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。     

长白山牛皮杜鹃群落物种多样性的海拔梯度变化及相似性

采用样地调查法,研究了牛皮杜鹃群落物种组成、群落结构特征、物种多样性及其沿海拔梯度的变化规律,对不同海拔牛皮杜鹃群落进行相似性分析。结果表明:(1)牛皮杜鹃群落相同海拔高度,草本层的物种多样性普遍高于灌木层的物种多样性。自海拔1926—1986m,灌木层α多样性指数先降低后升高,1986m后再次降低,到达海拔2010m处达到最低点,适应高山苔原带特殊生境条件的物种逐渐增多,多样性指数开始回升。海拔2250m,生物多样性指数的变化趋于平缓,物种组成相对较为稳定。海拔2528m以上,生物多样性再次呈降低趋势。草本层的α多样性指数中,物种多样性指数SW、丰富度指数D和均匀度指数R沿海拔梯度的变化趋势大致相同。海拔1986m处时出现最小值,海拔2350m时达最大值。牛皮杜鹃群落α多样性指数间呈P0.01水平极显著正相关性,物种丰富度指数对群落的物种多样性贡献率最大,表现为丰富度指数(D1、D2)种间机遇指数(H)生态优势度指数(SN)群落均匀度指数(R)。(2)牛皮杜鹃群落β多样性沿海拔梯度基本呈波形变化,草本层β多样性指数普遍高于灌木层β多样性指数。在牛皮杜鹃群落物种沿海拔梯度的替换速率上,草本植物高于灌木物种。Routledge指数的变化趋势不显著。海拔1986m处和海拔2250m处,草本层Cody指数出现两处极值,海拔2250m以上群落灌木层之间差异和变化较小,Whittaker多样性指数和Cody指数逐渐趋于平稳。(3)海拔梯度间生境及群落结构差异性越大,生物多样性变化越明显。海拔高度接近的群落间相似性系数较高,海拔是影响牛皮杜鹃群落差异的主要因素。     

太行山南段森林群落物种多样性研究

分别用多样性指数、丰富度指数、均匀度指数对山西太行山南段森林群落的物种多样性及其与环境的关系进行了分析.结果表明:(1)3个植被型的物种多样性指数的顺序为:落叶阔叶林>温性针阔叶混交林>温性针叶林.(2)落叶阔叶林中各群系的物种多样性指数的顺序为:漆树 青麸杨林>鹅耳枥 青榨槭林>青檀林>辽东栎林>栓皮栎林>白桦林>红桦林>山杨 白桦林.(3)温性针叶林中各群系的物种多样性指数的顺序为南方红豆杉林>油松林>白皮松林>侧柏林.(4)物种丰富度指数在群落梯度上的总体趋势表现为草本层>灌木层>乔木层;多样性指数的趋势则为灌木层>乔木层>草本层;各群落灌木层物种均匀度指数大于乔木层和草本层,乔木层均匀度与草本层相差不明显.(5)各群落多样性指数在海拔梯度上表现出明显的规律,呈单峰曲线变化,即中等海拔高度上的群落物种多样性较高,而高海拔和低海拔多样性较低,这主要是由于在中海拔(大约1 500 m)地段水热条件组合较好、人类活动干扰较少所致.     

退化土地植被恢复群落物种多样性与生物量分配格局

研究了湘西北女儿寨小流域7种典型植被恢复群落生物量的空间分配格局、物种多样性特征及其相互关系。结果表明:1)润楠次生林乔木层生物量最高,马尾松天然林灌木层生物量最大,油桐人工林草本层生物量最高,乔木层最低,毛竹-杉木林灌木层与草本层生物量最小,群落总生物量以马尾松天然林群落最高,荒草灌丛群落最低。2)乔木层物种以润楠次生林最丰富,多样性指数最高,物种分布最均匀;灌木层物种丰富度以毛竹-杉木混交林最高,油桐人工林多样性与均匀度指数最大,优势度最小,荒草灌丛群落的物种丰富度、多样性及均匀度最低;草本层物种丰富度以油桐人工林最高,马尾松天然林最低,杉木人工林草本层多样性指数与均匀度指数最大,润楠次生林优势度最高;群落总体物种丰富度以油桐人工林最高,润楠次生林群落的多样性指数最高,种群分布最均匀,荒草灌丛群落的多样性、均匀度与优势度都最低。3)女儿寨小流域退化土地物种丰富度与群落生物量之间的关系可用"S"曲线较好地描述,双曲线能较好地描述群落多样性指数、群落均匀度指数与生物量之间的关系,而生态优势度与生物量之间为非性线关系。     

