海南尖峰岭热带山地雨林近冠层CO2及通量特征研究

采用梯度法及CI-301PS CO2系统,实现了海南尖峰岭热带山地雨林近冠层CO 2、微气象因子梯度观测研究,结果表明雨季晴、晴间少云及多云天气,900～1800CO 2浓度平均值分别在349～350ml/m3(冠上2.8m)、346～348ml/m3(冠上0.8m)、345～349ml/m3(林内16m)、352～357ml/m3(林内5m),较旱季相应天气分别小14～17.5、10.1～23.7、1 6.4～35.7和18.1～36.1ml/m3;100～800,则雨季CO2浓度大于旱季;梯度浓度廓变量和实时动力计算反映出,800～1800CO2通量由大气向林冠层,旱、雨季平均CO2通量分别为(0.61×10-6kg/(m2·s)和0.71×10-6kg/(m 2·s),1900通量甚微,2000～700CO2通量则由林冠向大气,平均CO2通量分别为0.36×10-6kg/(m2·s)和0.32×10-6kg/(m2·s);雨季昼夜大气流向冠层的净CO2通量是相应旱季的1.56倍.总辐射、冠顶净辐射通量以1300～1 500为最大时域,相对林内21m,80%的辐射热能被冠层吸收,与CO2通量正相关;晴天冠上潜热、感热最高值分别在1300～1400和900,反映热带山地雨林近冠层的汇、源即白昼光合固定CO2大于夜间呼吸排放CO2效应,且雨季高于旱季.     

西双版纳片断化望天树林小气候边缘效应比较研究

对西双版纳片断望天树(Shorea chinensis)林林缘小气候的季节、水平变化进行了观测研究,对比分析了4个不同大小雨林斑块(30 hm2、25 hm2、20 hm2、3 hm2)的小气候边缘效应.结果表明:各雨林斑块林缘均存在明显的小气候边缘效应,其中在干季晴天最为明显,且在两个较小斑块林缘出现最高气温及气温日较差高于林外的现象;干季,部分林缘小气候要素(最高气温、总辐射、净辐射、最小相对湿度)林缘与林内的差值均是高于或大于雨季的相应值,而地表最高温林缘与林内的差值则是雨季强于干季;各斑块相比,小气候边缘效应波及林内的深度在最大斑块达到最浅(25 m),而在最小斑块达到最深(35 m),呈现出小气候边缘效应及其影响深度随片断雨林斑块面积减小而增强及向林内进一步延伸的趋势.     

西双版纳热带季节雨林干热季林冠上小气候特征及CO2通量的观测

热带森林在陆地生态系统中起着重要的作用,但是人们对它在碳循环中的作用却了解不多;近年来,为了对其进行深入研究,热带森林的CO2通量成为了研究的热点。应用微气象法中的开路系统涡度相关法,使用设置在西双版纳一片成熟的热带季节雨林中观测铁塔上的观测仪器所得的干热季7个晴好天气的CO2通量及小气候观测数据,对冠层的CO2通量及小气候特征进行了分析研究。研究结果表明:(1)热带季节雨林林冠上风速及摩擦风速在中午和上半夜较大,而后半夜和上午较小;风向有显著的昼、夜交替特征,昼间多为偏东风(45~135°),而夜间多为偏西风(250~280)°;(2)林冠上方气温和树冠面表温具有显著的日变化特征,树冠表温日变化幅度大于气温,热量由空气传向树冠中,在观测的7d中,气温有着较明显的升高趋势;(3)干热季林冠上湿度变化范围为26.5%~97.2%,饱和水汽压差数值大小介于0.3~30.5 hPa之间;(4)CO2浓度在364.5~408.5m l/m3之间变化,夜间浓度升高,而昼间CO2浓度降低;(5)地下5cm土壤温度与气温一样日变化规律明显,土壤含水量的变化幅度很小,在7d内其变化幅度维持在19.9%~23.3%之间,日变化幅度更小;(6)总体上讲林冠上方显热通量小于潜热通量,上午显热通量和潜热通量的数值基本相同,但是在中午和下午,潜热通量远大于显热通量,充分显示了西双版纳干热季热带雨林森林的热量支出主要是蒸腾耗热;(7)观测期间,生态系统净CO2交换(NEE)在-20.9~17.6μm o l/(m2.s)之间浮动,每天最大净CO2吸收速率在-20.9~-12.9μm o l/(m2.s)范围内。从生态系统净CO2交换的平均日变化看,昼间最大的净CO2吸收速率为-12.4μm o l/(m2.s),夜间最大的净释放速率为6.6μm o l/(m2.s)。净CO2交换的日累积量在-0.0665~0.0448m o l/m2范围内变化,7d的累积量为-0.0140 m o l/m2,表明在西双版纳干热季的7 d观测时间段里,热带季节雨林呈现弱的碳汇效应。     

