木焦油污染土壤中微生物特性的空间变异性研究

运用地统计学方法研究了木焦油污染土壤中微生物量、微生物群落结构、微生物活性等的空间变异特征.分别采用26种主要磷脂类脂肪酸(PLFA)的总含量(totPLFA)、PLFA的第一主成分和第二主成分(PLFA PC1和PC2)以及土壤培养过程中CO₂-C的累积释放量(Cre)来表征土壤中的微生物量、微生物群落结构以及微生物活性.结果表明,多数微生物特性指标均存在不同程度的空间自相关性,其半变异函数曲线可用带块金效应的球状模型进行拟合.变量的空间相关距离在2.50～16.60 m之间.PLFA PC1、totPLFA和Cre均具有较强的空间依赖性,其相对结构变差（由结构性因素引起的空间变异）分别为82.3%、79.6%和64.7%,而PLFA PC2 不存在明显的空间依赖性.克立格空间插值图表明,样地中存在几处微生物相对密集分布且代谢活性较高的区域,其中优势微生物菌群是由PLFAs 16:1ω7t,cy17:0,18:1ω7 和cy19:0所表征的革兰氏阴性细菌.土壤中主要污染物多环芳烃含量和空间分布是影响微生物特性空间分布格局的重要因素之一.     

Spatial patterns of phylogenetic diversity

Ecologists and conservation biologists have historically used species-area and distance-decay relationships as tools to predict the spatial distribution of biodiversity and the impact of habitat loss on biodiversity. These tools treat each species as evolutionarily equivalent, yet the importance of species' evolutionary history in their ecology and conservation is becoming increasingly evident. Here, we provide theoretical predictions for phylogenetic analogues of the species-area and distance-decay relationships. We use a random model of community assembly and a spatially explicit flora dataset collected in four Mediterranean-type regions to provide theoretical predictions for the increase in phylogenetic diversity - the total phylogenetic branch-length separating a set of species - with increasing area and the decay in phylogenetic similarity with geographic separation. These developments may ultimately provide insights into the evolution and assembly of biological communities, and guide the selection of protected areas.     

Microbial populations related to PAH biodegradation in an aged biostimulated creosote-contaminated soil

A previous bioremediation survey on a creosote-contaminated soil showed that aeration and optimal humidity promoted depletion of three-ringed polycyclic aromatic hydrocarbons (PAHs), but residual concentrations of four-ringed benzo(a)anthracene (B(a)A) and chrysene (Chry) remained. In order to explain the lack of further degradation of heavier PAHs such as four-ringed PAHs and to analyze the microbial population responsible for PAH biodegradation, a chemical and microbial molecular approach was used. Using a slurry incubation strategy, soil in liquid mineral medium with and without additional B(a)A and Chry was found to contain a powerful PAH-degrading microbial community that eliminated 89% and 53% of the added B(a)A and Chry, respectively. It is hypothesized that the lack of PAH bioavailability hampered their further biodegradation in the unspiked soil. According to the results of the culture-dependent and independent techniques Mycobacterium parmense, Pseudomonas mexicana, and Sphingobacterials group could control B(a)A and Chry degradation in combination with several microorganisms with secondary metabolic activity.     

Spatial patterns of dicot diversity in Argentina

In this paper, we analyzed the taxonomic diversity of the Argentine dicots to evaluate their relationships with area, latitude, and longitude. We also evaluated species diversity and higher taxa diversity relationships. The families, genera and species diversity in Argentine dicots was not explained by the area of each province but it varied through latitudinal and longitudinal gradients. The taxonomic diversity of these plants increased from high to low latitudes and west–east longitudes. These patterns would explain why the main diversity centers are located in the North region of this country. As we expected the species diversity and higher taxa diversity showed a positive relationship. At this scale, higher taxa diversity could be use as surrogate for species diversity.     

