大蜀山孤岛状山体植被演替阶段物种多样性变化规律

采用"空间差异代替时间变化"的研究方法,以位于安徽省合肥市的孤岛状山体——大蜀山国家森林公园的恢复植被为研究对象,调查了16个典型样地,利用丰富度指数(Margalef richness index,R)、Shannon多样性指数(Shannon diversity index,H)、均匀度指数(Pielou evenness index,Jsw)和生态优势度指数(Simpson index,D)等研究了4个不同演替阶段森林群落的特征变化。结果表明:从马尾松林向针阔混交林、麻栎林的演替过程中,群落乔木层Shannon指数分别为1.957、1.485、0.738,呈下降的趋势;而短毛椴林乔木层Shannon指数为1.694。麻栎林乔木层的物种丰富度和多样性显著低于其他3个群落(P0.05),均匀度显著低于马尾松林和短毛椴林(P0.05)。4种群落灌木层、草本层之间的多样性和均匀度差异均不显著(P0.05)。在群落的垂直结构中,麻栎林物种多样性表现为灌木层草本层乔木层,其他3种群落的物种多样性则表现为灌木层乔木层草本层。处于演替顶极群落的物种多样性并不是最高,群落演替过程的稳定性和多样性有着更为复杂的关系。除人为活动的干扰外,群落的发育程度和内部生境是影响该区演替阶段群落物种多样性变化的主要因素。     

江西信丰细迳坑自然保护区观光木群落研究

以江西省信丰县细迳坑自然保护区观光木Tsoongiodendron odorum群落为对象,开展样方调查和群落生态学分析。结果表明:(1)群落的种类组成包括维管植物146种,隶属于66科106属。其中,蕨类植物9科10属14种,种子植物57科96属132种。种子植物属的地理成分以热带分布占较大优势(77.66%)。(2)该区域的地带性植被以常绿阔叶林为主,有少部分落叶树种,使得群落秋冬季有一定的季相变化。群落垂直结构包括乔木3亚层及灌木层和草本层;乔木层以观光木、华润楠Machilus chinensis、南酸枣Choerospondias axillaris、锈叶新木姜子Neolitsea cambodiana为主要优势种,灌木层以硬壳桂Cryptocarya chingii、细枝柃Eurya loquaiana、鸭公树Neolitsea chuii为主要优势种。(3)群落各频度级分布规律为A级B级C级D级E级,从优势种群年龄结构分析看,该群落在演替上处于亚顶级状态。(4)群落的物种多样性Simpson指数和Shannon-wiener指数表现为:草本层乔木层灌木层;Pielou指数则表现为:乔木层灌木层草本层。观光木群落是该地区最重要的植被特征种和生境指示种。     

祁连山北坡退化林地植被群落的自然恢复过程及土壤特征变化

采用长期定位观测的方法,研究了祁连山北坡退化林地人工抚育下2001-2008年间植被群落的自然恢复过程和土壤特征变化。结果表明:人为干扰消除后,退化林地群落环境逐渐优化,群落的科、属、种均明显增加,物种成员更替频繁;灌木和乔木物种出现后,群落垂直高度增大,群落结构出现成层现象;群落总体多样性指数呈不断增大的趋势,在空间结构上,Patrick丰富度指数、Shannon-Wiener多样性指数和Simpson优势度指数表现出:草本层>灌木层>乔木层的规律,而Pielou均匀度指数变化相反;土壤含水量、土壤有机碳和全氮含量随植被恢复均不断增加。在实施封育禁牧措施后,退化林地实现了由草本群落-灌木群落-乔木群落方向的快速演替,当恢复到早期的先锋乔灌混交阶段时,群落的物种组成、结构和多样性趋于复杂化,土壤性状也得到一定改善,显示出相对较好的适应性和恢复效果。     

草海国家级自然保护区华山松群落特征及物种多样性研究

为探讨喀斯特地区森林群落的演替动态和生物多样性维持机制,采用样地调查法对草海国家级自然保护区的华山松(Pinusarmandii)群落的物种组成、植物区系特征、种群结构和物种多样性等进行了分析。结果表明,样地内共有种子植物37科69属81种,其中乔木11种、灌木32种、草本38种;群落内植物的科、属区系成分类型多样,以温带成分为主;生活型谱主要以高位芽植物(46.91%)和地面芽植物(27.16%)为主;乔木层华山松的重要值达58%,为群落的单优势种;径级结构呈左偏正态型分布,树高分布集中在12～21 m,冠幅分布呈V型;乔木层与灌木层、草本层间的多样性差异显著(P0.05),物种丰富度指数S和D_M、多样性指数H和D_S均为草本层灌木层乔木层,物种均匀度指数J为灌木层草本层乔木层。因此,草海国家级自然保护区内的华山松群落特征和物种多样性具有明显的地域特点。     