北京松山自然保护区森林群落物种多样性及其神经网络预测

物种多样性是群落结构和功能复杂性的一种度量,物种多样性的空间分布格局受许多环境因子的影响.运用多样性指数,多层感知器网络,分析了松山保护区森林群落物种多样性与群落类型、结构和生境之间的关系.结果表明:(1)大果榆+山杨混交林、油松+青杨混交林物种丰富度、多样性和均匀度均较高,而大果榆林、华北落叶松林的各项指数值均较低.Patrick指数和Shannon-Weiner指数在森林群落中均表现为草本层＞灌木层＞乔木层;Pielou指数在榆林中表现为草本层＞乔木层＞灌木层,而在其他森林群落中表现为灌木层＞草本层＞乔木层.(2)功能层物种多样性在海拔梯度上的变化趋势不同,在乔木层,丰富度、多样性和均匀度随海拔的升高逐渐降低;在灌木层,丰富度、多样性和均匀度均呈比较明显的单峰曲线变化趋势;在草本层,丰富度和多样性随海拔的升高都呈下降趋势,而在草本层,均匀度变化不大.(3)用多层感知器网络预测功能层多样性效果很好,结果发现坡向对乔木层和灌木层物种多样性的影响最大,而海拔高度对草本层物种多样性的影响最大.     

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。     

历山森林群落物种多样性与群落结构研究

采用多样性指数、丰富度指数和均匀度指数对山西历山森林群落物种多样性进行了研究.结果表明,各群落类型的物种多样性指数的顺序为：青榨槭＋五角枫林>青榨槭＋鹅耳枥林>辽东栎林>栓皮栎林>华山松＋红桦林>油松＋栎林>白桦林>侧柏＋栓皮栎林>红桦林>华山松林>侧柏林>油松林>红桦＋山杨林;森林群落灌木层多样性指数和丰富度指数大于草本层和乔木层,而均匀度指数在乔木层、灌木层和草本层则表现出多样化的趋势;海拔1 000～1 920 m之间,Shannon-Wiener指数、Hill多样性指数及物种丰富度与海拔梯度均呈正相关(P<0.05),海拔大于1 920 m则呈现负相关;这些指数沿海拔梯度的变化呈现出“中间高度膨胀”的规律,即中等海拔高度上物种多样性高而低海拔和高海拔物种多样性低.这主要是由于在中海拔（约1 900 m）地段水热条件组合较好,人类活动干扰较少所致.     

中国神农架地区的植被制图及植物群落物种多样性

在野外调查、资料搜集的基础上 ,辅以全球定位系统 (GPS)、GIS软件及 TM影像数据 ,绘制了该地区 1∶ 2 0万的植被类型图。制图结果表明 :1)制图区总面积 3476 .6 7km2 ,共计 5 0 4个斑块。 2 )神农架地区林地面积 2 ,6 0 7.4 5 km2 ,占该地区总面积的 75 % ;山地灌丛及亚高山灌丛总面积 35 8.6 2 km2 ,占总面积的 10 .3% ;草甸面积 15 6 .84 km2 ,占 4 .5 1%。 3)自然植被划分为8个植被型 ,4 6个群系以及农田 (居民点 )和茶园两种农业土地利用类型。其中针叶、落叶阔叶混交林面积最大 ,为 90 8km2 ,占总面积的 37.88%。 4 )对神农架地区 8个植被型中的 4 6个群系进行的群落物种 Shannon- Wiener多样性指数 (H′)及 Pielou均匀度指数 (J)的测定结果表明 ,1各群落物种多样性总趋势是 :灌木层 >草本层 >乔木层 (个别群落除外 ) 2与天然林相比 ,人工林群落内各层次结构相对简单 ,物种多样性较低。3针叶林 (7个群系 )和针阔叶混交林 (6个群系 )中 ,低海拔人工林群落各层次及高海拔天然林乔木层结构简单 ,伴生种类较少 ,物种多样性低。高海拔天然林群落灌木层和草本层物种多样性相对高 ,H′值一般在 1.2～ 2之间 ,J值在 0 .5～ 1之间。草本层物种多样性变化明显 ,低海拔区域较低。4分布于低海拔峡谷地带的常绿     

人为干扰对雅安莲花山青冈次生林群落结构和物种多样性的影响

以四川省雅安莲花山为研究区,采用典型样地法分别调查轻度、中度和重度人为干扰对青冈(Cyclobalanopsis glauca)次生林不同林分层次的物种组成、群落结构和物种多样性的影响。采用物种丰富度指数(S)、Shannon-Wiener指数(H)、Simpson优势度指数(H′)和均匀度指数(Jsw)来综合分析群落的物种多样性水平。结果表明:(1)在总面积为3 600m2的9个样地中,共记录到维管束植物161种,隶属于83科134属,以禾本科(Gramineae)、樟科(Lauraceae)、壳斗科(Fagaceae)、山茶科(Theaceae)等植物为主。(2)不同强度人为干扰下青冈次生林的群落结构不同,受轻度和中度干扰的群落乔木层处于小径级(胸径8cm以下)、低高度级(高度3~7m)的幼苗较多,林分具有潜在的天然更新能力,受重度干扰下群落乔木小径级、低高度级个体数少,群落结构不稳定,林分生产力低。(3)不同强度人为干扰下青冈次生林群落重要值差异显著,轻、中、重干扰下乔木层优势种数量差别不明显,物种组成单一;灌木层重度干扰下小果润楠(Machilus microcarpa)占据绝对优势地位;草本层优势种在中度干扰下数量最多。(4)随着人为干扰强度的增加,青冈次生林群落的S、H、H′和Jsw降低,群落物种多样性整体呈下降趋势。     