Spatial variation in microbial community structure, richness, and diversity in an alluvial aquifer

Relatively little is known regarding the spatial variability of microbial communities in aquifers where well fouling is an issue. In this study 2 water wells were installed in an alluvial aquifer located adjacent to the North Saskatchewan River and an associated piezometer network developed to facilitate the study of microbial community structure, richness, and diversity. Carbon utilization data analysis revealed reduced microbial activity in waters collected close to the wells. Functional PCR and quantitative PCR analysis indicated spatial variability in the potential for iron-, sulphate-, and nitrate-reducing activity at all locations in the aquifer. Denaturing gradient gel electrophoresis analysis of aquifer water samples using principal components analyses indicated that the microbial community composition was spatially variable, and denaturing gradient gel electrophoresis sequence analysis revealed that bacteria belonging to the genera Acidovorax , Rhodobacter , and Sulfuricurvum were common throughout the aquifer. Shannon's richness (H') and Pielou's evenness (J') indices revealed a varied microbial diversity (H' = 1.488-2.274) and an even distribution of microbial communities within the aquifer (J' = 0.811-0.917). Overall, these analyses revealed that the aquifer's microbial community varied spatially in terms of composition, richness, and metabolic activity. Such information may facilitate the diagnosis, prevention, and management of fouling.     

Spatial patterns of genetic diversity in Posidonia oceanica, an endemic Mediterranean seagrass

Posidonia oceanica is an endemic seagrass species in the Mediterranean Sea. In order to assess levels of genetic structure in this species, the microsatellite polymorphism was analysed from meadows collected in several localities, along the coasts of the Tyrrhenian Sea (Mediterranean Sea). The existence of single population units and the recruitment of seedlings collected in some localities were investigated. Moreover, genetic structure at different spatial scales and biogeographic relationships among populations were also assessed. Our analysis showed the existence of clear patterns of genetic structure in P. oceanica in the area considered in the analysis. P. oceanica, in fact, is present in separate meadows that represent discrete populations, characterized by low genetic diversity. Comparable levels of genetic variability between mature meadows and seedlings were found. Patterns of genetic relatedness among populations seem to be in accord with direction of dominant current flux in the whole area, separating South Tyrrhenian from North Tyrrhenian populations. Moderate levels of gene flow between populations and genetic substructure within populations, together with the finding of the limited role of sexual reproduction in increasing genetic variability, should be a cause for concern for the persistence of this essential resource in the Mediterranean basin.     

Spatial patterns of ground vegetation, soil microbial biomass and activity in a mixed spruce-birch stand

Trees directly and indirectly influence the above- and below-ground environment, and can be expected to modify the spatial patterns of organisms associated with the forest floor. This study aimed to examine the effects of a coniferous (Picea abies) and a broad-leaved (Betula pubescens) tree species on the spatial pattern of ground vegetation and soil microbial properties in a mixed stand in central Sweden. I have characterised the species composition of ground vegetation, soil microbial biomass and activity, photosynthetic active radiation (PAR), soil water content and soil pH in the stand, and tested whether the spatial patterns of these variables were related to the positioning of trees. Geostatistics were used to describe the spatial variation in ground vegetation, soil mirobiological properties and the soil surface environment. PAR, soil water content and the cover of the moss Brachytecium reflexum and associated herb species decreased with the influence of spruce trees. Microbial biomass, measured as the amount of phospholipid fatty acids, decreased with spruce influence but increased with the influence of birch trees. Microbial respiration was not affected by spruce but increased with the influence of birch. Ground vegetation and microbial respiration, which were influenced by one tree species only, aggregate on a scale of 4-5 m, corresponding fairly well with patches of a single tree species. Soil microbial biomass, which was affected by both tree species, aggregated on a scale of 7-8 m. roughly corresponding to the distance between patches of spruce and birch trees respectively. I suggest that spruce trees influenced vegetation mainly through shading, and that a difference in the availability of organic matter under birch and spruce trees caused spatial variation in microbial biomass and activity. Thus, spatial patterns in ground vegetation and soil microbial properties may develop in a mixed forest of coniferous-broad leaved trees, as a result of the difference in influence of tree species and nested variation associated with the arrangement of the trees.     

