外来树种日本落叶松和日本花柏对鄂西北森林群落的影响

【目的】研究大面积栽植外来树种日本落叶松和日本花柏对鄂西北森林群落物种多样性的影响,为评价外来树种的入侵风险提供依据。【方法】采用样地调查法对比研究外来树种日本落叶松和日本花柏人工林与当地森林群落特征差异。【结果】日本落叶松人工林样地林下植物种类丰富,样地平均物种数与当地天然林样地物种数相比无显著差异;林下灌木层和草本层多样性指数较高,草本层多样性指数与当地天然林相比无显著差异;林下未发现日本落叶松的更新苗。日本花柏人工林样地平均物种数显著少于当地其他人工林样地;乔木层、灌木层和草本层的4个多样性指数值均小于当地其他人工林样地;在3个样地中出现日本花柏更新苗,更新苗数量达479株·hm~(-2)。【结论】引种栽培日本落叶松不会导致当地森林群落的物种多样性降低,不会引起生物入侵风险;但引种栽培日本花柏会明显降低当地森林群落的物种多样性,对当地森林生态系统的稳定构成一定威胁。     

黄土高原马栏林区主要森林群落物种多样性研究

应用丰富度指数(S)、多样性指数(H1)、优势度指数(D)和均匀度指数(Js)对子午岭马栏林区的主要森林群落物种多样性进行了研究。结果表明:41个样地共记录草本151种,灌木111种,乔木33种。马栏林区森林植物群落其总体多样性是混交林>纯林>人工林;不同森林群落各层的物种多样性基本都表现为灌木层>草本层>乔木层;物种多样性乔木层以油松(Pinus tabulaeformis) 辽东栎(Quercus liaotungensis)混交林和落叶阔叶混交林较高,灌木层以油松 白桦(Betula platyphylla)混交林、白桦林和天然油松林多样性较高;草本层则是人工刺槐 (Robinia pseudoacacia)林、白桦林和山杨(Populus davidiana)林多样性较高。人工刺槐林和人工油松林在乔木层和灌木层多样性指数都较低。物种均匀度乔木层是落叶阔叶混交林最高,人工油松林和人工刺槐林最低;灌木层各群落的均匀度较为接近;草本层则表现为人工刺槐林均匀度最高,混交林最低。β多样性分析显示人工刺槐林与其它森林群落相异性较大,而辽东栎林、天然油松林和油松 白桦混交林均与油松 辽东栎混交林的相异性较小。研究表明多树种营造混交林可以增加群落的多样性,建造具有较高物种多样性的群落应种植混交林取代单一物种的人工纯林,在选择树种时应优先考虑乡土树种。     

五台山林区典型人工林群落物种多样性研究

对山西五台山林区4种典型人工林群落物种多样性特征进行了定量研究,结果表明: 1 4种人工林群落灌木层和草本层的Simpson指数 D 和Shannon-Wienner指数 H′ 差异不显著,物种丰富度指数和均匀度指数 Jsw 差异显著,均匀度指数 Ea 差异极显著,草本层发育明显好于灌木层; 2 各人工群落尚处于演替初期阶段,林下植被发育常以禾本科阳生性植物为主; 3 对4种人工林群落灌草层物种多样性显著性检验结果显示,在灌草层物种多样性特征上,油松林与桦木林、山杨林多样性差异显著 P<0.05 ,其它群落差异不显著.山杨林物种多样性程度较高,油松林最差; 4 不同人工林群落物种总体多样性特征分析表明,桦木和山杨人工林群落总体α多样性与油松林差异显著,且多样性较大,阔叶林更有利于林下植被的发育和更新; 5 对人工生态系统物种多样性研究是退耕还林、天然林保护等生态环境工程的延伸,对于植被恢复后的生物学效果评价有重要意义.     

海拔高度对江油地区杉木人工林群落结构和物种多样性的影响

物种多样性是群落功能复杂性和稳定性的重要量度指标,海拔高度是影响物种多样性的重要因素。该实验采用典型样地法,在800~900m(低海拔)和1 100~1 200m(高海拔)2个海拔高度分别取4个20m×20m的样地,对江油地区的杉木人工林群落结构和物种多样性进行研究,采用物种丰富度指数(D)、Shannon-Wienner多样性指数(H)、Simpson优势度指数(H′)和均匀度指数(Jsw)来综合衡量不同海拔杉木人工林群落的物种多样性。结果表明:(1)组成江油杉木人工林的物种共计205种,分属66科177属;低海拔地区乔木7种,灌木54种,草本47种;高海拔地区乔木10种,灌木60种,草本41种。(2)低海拔和高海拔的木本植物组成无明显差异,草本层的物种组成有明显差异。(3)群落各层次的物种多样性指数在低海拔和高海拔都表现为:灌木层草本层乔木层,乔木层的各项指数最低;物种多样性指数随海拔升高在特定区间内表现出一定规律性,D、H和Jsw值总体上呈高海拔低海拔,H′则相反,表明高海拔杉木人工林物种多样性和物种在群落中分布的均匀度都有增加的趋势,这与高海拔受人为干扰较轻以及环境因子的变化等密切相关。     