广东南岭大东山浙江润楠群落物种多样性与区系地理成分分析

应用植被调查样地法研究了广东南岭国家级自然保护区大东山片区的浙江润楠群落的物种多样性、区系地理成分,以及优势种种群的年龄结构。结果表明：（1）在1600m2的样地内共有维管束植物73科119属169种,群落的数量优势科为樟科、蔷薇科、山茶科、壳斗科及杜鹃花科等,种类组成的科、属地理成分中热带成分分别占74·51%和70·10%,温带成分分别占23·53%和33·64%;（2）该群落浙江润楠种群以幼、中龄树为主,其优势地位明显且稳定,乔木层的亚优势树种以罗浮栲、马尾松及荷木等为主;（3）群落垂直结构分为乔木层、灌木层和草本层3层,灌木层的物种最丰富,对群落物种多样性分析发现,Simpson指数：灌木层（乔木层=草本层,Shannon指数：灌木层（乔木层（草本层,Margalef指数：灌木层（乔木层（草本层,Pielou指数：乔木层（灌木层（草本层。     

湖南三道坑自然保护区珍稀濒危植物鹅掌楸群落的研究

采用5个物种多样性指数对湖南三道坑自然保护区珍稀濒危植物鹅掌楸(Liriodendronchinense(Hemsl.)Sarg.)群落进行物种多样性测定,并分析了群落的种类组成、外貌、演替等。结果表明(:1)群落垂直结构明显,可分为乔木层、灌木层、草本层、地被层。共有维管束植物76种,隶属48科57属。群落生活型谱以高位芽植物占优势(68.42%),与其它亚热带常绿落叶阔叶林相似。(2)群落的物种多样性高,灌木层的各项物种多样性指数均高于乔木层和草本层。整个群落的丰富度高达76;Simpson指数D为0.9516,接近Dmax;Shannon-Wiener指数H为3.3247;基于Simpson指数的均匀度指数JS为0.5843,而基于Shannon-Wiener指数的均匀度指数JSW为0.8826。(3)从鹅掌楸种群的生势衰退和数量削减以及幼龄个体的贫乏来看,目前这个群落已处于发育过程的衰老阶段。     

深圳大鹏半岛自然保护区钝叶假蚊母树群落特征

应用样方法对深圳大鹏半岛自然保护区的排牙山钝叶假蚊母树群落进行调查,分析群落的物种组成和结构特征。结果表明:(1)该群落共有维管植物106种,隶属于47科75属。其中蕨类植物有4科5属9种,种子植物43科70属97种。种子植物属的地理成分以热带分布占较大优势,占非世界属总数的81.16%;(2)群落按垂直结构可分为乔木上层、乔木下层、灌木层和草本层,乔木层以钝叶假蚊母树(Distyliopsis tutcheri)、鹿角锥(Castanopsis lamontii)、密花树(Myrsine seguinii)和粗脉桂(Cinnamomum validinerve)为主要优势种,灌木层以钝叶假蚊母树、锈叶新木姜子(Neolitsea cambodiana)、黄丹木姜子(Litsea elongata)和密花树为主要优势种;(3)群落Raunkiaer频度级分布规律为ABCDE,从优势种群年龄结构分析看,该群落在演替上处于亚顶级状态;(4)群落的物种多样性方面,Simpson指数和Pielou指数表现为灌木层乔木层草本层,而Shannon-wiener指数则表现为灌木层草本层乔木层。根据以上结果,认为该群落是一个保存完整的山顶常绿阔叶林,亦属于地带性珍稀植物群落。     

山西五鹿山植物物种多样性及其海拔梯度格局

采用典型取样法,沿海拔梯度对五鹿山自然植被进行调查。结果表明：五鹿山主要群落类型为辽东栎(Quercus wutaishanica)群落、油松(Pinus tabulaeformis) 群落、茶条槭(Acer ginnala) 群落、白皮松(Pinus bungeana)群落、暴马丁香-茶条槭（Syringa reticulate-Acer ginnala）群落和白桦(Betula platyphylla)群落。其中,辽东栎群落略占优势,这可能暗示着该地区植被具有继续向暖温带落叶阔叶林演替的倾向。各层次植物物种丰富度呈现出草本层>灌木层>乔木层特征,Shannon Wiener多样性指数和Simpson多样性指数整体规律为草本层>灌木层>乔木层。以五鹿山森林群落不同层次的各种物种多样性指数和森林群落总体重要值为测度指标,均暗示着五鹿山植被演替正处于亚顶极群落阶段。五鹿山植物多样性沿海拔梯度呈现出近似中海拔高的单峰格局,这是由于植物物种多样性受温度、湿度、人为等因素干扰。     