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。     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Apoptotic Regulation of Caspase Activity

Intracellular cysteine aspartate-specific proteases (caspases) play both signaling and effector roles in realizing the program of cell death. Caspases function as proteolytic cascades unique for each cell type and signal triggering apoptosis. All parts of the proteolytic cascades are duplicated and controlled by feedback signals. Amplification cycles between pairs of caspases (the third and the sixth, the ninth and the third, the twelfth and the sixth, and others) help multiply the initial apoptotic signal. The presence of physiological inhibitors of apoptosis that directly interact with caspases creates a multilevel regulatory network of apoptosis in cell. The caspase proteolytic cascades are also regulated by sphingolipid secondary messengers, among them ceramide, sphingosine, and their phosphates. Moreover, an association of the caspase signaling with ubiquitin-dependent proteolysis is shown in cells. In particular, the use of extracellular activators and inhibitors of caspases allows irreversible activation of apoptosis in tumor cells or the prevention of apoptosis in cortical neurons under neurodegenerative diseases.     

Analysis of twin of eyeless regulation during early embryogenesis in Drosophila melanogaster

The Drosophila Pax6 homolog twin of eyeless (toy) is so far the first zygotically expressed gene involved in eye morphogenesis in Drosophila. The study of its expression during embryogenesis is therefore informative of the initial events of eye development in Drosophila. We have analyzed how the initial expression domain of toy at cellular blastoderm is regulated. We show that the three maternal patterning systems active in the cephalic region (the anterior, terminal and dorsal-ventral systems) cooperate with zygotically activated gap genes to shape the initial expression domain of toy. Whereas Bicoid, Dorsal and Torso signaling synergistically act as activators, Hunchback, Knirps and Decapentaplegic act as repressors.     

New species of Peruvian Orchidaceae III

Sixteen new species are proposed in the generaAckermania, Dressleria, Epidendrum, Maxillaria, Oncidium, Rodriguezia, Sigmatostalix, andTrigonidium. All new species are illustrated.Maxillaria vittariifolia L. O. Williams is newly recorded for Peru. A key is provided forTrigonidium of Peru.Trigonidium loretoense Schltr. andT. peruvianum Schltr. are lectotypified.     

Host plants of someRhinanthoideae (Scrophulariaceae) of eastern North America

Twenty three species in 11 genera were examined in the field to determine hosts. OnlyStriga asiatica andSeymeria cassioides have a narrow host range being restricted to grasses and pines, respectively. These are the only species which cause pronounced and sometimes serious host damage. The other species attach to a great diversity of hosts.     

广西青藓科分类学修订

通过对采自广西24个县(市)的1 147份青藓科植物标本的逐一鉴定及相关文献的查阅,确认有广西青藓科植物11属、44种,其中包括广西青藓科植物新记录属1属,即拟异叶藓属(Pseudokindbergia),新记录种7种,分别为匐枝青藓(Brachythecium procumbens)、阔叶尖喙藓(Oxyrrhynchium latifolium)、泛生尖喙藓(O. vagans)、拟异叶藓(Pseudokindbergia dumosa)、华东细喙藓(Rhynchostegiella sinensis)、长肋拟青藓(Sciurohypnum populeum)和弯叶拟青藓(S. reflexum)。该文提供了修订后的广西青藓科植物名录,并对其中的新记录属、种的主要形态学识别特征、生境和地理分布等进行了详细描述。     

In vitro appraisal of the probiotic value of intestinal lactobacilli

Lactobacilli play a distinctive role in the microbial balance of the chicken gut. In experiments simulating the chicken crop, the antagonism of lactobacilli against Enterobacteriaceae and Salmonella typhimurium was demonstrated and was attributed to lactic acid production. Moreover, adhesion to the crop epithelium was a common characteristic of intestinal lactobacilli. As opposed to salmonellas, lactobacilli were sensitive to deconjugated bile salts at 2.5mm. This sensitivity could lower their chance of proliferation in the small bowel of the chicken tract.The authors are at the Laboratory of Microbial Ecology, Faculty of Agricultural Sciences, State University of Gent, Coupure L., 653, B-9000 Gent, Belgium.