西南地区生物文化多样性空间格局定量研究

自然条件的丰富性与独特性以及多民族聚居的特征使得西南地区成为我国生物多样性和文化多样性的热点地区,但当前仍然缺乏对区域生物文化多样性格局的定量研究。以西南地区603个县级行政区为基本单元,探讨了西南地区的文化多样性与生物多样性的分布格局,在此基础上定量计算了生物文化多样性,从而识别西南地区生物文化多样性空间格局,并分析不同因素对多样性空间分布的影响。文化多样性与生物多样性存在一定的空间分布差异,同时也存在高低值聚类的重叠区域。高生物文化多样性的区域与高生物多样性的区域分布较为相似,而低生物文化多样性的区域与低文化多样性的区域分布较为接近;生物文化多样性的高低值聚类区呈现明显的片状格局。由于生境条件与人为干扰等原因,西南地区文化多样性、生物多样性与生物文化多样性沿河流流向大多呈现"低-高"或"低-高-低"的变化状态。影响因素分析表明,文化多样性与生物多样性产生相互促进的作用;三种多样性的空间分布都受到平均坡度的重要影响;多样性高的单元聚集在地形坡度大、海拔与坡度的差异程度较大而水体覆盖率较低的区域。文化多样性与生物多样性的密切联系表现在地理空间上的交叉重合,因此,对文化多样性与生物多样性的保护应统筹兼顾,并更多从生物文化多样性的视角或者途径来开展相关研究与保护实践。     

Microbial diversity and activity of an aged soil contaminated by polycyclic aromatic hydrocarbons

Bioprocess and Biosystems Engineering - In-depth understanding of indigenous microbial assemblages resulted from aged contamination by polycyclic aromatic hydrocarbons (PAHs) is of vital importance...     

Spatial patterns of hypolithic cyanobacterial diversity in Northern Australia

Photosynthetic microbial communities under translucent rocks (hypolithic) are found in many arid regions. At the global scale, there has been little intercontinental gene flow, and at a local scale, microbial composition is related to fine‐scale features of the rocks and their environment. Few studies have investigated patterns of hypolithic community composition at intermediate distances. We examined hypolithic cyanobacterial diversity in semi‐arid Australia along a 10‐km transect by sampling six rocks from four adjacent 1 m² quadrats (“distance zero”) and from additional quadrats at 10, 100, 1,000, and 10,000 m to test the hypothesis that diversity would increase with the number of rocks sampled and distance. A total of 3,108 cyanobacterial operational taxonomic units (OTUs) were detected. Most were neither widespread nor abundant. The few that were widespread tended to be abundant. There was no difference in the community composition between the four sites at distance zero, but the samples 10 m away were significantly different, as were those at all other distances compared to distance zero. Many additional OTUs were recorded with increasing distance up to 100 m. These patterns of distribution are consistent with a colonization model involving dispersal from rock to rock. Our results indicate that distance was a significant factor that can be confounded by interrock differences. Most diversity was represented in the first 100 m of the transect, with an additional 1.5% of the total diversity added by the sample at 1 km, but only 0.2% added with the addition of the 10‐km site.     

Spatial and resource factors influencing high microbial diversity in soil.

To begin defining the key determinants that drive microbial community structure in soil, we examined 29 soil samples from four geographically distinct locations taken from the surface, vadose zone, and saturated subsurface using a small-subunit rRNA-based cloning approach. While microbial communities in low-carbon, saturated, subsurface soils showed dominance, microbial communities in low-carbon surface soils showed remarkably uniform distributions, and all species were equally abundant. Two diversity indices, the reciprocal of Simpson's index (1/D) and the log series index, effectively distinguished between the dominant and uniform diversity patterns. For example, the uniform profiles characteristic of the surface communities had diversity index values that were 2 to 3 orders of magnitude greater than those for the high-dominance, saturated, subsurface communities. In a site richer in organic carbon, microbial communities consistently exhibited the uniform distribution pattern regardless of soil water content and depth. The uniform distribution implies that competition does not shape the structure of these microbial communities. Theoretical studies based on mathematical modeling suggested that spatial isolation could limit competition in surface soils, thereby supporting the high diversity and a uniform community structure. Carbon resource heterogeneity may explain the uniform diversity patterns observed in the high-carbon samples even in the saturated zone. Very high levels of chromium contamination (e.g., >20%) in the high-organic-matter soils did not greatly reduce the diversity. Understanding mechanisms that may control community structure, such as spatial isolation, has important implications for preservation of biodiversity, management of microbial communities for bioremediation, biocontrol of root diseases, and improved soil fertility.     

