辽宁白石砬子国家级自然保护区植物区系的多样性

通过多样性指数、植物区系谱、相关分析和聚类分析等方法,对辽宁白石砬子国家级自然保护区植物区系多样性进行定量分析。结果表明:该区植物种类丰富,以被子植物、双子叶植物为主,优势科、属现象明显,单种属和少种属比例较高,有一定残遗性;种的分布型多样,来源较广泛,特有性不明显,区系温带属性较强,热带成分比较少,表明该区温带植物区系历史起源;与相邻植物区系多样性比较,Shannon-Wiener指数差异显著,其中泰山和昆嵛山较高,白石砬子和长白山较低,Simpson指数差异不明显;不同山地植物区系之间相似程度显著,相关系数为0.839～0.995,聚类分析显示:东北和华北植物区系的相似性及纬度分布格局,支持辽东半岛植物小区划归于华北山地植物亚地区的观点。     

Generation and maintenance of gradients in taxonomic diversity

Latitudinal gradients in diversity of organisms represent an equilibrium distribution for at least the last 270 x 10(6) years. Faunas endemic to tropical regions evolved significantly faster than extra-tropical faunas. The latitude-dependent difference in rates of evolution also represents an equilibrium condition for at least the last 270 x 10(6) years and has consequences for paleontological correlation of rocks because the attainable resolution depends on rate of evolution and will thus be greater in tropic regions than in extra-tropical ones.     

Evidence for low temperatures and biologic diversity in cretaceous high latitudes of australia

A diverse terrestial biota inhabited polar latitudes during the Cretacous, 105 to 130 Ma (million years ago), along what is now the southeast coast of Australia This biota, from rocks in the Otway and Strzelecki groups, cnsisted of more than 150 taxa of vertebrates, invertebrates, and plants. Oxygen isotope ratios in diagenetic calcite suggest that mean annual temperatures were most likely less than 5 degrees C, and rings present in the fossil araucarian-podocarp-ginko woods indicate saonality. Southeastern Austalia, thus, seems to have had a cool, seasonal, nontropical climate. Dinosaurs that have been recovered are up to five species and three genera of hypsilophodontids, all of which were endemic, and three species of theropods. The occurrence of Allosaurus sp. and labyrinthodont amphibians, which had become extinct elsewhere in the Jurassic, indicate that isolation may have allowed extended surival of these taxa in Australia. In that dinosaurs coped with high latitude for at least 65 million years [Valaginian to Albian time in Australia and Campanian to Maastrictian time (80 to 65 Ma) in Alaska] suggests that cold and darkness may not have been prime factors bringing about the extinction of dinosaurs and some other groups at the Cretaceous-Tertiary boundary, unless they were prolonged.     

增城市小楼西境村风水林植物多样性的保护与利用

利用样方调查法研究了增城市小楼西境村风水林的群落组成和结构.结果表明:在2400 m2的样方中,共记录了维管植物81种,隶属40科68属;该风水林乔木层优势种为白颜树、黄杞、竹节树和黄果厚壳桂等,灌木层优势种为九节、竹节树、中华卫矛、罗伞树和黄果厚壳桂等,草本层优势种为沙皮蕨、华山姜和黄果厚壳桂等;黄果厚壳桂在3个层次中均有分布,其种群呈金字塔型结构,Ⅰ级和Ⅱ级苗木贮备丰富,但小树和大树少.最后,针对西境村风水林的开发利用现状,对该风水林资源的保护与可持续利用提出了建议.     

白龙江中上游林区种子植物物种多样性与区系特征

在收集已有文献资料和补点调查的基础上,对白龙江中上游林区天然分布的种子植物进行了物种多样性和区系统计分析.结果表明:本区天然分布的种子植物共计有1 528种,1亚种,80变种,6变型,归属于115科,519属,其中木本植物565种;该区种子植物区系由多种地理成分组成,以温带成分占据绝对优势,温带分布属占75.1%,温带分布种占72.9%,表现出明显的区系过渡性;本区应划归中国-喜马拉雅森林植物亚区、横断山脉地区.     

Lepidoptera in cretaceous amber

The discovery of the head capsule of a lepidopterous larva in Canadian amber of the Cretaceous period is the first fossil evidence of Lepidoptera before the Tertiary period.     