我国南方4种常见人工林林下植物多样性特征及影响因素

为了解长期植被恢复的成熟人工林林下植物组成与多样性特征及其影响因素,基于广东鹤山生态系统国家野外科学观测研究站的南亚热带人工林生态系统,对环境相似(坡度、坡向、海拔)、30 a生4种类型人工林(桉树混交林、马占相思纯林、乡土混交林、针叶混交林)进行调查研究,分析林下植物组成和物种多样性(Shannon-Wiener指数、Simpson指数、Pielou指数)特征。结果表明,人工林林下植物类型丰富,均可形成乔-灌-草垂直结构;4种林型林下植物组成既有相似性,也有差异性,桉树混交林与针叶混交林、马占相思纯林与乡土混交林的灌木层组成相似;桉树混交林与马占相思纯林、乡土混交林与针叶混交林的草本层组成相似,而桉树混交林与针叶混交林的草本层组成极不相似。林分类型影响林下植物多样性,马占相思纯林林下灌草多样性显著低于其他3种混交林(P<0.05),灌木物种数、个体数最少;针叶混交林林下物种丰富度最高。林分郁闭度与林下植物多样性呈正相关(P<0.001),林下植物分布与土壤养分含量相关,桉树混交林、马占相思纯林林下植物多样性与不同形态氮含量相关,有效磷、全磷影响乡土混交林林下物种的分布,针叶混交林受土壤酸碱度、全钾的影响较为明显。在4种人工林林下植物群落中,乡土混交林多样性,均匀度最高,优势度最低,具有更佳的保育和维持林下生物多样性功能。因此,乡土树种混交林更适用于生态公益林构建或对一些针叶林及外来树种纯林进行林分改造。     

浙江古田山常绿阔叶林演替序列研究:群落物种多样性

采用较为成熟的“空间差异代替时间变化”的研究方法,应用相邻格子样方法调查了16个典型样地,利用Shannon-Wiener指数、Pielou均匀度指数、Simpson生态优势度指数计算了浙江古田山自然保护区常绿阔叶林演替序列4种群落的物种多样性。结果表明,从针叶林到针阔叶混交林、木荷林和甜槠林的演替过程中,4种群落乔木层的Shannon-Wiener指数分别为1.9670、2.4975、2.6140和2.4356,呈现先增大后变小的趋势;灌木层物种多样性以针阔叶混交林最高,Shannon-Wiener指数为2.8625;针叶林的草本层Shannon-Wiener指数为1.5334,高于其它3种群落。在群落的垂直结构中,演替序列中的针叶林、针阔叶混交林、甜槠林物种多样性均表现为灌木层>乔木层>草本层,而木荷林物种多样性大小则表现为乔木层>灌木层>草本层。演替过程中,乔木层、灌木层和草本层的物种多样性的变化幅度以草本层最大,H、JSW、JSI、D的变异系数分别为0.1572、0.0806、0.0899和0.1884;灌木层变化幅度最小,其H、JSWJ、SI、D的变异系数分别为0.0482、0.0385、0.0142和0.1553。     

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。     

林分因子对神木垒不同森林群落林下植物多样性的影响

为探究神木垒不同森林群落林下植物多样性的差异，本研究采用典型样地法，以夹金山神木垒的5种主要森林群落：云杉林、丽江云杉林、红杉林、针阔混交林、阔叶林为研究对象，对不同森林群落林下植物物种组成和物种多样性进行比较，并对林分因子和林下植物多样性进行冗余分析，确定影响林下植物多样性的主要林分因子，为当地森林经营管理提供理论依据。结果表明：（1）在研究区内共记录林下植物147种，隶属于61科，108属；云杉林群落林下植物的科属种组成最丰富。（2）各类型群落的H值、H"值、D值、JSW值均为：草本层＞灌木层；灌木层多样性最高的群落为云杉林群落，草本层多样性最高的群落为丽江云杉林群落，针阔混交林群落、阔叶林群落林下植物多样性较差。（3）平均枝下高与林分密度是影响灌木层物种多样性的主要林分因子（P<0.01），平均枝下高与灌木层的D值、H值、H"值呈负相关关系，林分密度与灌木层4个多样性指数均呈正相关关系；平均枝下高是影响草本层物种多样性的主要林分因子（P<0.01），平均枝下高与草本层H值、H"值、JSW值呈正相关关系。本研究认为，云杉林群落与丽江云杉林群落的林下植物多样性水平较高，平均枝下高与林分密度是影响神木垒不同森林群落林下植物多样性的主要林分因子。     

