安徽省皇藏峪自然保护区森林植被的数量分类

本文用聚类分析的方法,将皇藏岭自然保护区的森林植被划分出1个植被型,2个群系组和7个群系。并分别描述了各群系的主要群落学特征。通过排序揭示出植被沿水分梯度变化、分布的规律。样地在二维空间中集散分布的特点进一步印证了聚合分类的可信性结果。     

中条山混沟地区森林乔木种的数量分类与环境解释

通过对中条山混沟地区森林植被调查资料的多元分析——TWINSPAN分类、CCA排序与环境解释,划分了该地区的植被类型,给出了植被与环境因子的定量关系。结果如下:1)40个样地可划分为青檀林(Form.Pteroceltis tatarinowii)、栾树林(Form. Koelreuteria paniculata)、槲栎林(Form. Quercus aliena)、栓皮栎林(Form. Quercus variabilis)、鹅耳枥+葛萝槭林(Form. Carpinus turczaninowii+Acer grosseri)、元宝槭+千金榆林(Form. Acer truncatum+Carpinus cordata)和辽东栎林(Form. Quercus liaotungensis)7种群落类型,体现了中条山地带性植被类型为暖温带落叶阔叶林的特点。2)群落类型的划分主要反映了CCA排序第一、二轴的环境梯度,CCA排序第一轴突出反映了海拔与土壤养分梯度,第二轴与土壤pH值、湿度指数和坡度显著相关。总体来说,海拔和土壤因子是影响混沟地区乔木物种分布分异的最主要环境因子。3)环境因子和空间因子解释了物种格局变化的46.14%,其中环境因子占30.79%,空间因子占8.48%,空间因子和环境因子交互作用解释的部分占6.87%。良好的环境解释反映了调查取样和环境因子选取的合理性,同时也体现了混沟地区植被的原始性。     

准噶尔盆地东部卡拉麦里山有蹄类自然保护区主要植物群落及其特征

该文调查了准噶尔盆地东部卡拉麦里山自然保护区的主要植被类型, 通过对54个样地的样方数据分析, 量化描述了这一保护区的主要植物群落特征。结果表明, 这一地区植被主要分为梭梭群系(Form. Haloxylon ammodendron)、驼绒藜群系(Form. Krascheninnikovia ceratoides)、刺木蓼群系(Form. Atraphaxis spinosa)、红砂群系(Form. Reaumuria songarica)、准噶尔沙蒿群系(Form. Artemisia songarica)、刺旋花群系(Form. Convolvulus tragacanthoides)、盐生假木贼群系(Form. Anabasis salsa)、沙生针茅群系(Form. Stipa glareosa)和白茎绢蒿群系(Form. Seriphidium terrae-albae)等9个主要群系, 并进一步划分出16个群丛。     

遥感判图植被类型的研究

认识一个地区的植被,首先涉及到的是鉴别植物类型和植被分类问题.《中国植被》分出29个植被型,560余个群系,植被类型描述的主要对象是群系[1].《云南植被》根据所采用的植被分类原则和依据,划出12个植被型,169个群系和209个群丛,植被分类至群丛一级[2].面对如此庞大的分类系统,在中比例尺图上却只能反映到植被亚型和群系.为满足本课题研究目标,我们采用以反映现状植被的原则,便于今后动态监测.经过近二年的研究,金沙江流域(云南部份)1.091×105km2范围内有自然植被和栽培植被共23个植被类型,制作了1:250000的数字化植被图.     

中国东北西部地区沙质荒漠化过程与植被动态关系的生态学研究：植被的分类

根据东北沙质荒漠化地区呼化贝尔沙地、科尔沁沙地的７２个沙地植物群落样地、２７６种植物的调查数据,进行双向指标种分析（ＴＷＩＮＳＰＡＮ）,结合ＤＣＡ排序得到符合客观实际的分类结果,初步建立了中国东北沙质荒漠化地区植被分类系统,６个植被型,１１个植被亚型,４０个群系,５５个群丛。     

高黎贡山北段植物群落TWINSPAN 数量分类研究

采用TWINSPAN 数量分类方法对高黎贡山北段植物群落进行研究, 将研究区68 个样地归并为18 个聚组, 并参照《云南植被》和《中国植被》的分类原则和系统将研究区植物群落划归为6 个植被型、7 个植被亚型、7 个群系组、10 个群系和18 个群落; TWINSPAN 数量分类反映了群落分布随海拔和干扰变化的规律。     

