Why on the snow? Winter emergence strategies of snow‐active Chironomidae (Diptera) in Poland

A long‐term study of adult non‐biting midges (Chironomidae) active in winter on the snow in mountain areas and lowlands in Poland yielded 35 species. The lowland and mountain communities differed significantly in their specific composition. The mountain assemblage was found to be more diverse and abundant, with a substantial contribution from the subfamily Diamesinae, whereas Orthocladiinae predominated in the lowlands. Orthocladius wetterensis Brundin was the most characteristic and superdominant species in the winter‐active chironomid communities in both areas. Only a few specimens and species of snow‐active chironomids were recorded in late autumn and early winter. The abundance of chironomids peaked in late February in the mountain and lowland areas with an additional peak in the mountain areas in early April. However, this second peak of activity consisted mainly of Orthocladiinae, as Diamesinae emerged earliest in the season. Most snow‐active species emerged in mid‐ and late winter, but their seasonal patterns differed between the 2 regions as a result of the different species composition and the duration of snow cover in these regions. Spearman's rank correlation coefficient tests yielded positive results between each season and the number of chironomid individuals recorded in the mountain area. A positive correlation between air temperature, rising to +3.5 °C, and the number of specimens recorded on the snow in the mountain community was statistically significant. The winter emergence and mate‐searching strategies of chironomids are discussed in the light of global warming, and a brief compilation of most important published data on the phenomena studied is provided.     

内蒙古白音锡勒典型草原区鼠类群落多样性的研究

在草原生态系统中,鼠类既是消费者又是次级生产者,因此这个类群在草原生态系统中占有重要的地位。 鼠类群落结构是生态系统结构的一部分,它的存在是地理的、生态的和进化的诸因素共同作用的结果。鼠类群落的多样性,反映了同一地区各群落之间的相似程度,也反映了群落与其外界条件的关系,它作为群落的结构参数,是群落特征的重要方面,日益受到生态学工作者的重视。 1979年7-9月,我们曾对内蒙古白音锡勒典型草原区的鼠类群落空间配置及其结构进行研究(钟文勤等,1981)。本文将通过分析这些群落的多样性,进一步探讨鼠类群落与植被、土壤等条件的关系。     

阿拉善荒漠啮齿动物集合群落实证研究

当生态学家探求在破碎化的栖息地中,群落物种的共存机制、多样性、局域尺度的性质和过程被放到更广阔的时空框架内时,就出现了"集合群落"这一概念。Leibold提出了集合群落概念,他们将一个集合群落定义为局域群落集,这些群落由各个潜在的相互作用的物种的扩散连接在一起。集合群落理论描述了那些发生在集合群落尺度上的过程,并且提出思考关于物种相互作用的新方法。集合群落概念为群落生态学提供了一个新的革命性的范式,集合群落研究的最基本问题是同一系统中多物种共存的机理、多样性的形成原因与维持机制。该范式强调区域范围内群落中的综合变异,强调环境特证和栖息地之间通过扩散调节的生物相互作用和空间变化。Leibold等提出了解释集合群落结果理论上的4个生态范式,即(1)中性理论;(2)斑块动态理论;(3)物种分配理论;(4)集团效应理论。之后有大量有关检验这4种生态理论的研究,但是有关陆地脊椎动物系统的集合群落的研究较少。2010—2012年,通过在内蒙古阿拉善荒漠景观中的8个固定样地中,对啮齿动物、栖息地环境因子进行调查。利用冗余分析和偏冗余分析,评估环境特征和空间特征对物种组成的影响。结果表明,环境特征独自解释72.8%的啮齿动物物种组成变化,空间特征独自解释33.8%的物种组成变化,环境特征和空间特征共同解释86.5%的啮齿动物物种组成变化,结果显著(P=0.032);去除环境特征之后,空间特征解释13.7%的变化(P=0.246),结果不显著;去除空间特征之后,栖息地变化解释52.7%的变化(P=0.016);环境特征和空间特征的交互作用解释20.1%的物种组成的变化,该区域啮齿动物群落构成集合群落,物种共存中环境特征起着主导作用,由物种分配理论解释该集合群落结构。     