珠江流域中上游防护林冠层结构对林下植被的影响

防护林林下植被对水源涵养、土壤保育和提升生态服务功能具有重要意义。以珠江流域中上游广西都安县5种典型珠江防护林(桉树、任豆、马尾松人工纯林,马尾松+荷木人工混交林和青冈栎天然林)为研究对象,应用半球影像技术获取林分冠层结构(林冠开阔度CO和叶面积指数LAI)和林下光环境指标(林下直射光、林下散射光和林下总光照),并分析两组指标之间的关系及其对林下植被特征的影响。结果表明:1)马尾松+荷木混交林较人工纯林更有利于林下灌木层植被多样性的维持。2)各林分冠层结构与林下光照指标极显著相关(P0.001),冠层结构对林下散射光的影响比对林下直射光大。3)CO和林下光环境指标与灌木层物种丰富度(S)和多样性指数(H)呈极显著负相关(P0.001),较高的林下光照不利于林下灌木层植被多样性的维持。冠层结构是影响林下灌木层植物多样性和更新的关键因素,而灌木层和草本层种间竞争可能是影响物种多样性的另外一个重要因素。人工纯林改造和结构调整中,对乔木层可通过适当补植伴生树种,增加林下郁闭度,促进灌木层物种发育;对草本层可适度降低单优草本优势度,为灌木和幼苗更新提供空间。     

西双版纳热带山地雨林的植物多样性研究

 根据6块样地的调查资料,分析了西双版纳热带山地雨林植物多样性特征。结果表明：在2 500 m2的样地上,西双版纳热带山地雨林群落共有植物物种99～181种。其中乔木层的物种丰富度（S）为54～113,Shannon-Wiener指数（H′）为1.648 7～4.049 1,Simpson指数（λ）为0.503 5～0.969 5,Pielou 均匀度指数（Jsw）为0.413 3～0.854 9。灌木层的S为35～89,H′为2.413 2～3.716 2,λ为0.762 7～0.958 2,Jsw为0.678 8～0.859 3。草本层的各指数值：S为31～65,H′ 为2.792 1～3.499 2,λ为0.902 0～0.938 2,Jsw为0.729 3～0.838 2。低海拔带上的山地雨林（Ⅰ号、Ⅱ号样地）的各指数值（H′、λ、Jsw）在群落不同层次中均表现为草本层 > 灌木层 > 乔木层,而物种丰富度在不同层次中无一定变化规律;高海拔带上山地雨林（Ⅲ号、Ⅳ号、Ⅴ号、Ⅵ号样地）的物种丰富度和多样性指数（H′、λ）表现为乔木层 > 灌木层 > 草本层,而均匀度指数（Jsw）在不同层次中则无一定变化趋势。高海拔带上的山地雨林乔木层和灌木层的物种丰富度、多样性和均匀度指数均明显高于低海拔带上的山地雨林,这是由于前者所处生境较为优越。沿着海拔梯度,群落乔木层的物种丰富度、多样性和均匀度指数均在中等海拔高度地带（约1 200～1 220 m）达到最高值,这是由于中等海拔高度的山地雨林位于生境条件最为优越的沟谷地带,而且与低地季节雨林毗邻,热带雨林植物成分丰富。     

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.     

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.     

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.     

The mechanism of hatching of eggs of Haemonchus contortus

Fluid collected from hatching eggs of Haemonchus contortus contained a lipase which hydrolysed 2-naphthyl laurate (about 0·7 μmol naphthol freed /h/10⁶ eggs). The fluid also hydrolysed l-leucinamide (about 2·3 μmol leucine freed/h/10⁶ eggs). The fluid when added to normal or heated eggs caused ‘hatching’. ‘Hatching’ also occurred in exsheathing fluid from infective juveniles and in a preparation of pancreatic lipase containing leucine aminopeptidase. A purified mammalian leucine aminopeptidase in combination with several different lipases did not attack egg shells.The ‘spontaneous’ hatching of eggs of H. contortus was strongly inhibited by 1,10-phenanthroline, 10^?3M, and this inhibition was reversed by Zn²⁺. However, the inhibition of ‘hatching’ of eggs in externally applied hatching fluid, or the hydrolysis of leucinamide in hatching fluid was generally less marked.     

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.