北京市平原区土壤有机碳垂直分布特征

研究土壤有机碳垂直分布特征规律对精确测算土壤有机碳储量具有重要意义。本文通过野外调查实地挖取北京市平原区40个典型土壤剖面共169个样品数据,研究土壤有机碳垂直分布特征。结果表明:1)北京市平原区0—150 cm土壤平均有机碳含量为(5.98±2.62)g/kg,垂直分布上,随剖面深度增加土壤有机碳含量逐渐降低,且在浅层(≤60 cm)下降速度显著快于深层(60 cm);2)各发生层次不同土壤质地的有机碳含量差异整体上均表现为粉粒及黏粒含量比例越高,即质地越黏重,土壤有机碳含量越高;3)不同土体构型的平均土壤有机碳含量大小关系为通体砂通体壤上壤下黏夹黏,通体砂型土壤有机碳含量垂直变化相对平缓,上壤下黏型土壤有机碳含量在垂直方向呈“降—升—降”趋势,通体壤及夹黏型则均呈先快速下降后缓慢下降趋势;4)耕地和园地土壤平均有机碳含量高于荒草地,耕地在整个剖面中土壤有机碳含量均居于三种土地利用类型之首,耕地和园地的土壤有机碳含量在0—20 cm和40—60 cm之间下降速度高达40.10%和55.92%,剖面深度超过60 cm后下降速度显著放缓,受人类活动直接影响相对较少的荒草地在垂直方向上变化相对平缓。     

罗浮栲天然林土壤可溶性有机碳的剖面分布及季节变化

对罗浮栲天然常绿阔叶林土壤1m剖面内可溶性有机碳(DOC)进行了研究,结果表明:林地土壤DOC的平均含量随土层深度增加呈下降趋势,表层(0～5cm)土壤DOC的平均含量为55.69 mg·kg-1,分别与其他土层间含量存在显著性差异(P<0.01);不同土层的DOC含量占土壤有机碳的比例也随土层深度增加而降低,1m剖面内DOC的平均含量占土壤有机碳含量的0.14%;各季节土壤剖面DOC含量随土层深度增加均呈下降趋势,冬季下降趋势最为显著,夏季下降趋势相对平缓.土壤剖面DOC含量的季节变化为:冬季>秋季>春季>夏季,各季节不同土层DOC含量占土壤有机碳比例的变化趋势均不明显;不同土层土壤DOC含量的季节变化差异显著(P<0.01),表层(0～5cm)土壤间差异最为明显.     

喀斯特峰丛洼地不同土地利用类型土壤有机碳和氮素分布特征

为探讨喀斯特峰丛洼地景观类型表层土壤和土壤剖面有机碳和氮素的分布特征,在广西壮族自治区环江毛南族自治县采集典型景观类型耕地、退耕还草地、退耕还林地和林地表层样品及耕地、退耕还草地、退耕还林地剖面样品,进行了系统的分析。结果表明:林地土壤土层浅薄,但其表层土壤有机碳和全氮含量平均高达46.14和4.87g·kg-1,耕地土壤有机碳和全氮含量为13.96和1.88g·kg-1,退耕还林地表层土壤有机碳和全氮含量比耕地明显提高,退耕还草地比耕地略高;耕地0～40cm和退耕还草地0～30cm土壤有机碳和全氮含量随剖面深度增加急剧下降,耕地40～100cm和退耕还草地30～100cm则缓慢下降,退耕还林地土壤厚度一般小于1m,土壤有机碳和全氮含量在整个剖面均随深度增加急剧下降;说明地形、人类活动和土层厚度等影响表层土壤有机碳和全氮含量,其中地形和人类活动是关键影响因子;植被类型影响土壤有机碳和全氮的剖面分布,退耕还林(草)使土壤有机碳和氮储量增加。     

