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1.
Strains of hydrogen-oxidizing bacteria, Pseudomonas facilis, Nocardia opaca 1 b, Paracoccus denitrificans and Corynebacterium autotrophicum 7 C, were grown both under chemolithoautotrophic (referred to as autotrophic) and under chemoorganoheterotrophic (referred to as heterotrophic) conditions and harvested during the phase of stationary growth. The lipid patterns of all strains were studied by quantitative chemical analyses, UV spectra, TLC and GLC of fatty acid methyl esters. In general, there were no essential qualitative differences between lipid patterns of autotrophically and those of heterotrophically grown bacteria of the same strain. The conditions of growth apparently influence only the quantitative composition of lipids. In particular, Nocardia opaca is comparatively rich in triglycerides. Ubiquinones were found in Pseudomonas facilis and in Corynebacterium autotrophicum. The latter finding is quite unusual in a Corynebacterium. Carotenoid glycosides are probably present in Corynebacterium autotrophicum, thus explaining the orange color of this organism. The bacteria studied contain a C19 cyclopropane acid, Pseudomonas facilis and Corneynebacterium autotrophicum also  相似文献   

2.
稀有种不仅影响群落的物种多度分布格局, 同时也是α多样性的重要贡献者。本研究主要通过加性分配和Fortran软件的RAD程序包拟合的方法, 研究了甘南亚高寒草甸不同坡向物种多样性及多度分布格局的变化, 分析了物种多度分布格局及其α多样性的变化特征, 确定了稀有种在物种多度分布格局中的相对贡献。结果表明: (1)在南坡到北坡的变化中, 环境因子差异比较明显, 其中, 土壤全磷、有机碳、速效磷、碳氮比及含水量呈递增趋势; 土壤氮磷比和pH值呈递减趋势; 土壤全氮在西坡显著低于其他坡向, 而速效氮在所有坡向上差异不显著。(2)稀有种对群落物种多样性的影响在南-北坡向梯度上依次增大, 去除稀有种的影响在各坡向均高于去除非稀有种, 可见, 稀有种在甘南亚高寒草甸物种多样性中的相对贡献高于非稀有种。(3)各坡向的稀有种资源获取模式以随机分配占领模式(random fraction模型)为主, 而非稀有种则以生态位优先占领模式(geometric series模型)为主。由于稀有种有较大的扩散率, 在物种多样性较高的生态系统中, 物种之间的生态位重叠会更加明显, 从而抑制物种多样性的增加, 因此能达到维持原有物种多样性的目的。  相似文献   

3.
河南周口地区蚂蚁多样性调查   总被引:4,自引:0,他引:4  
王玉玲 《昆虫知识》2008,45(1):146-149
蚂蚁是地球上最常见的昆虫,也是周口地区土壤动物的优势类群,其种类繁多,种群数量庞大,分布较广,对生态环境的影响十分显著。调查结果显示,在周口地区分布的蚂蚁目前有5亚科18属33种,优势种是铺道蚁Tetramorium caespitum(L.),日本弓背蚁Camponotus japonicus Mayr、上海举腹蚁Crematogaster zoceensis Santschi。不同生境、不同区域分布的蚂蚁有所不同。  相似文献   

4.
Quickly predicting which species are most susceptible to extirpation in a defined area is important for conservation and environmental monitoring. We hypothesised that the susceptibility of tree species to extinction in an area could be inferred by the spatial and temporal dynamics of its populations. Here we use change in population size, population spatial variability, spatial autocorrelation, spatial cohesion, crash rate, and recovery rate to characterise the relative susceptibility to extirpation for seven tree species along the Northeast China Transect from 1986 to 1994. Betula dahurica Pall. and Populus davidiana Dode. were found to have a higher susceptibility to loss than Pinus koraiensis Siebold et Zucc., Betula costata Trautv., and Larix olgensis A. Henry in this area during this time period. The same methods could be useful to monitor and predict the susceptibility of species extinction at a larger regional scale.  相似文献   

