长毛风毛菊、垂穗披碱草、甘肃嵩草、线叶嵩草等在群落中的比例增加．α多样性分析表明,随着演替的进展,群落物种丰富度指数(O)显著增加,其排列顺序为：阶段1<阶段2<阶段3<阶段4<原生植被;均匀度指数(Pielou均匀度指数)的变化趋势与丰富度指数相同;多样性指数(Simpson指数D和Shannon-．Wiener指数H’)按群落的演替梯度呈增加趋势．卢多样性分析表明,阶段1与原生植被及阶段1与阶段4植物群落物种组成的相似系数最小,为0．18;阶段1与阶段2植物群落物种组成的相似系数最大,为0．62．同时,群落生活型功能群组成也随鼠丘的演替进展而发生变化,反映出不同演替阶段的鼠丘植物群落和微生境都发生了改变．     

On the Species Structure of a Competitive Marine Community

Some examples of marine animal and plant communities with a structure determined by competitive inter-species relationships are discussed. It has been shown that the ranked species structure of these communities obeys a geometric progression, whose coefficient does not differ significantly from the constant exp(–1) = 0.368. A relationship between a certain parameter of this progression and the species diversity of a community has been found.     

A comparative study of the impact of species composition on a freshwater phytoplankton community using two contrasting biotic indices

Biodiversity index based on species richness and evenness has been a frequently used measure to describe phytoplankton community composition and the impact of water pollution on biotic components, despite it could not reflect clearly the impact of a particular species on the structure and function of phytoplankton community. On the contrary, an index based on the niche theory has been developed and used to elucidate the changes of phytoplankton community with the alteration of species composition under various levels of water quality. Through comparison on the Shannon–Wiener biodiversity index (H′) and the community pollution value (CPV), this paper depicted the algal species composition change along the gradation of water quality and quantified the impact of species composition on the structure and function of a freshwater phytoplankton community in four urban lakes in central China. This study found that not only CPV could indicate water pollution status but also the fluctuation of CPV along water pollution gradient could show the influence of dominant species composition on community function. The comparison between Shannon–Wiener biodiversity index and CPV shows that the presence of dominant species sustains the stability and the succession of phytoplankton community under the changing water environments. The results of this study indicate that the combination of biodiversity index and CPV can provide a systematic way to understand biotic interactions and species responses to altered habitats at the community level. Most importantly, these indicators will provide valuable information for lake management and restoration practices.     

Season dynamics of agal dominant community in small lakes of Central Chernozem Nature Reserve (forest-steppe zone)

Freshwater algal community dynamics of four small model lakes was studied at the Central Chernozem Nature Reserve (Kursk region, Russia). Fluctuation of species abundance and succession of main algal communities during the ice-free season were observed. Species diversity dynamics was correlated with dominant species abundance and unique species quantity. Diatoms were the basis of the dominant algal community. Species diversity of diatoms was the highest: it reached up to 90% of total species abundance in samples during the season.     

Pathways, mechanisms and predictability of vegetation change during tropical dry forest succession

The development of forest succession theory has been based on studies in temperate and tropical wet forests. As rates and pathways of succession vary with the environment, advances in successional theory and study approaches are challenged by controversies derived from such variation and by the scarcity of studies in other ecosystems. During five years, we studied development pathways and dynamics in a chronosequence spanning from very early to late successional stages (ca. 1–60 years) in a tropical dry forest of Mexico. We (1) contrasted dynamic pathways of change in structure, diversity, and species composition with static, chronosequence-based trends, (2) examined how structure and successional dynamics of guilds of trees shape community change, and (3) assessed the predictability of succession in this system. Forest diversity and structure increased with time but tree density stabilized early in succession. Dynamic pathways matched chronosequence trends. Succession consisted of two tree-dominated phases characterized by the development and dynamics of a pioneer and a mature forest species guild, respectively. Pioneer species dominated early recruitment (until ca. 10 years after abandonment), and declined before slower growing mature-forest species became dominant or reached maximum development rates (after 40–45 years). Pioneers promoted their replacement early in succession, while mature-forest species recruited and grew constantly throughout the process, with their lowest mortality coinciding with the peak of pioneer abundance. In contrast to prevailing stochastic views, we observed an orderly, community driven series of changes in this dry forest secondary succession. Chronosequences thus represent a valuable approach for revealing system-specific successional pathways, formulating hypotheses on causes and mechanisms and, in combination with repeated sampling, evaluating the effects of vegetation dynamics in pathway variation.     