Response of copronecrophagous beetle communities to habitat disturbance in two mountains of the Mexican Transition Zone: influence of historical and ecological factors

We analyze the influence of historical and ecological factors on the diversity and composition of communities of copronecrophagous beetles associated with conserved and disturbed habitats on two mountains of the Mexican Transition Zone: one mountain of xeric (Las Derrumbadas) and the other of temperate (El Pinal) climate. We collected a total of 1113 beetles of 14 species. While abundance was similar between mountains, the number of species found on the temperate mountain (589 individuals: 11 species) was higher than on the xeric mountain (524 individuals: 5 species). On the temperate mountain, the disturbed habitat was approximately twice as diverse as the conserved habitat, while the opposite pattern was observed on the xeric mountain. Analysis of species turnover between mountains indicated the presence of two relatively different communities and the magnitude of the species turnover related to habitat disturbance depended on the type of mountain, having a higher turnover between habitat types in the temperate mountain. The xeric mountain was dominated by species belonging to the Paleoamerican Plateau distribution pattern, while the Paleoamerican Montane pattern dominated on the temperate mountain, whose species increased their abundance in disturbed habitats together with species of Nearctic affinity. Our results suggest a negative effect of habitat disturbance on the xeric mountain. While on the temperate mountain, beetle diversity seems to increase with disturbance. These results reiterate the need to consider regional-scale historical and ecological processes in order to understand the effects of disturbance and permit the establishment of conservation strategies to adequately protect the organisms, as well as the functions they provide for natural and anthropic ecosystems alike.     

Periphytic and drifting microalgae in a tributary stream of Øvre Heimdalsvatn

Samples of drifting and periphytic microalgae were collected during 1972 from a fast-flowing, stony stream (Brurskardsbekken) in the Jotunheimen mountain area, central southern Norway. The predominant algal groups in the drift and the periphyton were diatoms and green algae, while only a few species were recorded in both communities. A considerable number of species from Chrysophyceae, Cryptophyceae and other algal classes were also recorded in the drift samples. The species composition was in good agreement with microalgal communities earlier described from mountain areas in Scandinavia, although species which probably are new to Norway, were also recorded. A quantitatively important fraction of planktonic species in the drift is interpreted as a contribution from lacustrine habitats in the watercourse. A general change in the periphyton during the summer, from green algae to diatoms, was observed, Altitudinal differences in the periphyton included a delayed green algal maximum at higher altitudes compared to lower. In the zone around the upper birch limit, a transition in species composition as one goes up stream, described in other investigations, was not observed.     

The role of historical processes in determining tree species richness in the forests of Western Caucasus

To estimate the role of history in variation of tree species richness in the forests of the Western Caucasus we analyzed correlation between their local richness (S--the mean number of species per 300 m2) and size of actual species pool (N--the number of species per 1 ha). If compared communities are differently distant from the point of evolutionary equilibrium one should expect a significant variation in correlation between S and N (determined with the greater sensitivity of N than S in respect of historical factors). The lower value of N/S corresponds to less saturated level of historically determined species richness. A mean N/S ratio in Japana temperate broadleaved forests (Masaki et al., 1999) provided the basis for analysis. The present tree species richness of the forest communities in the 1 ha plots seem essentially determined by the historical processes. The mountain forest communities of Western Caucasus are characterized on the average with lower saturation level of the actual tree species pool in comparison with the Japan temperate broad-leaved forest communities. On the Western Caucasus the middle mountain beech and coniferous-broadleaved communities (400-1600 m a.s.l.) are characterized with the higher saturation level of the actual species pool in comparison with communities located lower and higher. These results confirm published historical reconstructions, according to which the middle mountain forest communities in the Western Caucasus are older than forests located higher or lower. Present low mountain forests of the southern (to Black Sea) and the northern macroslopes of the Western Caucasus are characterized with similar saturation level of the actual species pool. These data agree with the assumption of Dolukhanov (1980) that low mountain zone of the southern macroslope was not a refuge for tree species in Pleistocene.     