黄土丘陵区坡面林-草边界土壤水分特征

研究了黄土高原丘陵区林-草边界上旱季和雨季土壤水分的空间分布变化特征.结果表明,旱季林地土壤水分的变异系数都小于草地,林地内各个层次土壤含水量差异不大,草地内各个层次土壤含水量差别较大;雨季林地土壤水分的变异系数都大于草地,林地内各个层次土壤含水量差别较大,而草地内各个层次土壤含水量差异不显著;林-草边界各个层次土壤水分的变异程度为弱变异或中等变异.林-草边界在旱季和雨季具有不同的影响域,旱季边界影响域为从林外0.4倍树高距离到林内0.4倍树高距离;雨季边界影响域为从林外0.4倍树高距离到林内0.8倍树高距离.因此,可将林-草景观划分为3个区：草地区,即由距林缘0.4倍树高距离处向草地方向延伸;林缘区,即由林外0.4倍树高距离到林内0.4倍树高距离(旱季)或0.8倍树高距离(雨季);林地区,即由林内0.4倍树高距离(旱季)或0.8倍树高距离(雨季)处向林内方向延伸.林-草边界水平方向上3个分区的土壤水分垂直分布呈现出不同的变化规律,而且旱季的规律特征与雨季相反.     

西双版纳片断化望天树林气候边缘效应比较研究

对西双版纳片断望天林树（Shorea chinensis)林林缘小气候的季节、水平变化进行了观测研究,对比分析了4个个不小雨林斑块（30hm^2,25hm^2,20hm^2,3hm^2)的小气候边缘效应。结果表明：各雨林斑块林缘均存在明显的小气候边缘效应,其中在干季晴天最为明显,且在上较小斑块林缘出现最高气温及气日较差高于林外的现象;干季,部分林缘小气候要素（最高气温、总辐射、净辐射、最小相对湿度）林缘与林内的差值均是高于或大于雨季的相应值,而地表最高温林缘与林内的差值则是雨季强于干季,各斑块相比,小气候边缘效应波及林内的深度在最大斑块达至最浅（25m),而在最小斑块达到最深（35m)呈现出小气候边缘效应及其影响深度随片继雨林斑块面积减小而增强及向林内进一步延伸的趋势。     

热带山地雨林尖峰栲边材液流及其与环境因子的关系

应用热扩散法,采用ICT-2000TE环境与蒸腾系统同步监测了热带山地雨林尖峰栲边材液流速率和环境因子的变化.结果表明：尖峰栲边材液流速率的变化规律是晴天为单峰曲线、阴雨天气为双峰或多峰曲线.边材液流速率与太阳辐射、空气温度、蒸汽压亏缺、林内风速呈极显著正相关,与空气相对湿度呈极显著负相关.在旱季监测期间,其与土壤温度呈极显著正相关、与土壤湿度相关不显著;而在雨季,其与土壤湿度呈极显著正相关,与土壤温度相关不显著,说明降雨过程对边材液流影响较大.建立了旱季和雨季监测期间的边材液流与环境因子多元线性回归模型,经过F值检验,达极显著水平.旱季、雨季监测期间尖峰栲单株平均蒸腾量分别为103.5和41.3 kg·d^-1,单位林地面积蒸腾量分别为1.94和0.77 mm·d^-1.     

西双版纳热带季节雨林晴天CO2交换的日变化和季节变化特征

应用2003年11月-2004年10月晴好天气涡度相关通量观测资料,对西双版纳热带季节雨林CO2交换的日变化和季节变化进行分析。结果表明：雾凉季、干热季和雨季的净生态系统CO2交换（NEE）均呈现出单峰型曲线的日变化趋势,昼间其变化规律较强,夜间呈波动状态。昼间NEE（取绝对值）雾凉季和雨季均显著大于干热季;夜间NEE雨季显著大于干热季,而干热季显著大于雾凉季。光合有效辐射是影响NEE日变化的主要因素,但不是造成季节差异的主要因素;饱和水汽压差和气温对NEE的季节差异有较大贡献。另外,应用Michaelis-Menten模型对昼间不同饱和水汽压差和气温下NEE对光合有效辐射的响应进行分析,结果表明：各季节较高饱和水汽压差下的表观最大光合速率（Pmax）、表观暗呼吸速率（Re）比较低饱和水汽压差下的Pmax、Re大,而表观光量子产额（α）则相反。各季节较高气温下的Re比较低气温下的Re大;雾凉季气温的差异对Pmax和α的影响较小;干热季和雨季较高气温下的α较小。     