黄河首曲-玛曲县高寒草甸沙化演替进程中群落结构及种群生态位特征

以甘肃省玛曲县高寒沙化草甸为对象,应用空间序列代替时间序列的方法,对其不同沙化演替阶段植物群落主要种群结构及其生态位特征进行了研究.结果表明:(1)随着沙化演替的进行,物种组成数呈单峰式曲线变化规律,在轻度沙化阶段物种数最多(43种),禾草类和豆科类物种的重要值和生态位宽度均呈逐渐减少规律,优势度逐渐减弱;在极度沙化阶段(除垂穗披碱草外)几乎完全消失,莎草类和杂类草一些物种的重要值和生态位宽度则均呈逐渐增大规律,优势度逐渐增加,并在重度或极度沙化阶段成为优势种、次优势种或重要伴生种;随沙化演替进程,蒲公英、狼毒和乳白香青等物种则表现出波动性,最后消失,物种组成和数量的变化导致沙化演替进程中高寒草甸草场质量逐渐降低.(2)相邻沙化演替阶段植物群落的物种组成相似性指数较高,而相距较远的沙化演替阶段植物群落的物种组成相似性指数较小,沙化演替系列两个极端阶段的植物群落的物种组成相似性指数最小.(3)垂穗披碱草在整个沙化演替过程中重要值和生态位宽度均逐渐减小,但其值都较大.(4)生态位总宽度占前5位的物种依次是:垂穗披碱草、莓叶委陵菜、矮嵩草、高山唐松草和苔草,其值分别为1.653、1.438、1.387、1.295和1.204.(5)种群之间生态位重叠系数的平均值随沙化程度加深呈单峰式曲线变化规律,轻度沙化阶段种群的生态位重叠程度较高,为0.824.     

Degradation succession of heterotrophic flagellate communities in microcosms

Degradation succession of heterotrophic flagellate communities was studied in samples of detritus and water from a small swamped lake in the environs of the settlement Borok, Yaroslavl province. Three stages of succession with different species composition of the heterotrophic flagellate community were clearly recognized. Cumulative properties of the community change with time. Maximum species richness, diversity, and abundance were observed on the fourth day of succession; their values gradually decreased later. The trophic and taxonomic community structure was most diverse at the earlier stages of succession. Primordial food (bacteria) concentration affects only the size of peak community properties, but has no influence on the pattern of succession changes. The influence of predators considerably reduced heterotrophic flagellate abundance and can shift the time of the stage with maximum species diversity in the course of succession.     

