长白山区苔草泥炭沼泽植物物种多样性

本研究以长白山区典型苔草沼泽为对象,分析了密丛型苔草(瘤囊苔草、乌拉草)沼泽和疏丛型苔草(毛苔草)沼泽的植物物种多样性.结果 表明:3种苔草沼泽植物群落共有83个物种,隶属于36科59属.其中,乌拉草沼泽有71个物种,瘤囊苔草沼泽有61个物种,毛苔草沼泽有26个物种.密丛型苔草沼泽植物物种数和物种丰富度明显高于疏丛型苔...     

Epilithic and epipelic diatoms in the Sandusky River,with emphasis on species diversity and water pollution

Benthic diatom communities were collected seasonally from silty and rocky substrates to survey the water quality of the Sandusky River. Even though species composition was highly variable along the river, recurrent changes in relative abundance of specific diatom taxa and changes in overall community composition delineated areas where discharge of treated sewage affected water quality of the river. Changes in species diversity (Shannon formula), not decreases in diversity, marked the site where greatest pollution had occurred. Problems with using species diversity indices to indicate pollution tend to be related to predicting decreases in diversity in response to decreases in water quality. Evidence in the Sandusky River and the theories of diatom community dynamics suggest that species diversity can be greater in polluted areas than less polluted areas.     

Hydrological and environmental variables outperform spatial factors in structuring species,trait composition,and beta diversity of pelagic algae

There has been increasing interest in algae‐based bioassessment, particularly, trait‐based approaches are increasingly suggested. However, the main drivers, especially the contribution of hydrological variables, of species composition, trait composition, and beta diversity of algae communities are less studied. To link species and trait composition to multiple factors (i.e., hydrological variables, local environmental variables, and spatial factors) that potentially control species occurrence/abundance and to determine their relative roles in shaping species composition, trait composition, and beta diversities of pelagic algae communities, samples were collected from a German lowland catchment, where a well‐proven ecohydrological modeling enabled to predict long‐term discharges at each sampling site. Both trait and species composition showed significant correlations with hydrological, environmental, and spatial variables, and variation partitioning revealed that the hydrological and local environmental variables outperformed spatial variables. A higher variation of trait composition (57.0%) than species composition (37.5%) could be explained by abiotic factors. Mantel tests showed that both species and trait‐based beta diversities were mostly related to hydrological and environmental heterogeneity with hydrological contributing more than environmental variables, while purely spatial impact was less important. Our findings revealed the relative importance of hydrological variables in shaping pelagic algae community and their spatial patterns of beta diversities, emphasizing the need to include hydrological variables in long‐term biomonitoring campaigns and biodiversity conservation or restoration. A key implication for biodiversity conservation was that maintaining the instream flow regime and keeping various habitats among rivers are of vital importance. However, further investigations at multispatial and temporal scales are greatly needed.     

Production and chlorophyll concentration of epipelic and epilithic algae in fertilized and nonfertilized subarctic lakes

The production and chlorophyll concentration of epipelic and epilithic algae was measured during four years (1972–1975) in two shallow, Swedish subarctic lakes. One lake (Lake Hymenjaure) was fertilized with phosphorus or a combination of phosphorus and nitrogen while the other (Lake Stugsjön) served as a reference. The benthic algae in both lakes were dominated by Cyanophyceae of the same species during the whole investigation. The chlorophyll concentration of epipelic and epilithic algae was 100 and 20 mg·m^–2 respectively and fairly constant during the season. In 1974–1975 there was a significant increase in chlorophyll concentration of the benthic algae in Lake Hymenjaure, probably as a response to the poorer light climate in the lake due to a large phytoplankton development. The annual benthic production was 3.4–7.2 gC·m^–2 and it was not enhanced by the fertilization. Compared to the other primary producers (phytoplankton and macrophytes) the benthic algae constituted 70–83% of the total production in Lake Stugsjön. In Lake Hymenjaure, however, the importance of the benthic algae decreased from 50 to 22% of the total due to the great increase in phytoplankton production induced by the lake fertilization.     