西双版纳热带季节雨林林冠上方湍流谱特征

利用中国陆地生态系统通量观测网络(ChinaFLUX)西双版纳热带森林通量观测站涡度相关方法测定的热带季节雨林林冠上方三维方向风速(u,v,w)以及CO2浓度、H2O浓度、气温等变量的10 Hz观测资料,选取1、4、7和10月4个代表性月份晴好天气,在全天5个不同时段内(8:00-11:30,12:00-15:00,15:30-19:00,19:30-23:30,0:00-7:30)求算了各要素的功率谱和与垂直风速的协谱,探讨了热带季节雨林林冠上方数据的高低频响应问题.结果表明:在热带季节雨林林冠上方,晴好天气且湍流条件良好状况下,6个变量的功率谱点阵曲线斜率在惯性副区内均满足-2/3定律;并且各要素与垂直风速的协谱点阵曲线斜率在惯性副区内满足-4/3定律.说明大尺度运动对物质和能量传输的贡献在高频率和中等强度频率信号范围内的响应能力能够满足观测所需要求,可以认为在复杂地形条件下西双版纳热带季节雨林进行通量测定的采样频率合理,所获得数据可以用来作为实际通量的结果加以使用.     

安吉毛竹林生长季CO_2浓度的时空特征

试验采用7层CO2廓线系统对安吉毛竹林生长季(5—10月)CO2浓度进行连续监测,同时结合同步CO2通量和气象资料,分析安吉毛竹林CO2浓度的时空动态和CO2储存通量的变化特征。结果表明:安吉毛竹林生长季CO2浓度表现出明显的日变化、季节变化和垂直梯度。日尺度上,CO2浓度在日出前后达到最大,随后出现一段快速释放过程,午后达到全天最低值;整个生长季尺度上,7月份林间CO2浓度最低(368.1μmol·mol-1),10月份最高(402.6μmol·mol-1);垂直梯度方面,林冠上层CO2垂直梯度明显小于林冠层和林冠下层;林冠层和林冠上层垂直梯度变化趋势较为一致,白天均为正值,呈现为碳汇,夜间为负值,呈现为碳源,林冠下层CO2梯度全天均为负值。利用廓线系统计算毛竹林CO2储存通量,半小时和日尺度上,CO2储存通量分别占净生态系统CO2交换量(NEE)的25.5%和8.9%,而在月尺度上仅占NEE的0.22%。因此,在半小时及日尺度上计算NEE时不可忽略CO2储存通量,而在计算月尺度及更长时间尺度NEE时可以忽略CO2储存通量。     

西双版纳不同海拔热带雨林凋落量变化研究

在3个海拔梯度(600、1 100和1 600 m)选取8块热带雨林样地,研究了印度季风环境下西双版纳热带季节雨林和山地雨林的凋落动态随海拔的变化及其与气候的关系。在3个梯度上,年平均温度分别为22.1、20.1和16.6 ℃,年平均温度递减率为-0.005 3 ℃·m^-1。随海拔增加,年平均降雨量增加(分别为1 532、1 659和2 011 mm),但旱季的降雨量基本相同(282~295 mm);年蒸发量变化较小(分别为1 369、1 374和1 330 mm);年平均空气相对湿度降低(分别为86%、81%和84%),旱季后期湿度降低更明显;样地土壤含水显著增加。热带季节雨林凋落量(1 072~1 285 g·m^-2·a^-1)显著高于热带山地雨林凋落量(718~1 014 g·m^-2·a^-1)。凋落量和凋落进程变异系数与海拔之间存在线性显著负相关,凋落量与温度线性显著正相关而与降雨量显著负相关。旱季凋落高峰受到空气相对湿度和土壤含水量影响,随海拔增加空气相对湿度降低使得海拔1 105~1 720 m的凋落高峰提前,但土壤含水量继续增加又会使凋落高峰推后。研究结果得出:1)热带季节雨林凋落量与东南亚热带潮湿雨林相近;2)旱季水分限制随海拔增加而变化,影响凋落高峰出现时间;3)随海拔增加,热带山地雨林凋落年进程由季节性向平稳过渡。     

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.     

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.     

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.     

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.     

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.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

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.