贡嘎山冰川退缩区植物-土壤反馈与植物间相互作用

植物-土壤反馈是揭示陆地生物群落动态变化的关键环节,为理解植物间相互作用及植被群落变化过程奠定基础。本研究以贡嘎山冰川退缩区原生演替早(5~10年)、中(30~40年)和晚期(80~100年)3个阶段典型土壤以及各阶段优势植物为对象,采用盆栽控制试验,比较优势植物在不同土壤条件下的生物量,并量化植物间相互作用以及植物-土壤反馈的方向与强度,为探究贡嘎山冰川退缩区植被群落演替规律提供依据。结果表明:(1)植物-土壤反馈作用显著影响植物在本土中的生物量,早期沙棘(Hippophae rhamnoides)在本土中生长最差,沙棘的植物-土壤反馈系数为负值;演替中期冬瓜杨(Populus purdomii)的反馈系数趋于零;晚期峨眉冷杉(Abies fabri)在本土中生长最好,峨眉冷杉的反馈系数为正值。(2)混种时,早期沙棘与演替中、晚期植物间相互作用指数为负值;中期冬瓜杨、川滇柳(Salix rehderiana)与演替早、晚期植物的相互作用指数接近于零,晚期植物峨眉冷杉、麦吊云杉(Picea brachytyla)与演替早、中期植物相互作用指数为正值。从植物-土壤反馈的方向来看,贡嘎山植被演替从早期负反馈,中期中性反馈,过渡到晚期正反馈。此外,演替早期沙棘促进演替中晚期植物生长,演替中期冬瓜杨、川滇柳对演替早晚期植物无显著影响,晚期峨眉冷杉、麦吊云杉更利于与演替早中期植物相互竞争。结果显示,植物-土壤反馈与植物间相互作用共同驱动了贡嘎山冰川退缩区植被快速演替,直至顶极群落。     

红松林不同演替阶段夏季鸟类群落研究

红松林不同演替阶段夏季鸟类群落研究常家传鲁长虎刘伯文许青（东北林业大学,哈尔滨１５００４０）ＳｔｕｄｙｏｆｔｈｅＢｉｒｄｓＣｏｍｍｕｎｉｔｙＳｔｒｕｃｔｕｒｅｉｎＤｉｆｅｒｅｎｔＳｕｃｃｅｓｉｏｎＰｅｒｉｏｄｏｆＫｏｒｅａｎＰｉｎｅＦｏｒｅｓｔ．Ｃｈ...     

Seasonal succession and strategies of phytoplankton development in two lakes of different trophic states

This study describes the metabolism and structure of phytoplanktoncommunities during seasonal periodicity and discusses strategiesof development adopted by species during succession. The studywas conducted in two trophically different lakes. Each lakedemonstrates a different degree of the ecological succession,which prescribes an increasingly complex taxocenose. In oligomesotrophicLake Pavin the autogenic succession lasts from spring overturnuntil mid-summer. In eutrophic Lake Aydat the autogenic successionis strictly limited to spring. The seasonal changes of the communityproductivity, turnover rate (P/B) and adenylate energy chargeconfirm the hypothesis of a change of the ‘metabolic orientation’of phytoplankton cells during seasonal succession. The autogenicsuccession represents the progression from a growth-orientedstrategy to an equilibrium-oriented one.     

Ecology and role of zooplankton in the fishery of Lake Naivasha

Taxonomic composition, distribution, community structure and seasonality of Lake Naivasha zooplankton between 1978 and 1980 are described. The ecological status of the zooplankton in relation to prevailing ecological factors and the lakes fishery are discussed. Species composition of the zooplankton community in Lake Naivasha has been remarkably constant since first observations between 1929 and 1931. The community structure and distribution of the zooplankton in the lake varied little from July 1978 to July 1980, however, there was evidence of species succession among the larger zooplankters, especially the cladocerans. In the littoral area zooplankton contribute significantly to the food and production of juvenile fish. There is an absence of fish zooplanktivores in the limnetic area of the lake. Consequently the limnetic zooplankton is not utilised by higher trophic levels.     

Cladoceran assemblages, seasonal succession and the importance of a hypolimnetic refuge

SUMMARY. 1. We investigate the importance of a refuge from fish predation to the abundance, species composition and seasonal succession of zooplankton. Thirty lakes representing a range of depths were sampled twice in summer for physical/chemical parameters and zooplankton community structure.
2. We define the refuge from centrarchid predators to be that space between the thermocline and the zone of anoxia. As lakes vary in rate of oxygen depletion from the hypolimnion. the refuge size and lake depth are independent: refuge size decreases during the summer period.
3. Lake depth and refuge size independently explain variation among lakes in zooplankton species composition, but seasonal community change within lakes is best predicted by loss of refuge size.
4. Refuge size also explains the substantial variation in the relative dominance of the two major daphnid species. Lakes possessing a large refuge are dominated by D. pulicaria ; those with a small refuge are dominated by the smaller, D. galeata mendotae . We suggest that lakes of intermediate refuge size, which are characterized by high species diversity, represent a more equitable balance of predation and competition.     