The role of phylogeny in desert rodent community assembly

Recent advances in molecular genetics and phylogenetic reconstruction have the potential to transform ecology by providing new insights into the historical evolution of ecological communities. This study by Stevens and collaborators complements decades of previous research on desert rodents, by combining data from a field study and a phylogenetic tree for Mojave Desert rodents to address patterns and processes of community assembly. The number of coexisting rodent species is positively correlated, and the average phylogenetic distance among these species is negatively correlated with perennial plant species richness. As rodent species diversity increases along a gradient of increasing environmental heterogeneity, communities are composed of increasingly related species: there is a consistent pattern of phylogenetic structure from over-dispersed through random to clumped. I discuss this pattern in the light of complementary results of previous studies. This paper is noteworthy for calling attention to still unanswered questions about how the historical events of speciation, colonization, extinction, and trait evolution and their relationship to past climates and vegetation have given rise to current patterns of community organization.     

The concepts of elasticity, invulnerability and invadability

Users of mathematical models in ecological research have emphasized mathematical elegance in elucidating the dynamics of ecosystem models with fixed collections of state variables instead of addressing the equally important question of what effects a changing ecosystem structure has on the system's dynamics. Our work addresses the effect of invasion on the species composition of communities. In the context of a linear model, we found that as communities were made more complex (in terms of the number of species they contained and the number of interactions among these species) the probability of their being stable decreased, but the probability of their being invulnerable to invasion by other species increased. These results are consistent with the hypothesis that, through time, communities approach an intermediate complexity at which the influences of environmental stochasticity (which tends to destabilize complex communities) and invasion pressure (which tends to add species to simple communities) counterbalance one another. At this intermediate complexity the average rate of change of species composition is low.     

海南岛坝王岭热带天然要植物物种多样性研究

采用植物群落学和植物种群学的研究方法,从数量和质量 特征两个方面研究了海南岛坝王岭热带天然林的植物物种多样性。结果表明：⑴该地区不同植物群落的优势种类组成差别较大,彼此之间的物种相似性水平低;⑵相对于低地雨林而言,该地区的山地雨林物种数量较多,物种均匀度较高,主要优势种的优势程度较弱;⑶在优先考虑物种稀有性的前提下,根据各物物种在群落中所处的位置及其分布情况,可将该地区的植物物种分为珍稀濒危种、特     

Community composition and size structure of murid rodents in relation to the biogeography of the Japanese archipelago

We investigated the geographical patterns of community composition and size structure of murid rodent assemblages in Japan. Rodent faunal composition showed three biogeograpbic zones in the studied area (Hokkaido, northern Honshu and southern Honshu), which are characterized by endemic species or genera. There was a large discrepancy between distribution patterns of murine species, which are generalist and widespread in Japan, and arvicoline species, which are more specialized and locally restricted. We also found a strong degree of nestedness of the murid rodent fauna, i.e. smaller faunas were subsets of larger ones, which is typical of relict fauna. The structure of murid rodent assemblages was studied using the size and shape of the lower incisor, in order to test for the effect of interspecific competition on community-wide patterns. We used two different approaches: one tests for regularity in the size structure of the community (Barton and David test), and the other one tests for minimum mean overlap size in the community between species (randomization procedure). There was no congruence between the results of the two tests: we did not find any case of regular size structure, whereas mean size overlaps were minimum or even zero in about half of the cases studied. Thus, the evolution of rodent communities on islands seems to be characterized by minimization of size overlaps, perhaps as a result of interspecific competition. Also, the reduction of island area, which is correlated with a decrease in species richness, is accompanied by an increase in Hutchinsonian size ratios and a decrease in the total size range of the community. These patterns may be linked to the reduced diversity of environmental resources on islands.     

