北方典型沼泽湿地高低土壤水分下植物群落特征

北方沼泽湿地在水源供给、缓解水土流失、遏制草地沙化等方面具有重要作用,明确其植物群落物种组成和多样性特征对提升其生态系统服务功能具有重要意义。目前,在北方地区开展大尺度湿地植被调查的研究仍相对较少。土壤水分是驱动植物群落发展的主导环境因素之一,为了解高低土壤水分背景下湿地植物群落特征差异及关键驱动要素,对我国7个北方典型沼泽湿地的植物群落物种组成及多样性特征进行了调查,分析了植物群落物种组成及多样性特征与环境因子的关系,以及沼泽湿地植物群落内克隆植物的分布特征。研究结果发现不同沼泽湿地的植物群落物种组成和多样性差异显著,但无明显的地带性分布规律,物种分布呈现区域性。群落物种多样性受降水、温度、土壤养分等多种环境因素的共同影响。沼泽湿地高低土壤水分背景下植物群落的物种组成和多样性差异显著,低土壤水分下植物群落物种多样性指数显著高于高土壤水分下植物群落。低土壤水分下物种多样性主要受降水和总氮影响,而高土壤水分下物种多样性主要受温度和总磷的影响。高土壤水分下克隆植物物种数和盖度在沼泽湿地植物中占有较高的比例,表明克隆植物比非克隆植物更适应高土壤水分环境。研究结果表明了7个沼泽湿地植被的区域性...     

黄河三角洲芦苇种群特征对水深环境梯度的响应

通过野外调查芦苇种群特征及获取的监测数据,应用多元统计法、函数极值法以及β多样性指数测度法,对黄河三角洲芦苇种群在不同环境梯度（以水深为主）条件下的生物生态学特征及β多样性进行了分析.（1）通过离差平方和聚类分析方法,将研究区的10个调查样地划分为6个类型.随水深环境梯度变化,各样地群落优势植物也发生相应变化.（2）芦苇的平均高度和平均茎粗与平均水深呈显著相关.芦苇平均密度和平均盖度值与平均水深拟合曲线的变化呈非线性变化趋势.在平均水深为0.3m时,芦苇平均密度和平均盖度出现明显的峰,随水深变化向峰两侧递减,而芦苇平均株高和平均茎粗随水深增加呈递葺增趋势.（3）通过β多样性分析,黄河三角洲存在明显的环境梯度变化,随着水深的变化,物种间存在明显的替代关系.通过离差平方和聚类分析后得出的各相邻样地（水深段）间的Sorensen指数值均大于不相邻样地（水深段）间的值.水生环境植物群落间的相似性程度较大,而旱生环境植物群落间相似性程度较小.     

环境筛选和扩散限制对长江流域湖北段湿地植物群落构建的共同影响

湿地植物群落构建机制的研究可为湿地生态系统管理和受损湿地生态恢复与重建提供重要理论依据。地处长江流域的湖北省是我国湿地资源最为丰富的地区之一,通过野外调查研究了长江流域湖北段内不同类型湿地中的主要湿地植物群落类型,分析了研究区内湿地植物群落物种β多样性格局;利用相关性检验(Mantel test)方法和基于相似或相异度矩阵的多元回归模型(MRM)分析了环境差异和地理距离与湿地植物群落的物种相异性的相关性,及其对该区域湿地植物群落构建的相对贡献率。结果表明长江流域湖北段8个不同类型湿地内的湿地植物群落物种相异性指数差异显著,群落间物种相异性指数与地理距离和环境距离均呈显著正相关关系;MRM分析表明环境筛选和扩散限制共同解释了研究区内群落物种变异指数的54.72%;其中,环境距离独立解释率为22.03%,地理距离独立解释率为9.98%,二者联合解释率为22.71%。结果表明环境筛选和扩散限制共同影响了长江流域湖北段湿地植物群落构建过程,且环境筛选贡献更大。建议除了考虑空间尺度、环境因子、植被类型外,未来需进一步研究时间尺度及人类干扰等因子对该区域湿地植物群落构建的影响。     