土地利用和环境因子对表层土壤有机碳影响的尺度效应——以陕北黄土丘陵沟壑区为例

土壤表层有机碳对土地利用和环境因子的变化非常敏感,并具有尺度变异特征。研究不同尺度上表层土壤有机碳的空间分布及其与土地利用与环境因子的关系对于评价黄土丘陵沟壑区表层土壤有机碳状况具有重要意义。选择黄土丘陵沟壑区安塞集水区和集水区内典型小流域——沐浴小流域作为研究区,探讨两个尺度上,表层土壤有机碳的分布特征及其与土地利用、环境因子的关系。结果表明:(1)土地利用方式对有机碳的影响在不同尺度上差异明显,对于不同利用方式下的有机碳含量,沐浴小流域从高到低依次是荒草地林地灌木林地耕地,安塞集水区则依次为林地灌木林地耕地荒草地;(2)对于不同利用方式下的土壤有机碳密度,沐浴小流域从高到低依次是荒草地林地耕地灌木林地,安塞集水区则是林地耕地荒草地灌木林地;(3)在沐浴小流域和安塞集水区两个尺度上,坡向、坡度和植被盖度均与有机碳含量和有机碳密度正相关,而相对海拔、土地利用与有机碳密度负相关;(4)在小流域尺度上,海拔高度、坡位、土地利用与有机碳含量负相关,坡位与有机碳密度负相关,但是在集水区尺度上,相关性则与此相反。     

短期围栏封育对荒漠草原沙化灰钙土有机碳组分及物理稳定性的影响

以宁夏盐池县荒漠草原5年围栏封育草地(围栏内)和自由放牧草地(围栏外)为对象,分析0～ 40 cm土层土壤有机碳、易氧化有机碳和颗粒有机碳含量以及土壤粒径组成,研究围栏封育早期沙化灰钙土有机碳组分及物理稳定性的变化规律.结果表明:围栏内外土壤有机碳含量和颗粒组成差异不显著;围栏内外0～40 cm土层土壤有机碳含量平均为3.25g·kg-1,沙粒、粉粒、黏粒的相对比重平均为72％、16％、12％,土壤物理稳定性指数为1.30％～1.31％.土壤活性有机碳的显著变化集中在10～20 cm土层,围栏内易氧化有机碳含量达0.80 g·kg-1,显著高于围栏外的0.62 g·kg-1,围栏内颗粒有机碳的分配比例为50.9％,显著高于围栏外的31.7％.随土层深度的增加,围栏内0～ 40 cm土壤质地由沙性土向沙壤土转变,各层间土质差异显著,易氧化有机碳含量逐渐升高;而围栏外土壤质地的垂直变化相对平缓,基本为沙性土质.退化荒漠草原短期围栏封育条件下,沙化灰钙土土壤有机碳尚处于一个消耗与积累的平衡阶段,土壤质地状况相对稳定,土壤物理稳定性变化较小.10～20 cm土层土壤活性有机碳含量及其相对分配比例可作为围栏封育早期土壤质量变化的指示指标.     

不同土地利用方式对潮棕壤有机碳含量的影响

对潮棕壤不同土地利用方式下0~100 cm土体中土壤有机碳含量的剖面分布、有机碳储量及C/N进行了研究.结果表明:不同土地利用方式下土壤有机碳含量的剖面分布差异明显,林地、割草地、荒地及裸地各土层有机碳含量高于农田生态系统;不同土地利用方式下的土壤有机碳与全氮呈极显著的正相关;土壤C/N随剖面土层深度的增加呈下降趋势,林地土壤的C/N相对较高,割草地、荒地和裸地次之,农田生态系统的土壤C/N较低.在0~100cm深度土壤,荒地每年截获的土壤有机碳分别比农田不施肥、农田循环猪圈肥处理、农田化肥NPK处理、农田化肥NPK 循环猪圈肥处理高4.52、4.25、4.46和3.58 t.hm-2.说明荒地在增加土壤有机碳储量方面有很大潜力.     

黑河流域中游芦苇湿地土壤碳垂直分布特征

黑河流域是中国的第二大内陆河流域, 在该流域中游分布的湿地面积有170411.2 hm2, 其中水陆交错带芦苇湿地面积30000 hm2。以黑河流域中游芦苇湿地为例, 探讨了其土壤剖面中碳的垂直变化规律。结果表明, 土壤剖面0-20 cm 土层的容重较小, 容重均值为 0.365 g·cm3, 在 20-50 cm 容重均值急剧升高; 50 cm 以下, 容重均值均在1.29 g·cm3 以上, 容重随土壤深度增加呈“S”型增长; 土壤有机碳主要集中在土壤表层0-40 cm 处, 40 cm 以下不同土层有机碳含量之间无显著性差异(p<0.01), 土壤有机碳随土层深度的增加呈指数下降趋势; 土壤有机碳含量和土壤容重之间存在显著的相关性。     