Phylogenetic structure illuminates the mechanistic role of environmental heterogeneity in community organization

1. Diversity begets diversity. Numerous published positive correlations between environmental heterogeneity and species diversity indicate ubiquity of this phenomenon. Nonetheless, most assessments of this relationship are phenomenological and provide little insight into the mechanism whereby such positive association results. 2. Two unresolved issues could better illuminate the mechanistic basis to diversity begets diversity. First, as environmental heterogeneity increases, both productivity and the species richness that contributes to that productivity often increase in a correlated fashion thus obscuring the primary driver. Second, it is unclear how species are added to communities as diversity increases and whether additions are trait based. 3. We examined these issues based on 31 rodent communities in the central Mojave Desert. At each site, we estimated rodent species richness and characterized environmental heterogeneity from the perspectives of standing primary productivity and number of seed resources. We further examined the phylogenetic structure of communities by estimating the mean phylogenetic distance (MPD) among species and by comparing empirical phylogenetic distances to those based on random assembly from a regional species pool. 4. The relationship between rodent species diversity and environmental heterogeneity was positive and significant. Moreover, diversity of resources accounted for more unique variation than did total productivity, suggesting that variety and not total amount of resource was the driver of increased rodent diversity. Relationships between environmental heterogeneity and phylogenetic distance were negative and significant; species were significantly phylogenetically over-dispersed in communities of low environmental heterogeneity and became more clumped as environmental heterogeneity increased. 5. Results suggest that species diversity increases with environmental heterogeneity because a wider variety of resources allow greater species packing within communities.     

Convergence of community composition during secondary succession on Zokor rodent mounds on the Tibetan Plateau

Aims The community succession theory is much debated in ecology. We studied succession on Zokor rodent mounds on the Tibetan Plateau to address several fundamental questions, among them: (i) During secondary succession, does the community composition converge towards one community state or multiple states depending on the initial colonization? (ii) Do mound communities located in different background communities exhibit different assembly trajectories?Methods In a sub-alpine meadow, we investigated a total of 80 mound communities at several successional stages in three different background communities resulting from different management histories and compared their changes in species composition. The distribution of plant communities over time was analyzed with quantitative classification and ordination methods. The co-occurrence patterns of species were evaluated at each successional stage, and the degree of convergence/divergence among communities was obtained by calculating two beta-diversity indices.Important findings During secondary succession, species richness of mound communities changed over time, and this change was dependent on the background community. Five life-form groups exhibited different dynamic patterns in species richness and plant cover. Community composition and the degree of species co-occurrence between communities increased over time since disturbance. There was much variation in species composition at earlier stages of succession, but communities on older mounds became more similar to each other and to their surrounding vegetation over the course of secondary succession. Post-disturbance succession of Zokor mound communities transitioned from 'multiple alternative states' to 'background-based deterministic community assembly' over time. Tradeoffs between competition and colonization, as well as the characteristics of different life-forms and mass effects within a limited species pool are the mechanisms responsible for convergence of mound communities.     

新疆吉木萨尔县蝴蝶群落多样性

蝴蝶作为指示生物, 被广泛地应用于生物多样性监测及环境质量评估。探究新疆吉木萨尔县蝴蝶群落多样性, 可为当地蝴蝶多样性的保护及环境监测提供基础数据。本研究采用样线法在新疆吉木萨尔县选取山前荒漠、农田、山地草原、山地森林、亚高山草甸5种不同的生境类型, 对蝴蝶种类和群落多样性进行调查。共记录蝴蝶4,401号, 隶属于7科26属38种。其中蛱蝶科有9属12种, 为优势科; 粉蝶科的个体数最多, 占比55.01%; 绢蝶科、凤蝶科和弄蝶科的种类数和个体数最少, 均为单科种, 是该地区的稀有类群。对不同生境蝴蝶群落多样性和相似度分析比较的结果显示: 5种生境中多样性指数从高到低依次为亚高山草甸、山地森林、山地草原、农田及山前荒漠, 其中山地森林和亚高山草甸的相似性系数较高, 达到0.77, 山前荒漠和山地草原的相似性系数最低, 为0.37。蝴蝶物种数及多样性指数随海拔的增加呈上升趋势。蝴蝶群落随月份发生变化, 蝴蝶种类和数量在5月发生、7月达到峰值。蝶类个体数在3年内呈下降趋势。研究结果表明, 蝴蝶物种的组成和多样性与生境类型具有密切联系, 保护生态环境, 维持该地区植物群落的多样性、降低人为干扰程度是保护蝶类多样性的关键。     