干扰对植物群落物种组成及多样性的影响

在介绍了干扰的概念及其性质和干扰对物种多样性影响的有关假说基础上,以森林干扰为主要对象,探讨了干扰对植物群落物种组成的影响,并从干扰类型、干扰强度和干扰频率等几个方面阐述了干扰对植物群落物种多样性的影响;另外,还分析了重要的小尺度干扰——林隙在该方面的影响。分析总结出干扰对植物群落的影响差异主要与干扰特征、植物群落特征及植物的生物学特性和受干扰地点的资源条件有关。最后,总结分析了国内外在该方面研究存在的问题,并对今后研究提出一些建议,为相关工作提供参考。     

兰州五泉山的藻类及其分布

以兰州五泉山为该地藻种资源库,对其中水生、陆生生境中藻类的种类多样性、群落结构、分布特点进行了研究。结果发现该地藻类植物65种(含4变种),包括蓝藻、绿藻、硅藻和红藻,其中硅藻种类最多(29种),其它依次为蓝藻(24种)、绿藻(11种)和红藻(1种)。水体中共42种,硅藻最多,有26种,其次蓝藻8种,绿藻7种,红藻1种,不同水体中优势种和亚优势种不同。土壤生境中发现20种,蓝藻13种,绿藻4种,硅藻3种,且非洲席藻和小球藻分为优势种和亚优势种。7个种类在水、陆两大生境都有分布,而且它们主要是丝状蓝藻。     

The effects of human disturbance on the species composition,species diversity and functional diversity of a Miombo woodland in northern Malawi

Anthropogenic disturbances have serious impacts on ecosystems across the world. Understanding the effects of disturbance on woodlands, especially in regions where local people depend on these natural resources, is essential for sustainable natural resource management and biodiversity conservation. In this study, we evaluated the effects of anthropogenic disturbance, specifically selective logging of Brachystegia floribunda, on woodlands by comparing species composition, species diversity and functional diversity of woody plants between disturbed and undisturbed woodlands. We combined species data and functional trait data for leaves, fruits and other traits related to resource and disturbance responses to calculate functional indices (functional richness, evenness and divergence) and community‐weighted means of each trait. Shifts in taxonomic species composition were analysed using nonmetric multi‐dimensional scaling. Species composition differed significantly between disturbed and undisturbed woodlands. Tree density was greater in disturbed woodlands, whereas evenness, functional evenness and functional divergence were greater in undisturbed woodlands. In terms of forest cover, selective logging of B. floribunda appeared to have little impact on Miombo woodlands, but some shifts in functional traits, such as the shift from a deciduous to evergreen phenology, may increase the vulnerability of these ecosystems to environmental change, especially drought.     

Taxonomic identification of algae (morphological and molecular): species concepts,methodologies, and their implications for ecological bioassessment

Algal taxonomy is a key discipline in phycology and is critical for algal genetics, physiology, ecology, applied phycology, and particularly bioassessment. Taxonomic identification is the most common analysis and hypothesis‐testing endeavor in science. Errors of identification are often related to the inherent problem of small organisms with morphologies that are difficult to distinguish without research‐grade microscopes and taxonomic expertise in phycology. Proposed molecular approaches for taxonomic identification from environmental samples promise rapid, potentially inexpensive, and more thorough culture‐independent identification of all algal species present in a sample of interest. Molecular identification has been used in biodiversity and conservation, but it also has great potential for applications in bioassessment. Comparisons of morphological and molecular identification of benthic algal communities are improved by the identification of more taxa; however, automated identification technology does not allow for the simultaneous analysis of thousands of samples. Currently, morphological identification is used to verify molecular taxonomic identities, but with the increased number of taxa verified in algal gene libraries, molecular identification will become a universal tool in biological studies. Thus, in this report, successful application of molecular techniques related to algal bioassessment is discussed.     

Species pools,community completeness and invasion: disentangling diversity effects on the establishment of native and alien species

Invasion should decline with species richness, yet the relationship is inconsistent. Species richness, however, is a product of species pool size and biotic filtering. Invasion may increase with richness if large species pools represent weaker environmental filters. Measuring species pool size and the proportion realised locally (completeness) may clarify diversity‐invasion relationships by separating environmental and biotic effects, especially if species’ life‐history stage and origin are accounted for. To test these relationships, we added seeds and transplants of 15 native and alien species into 29 grasslands. Species pool size and completeness explained more variation in invasion than richness alone. Although results varied between native and alien species, seed establishment and biotic resistance to transplants increased with species pool size, whereas transplant growth and biotic resistance to seeds increased with completeness. Consequently, species pools and completeness represent multiple independent processes affecting invasion; accounting for these processes improves our understanding of invasion.     