5.
围封是修复退化草原生态系统的主要措施之一,科学与优化围封方式是目前草地资源管理中急需解决的科学问题。以内蒙古围栏封育10年和未围封的荒漠草原为研究对象,分析围封和未围封对内蒙古荒漠草原群落物种多样性和优势种空间分布格局的影响,旨在为荒漠草原的恢复与重建提供科学依据。结果显示:(1)围封10年显著提高了荒漠草原的植被盖度、密度、高度和地上生物量;(2)围封10年对Margalef多样性指数、Shannon-Wiener多样性指数、Simpson丰富度指数和Pielou均匀度指数无显著影响,但围封均低于未围封样地;(3)围封10年对优势种短花针茅(Stipa breviflora)及糙隐子草(Cleistogenes squarrosa)的空间分布格局有较为显著的影响,与未围封相比围封后糙隐子草的分布格局变得单一,短花针茅分布格局变得多样。总体看来,围封10年后,荒漠草原群落物种组成、物种优势度和优势种的空间分布格局均发生一定程度变化,反映出围封后草地生态系统中植物适应其生存环境的策略,围封方式应根据立地条件,科学制定围封年限以达到较好的生态恢复效果。  相似文献   

6.
The checkerboard score and species distributions   总被引:12,自引:0,他引:12  
Summary There has been an ongoing controversy over how to decide whether the distribution of species is random — i.e., whether it is not greatly different from what it would be if species did not interact. We recently showed (Roberts and Stone (1990)) that in the case of the Vanuatu (formerly New Hebrides) avifauna, the number of islands shared by species pairs was incompatible with a random null hypothesis. However, it was difficult to determine the causes or direction of the community's exceptionality. In this paper, the latter problem is examined further. We use Diamond's (1975) notion of checkerboard distributions (originally developed as an indicator of competition) and construct a C-score statistic which quantifies checkerboardedness. This statistic is based on the way two species might colonise a pair of islands; whenever each species colonises a different island this adds 1 to the C-score. Following Connor and Simberloff (1979) we generate a control group of random colonisation patterns (matrices), and use the C-score to determine their checkerboard characteristics. As an alternative mode of enquiry, we make slight alterations to the observed data, repeating this process many times so as to obtain another control group. In both cases, when we compare the observed data for the Vanuatu avifauna and the Antillean bat communities with that given by their respective control group, we find that these communities have significantly large checkerboard distributions, making implausible the hypothesis that their species distributions are a product of random colonisation.  相似文献   

7.
Abstract

The study analyses the changes in vegetation structure and composition within a sere of secondary succession at Pantelleria Island (Sicilian Channel, Italy). It aims to show that not only phytosociological data but also structural parameters, like woody species’ height and spatial distribution indices are useful to describe and interpret renaturation processes. Woody species structure was recorded on abandoned terraces, both on north-facing and on south-facing slopes. Relevés were made in fallows representing five different stages of succession. The pace of succession, measured through the analysis of woody species cover, basal area, height distribution and spatial indices, resulted quite rapid: already after 50 years of abandonment terraces are covered by dense maquis communities. Our study also revealed that different plant species or groups prevail during colonisation dynamics, mostly depending on exposition, a factor which strongly influences also the speed of colonisation by woody species. In this case study, human activity seems to be unnecessary to accelerate the process of renaturation, except in some unfavourable contexts. Species turnover rate, biodiversity value, and structural evolution along progressive succession must be taken into account in nature management and conservation policies of terraced landscapes, which are nowadays one of the most endangered landscape types throughout the Mediterranean area.  相似文献   

8.
关帝山华北落叶松、云杉、杨桦天然次生林植被类型是华北高海拔地带代表性的森林类型。以该地区上述3种典型的天然次生林群落为例,运用点格局分析中的单变量O-ring统计方法,分析各群落主要树种的种群空间分布格局;用双变量O-ring统计方法,分析各群落中树种间的空间关联性;并对同一树种在不同森林群落类型中种群空间分布格局和种间关联性的变化进行比较,以探讨华北山地次生林群落空间格局形成和种群维持与动态机制。研究结果表明,(1)各种群在相对小的尺度上聚集分布特征明显,随尺度增加树木种群的聚集性减弱并逐渐表现出随机分布的格局特征;(2)同一树种在不同森林群落类型中空间分布格局差异很大。红桦、白桦和山杨在阔叶林中呈明显的小尺度聚集分布格局,而在针叶林群落呈随机分布。在阔叶次生林中混生的小龄级华北落叶松呈现聚集性空间分布格局。在华北落叶松为优势树种的针叶林中,大龄级的华北落叶松表现出小尺度上均匀分布和较大尺度上随机分布的格局特征;(3)各群落中树种间的空间关联性主要表现在小尺度范围,随尺度加大空间关联性逐渐不明显;(4)在阔叶树占优势的次生林,小龄级华北落叶松与桦木的分布有较明显的空间正关联性,而在华北落叶松为优势树种的针叶林,桦与华北落叶松并未表现明显的空间关联性。种群分布格局和种群间的空间关联性随群落结构、空间尺度和龄级结构不同而有较大变化。  相似文献   