Structure and function of pelagic zooplankton in various types of lakes (using the example of small lakes in northwestern Russia

Changes of structure and functioning of pelagic zooplankton under lake eutrophication were studied in a group of small (without outlet) lakes in southern Karelia and Leningrad region. The lakes were morphologically similar and located within the same climatic zone. Differences in their trophic status were connected with anthropogenic eutrophication. Correlation between species number and feeding resources of a lake is determined as: Y = (8.01 +/- 3.85) + (0.29 +/- 0.07)X1 + (6.75 +/- 1.52)X2, r2 = 0.95, (1) Y--number of zooplankton species, X1--average chlorophyll concentration for the season, mg/1; X2--average value of biochemical oxygen demand (expressed in mgC/1). Average biomass of zooplankton for season also depends on food: logY = (-0.054 +/- 0.224) + (0.242 +/- 0.094)logX1 + (0.170 +/- 0.179)logX2, n = 13, r2 = 0.87, (2) Y--average zooplankton biomass for the season, kcal/m3, X1 and X2 the same as (1). Increase in species number and zooplankton bimass determined primarily by Rotatoria occur in parallel to chlorophyll concentration and activity of bacteria. In acid lakes rotifers are not important in energy balance. In mezotrophic lakes two main energy paths are formed--through rotifers and through Crustacea. The role of rotifers is extremely important in eutrophic lakes where about 80% of energy paths through them. The ratio community production to energy consumption for the growing season is also depended on the community structure (species number, equitability, connectence): Y = (2.257 +/- 0.026) - (0.368 +/- 0.031)X1 + (5.160 +/- 0.442)X2, r2 = 0.99, (3) Y--average seasonal production of zooplankton, kcal/m2; X1--maximal meaning of Shannon index (bites), calculated on biomass value; X2--connectence of the community, calculated according Briand (1983). Eutrophication changes the stability of lakes relative to external influences, while low productive lakes are very sensitive to the increase in nutrient load, high productive lakes are more influenced by changes in fish predation.     

The Influence of Biotic and Abiotic Factors on Psammic Rotifers in Artificial and Natural Lakes

The effect of sand grain size, porosity and the abundance of algae on the community structure of psammic rotifers was tested in three anthropogenic lakes (Upper Silesia) and compared with three natural ones (West Pomerania). The structure of grain size in the studied beaches of artificial and natural lakes was similar but differences were found in the abundance of algae. The structure of the psammic rotifer community in Upper Silesian lakes was different from natural lakes in West Pomerania. The structure of psammic rotifer communities in anthropogenic reservoirs and lakes (West Pomerania) differed in numbers of species and numbers of psammobiont species, and also diversity index. The most altered structure of rotifer assemblages was observed in the psammon rotifers of the strongly contaminated Dzierżno Duże Lake.     

Seasonal and inter-annual scales of variability in phytoplankton assemblages: comparison of phytoplankton dynamics in three peri-alpine lakes over a period of 28 years