Meta‐analysis of the effects of small mammal disturbances on species diversity,richness and plant biomass

The disturbance activities of many small mammals, including building burrows, mounds, trails and tunnels, and herbivory, can have significant impacts on their ecosystems, both through trophic and non‐trophic interactions. Some species have large enough impacts through their disturbances to be classed as ecosystem engineers and/or keystone species. Others have negative or null effects. However, at present it is difficult to predict whether the disturbances created by a given species will have significant effects on common measures of ecosystem response such as species richness, diversity and biomass. We ask whether variables characterizing disturbance type, responding species, disturbance‐making species and the environment can predict changes in magnitude and direction of effects on biomass, richness and diversity. We test these predictions with a meta‐analysis of 106 data entries in a database derived from 63 papers, representing 40 small mammal species. We find that small mammal disturbances in general increase biomass, and both increase and decrease richness and diversity. We also identify individual environmental, disturbance‐related, and species‐related variables associated with these changes in magnitude and direction. We discuss the likely interactions between these variables, and how current proxy measures of disturbance impact could be replaced by more accurate direct measures. We recommend that future studies focus on conditions characterized by combinations of variables we identify as significant, in order to understand how these variable interactions (which cannot be analysed through meta‐analysis) affect disturbance outcomes. Based on the gaps in our database and results, we also recommend that future studies directly measure disturbance impact, measure disturbance effects on animal and well as plant taxa, and take measurements on multiple scales.     

Measuring size and composition of species pools: a comparison of dark diversity estimates

Ecological theory and biodiversity conservation have traditionally relied on the number of species recorded at a site, but it is agreed that site richness represents only a portion of the species that can inhabit particular ecological conditions, that is, the habitat‐specific species pool. Knowledge of the species pool at different sites enables meaningful comparisons of biodiversity and provides insights into processes of biodiversity formation. Empirical studies, however, are limited due to conceptual and methodological difficulties in determining both the size and composition of the absent part of species pools, the so‐called dark diversity. We used >50,000 vegetation plots from 18 types of habitats throughout the Czech Republic, most of which served as a training dataset and 1083 as a subset of test sites. These data were used to compare predicted results from three quantitative methods with those of previously published expert estimates based on species habitat preferences: (1) species co‐occurrence based on Beals' smoothing approach; (2) species ecological requirements, with envelopes around community mean Ellenberg values; and (3) species distribution models, using species environmental niches modeled by Biomod software. Dark diversity estimates were compared at both plot and habitat levels, and each method was applied in different configurations. While there were some differences in the results obtained by different methods, particularly at the plot level, there was a clear convergence, especially at the habitat level. The better convergence at the habitat level reflects less variation in local environmental conditions, whereas variation at the plot level is an effect of each particular method. The co‐occurrence agreed closest the expert estimate, followed by the method based on species ecological requirements. We conclude that several analytical methods can estimate species pools of given habitats. However, the strengths and weaknesses of different methods need attention, especially when dark diversity is estimated at the plot level.     

与物种多样性有关的长白落叶松人工林生物量

对不同龄组长白落叶松(Larix olgensis)人工林群落的物种多样性和生物量及二者关系研究分析。结果表明:1)随林龄增大,群落物种组成结构和多样性特征发生了很大变化。物种更迭现象明显,春榆等阔叶树重要值上升,长白落叶松优势地位逐渐下降,植被类型向针阔混交林演替。群落Sorensen相似性指数降低,Shannon-Winner多样性指数呈"S"型曲线增长,Pielou均匀度指数呈反"S"型曲线下降,Margalef丰富度指数呈单峰曲线增长趋势;2)随林龄增大,群落生物量"S"型曲线增长趋势明显,分配序列为:乔木层木质物残体层灌木层草本层,占群落生物量比例分别为82.41%、15.10%、1.69%和0.81%。长白落叶松生物量占据主导地位,但所占比例持续下降,属于衰退型种群,而春榆等阔叶树比例上升。林下植被层中,草本的主导地位逐渐丧失,灌木取而代之,生物量所占比例明显升高。地表木质物残体生物量比例缓慢下降;3)群落中物种多样性测度指标与生物量之间单调线性增长的关系明显,Shannon多样性指数较之Pielou均匀度指数更适合作群落生物量度量指标,生物量与Margalef丰富度指数无明显相关性。     