Spatial patterns of photobiont diversity in some Nostoc-containing lichens

Patterns of photobiont diversity were examined in some Nostoc -containing lichens using the nucleotide sequence of the cyanobacterial tRNA^Leu (UAA) intron. Lichen specimens collected in northwestern USA were analysed and the sequence data were compared with tRNA^Leu(UAA) intron sequences previously obtained from lichens in northern Europe. Generally, it is the species identity of a lichen rather than the geographical origin of the specimen that determines the identity of the cyanobiont. Identical intron sequences were found in Peltigera membranacea specimens collected in Oregon (USA) and in Sweden, and very similar sequences were also found in Nephroma resupinatum thalli collected in Oregon and Finland. Furthermore, in mixed assemblages where two Peltigera species grew in physical contact with each other, the different lichen species housed different photobiont strains. There is however not a one-to-one relation between mycobiont and photobiont as some intron sequences were found in more than one lichen species, and different intron sequences were found in different samples of some lichen taxa. Peltigera venosa exhibited a higher level of photobiont diversity than any other lichen species studied, and several intron sequences could for the first time be obtained from a single thallus. It is not clear whether this is evidence of lower cyanobiont specificity, or reflects an ability to exhibit different degrees of lichenization with different Nostoc strains. In one specimen of P. venosa , which contained bipartite cyanosymbiodemes and tripartite, cephalodiate thalli, both thallus types contained the same intron sequence.     

青藏高原高寒草甸不同海拔梯度下土壤微生物群落碳代谢多样性

土壤微生物群落功能多样性对维持生态系统功能和稳定性具有非常重要的意义。为探究青藏高原高寒草甸不同海拔梯度下土壤微生物碳源利用差异以及影响机制,运用Biolog微平板技术,研究了西藏当雄县草原站4300—5100 m的6个不同海拔梯度下土壤微生物群落碳源代谢多样性。研究结果表明:(1)不同海拔下高寒草甸土壤微生物碳源的利用程度均随培养时间的延长而升高;微生物代谢活性和群落多样性指数均随海拔升高呈现先上升后下降的单峰变化趋势,整体表现4800 m4950 m4400 m4650 m5100 m4300 m;(2)主成分分析表明不同海拔显著影响了土壤微生物群落碳源代谢多样性,其中碳水化合物类、氨基酸类和胺类碳源是各海拔土壤微生物的偏好碳源;碳水化合物类、羧酸类、氨基酸类和胺类碳源的利用强度受海拔影响较大;(3)分类变异分析表明,土壤、植物和气候因素是影响不同海拔碳源利用变异的主要影响因子,可解释不同海拔的碳源利用差异的79.0%;排除环境因子之间的多重及交互作用,偏曼特尔检验表明土壤含水量、植被丰富度和年均降水量是影响不同海拔微生物碳源利用多样性的最重要的环境因子。综上,研究表明青藏高寒草甸不同海拔土壤微生物碳源代谢多样性呈现显著的海拔差异趋势,其海拔差异主要受到土壤含水量、植被丰富度和年均降水量的影响。     