贺兰山西坡主要山地灌丛群落的基本特征

灌丛是贺兰山最主要的植被组分, 但关于该地区灌丛群落的专门研究并不多见。为了解该地区灌丛资源的分布及生长状况, 该研究对内蒙古贺兰山国家级自然保护区内主要的山地灌丛群落进行样方调查, 通过分析样方数据, 量化描述了各群落的基本特征。结果表明: 贺兰山自然保护区沿海拔梯度主要有准噶尔栒子群系(Form. Cotoneaster soongoricus)、紫丁香群系(Form. Syringa oblata)、小叶金露梅群系(Form. Potentilla parvifolia)、虎榛子群系(Form. Ostryopsis davidiana)、小叶忍冬群系(Form. Lonicera microphylla)、银露梅群系(Form. Potentilla glabra)、山生柳群系(Form. Salix oritrepha)和鬼箭锦鸡儿群系(Form. Caragana jubata) 8种主要的山地灌丛群系。     

高黎贡山北段植物群落TWINSPAN数量分类研究

采用TWINSPAN数量分类方法对高黎贡山北段植物群落进行研究,将研究区68个样地归并为18个聚组,并参照《云南植被》和《中国植被》的分类原则和系统将研究区植物群落划归为6个植被型、7个植被亚型、7个群系组、10个群系和18个群落;TWINSPAN数量分类反映了群落分布随海拔和干扰变化的规律。     

Species composition and structure characteristics of the major montane shrub communities in the west slope of Helan Mountains,Nei Mongol,China

灌丛是贺兰山最主要的植被组分, 但关于该地区灌丛群落的专门研究并不多见。为了解该地区灌丛资源的分布及生长状况, 该研究对内蒙古贺兰山国家级自然保护区内主要的山地灌丛群落进行样方调查, 通过分析样方数据, 量化描述了各群落的基本特征。结果表明: 贺兰山自然保护区沿海拔梯度主要有准噶尔栒子群系(Form. Cotoneaster soongoricus)、紫丁香群系(Form. Syringa oblata)、小叶金露梅群系(Form. Potentilla parvifolia)、虎榛子群系(Form. Ostryopsis davidiana)、小叶忍冬群系(Form. Lonicera microphylla)、银露梅群系(Form. Potentilla glabra)、山生柳群系(Form. Salix oritrepha)和鬼箭锦鸡儿群系(Form. Caragana jubata) 8种主要的山地灌丛群系。     

神农架川金丝猴栖息地森林群落的数量分类与排序

在神农架川金丝猴生境典型地段设立样方58块,根据样方资料对神农架川金丝猴栖息地的森林群落用组平均法分类和DCA排序.用组平均法将58块样地分为9个群系,依据《中国植被》的分类原则和系统将研究区植物群落划归为7个植被型.样地的DCA排序较好地揭示了该区森林群落的分布格局与环境梯度的关系;DCA第二轴明显地反映出森林群落的海拔梯度变化,沿DCA第二轴从右到左,海拔逐渐升高;第一轴表现了各植物群落或植物种所在环境的坡度、坡向,即水分和光照因素,沿第一轴从下到上,坡度渐缓、坡向渐向阳.其中海拔梯度是环境因子中对森林群落起决定性作用的因子.研究表明,巴山冷杉+糙皮桦-大齿槭+尾萼蔷薇-高原露珠草+星果草群系发育较好,高大树木占有较大的比例,是神农架川金丝猴最适宜栖息地.7个植被型物种丰富度指数在群落梯度上呈规律性波动.其中针叶林和针叶-阔叶混交林中,物种丰富度指数在群落梯度上的总体趋势表现为灌木层＞草木层＞乔木层;在常绿阔叶林和常绿-落叶阔叶混交林中,该趋势为灌木层＞乔木层＞草本层;在落叶阔叶林中,其丰富度指数的趋势为灌木层＞草本层和乔木层.不同植被类型川金丝猴食源植物种类在群落梯度上的变化趋势与物种丰富度指数相同,但地衣类植物作为川金丝猴冬季的重要食物只在针叶林和针叶-阔叶混交林中生长.本研究为制定栖息地保护计划,更好地保护神农架川金丝猴提供了科学理论依据.     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.