世界自然遗产地陆生藻类物种多样性比较研究

藻类是真核生物进化、植物起源与进化、生物地理学研究的良好材料,研究藻类物种多样性对理解生命起源与早期进化,探明地球地质地貌演化有着非常重要的意义。以两世界自然遗产地施秉云台山白云岩喀斯特、赤水丹霞的陆生藻类为研究对象,通过G-F多样性指数、Jaccard相似性系数、Bray-Curtis矩阵比较分析了不同地质地貌的两世界自然遗产地陆生藻类的物种多样性及种组特征,结果如下：（1）两地陆生藻类丰富,均以蓝藻为优势,共有优势科为色球藻科Chroococcaceae、颤藻科Oscillatoriaceae,施秉云台山还具伪枝藻科Scytonemataceae、念珠藻科Nostocaceae优势,优势属为粘球藻属Gloeocapsa、色球藻属Chroococcus,赤水丹霞仅以粘球藻属Gloeocapsa为优势。（2）施秉云台山G-F多样性指数高于赤水丹霞。（3）两地陆生藻类泛热带成分明显,施秉云台山中国特有成分较赤水丹霞丰富;两地科、属、种相似性系数依次为：56.25%、44.05%、37.62%,科的相似性达到中度水平,与同纬度范围其它地区的Bray-Curtis矩阵聚类结果显示不同地质地貌的两地首先聚为一类。从陆生藻类多样性组成上,初步反映两世界自然遗产地的地质历史、地层岩性及地理位置的异同。     

践踏干扰对碧塔海高寒草甸植被茎叶性状、物种多样性和功能多样性的影响

高寒草甸具有重要的生态服务功能,然而固有脆弱性使其极易遭受气候变化和人为干扰等多重因素的影响。作为滇西北旅游资源中重要的组分之一,高寒草甸吸引了大批游客前往开展徒步旅行活动,但伴随着的践踏干扰作用会不可避免地对高寒草甸生态系统带来负面影响。然而,目前关注践踏干扰对滇西北高寒草甸植被的影响,特别是植被功能性状和功能多样性如何发生变化方面的研究还十分欠缺。以云南省香格里拉市碧塔海自然保护区内的典型高寒草甸生态系统为研究对象,采用实验践踏的方式(一共5种不同强度的践踏处理)来模拟旅游活动对草甸植被的干扰作用,并以草甸植被的茎叶性状特征为切入点,重点探讨践踏干扰对茎叶性状的平均大小和变异程度的影响,以及物种丰富度(以物种形态分类为基础)和功能丰富度(以功能性状为基础)之间的关系。研究结果显示,随着践踏强度的增加,植株高度和叶片大小的平均值,而不是茎叶性状的变异程度,出现明显下降趋势。此外,物种丰富度和功能丰富度均随践踏强度的增强而减小,且两者之间呈现显著正相关关系。然而,较之轻度践踏实验组,重度践踏实验组中的功能均匀度和功能分离度水平均有所增加,表明践踏干扰可能会在短期内打破优势种对资源的绝对占有格局和减少物种间的生态位重叠程度。尽管高寒草甸对人类践踏活动有一定的承受能力,但气候变化和人为干扰等多重因素势必会改变和影响高寒草甸群落的结构和功能可持续性,这也对高寒草甸的保护与管理工作提出了更加紧迫的要求。     

Biomass,carbon density and diversity of tree species in tropical dry deciduous forests in Central India