湿地植被对北京地区蜻蜓生态分布的影响

蜻蜓目（Odonata）昆虫是半变态类（Hemimetabola）昆虫,它的一生经过卵、若虫和成虫3个阶段。和其他水生昆虫一样,蜻蜓目昆虫是淡水生物群落的重要组成部分,对淡水生态系统起到重要作用。蜻蜓目昆虫在其生活史中,取食、交配等活动离不开水生植物和水域附近的植被。为了研究蜻蜓栖息生境中的湿地植被特征对蜻蜓生态分布影响,对北京地区不同湿地类型的17块样地中296个样方分布的蜻蜓种类、多度以及湿地植被的特征和植物多样性进行调查,记录到蜻蜓6科26属36种,维管植物40科99属150种。应用TWINSPAN对蜻蜓种类和样地进行双向聚类分析,所有样地被划分成为四组。同时,将植被特征因子和湿地植物的多样性视为影响蜻蜓数量及分布的因子进行CCA分析。结果表明：湿地植物的丰富度与植物群落结构的完整性是影响蜻蜓分布的主要因素;各湿地植被特征因子对于蜻蜓生态分布的影响不一,依贡献率由大及小依次为浮水植物层盖度、湿生植物盖度、G1eason丰富度指数、沉水植物层盖度、G-F多样性指数、挺水植物层盖度。并且首次应用G-F多样性指数分析湿地植物的多样性。对于蜻蜓栖息地的保护、城市中对于湿地的兴建和改造也提出了相关保护建议。     

伊犁河谷山地植物群落物种多样性分布格局及环境解释

结合对新疆伊犁河两岸科古琴山南坡(河谷北坡)和乌孙山北坡(河谷南坡) 94个样地的调查资料, 采用DCCA (detrended canonical correspondence analysis)排序法, 分析了物种多样性指数与环境因子之间的关系, 运用广义可加模型拟合植物群落总体多样性指数对海拔梯度的响应曲线, 探讨了伊犁河谷山地植物群落物种多样性的垂直分布格局。结果表明: 在调查的94个样地中, 共出现259种植物, 其中, 草本植物的种类极其丰富, 多达235种, 木本植物的种类极其有限; 垂直结构完整的植物群落具有较高的多样性指数; 河谷北坡植物群落物种多样性的分布格局受海拔、坡度、坡向以及土壤全氮、全钾、有机质、含水量等环境因子的影响较大, 而在河谷南坡, 物种多样性分布格局主要受坡度、海拔、有效磷含量和土壤含水量等环境因子的影响; 在河谷北坡, 植物群落的Patrick丰富度指数与Shannon-Wiener指数与海拔呈明显的双峰曲线关系, Simpson指数与Pielou均匀度指数呈不对称的单峰格局, 而河谷南坡的物种多样性指数随海拔均呈双峰格局, 尽管Patrick丰富度指数不甚明显。山地植物群落物种多样性的垂直分布格局是由海拔为主的多种环境因子综合作用的结果。     

地理距离和环境因子对阿拉善戈壁植物群落β多样性的影响

内蒙古阿拉善地区分布着超过20万km²的典型戈壁生态系统, 且这些戈壁生态系统正遭受着持续性气候变暖与极端天气的影响。然而, 土壤、气候、空间变量等因子对阿拉善戈壁大尺度植物β多样性及其关键组分的相对影响还没有得到系统研究。本文通过对阿拉善典型戈壁生境的276个样方进行植物群落组成调查, 并结合气候、土壤等数据, 探讨了地理距离和环境因子对阿拉善戈壁区植物群落β多样性及其组分的影响。研究表明: (1)在阿拉善戈壁区, 随着地理距离的增加, 植物群落β多样性及物种周转组分显著增加, 而且β多样性主要源于物种周转组分, 物种嵌套组分的贡献非常有限; (2)偏Mantel分析显示环境因子和地理距离对β多样性及其物种周转组分均有显著的单独作用; 方差分解结果进一步表明, 环境因子和地理距离共同解释了植物β多样性及其物种周转组分10.84%-17.67% (Bray-Curtis)和15.47%-24.81% (Sørensen)的变异, 但环境因子可以单独解释更多的变异(6.62%-9.97% (Bray-Curtis)和8.98%-14.51% (Sørensen))。在众多环境因子中, 气温日较差、土壤含水量和地表砾石盖度对植物群落β多样性和物种周转组分的贡献更大。以上结果表明, 环境过滤、扩散限制以及其他未知过程可能共同影响阿拉善戈壁区植物群落β多样性格局, 其中环境过滤可能具有更大的影响。     

环境因子对巴山冷杉-糙皮桦混交林物种分布及多样性的影响

对太白山巴山冷杉(Abies fargesii)-糙皮桦(Betula utilis)混交林及其环境因子进行了调查,采用CCA排序法分析了环境因子与物种分布的关系,偏CCA评估了各个环境因子的重要程度,GAM拟合了物种丰富度对各个环境因子的响应。结果显示,土壤pH、海拔、岩石盖度对物种分布有显著影响(P<0.05),其影响强度为:海拔>岩石盖度>pH,其它环境因子(土壤有机质、全N、全P含量和坡度)影响不显著(P>0.05)。GAM拟合结果表明,土壤pH、岩石盖度、海拔和全N含量是影响物种丰富度的主要环境因子(P<0.01),物种丰富度随pH值升高而增加,随岩石盖度和海拔升高而减小,而随全N含量的变化较为复杂;土壤有机质、全P含量和坡度对物种丰富度没有显著影响(P>0.05)。巴山冷杉-糙皮桦混交林物种分布及多样性是由海拔、岩石盖度和土壤pH值为主的多种环境因子综合作用的结果。     