被子植物芽的类型

芽的特征在被子植物分类、生态等研究以及在农业和林业等行业生产实际中具有一定的意义。该研究归纳了被子植物芽的类型。类型划分的依据包括着生位置、形态特征、活动状态、季节性特征、发育阶段和状态以及生活型方面。类型包含不常见的隐芽等以及近些年提出的拟花芽。     

白龙江干旱河谷木本植物多样性及其区系地理特征

基于历年植物区系调查和补点采集,对白龙江流域干旱河谷地带木本植物区系进行了物种多样性统计和区系分析.结果表明:白龙江流域干旱河谷地带木本植物计有59科、138属、269种、1亚种、26变种、2变型.组成群落的建群种或优势种约有50余种.世界分布属、热带分布属和温带分布属分别占本区木本植物总属数的5.1%、31.3%和66.4%,植物区系整体具有明显的温带属性,在起源上也与热带、亚热带植物区系有一定的渊源关系.木本植物的个体和营养器官对干暖河谷生境具有多样化的适应形式,以落叶、植株矮化、减少叶面积、阻滞蒸散、枝叶刺化为主要适应途径.主要生长型为落叶阔叶小乔木和低矮落叶阔叶灌木,落叶树种占总种数的90.33%.叶级以小型叶为主,占总种数的57.99%,其次是微型叶和中型叶,分别占26.77%和10.78%.叶片质地多半为中生形态草质叶和以坚纸质叶和薄革质为主的旱生形态硬叶.很多种以叶片被毛或鳞片和枝叶刺化适应干旱生境.依据优势种原则将干旱河谷木本植物群落大致划分为38个群系,其中落叶阔叶灌丛有28个群系,是构成干旱河谷植被的主体,其次为常绿针叶林、落叶阔叶林和半灌木灌丛.     

云南省石葵河不同海拔梯度的植物多样性分析

石葵河作为丘北县的主要河流,对当地的经济和环境发展有着重要的作用。通过对石葵河山区植物多样性的调查分析,以达到对山区不同海拔植物进行合理配置,为后期的研究提供理论依据。通过典型样地采样分析,结果表明在海拔950~1 200 m范围内共有6个典型群落,其中海拔1 050 m以下主要以灌木和草本为主,海拔1 050 m以上主要以乔木和灌木为主;Simpson优势度指数、Shannon-Wiener多样性指数和Pielou均匀度指数基本变化趋势相同,总体规律为灌木层草本层乔木层;乔灌木多样性受海拔影响较大,草本较小,群落多样性指数在海拔1 050 m为灌木层乔木层草本植物层,在海拔1 200 m为草本层灌木层乔木层,整体上石葵河山区植被多样性随着海拔的升高而降低。     

内蒙古被子植物分布新记录

报道了内蒙古被子植物新记录2个属:车前科(Plantaginaceae)水八角属(Gratiola)和莎草科(Cyper-aceae)水蜈蚣属(Kyllinga),对2个新记录种白花水八角(Gratiola japonica Miq.)和短叶水蜈蚣(Kyllinga brevifolia Rottb.)进行了描述.所有凭证标本存放在内蒙古毕拉河自然保护区标本室.     

山西被子植物属种新资料

报道了山西被子植物2个新记录属,即马兜铃科(Aristolochiaceae)马蹄香属(Saruma Oliv.)和荨麻科(Urticaceae)花点草属(Nanocnide Bl.),以及被子植物新记录5种——马蹄香(Saruma henryi Oliv.)、紫花前胡(Angelica decursiva(Miquel) Franchet et Savatier)、花点草(Nanocnide japonica Bl.)、宝珠草[Disporum viridescens(Maxim.)Nakai]和饭包草(Commelina benghalensis Linnaeus),并列出每个种的标本引证和地理分布,凭证标本保存于山西大学标本馆(SXU)。     

被子植物的试管受精及其意义

对被子植物广义的试管受精进行了综述，对不同时期、不同研究方法和实验手段以及研究结果予以总结，并简述了植物试管受精的理论意义。     

Reproductive and vegetative morphology of a cretaceous angiosperm

Recent collections from plant-bearing deposits of Cenomanian age in central Kansas have yielded angiosperm axes with helically arranged, seed-bearing, conduplicate carpels. Large leaves associated with these fruits are thought to represent parts of the same kind of plant because the leaves and fruits are the only plant fossils at this locality to have distinctive, morphologically identical, yellow bodies within their carbonaceous remains. These fossils provide a rare opportunity to study the morphology of an ancient angiosperm and illustrate the antiquity of certain features considered primitive by comparative angiosperm morphologists.     

Avascular necrosis: occurrence in diving cretaceous mosasaurs

A study of vertebrae of extinct giant marine lizards showed the presence of avascular necrosis in two of the three most common genera of these mosasaurs, Platecarpus and Tylosaurus. This bone disease was invariably present (involving 5 to 66% of vertebrae) in these genera, but absent in a third genus Clidastes. Differential occurrence of avascular necrosis may be related to decompression syndrome, suggesting different habitat and diving habits of the respective genera.