Tropical dry deciduous forests play a significant role in regulating the biogeochemical cycles. Present study assesses the carbon stock of tropical dry deciduous forests varying in tree density, basal cover, and diversity located in Singrauli district of Madhya Pradesh in Central India. Field sampling was carried out in six forest sites viz., Chitrangi, East Sarai, Gorbi, Renukoot, West Sarai, and Waidhan, of Singrauli. A total of 29 tree species belonging to 18 families were recorded across the forest ranges where tree density, basal area and diversity values varied from 702 (Gorbhi Range) – 1671 (East Sarai range) individuals ha^?1; 15.43 (Renukhund range) – 71.76 m² ha^?1 (Chitrange range) and 0.69 (West Sarai range) – 2.52 (Gorbi range), respectively. Total biomass estimated ranged from 103.32 (Renukhund range) – 453.54 Mg ha^?1 (Chitrange range) while the total tree carbon density varied from 48.97 to 214.97 Mg C ha^?1. The variation in carbon storage in the studied ranges was found dependent on density of trees in different diameter and age classes and tree species diversity. Diospyros melanoxylon, Butea monosperma, Shorea robusta, Senegalia catechu, Spondias pinnata, and Lagerstroemia parviflora were the dominant species at different study sites (forest ranges) and contributed towards higher carbon storage in respective forest ranges. Study endorses field-based approach for carbon estimations based on above and belowground assessments as a more realistic approach to understand sink potential of natural forests.     

Seasonal succession of phytoplankton and its diversity in two highly eutrophic lakes with different conditions of stratification

Seasonal succession of phytoplankton biomass, its diversity and its photosynthetic activity in two highly eutrophic lakes have been compared. In order to test the intermediate disturbance hypothesis, the lakes have been chosen with almost the same level of trophy but different conditions of stratification, through two ice-free periods of open water with different weather conditions.High phytoplankton diversity throughout the period of investigation was characteristic for the shallower Lake Lobardzu. The number of species here was usually more than 30 and the Shannon diversity changed from 1.2 to 4.2. Owing to the frequent external disturbances, periods characterized by autogenic succession with establishing dominance and declining diversity alternated with periods of biomass reduction and rises of diversity and photosynthetic activity. In the warmer summer of 1983, with more intense warming of bottom layers and predominance of blue-greens, phytoplankton biomass was higher and diversity lower than in the cold summer of 1982.In stratified Lake Rudusku, phytoplankton diversity and number of species were usually much lower. During the long summer stratification up to three-four dominant species of blue-greens and dinoflagellates become established and competitive exclusion leading to low diversity advanced. Some changes in biomass and diversity, were caused by zooplankton activity.     

Comparison of the long-wave chlorophyll fluorescence in various green and blue-green algae and diatoms

Two types of long-wave fluorescence bands with similar band shape occur at room temperature in various algae: F_II700 and F_I715. F_II700 occurs in a limited number of algae, follows PS II transients, increases with culture age and is moderately increased by cooling to 83 K. F_I715 occurs in most algae, especially Anabaena, but much less in most diatoms and Tribonema. It does not follow PS II transients, does not increase with culture age and is much increased by cooling to 83 K.An interpretation for the characteristics of F_II700 and F_I715 is given.     

Disturbance events affecting phytoplankton biomass,composition and species diversity in a shallow,eutrophic, temperate lake

The seasonal changes in phytoplankton biomass and species diversity in a shallow, eutrophic Danish lake are described and related to different disturbance events acting on the phytoplankton community.Both the spring diatom maximum and the summer bloom of the filamentous blue-green alga, Aphanizomenon flos-aquae (L.) Ralfs, coincided with low values of phytoplankton species diversity and equitability. Diatom collapse was mainly due to internal modifications as nutrient depletion (Si, P) caused by rapid growth of phytoplankton, and increased grazing activity from zooplankton. A large population of Daphnia longispina O.F. Müller in June effectively removed smaller algal competitors, thus favouring the development of a huge summer bloom (140 mm³ l^–1) of Aphanizomenon flos-aquae. Heavy rainfall and storms in late July increased the loss of Apahnizomenon by out-flow and disturbed the stratification of the lake. These events caused a marked decline in phytoplankton biomass but had no effect on species diversity. A second storm period in late August circulated the lake completely and was followed by a rapid increase in phytoplankton diversity, and a change in the phytoplankton community structure from dominance of large, slow-growing K-selected species (Aphanizomenon) to small, fast-growing r-selected species (cryptomonads).