黄河首曲湿地植物群落生产力、物种多样性及其与生境的关系

近年来，在气候变化与人为干扰等因素的驱动下，高寒湿地退化导致生物多样性的丧失如何影响生态系统功能尚无共识。以黄河首曲高寒湿地为研究对象，基于野外采样数据和植物群落多样性指数，重点分析植物物种多样性、地上生物量空间分布格局及其与土壤因子关系。结果表明：首曲湿地存在一定程度退化，植物群落组成主要集中在菊科和禾本科，莎草科和豆科植物较少；植物群落物种多样性和地上生物量未表现出显著的经纬度和海拔梯度变化；Patrick丰富度指数(R)和Shannon-Weiner多样性指数(H)与地上生物量呈显著正相关，说明保护区植物多样性的保护有利于生产力维持；土壤含水量影响着高寒湿地植被群落结构，与多样性指数呈显著相关性，是高寒湿地植被恢复和重建的关键性因子。该研究结果对于认识黄河首曲高寒湿地植物生物量和物种多样性及土壤因子的空间分异规律具有一定的参考价值，同时为高寒湿地退化生态系统功能的恢复及生物多样性的保护提供科学依据。     

三峡水库秭归段消落带植物群落特征及其与环境因子的关系

消落带植被群落特征及物种多样性的研究一直是植物生态学和恢复生态学研究的热点。三峡水库的运行对消落带生态系统造成了极大的影响,如引起绝大部分河岸带土著植物消失、生物多样性降低以及土壤侵蚀严重等一系列生态学问题。研究消落带植物群落特征及其影响机制,旨在丰富消落带新生湿地生态学研究内容,为消落带植被的恢复、湿地保护和管理提供科学依据。通过对三峡水库秭归段香溪河与童庄河陡坡消落带植物群落及其环境因子的实地调查,并结合双向聚类分析及典范对应分析(CCA),研究了三峡水库消落带植物群落特征、物种多样性及其与环境因子之间的关系。结果表明:(1)在三峡水库秭归段消落带共发现维管植物34种,隶属于15科32属,其中菊科(Compositae)和禾本科(Gramineae)种类数较多,为优势物种,植物群落组成以草本植物为主,一年生和多年生草本植物为23种和11种,分别占67.65%和32.35%,一年生植物占绝对优势;(2)随海拔升高,物种数、Shannon多样性指数、Pielou均匀度从低海拔到高海拔随着海拔的增加而升高,而Simpson优势度指数指数从低海拔到高海拔呈下降趋势;(3)双向聚类显示消落带...     

博斯腾湖湖滨湿地植被数量分类与排序

应用双向指示种分析(TWINSPAN)方法对湿地植物群落进行分类,采用除趋势对应分析(DCA)、典范对应分析(CCA)对群落进行排序,以明确博斯腾湖湖滨湿地的主要植物群落类型及影响植被类型变化和分布的主要环境因子。结果表明,博斯腾湖湖滨湿地植被可分为7个主要群丛,分别为长苞香蒲(Ass.Typha angustata)、芦苇+长苞香蒲(Ass.Phragmites australis+Ty.angustata)、芦苇+水烛(Ass.P.australis+Ty.Angustifolia)、多枝柽柳-芦苇(Ass.Tamarix ramosissima-P.australis)、胡杨-多枝柽柳(Ass.Populus euphratica-Ta.ramosissima)、旱柳-多枝柽柳(Ass.Salix matsudana-Ta.ramosissima)和多枝柽柳(Ass.Ta.ramosissima),它们分布于湖滨浅水带、湖滨沼泽带、湖岸乔灌林带和旱生灌丛带;TWINSPAN分类产生的7个主要群丛在DCA排序图上被很好地反映出来。CCA排序与DCA排序结果基本一致,说明土壤含水量和土壤总含盐量是决定该地区植被分布格局的主要环境因子。博斯腾湖湖滨湿地植被种类单一,生态结构简单,水盐动态及其相互作用是影响该地区植被分布的主要因素之一。因此,在对博斯腾湖湖滨湿地进行植被保护与重建过程中,需重点考虑土壤含水量和土壤总含盐量这2个主要环境因子的影响,合理开发、利用水资源,防止土壤盐渍化的发生。     

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.     

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.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.