9.
亚热带常绿阔叶林优势种个体及生物量的点格局分析   总被引:1,自引:0,他引:1  
在广东康禾自然保护区的亚热带常绿阔叶林内设置4 hm2固定样地进行每木调查,分析群落优势种米槠(Castanopsis carlesii)和木荷(Schima superba)种群的年龄结构,并分别用Ripley's L函数和标记相关函数(mark correlation function)对种群个体和生物量空间点格局进行可视化解析。结果表明:1)米槠和木荷种群的径级结构为金字塔型,种群中有大量幼年个体,属增长型种群。2)米槠和木荷种群在0—50 m尺度上均呈聚集分布,说明生境异质性在种群空间格局形成中发挥重要作用。米槠种群聚集强度随空间尺度的增大逐渐增强,木荷种群在0—29.5 m尺度上聚集强度随尺度增大而增强,随后开始减小。3)米槠和木荷种群生物量分布格局与个体分布格局并不耦合,米槠生物量在个体间主要呈负相关,说明个体间存在显著的资源竞争。木荷个体间生物量分布相互独立,竞争不明显,显示出作为亚热带先锋树种的木荷有很高的资源利用效率。个体及生物量空间分布格局分析表明两个种群的分布模式均有利于实现物种共存。  相似文献   

10.
吸果夜蛾优势种群的发生与防治   总被引:2,自引:0,他引:2  
在湖北,鸟咀壶夜蛾与咀壶夜蛾是吸果夜蛾的优势种群。鸟咀壶夜蛾一年出现4次为害高峰;咀壶夜蛾一年出现4次为害期,但仅第4次形成为害高峰期。两者的幼虫均以木防己为食,木防己的分布及密度直接与两种夜蛾的发生及虫口密度相关。根除果园周围吸果夜蛾幼虫的寄主植物--木防己是防治吸果夜蛾的有效措施。用除草剂涂茎防除木防己是一种简便易行、一次防除、长期受益的好方法。  相似文献   

11.
ABSTRACT

The detailed analysis and scoring of concept maps may not be necessary in order for students to gain from their use in the classroom. A simplified recognition of different types (‘species’) of map may increase the likelihood of teachers employing maps in their classrooms so that more teachers and students might benefit from concept mapping on a regular basis. A greater familiarity and level of engagement with concept maps is likely to support an increase in the level of mapping expertise developed by both teachers and students, enabling maps to be used to support higher order thinking skills – as intended. The counter-intuitive conclusion to this prospect is that the adoption of a non-analytical consideration of maps may actually make them a more valuable classroom asset. However, this requires a greater level of expertise in the application of concept maps on the part of the teacher. A simplified typology of ‘map species’ is presented to support the development of this perspective.  相似文献   

12.
运用石蜡切片技术,对樟科的紫楠(Phoebe sheareri(Hemsl.)Gamble),浙江楠(Ph.chekiangensis S.B.Shang)香樟(Cinnamomum camphora (Linn.)Presl.)浙江桂(C.chekiangensis Nakai),细叶香桂(C.subaveniumMiq.)、江浙山胡椒(Lindera chienii Cheng)、钓樟(L.r  相似文献   

13.
The spatial pattern analysis of population and community is important to understand community structure and has become one key topic in modern plant ecology. There are many techniques for analyzing one-dimensional pattern in ecological literature. Two-dimensional pattern analysis is better than one-dimensional analysis in the study on community spatial characteristics and structure. However, it is hard to analyze these two-dimensional patterns due to poor effective methodology. The two-dimensional sampling using two transects that meet at right angles was applied to get quadrat data in this work. And then the data from the two transects were analyzed separately by one-dimensional pattern analysis method, two-term local quadrat variance. The length, width, and area of patches at different scales of pattern for populations were obtained from the analysis. For community pattern, detrended correspondence analysis (DCA) was employed to summarize the species information firstly, and then the first DCA axis scores were analyzed to check its pattern. The application of this method to the pattern analysis on dominant populations and community for subalpine meadow (Comm. Polygonum viviparum + Carex rigescens + Kobresia bellardii) in the Luya mountains showed that it could release the characteristics of spatial pattern clearly and was a very effective technique. The method is easy to use and saves time with obvious advantages, compared with the two-dimensional pattern analysis methods presented in the literatures. In the study meadow, the patterns of the main dominant species, Polygonum viviparum, Carex rigescens, and Kobresia bellardii, were apparent and comparatively regular in shape with large areas of patches at the same scale compared with other species such as Festuca sp. and Thalictrum petaloideum. There were two or three scales of patterns for each plant population studied. This was related to population features, the interaction with environmental factors, and their dominant position in the community. The two scales of patterns for the meadow community were clear. The pattern of community was closely correlated with that of the main dominant species. The patches of dominant species were inter-distributed and overlapped, and formed the community pattern together. This is beneficial for utilization of resources, and keeping the community stable. __________ Translated from Acta Ecologica Sinica, 2005, 25(6): 1264–1268 [译自: 生态学报]  相似文献   