土壤微生物多样性海拔格局研究进展

生物多样性的海拔分布格局与维持机制是生物多样性与生态系统功能研究的热点领域。相比动植物多样性海拔分布格局,土壤微生物多样性海拔分布格局的研究还处在起步阶段。近年来,随着以罗氏454、Illumina Mi Seq等为代表的高通量测序平台的发展,土壤微生物海拔梯度分布格局的研究进展较快。对土壤微生物多样性海拔分布格局最新研究综述发现,土壤微生物海拔分布模式并不明确,表现为无趋势、下降、单峰或者下凹型等多种海拔分布模式。这与大型动植物并不相同,暗示其驱动机制可能存在一定的差异。微生物由于其个体微小、扩散能力强以及较高的多样性和个体丰度而在局域尺度上可能更易受到气候环境因素的影响。土壤pH、碳、氮等因子是影响微生物多样性和群落组成在海拔梯度上变异的重要因素。此外,温度和降水也具有重要作用。另外,除微生物自身属性以及取样限制外,测序深度可能是影响土壤微生物物种丰富度海拔分布格局的重要因素。目前,对土壤微生物群落的研究在功能基因、群落构建机制以及生态学理论的验证方面还存在着不足。未来的研究应进一步加大测序深度,增加取样密度,着重关注全球气候变化及生物多样性丧失背景下土壤微生物群落的构建和维持机制及其生态系统功能等方面。     

珠江水系鱼类群落多样性空间分布格局

珠江是我国南方第一大河,是我国重要淡水渔业生产基地和水生生物资源基因库。珠江鱼类在维持生物多样性、提供鱼类种质资源方面举足轻重。但是到目前为止,关于其鱼类空间分布格局的研究甚少。特别是近几十年来各种水工建设和过度捕捞使得渔业资源急剧衰退,鱼类空间分布的研究显得尤为重要。2015年对珠江全流域13个站位进行了全面调查,共采集渔获物10119尾,隶属于94种72属17科。鲤科鱼类占显著优势,其次种类较多的依次为鲿科、鳅科。采用非度量多维标度排序(NMDS)方法对鱼类群落空间分布特征进行了分析,结果表明珠江鱼类被划分为3个类群,即以餐、南方拟餐、黄颡鱼等小型鱼类为主的中上游类群、以赤眼鳟、鲮鱼、广东鲂等中型鱼类为主的中下游类群和以罗非鱼为主的重要支流类群。同时发现中下游物种多样性高,上游及河口江段多样性低的格局。采用冗余分析方法(RDA)分析了鱼类多样性与环境因子的关系,发现年均气温、降雨量、年均径流量、河流宽度与透明度是珠江水系河流鱼类群落结构差异的主要影响因子,其中年均气温是影响鱼类群落分布的最关键因子之一。与历史资料对比后发现,珠江鱼类种类明显减少、空间分布也发生了巨大改变。研究是珠江水系野生渔业资源长期调查的一部分,研究结果将对渔业资源的多样性保护和可持续利用具有指导意义。     

Spatial diversity patterns of Pristimantis frogs in the Tropical Andes

Although biodiversity gradients have been widely documented, the factors governing broad‐scale patterns in species richness are still a source of intense debate and interest in ecology, evolution, and conservation biology. Here, we tested whether spatial hypotheses (species–area effect, topographic heterogeneity, mid‐domain null model, and latitudinal effect) explain the pattern of diversity observed along the altitudinal gradient of Andean rain frogs of the genus Pristimantis. We compiled a gamma‐diversity database of 378 species of Pristimantis from the tropical Andes, specifically from Colombia to Bolivia, using records collected above 500 m.a.s.l. Analyses were performed at three spatial levels: Tropical Andes as a whole, split in its two main domains (Northern and Central Andes), and split in its 11 main mountain ranges. Species richness, area, and topographic heterogeneity were calculated for each 500‐m‐width elevational band. Spatial hypotheses were tested using linear regression models. We examined the fit of the observed diversity to the mid‐domain hypothesis using randomizations. The species richness of Pristimantis showed a hump‐shaped pattern across most of the altitudinal gradients of the Tropical Andes. There was high variability in the relationship between area and species richness along the Tropical Andes. Correcting for area effects had little impact in the shape of the empirical pattern of biodiversity curves. Mid‐domain models produced similar gradients in species richness relative to empirical gradients, but the fit varied among mountain ranges. The effect of topographic heterogeneity on species richness varied among mountain ranges. There was a significant negative relationship between latitude and species richness. Our findings suggest that spatial processes partially explain the richness patterns of Pristimantis frogs along the Tropical Andes. Explaining the current patterns of biodiversity in this hot spot may require further studies on other possible underlying mechanisms (e.g., historical, biotic, or climatic hypotheses) to elucidate the factors that limit the ranges of species along this elevational gradient.     