巫山高山移民迁出区不同弃耕年限对植物物种多样性的影响

以典型高山移民迁出区耕地(A1)、弃耕1a(A2)、弃耕5a(A3)、弃耕8a(A4)、弃耕5a生长大量白花银背藤(R1)为研究对象,采用空间序列代替时间序列的方法,比较不同弃耕年限植物重要值(P)、Margalef丰富度指数(R)、Shannon多样性指数(H′)、Pielou均匀度指数(J_w)、Simpson优势度指数(D)、Jaccard相似性指数(C_j)、Sorenson相似性指数(C_s)及多样性阈值(D_v),旨在探究不同退耕年限对植物物种多样性和群落结构的影响。结果显示,随弃耕年限增加,群落结构从草本+灌木转变为草本+灌木+乔木,群落优势物种由喜阳的一年生或多年生草本转变为耐阴的多年生草本;草本层和灌木层植物物种多样性随着演替年限的延长而增长,在演替的中后期达到最大值;A2与A3间群落的相似性指数最大;对不同弃耕年限样地植被群落多样性进行评定,都未达到"较好Ⅲ"级别,还需长期的恢复。恢复过程中注意对白花银背藤的监测,防止植物入侵。     

太行山南段油松群落物种多样性研究

油松是太行山区重要的植树造林树种。本文以太行山南段为研究区域,采用随机取样法对武乡、黎城、襄垣、平顺、壶关、屯留6个地区油松的物种多样性与群落多样性进行了分析比较。结果表明:(1)6个地区油松群落中共有种子植物34科70属81种,包含乔木4科4属5种、灌木7科12属15种、草本23科54属61种;(2)太行山南段油松群落种子植物属的区系成分类型多样,以温带成分占绝对优势;(3)武乡、黎城、襄垣、平顺、壶关5个地区油松群落的物种多样性表现出较为一致的变化趋势,即草本层灌木层乔木层,而屯留的不同功能群物种多样性表现为草本层=灌木层乔木层;(4)6个地区油松群落多样性从高到低依次为平顺黎城襄垣武乡屯留壶关;(5)油松群落多样性和物种多样性水平受群落演替进程、地理环境、人为干扰等诸多因子的协同作用。     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

真菌类遗传学分析的知识结构教学

本文以认知结构理论为指导,讨论了真菌类遗传分析与高等动植物遗传分析的内在联系,认为利用这种内在联系进行教学可收到好的效果并说明了作者的具体教学过程。 Abstract:In the paper, the relationship between genetic analysis of Fungi and genetic analysis of high animal and plant was discussed.A good results were obtained when we adopted this method in the teaching.     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

History of the discovery of the mode of transmission of yellow fever virus

This essay documents and examines the historical circumstances and events surrounding the discovery of the mode of transmission of yellow fever virus in Cuba. Close scrutiny of the articles published by Walter Reed and his colleagues in 1900, 1901 and 1902 reveals their limitations as historic documents. Fortunately, other sources of information from that period survive in letters and documents written by individuals involved in the quest for the mode of transmission. Examination and comparison of those sources of information unveiled a fascinating story which reveals that misunderstandings engendered by published articles accorded merit where it was not fully due.     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.     

Time of detection of recessive genes: effects of system of mating and number of examined individuals

Summary Anthers were cultured from two sets of seven lines of hexaploid wheat (Triticum aestivum L.) with different cytoplasms, the euplasmic nucleus donors, Siete Cerros 66 and Penjamo 62, as well as their six alloplasmic lines derived from wild relative species of the genera Triticum and Aegilops. Significant cytoplasmic and nuclear effects but no cytoplasmic-nuclear interaction were found for embryogenic anther response, with the best performance of Penjamo 62 in Ae. kotschyi cytoplasm. Plant regeneration was not affected significantly by the cytoplasmic background of the lines cultured. The possible genetic implications of the observed cytoplasmic and nuclear influences on the in vitro haploid induction of wheat are discussed.