Diatom and desmid relationships with the environment in mountain lakes and mires of NW Spain

The mountain ranges in NW Spain have a large number of little known wetlands. We report the results of a study carried out on a group of 77 small lakes and mires in the Sierra Segundera and Cordillera Cantábrica. The main physical and chemical variables, and phytoplankton communities from littoral samples were studied. Cantabrian wetlands showed greater variability in all environmental variables measured as well as higher values in those related to mineralisation than the Segundera ones. Many of these ecosystems were oligotrophic and showed a high species richness. Desmids and diatoms were the two most abundant groups, both in the species number and in biovolume. Desmids were the most numerous group in taxa in Sierra Segundera, whereas diatoms were in Cordillera Cantábrica. Differences in species composition of algae communities between both mountain ecosystems were studied. Canonical Correspondence Analysis (CCA) was carried out on diatom and desmid flora composition. This analysis showed that alkalinity was the most important parameter in diatom distribution and pH the most important one in that of desmids.     

甘肃河西走廓不同生境中鼠类群落结构初步研究

本文对河西走廓不同生境中鼠类群落的物种组成和多样性进行了初步研究,在6种生境中进行了定量调查和采集,共获13种标本,隶于6（亚）科9属,其中古北界种类占优势。多样性分析结果表明：6种生境的物种丰富度指数RMargaler在.6139-1.9689之间。Shannon-Wiener指数（H')为1.0695-1.5607,Pielou旨数（J')和Simpson指数（D）分别为0.7242-0.9735和0．2768－0．4683,不同生境的丰富种数量（N1)变化趋势与H'相似,而非常丰富种数量（N2）的变化趋势为：半莫荒灌丛生境＞山地草原生境＞戈壁荒漠生境＞农田生境＞森林生境＞山地半荒漠灌丛生境。降水对不同生境类型中鼠类群落物种组成和多样性起直接的限制作用,同时海拔和人类干扰也是影响的因素。     

Changes in the roles of spatial and environmental processes in the structuring of rodent metacommunities

We studied the role of spatial (regional) and environmental (local) processes in the structuring of rodent metacommunities in three contiguous ecoregions that share the same species pool. The two northern ecoregions are mainly affected by anthropogenic processes (agriculture and urbanization) while the southern one is mainly affected by natural processes (flood and drought pulses). Local communities were described based on the analysis of 77 samples of barn owl pellets. To identify which processes (patch dynamics, species sorting, mass effect or neutral theory) structure each metacommunity we evaluated the percentage of variance explained by space (spatial arrangement of communities) and environment (topography, climate and land cover) in three Variation Partitioning Redundancy Analyses. The percentage of variance in rodent metacommunities composition explained by space and environment was between 38 and 61%, and was significant in all three analyses. The pure space fraction was significant for two of the three ecoregions, while the pure environmental fraction was significant for all three ecoregions. The processes that structure rodent metacommunities change across the region. In all three ecoregions the species sorting played a key role, while, mass effect was a structuring factor for northern metacommunities. These results can be explained by species-specific dispersal characteristics and environmental filtering.     