14.
芦芽山亚高山草甸优势种群和群落的二维格局分析   总被引:11,自引:0,他引:11  
张金屯 《生态学报》2005,25(6):1264-1268
种群和群落的二维空间格局研究能够更好地揭示群落的空间和结构特征,但在分析方法上有较大的困难。用垂直相交的两条样带在两个方向上同时取样的二维取样法,获得数据,用一维格局分析方法分别分析,可以得到各个种不同格局规模斑块的长、宽及面积,实现二维格局研究。用DCA排序和格局分析方法相结合,可以完成群落的二维格局分析。在山西芦芽山亚高山草甸应用的结果表明这样的垂直样带二维取样及分析方法较好地反映了种群和群落的空间特性,是非常有效的,并且该方法简单易做,具有较大的可操作性。所研究的草甸主要优势种格局斑块的形状比较规则,面积也较大。次要种斑块多为不规则形,面积也较小。群落格局与主要优势种的格局关系密切。  相似文献   

15.
The spatial pattern analysis of population and community is important to understand community structure and has become one key topic in modern plant ecology.There are many techniques for analyzing one-dimensional pattern in ecological literature.Two-dimensional pattern analysis is better than one-dimensional analysis in the study on community spatial characteristics and structure.However,it is hard to analyze these two-dimensional patterns due to poor effective methodology.The two-dimensional sampling using two transects that meet at right angles was applied to get quadrat data in this work.And then the data from the two transects were analyzed separately by one-dimensional pattern analysis method,two-term local quadrat variance.The length,width,and area of patches at different scales of pattern for populations were obtained from the analysis.For community pattern,detrended correspondence analysis (DCA)was employed to summarize the species information firstly,and then the first DCA axis scores were analyzed to check its pattern.The application of this method to the pattern analysis on dominant populations and community for subalpine meadow (Comm.Polygonum viviparum+Carex rigescens+Kobresia bellardii)in the Luya mountains showed that it could release the characteristics of spatial pattern clearly and was a very effective technique.The method is easy to use and saves time with obvious advantages,compared with the twodimensional pattern analysis methods presented in the literatures.In the study meadow,the patterns of the main dominant species,Polygonum viviparum,Carex rigescens,and Kobresia bellardii,were apparent and comparatively regular in shape with large areas of patches at the same scale compared with other species such as Festuca sp.and Thalictrum petaloideum.There were two or three scales of patterns for each plant population studied.This was related to population features,the interaction with environmental factors,and their dominant position in the community.The two scales of patterns for the meadow community were clear.The pattern of community was closely correlated with that of the main dominant species.The patches of dominant species were inter-distributed and overlapped,and formed the community pattern together.This is beneficial for utilization of resources,and keeping the community stable.  相似文献   

16.
以浙江省天目山国家级自然保护区为例,采用多尺度分析思想,利用多重分形分析方法,研究了不同尺度下物种多样性的变化、空间分布格局以及多样性与空间格局之间的关系。研究主要得到3方面的结论:(1)物种多样性具有尺度依赖性,随着空间尺度的增大,Shannon-Wiener多样性指数Ⅳ增大,Margalef多样性指数足和均匀度指数E减小;(2)多重分形参数αmin。多重分形谱的变化范围SR等能够定量反映物种的空间分布特征,空间大尺度越大,物种越聚集,空间分布越不均匀;(3)物种多样性与空间格局存在线性或幂函数关系。研究表明多重分形分析定量描述物种空间格局是有效性的,多重分形参数与生物多样性之间的定量关系为研究物种空间格局、生态属性与尺度之间的关系奠定了基础。因此,分形结合传统方法,在生物多样性方面的研究将有很大的潜在价值。  相似文献   