Dehalogenase gene detection and microbial diversity of a chlorinated hydrocarbon contaminated site

In recent years large quantities of mixtures of chlorinated hydrocarbons have accumulated in the environment due to the widespread use and production of these compounds. Microbes have been found to demonstrate a widespread and diverse potential to adapt to the dechlorination of such compounds. Therefore the aim of this study was to investigate the presence and diversity of reductive and hydrolytic dehalogenase genes in a site contaminated with a mixture of chlorinated hydrocarbons. Primers targeting reductive and hydrolytic bacterial dehalogenase genes were designed. In addition, DGGE analysis was performed in order to determine the presence of any known dehalogenase-producing organisms. Total DNA isolated from borehole water samples was used as the template for the amplification reactions. All PCR products obtained with the reductive and hydrolytic gene primers, as well as the dominant bands present on the DGGE gel were cloned and sequenced. Sequencing of the individual amplicons revealed significant identities to the tceA gene of Dehalococcoides ethenogenes 195, the vcrA gene of Dehalococcoides sp. VS as well as the dhlA and dhlB genes of Xanthobacter autotrophicus GJ10. DGGE analysis indicated a high level of commonality with the different sampling times and depths. However, sequence analysis revealed that 66% of the cloned fragments showed significant (95–99%) identity with uncultured microorganisms. Phylogenetic analysis of the sequences revealed that the DGGE clones clustered into two groups when compared to known bacteria having hydrocarbon degradative capabilities. This indicated that the sequences of the clones were diverse when compared to known microorganisms. This diversity represents a largely untapped genetic pool that can be exploited for the discovery of novel biocatalysts that can be employed in bioremediation. In addition, the presence of both hydrolytic and reductive dehalogenases provided strong evidence that bacteria capable of dehalogenation of chlorinated hydrocarbons may be present in sites contaminated with these compounds.     

Spatial patterns of diatom diversity and community structure in ancient Lake Ohrid

For effective lakes’ management, high-frequent water quality data on a synoptic scale are essential. The aim of this study is to test the suitability of the latest generation of satellite sensors to provide information on lake water quality parameters for the five largest Italian subalpine lakes. In situ data of phytoplankton composition, chlorophyll-a (chl-a) concentration and water reflectance were used in synergy with satellite observations to map some algal blooms in 2016. Chl-a concentration maps were derived from satellite data by applying a bio-optical model to satellite data, previously corrected for atmospheric effects. Results were compared with in situ data, showing good agreement. The shape and magnitude of water reflectance from different satellite data were consistent. Output chl-a concentration maps, show the distribution within each lake during blooming events, suggesting a synoptic view is required for these events monitoring. Maps show the dynamic of bloom events with concentration increasing from 2 up to 7 mg m^?3 and dropping again to initial value in less than 20 days. Latest generation sensors were shown to be valuable tools for lakes monitoring, thanks to frequent, free of charge data availability over long time periods.     

Spatial interrelationships between terrain, snow distribution and vegetation patterns at an arctic foothills site in Alaska

A multidisciplinary approach combining field surveys, aerial photographic techniques, digital terrain modelling, and GIS technology was used to analyze spatial interrelationships at a study site in the northern foothills of the Brooks Range, The sensitivity of snow drifting to topography at the site is pronounced. The drift patterns indicate winter winds are predominantly from the south with a major secondary component from the southwest. These southwest winds are likely in conjunction with storm events. The deepest snow beds are found on the steeper, north-facing slopes. Snow also has an effect on vegetation that is evident at the scale of mapping (1:6000). Communities dominated by Cassiope tetragona are associated with deeper snow regimes, and may be useful indicators of deeper snow regimes even at much smaller scales because of their unique spectral signatures. The analyses conducted to date demonstrate the power of the GIS for analyzing terrain-geobotanical interrelationships, which will increase as we add new layers for other variables, and are able to correlate these with satellite data.