北京地区的兽类区系及生态地理特征

北京地区的兽类,解放前有些调查记录(Allen 1938、1940),解放后也有一些零星的调查报道(Ellerman 1951,李汝琪;1956,北京师范大学生物系动物教研组,1960;伊佩衡,1964;北京大学生物系,1964等),但工作均较局部,更缺乏生态学方面的材料。     

Macrophyte communities in unimpacted European streams: variability in assemblage patterns, abundance and diversity

Macrophytes are an important component of aquatic ecosystems and are used widely within the Water Framework Directive (WFD) to establish ecological quality. In the present paper we investigated macrophyte community structure, i.e., composition, richness and diversity measures in 60 unimpacted stream and river sites throughout Europe. The objectives were to describe assemblage patterns in different types of streams and to assess the variability in various structural and ecological metrics within these types to provide a basis for an evaluation of their suitability in ecological quality assessment. Macrophyte assemblage patterns varied considerably among the main stream types. Moving from small-sized, shallow mountain streams to medium-sized, lowland streams there was a clear transition in species richness, diversity and community structure. There was especially a shift from a predominance of species-poor mosses and communities dominated by liverwort in the small-sized, shallow mountain streams to more species-rich communities dominated by vascular plants in the medium-sized, lowland streams. The macrophyte communities responded to most of the features underlying the typological framework defined in WFD. The present interpretation of the WFD typology may not, however, be adequate for an evaluation of stream quality based on macrophytes. First and most important, by using this typology we may overlook an important community type, which is characteristic of small-sized, relatively steep-gradient streams that are an intermediate type between the small-sized, shallow mountain streams and the medium-sized, lowland streams. Second, the variability in most of the calculated metrics was slightly higher when using the pre-defined typology. The consistency of these results should be investigated by analysing a larger number of sites. Particularly the need of re-defining the typology to improve the ability to detect impacts on streams and rivers from macrophyte assemblage patterns should be investigated. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

洞庭湖区鼠类群落的物种多样性分析

通过对洞庭湖区黑线姬鼠褐家鼠主害区桃源的害鼠群落调查,揭示了平原农田生态类型区、丘陵农林复合生态类型区和山区林农复合生态类型区及其不同生境的鼠类群落的物种多样性。在人类干扰程度最高的平原生态类型区,鼠类群落的优势种突出,优势集中性指数最高,丘陵生态区次之,而具有大片森林、受干扰较低的山区林农复合生态区,优势集中性指数最低。物种多样性Shannon—Weiner指数和均匀性指数亦显示同样的规律：适度干扰的山区复合生态区的多样性指数最高,均匀性最好,丘陵生态区居中,平原生态区最低。不论何种生态类型区,农田生境鼠类群落的优势种都较突出,优势集中性指数也较高,群落多样性和均匀性较低;林地生境的优势集中性有较大下降,山区林地内的鼠种比丘陵区要多,优势集中性指数也较低,多样性指数和均匀度都有提高。林缘农田在同一生态类型不同生境内优势集中性最低、多样性指数和均匀性最高。比较不同生境鼠类群落的相似性,最不相似的群落是农田与受人类干扰较小的森林。这些现象说明人类的社会生产活动使害鼠群落的物种多样性降低、优势度下降、优势种突出、均匀性降低,形成了只利于少数几个种群栖息和生产发展的环境,最终导致少数种群的暴发,形成危害。但适度干扰能提高物种多样性。     

江西省三清山长柄双花木优势群落研究

对世界自然遗产地三清山长柄双花木（D isanthus cercidifolius subsp. longipes）优势群落进行了野外调查和分析,结果表明：三清山长柄双花木优势群落为多优势种并存的中亚热带中山常绿阔叶林群落,乔木层的次优势种不明显。长柄双花木是该群落的关键种之一。在植物区系特征上,该群落优势种既具有温带性质又具中亚热带性质,在整体上表现出温带性质和亚热带性质交汇的特点。群落的物种多样性指数和频度指数为：SP=0.92、SW=4.20、E=0.94、E′=0.79。三清山长柄双花木优势群落与江西官山和湖南千家洞长柄双花木群落相比,三地群落存在一定差异,但三清山长柄双花木群落多样性指数和均匀度均高于另两地。三清山和千家洞的长柄双花木群落结构更相似;官山的长柄双花木群落为山地灌丛,群落结构单一,样地中长柄双花木占绝对优势。通过分析三地气象资料和群落特点,表明不同地区长柄双花木群落的差异与年降水量和年平均日照时数相关,而与年平均气温无直接相关关系。