长三角典型水稻土有机碳组分构成及其主控因子

准确把握水稻土有机碳组分构成特征及其主控因子,对定量化评价土壤有机碳质量和未来演变趋势具有重要意义。通过室内土壤呼吸培养实验结合有机碳三库一级动力学方程,模拟得到长三角地区典型水稻土剖面(0—100 cm)各土层有机碳组分含量及其分布特征;并利用主成分分析获取主控因子,建立有机碳组分回归预测模型。结果表明:水稻土活性碳、慢性碳和惰性碳含量随剖面深度增加而降低,上层土壤(0—40 cm)有机碳组分含量下降速度明显快于下层土壤(40—100 cm);水稻土活性碳构成比例不超过5.3%,惰性碳构成比例大于活性碳与慢性碳比例之和,达到60%以上,水稻土有机碳总量变异主要取决于慢性碳和惰性碳组分变异。因此,水稻土固碳重点在于慢性和惰性组分。同时,研究还发现水稻土类型和剖面深度主要在表层对有机碳组分含量和比例构成产生显著影响,土壤有机碳量、全氮和pH是影响水稻土有机碳组分含量分异的主控因子,利用主控因子可较好预测水稻土有机碳组分含量。     

干旱区沙枣-芨芨草群落土壤有机碳的空间格局

对宁夏干旱区的沙枣 芨芨草群落进行调查,分析土壤有机碳含量与地下生物量、土壤水分等因子的关系,以及土壤有机碳的积累机制.结果表明: 在沙枣-芨芨草群落中,随着土层深度的增加,土壤有机碳含量逐渐减少,且在水平和垂直方向上的变化格局较为平缓.不同区位土壤有机碳含量与其影响因子的相关性具有明显差异.0～30 cm层中,土壤有机碳含量与土壤含水量呈显著负相关;60～150 cm层中,土壤有机碳含量与根系生物量及土壤含水率呈显著正相关.经偏回归分析,0～30 cm层土壤中芨芨草根系生物量密度对土壤有机碳含量具有显著贡献;60～150 cm层中土壤有机碳格局主要受沙枣根系和土壤含水率的影响;而30～60 cm层土壤有机碳含量与根系生物量密度和土壤含水率的关系不显著.在沙枣 芨芨草群落内,不同层次、不同区位的土壤有机碳积累机制具有明显的差异.     

芦芽山典型植被土壤有机碳剖面分布特征及碳储量

摘要: 基于芦芽山沿海拔梯度分布的灌丛草地、针阔混交林、寒温性针叶林和亚高山草甸四类典型植被下土壤剖面实测数据,分析了土壤有机碳的垂直分布特征及其与土壤理化因子的关系。结果表明,各植被类型下土壤剖面上层SOC含量最高,最大值往往出现在10—20 cm层,然后向下逐渐减小。土壤有机质含量由剖面上层最大值向下降低过程中,某深度土壤剖面层段有机质含量急剧减小。亚高山草甸剖面这一深度为20 cm,寒温性针叶林剖面为50 cm,针阔混交林剖面为20 cm,灌丛草地剖面为40 cm。0—10 cm层各植被类型间SOC含量差异不显著;10—20 cm层,亚高山草甸和寒温性针叶林SOC含量显著高于其他类型;20—50 cm层,亚高山草甸SOC含量与灌丛草地接近,显著高于针阔混交林,低于寒温性针叶林。植被类型对有机碳剖面分布影响较大。土壤剖面各层有机碳含量与容重呈显著负相关,与土壤含水量和全氮含量呈显著正相关,与土壤pH值呈弱的负相关,与深层黏粒和粉粒含量正相关,在30—50 cm正相关性显著。逐步回归分析结果表明,亚高山草甸SOC含量与土壤总氮含量、含水量和容重的显著相关,寒温性针叶林SOC含量与全氮含量显著相关,针阔混交林SOC含量则与总氮含量和土壤容重显著相关,而灌丛草地SOC含量与容重显著相关。在20 cm深度,四种植被土壤有机碳密度差异不显著;50 cm深度亚高山草甸、寒温性针叶林土壤有机碳储量显著高于针阔叶混交林和灌丛草地,50 cm深度土壤有机碳储量与海拔高度呈显著线性正相关（R2=0.299,P=0.01）。     

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.     

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.     

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.     

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。     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Specificity of action of piperidylcholine derivatives as substrates of cholinesterases of various origin

The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate, N-(β-acetoxyethyl) piperidinium iodomethylate (“piperidylcholine”), and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic hydrolysis parameters—activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholinesterase substrate—N-(β-acetoxyethyl) piperidinium.     

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.