17.
The spatial pattern of a tree species is an important characteristic of plant communities, providing critical information to explain species coexistence. The spatial distribution and association of four different successional species were analyzed among different life-history stages in an old-temperate forest. Significant aggregation patterns were found, and the degree of aggregation decreased with the scales and life-history stages. Significant interspecific spatial associations were detected. In comparing the relationships among the different life-history stages, positive associations were found at small scales in all of the juvenile species pairs. In the adult stage, negative associations were detected in coniferous vs. deciduous species pairs, while the deciduous species pairs, which have identical resource requirements, showed a positive association in this study. The coniferous species pairs showed a positive association at small scales. We infer that seed dispersal, competitive ability, or the requirement for specific topographic and light environments may contribute to the coexistence of these species.  相似文献   

18.
长白山主要生态系统地面藓类植物分布格局研究   总被引:17,自引:5,他引:12  
基于51个样点3305个样方地面藓类的盖度,应用双向指示种法,将长白山主要生态系统中地面藓类群落分成落叶松沼泽、高山苔原、岳桦林、亚高山过渡林、暗针叶林及红松阔叶林6种类型,这6种生态系统中的地面藓类总盖度分别为80.94%、25.42%、59.83%、26.88%、44.11%和1.67%.在调查的51个样点中,随着土壤pH值下降、含水量上升,地面藓类群落盖度增加,在苔原带以下红松阔叶林以上的森林中,随着冠层郁闭度加大,林下地面藓类盖度下降.地面藓类的生态位宽度(B)与种数(N)的关系符合N=74.6475×e-20.6705×B,除塔藓等少数种类外,大多数藓类的生态幅很窄  相似文献   

19.
长江流域鱼类物种多样性大尺度格局研究   总被引:25,自引:0,他引:25  
作者以长江流域鱼类编目数据库为基础数据,研究了长江流域鱼类物种多样性的大尺度格局。长江流域内共记录了鱼类378种(亚种),隶属于14目32科144属。其中淡水鱼338种(亚种),以鲤形目为主,达到269种(亚种),洄游鱼类11种,河口鱼类29种;流域内特有种和受威胁物种分别有162种(亚种)和69种(亚种)。根据鱼类分布特点,按水系将长江流域分为19个区域,除了江源区和金沙江中上游外,物种数和G-F多样性指数上游高于中下游,但各区域内差异不大,然而特有种比例从上游到下游随海拔降低而逐渐降低。利用Jaccard物种相似性系数对19个区域进行聚类分析,将整个流域分成三部分:(1)江源区和金沙江中上游,地理上属于青藏高原东南部波状平原部分和横断山区,(2)上游其他流域,地理上属于川西高原、云贵高原、四川盆地及秦巴山区,(3)中下游流域,地理上属于淮阳山地、江南丘陵和长江中下游平原,基本反映了流域内自然地理环境及我国大陆地势三级台阶变化的特点。  相似文献   

20.
中国蚂蚁丰富度地理分布格局及其与环境因子的关系   总被引:1,自引:0,他引:1  
物种丰富度分布格局及其形成机制的研究对于生物多样性保护具有重要意义。为了了解中国蚂蚁物种丰富度分布格局,利用中国省级尺度蚂蚁物种分布数据和环境信息,结合GIS和数理统计方法,探讨蚂蚁物种丰富度的地理分布格局与环境因子之间的关系。研究结果表明:(1)蚂蚁丰富度随纬度增加呈逐渐递减趋势,但缺乏显著的经度梯度。丰富度最高的地区主要集中在南方省份,我国北方、西北干旱区和青藏高原北部地区丰富度较低;(2)简单线性回归分析表明,能量、水分和季节性因素中,影响蚂蚁物种丰富度最强的因子分别为最冷月均温(TEMmin)(R2adj=0.532)、年均降水量(PREC)(R2adj=0.376)和年温度变化范围(TEMvar)(R2adj=0.539),而单个生境异质性因子对蚂蚁物种丰富度的影响均不显著;(3)最优模型由年均温(TEM)、海拔变化范围(ELErange)和年温度变化范围(TEMvar)组成,能够解释68.4%的蚂蚁丰富度地理分异。鉴于海拔变化范围更多地反映与温度相关的生境异质性,因此温度是限制中国蚂蚁分布的最重要因素。另外,分析结果还表明,海南、贵州、江西、四川、安徽和山西等6省蚂蚁区系调查最不充分,是未来发现蚂蚁新分布的热点地区。  相似文献   

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