1. A method based on hierarchical clustering and Bayesian probabilities is used to identify phytoplankton assemblages and analyse their pattern of occurrence and temporal coherence in three deep, peri‐alpine lakes. The hierarchical properties of the method allowed ranking by order of importance of the effects of changes related to climate and to human activity on the phytoplankton structure. 2. The three deep, peri‐alpine lakes (the Lower Zurich, Upper Zurich and Walen lakes) investigated in this study have been monitored since 1972. During that period they have undergone oligotrophication as a result of management programmes and they have been subject to similar meteorological effects that have led to higher water temperatures since 1988. 3. The phytoplankton assemblages of the most eutrophic lake (Lower Zurich) differ strongly from those observed in the two meso‐oligotrophic lakes. Local environmental conditions appear to be the main factor responsible for species composition and change in climate characterised by the warmer water temperatures observed since 1988 have had a major impact on the winter composition of the lower basin of Lake Zurich by promoting Planktothrix rubescens. 4. Some phytoplankton assemblages are found in all the lakes. Their patterns of occurrence display strong synchrony at the annual and/or inter‐annual scales. However, temporal coherence between the lakes sometimes also involves different assemblages. 5. The reduction in phosphorus had a great influence on long‐term changes in composition. In all three lakes, decreases in phosphorus are associated with a community characterised by some mixotrophic species or species adapted to low nutrient concentrations or sensitive to transparency. In the Lower Lake Zurich the decrease in phosphorus has also led to the development of species adapted to low light intensities. 6. Seasonal meteorological forcing has also induced synchronous changes, but the same assemblages are not necessarily involved, because the pool of the well‐placed candidate taxa that may develop is determined by the local environmental conditions, and mainly by phosphorus concentrations. In the most eutrophic lake, the seasonal pattern is characterised by a succession of more stages. However, the seasonal assembly dynamics involve the succession of species sharing common selective advantages that make them relatively stronger under these nutrient and light conditions.     

Testing for deterministic succession in metazoan parasite communities of marine fish

Parasite communities are similar to free‐living communities; decay of similarity over geographic distance, theory of island biogeography, species–area relationships and nestedness have been documented in both communities. Ecological succession has been studied in free‐living communities but has rarely been examined in parasite communities. We use seriation with replication to test the hypothesis that succession of parasite community structure is deterministic, thus developing throughout consecutive changes along the fish ontogeny, via a seriated pattern. 12 306 marine fishes (95 species) were studied. In 40 species, a seriated pattern was detected; 25 had a tendency towards a seriated pattern, and for 31 species, succession was at random. Age‐classes for each host species explained deterministic successional patterns for whole parasite communities and ectoparasites. Richness and number of age‐classes explained this pattern for endoparasites. Seriated successional pattern was evident for parasite communities of long‐lived marine fish, indicating that parasite communities follow sequential changes over time, like many free‐living communities.     

安太堡矿区复垦地植被恢复过程多样性变化

植被生态系统的重建是矿区复垦地恢复的主要环节之一。通过群落调查和实验分析,采用丰富度指数、物种多样性指数和均匀度指数,结合DCCA排序、多元线性回归和相关分析,研究了平朔安太堡矿区复垦地植被恢复过程中多样性的变化。群落多样性分析结果表明:(1)直接种植植被演替后期的植物种大大加速了原始植被演替进程;(2 )多样的人工配置群落比单一的人工配置群落更能促进群落向正向演替的方向发展;(3)能够适应矿区特殊生境的植被配置方式在恢复进程中与自然植被表现出一定的差异,这种差异只持续发生植被恢复的前3a,3a之后群落的演替与自然植被的演替表现出趋同性;(4)森林群落是较灌丛群落更适合安太堡矿区特殊生境的植被配置方式,其中刺槐和油松的混交效果较好。物种多样性的分析表明:(1)多样性偏高的群落与有机质和时间联系较为紧密,而多样性偏低的群落则与锰的联系较为紧密;(2 )制约矿区物种多样性变化的主要因素是土壤水分和演替时间;(3)锌对各多样性指数都有一定的影响(4)有机质、时间与丰富度指数相关显著;(5 )海拔与综合多样性指数相关显著;(6 )铜对均匀度指数的影响较大。方法的比较结果表明:(1)多元线性回归的灵敏度比相关分析高;(2 ) DCCA可以作为对定量分析的补充,解释那些在定量分析中不显著的因