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1.
在传统的植物群落分类系统中,群丛是植物群落分类的基本单位.从群丛分类的必要性出发,综述了传统植物群落分类系统中对群丛的定义及其划分方法,即在群丛的划分中主要依据群落中不同层片的优势种或特征种;但是在利用传统植物群落分类方法划分群丛时也存在一些不确定性因素,主要表现在确定群丛的特征种(组)时需要人为确定;同时,论述了当前植物群落数量分类的研究现状,分析了利用双向指示种分析法(TWINSPAN)、主成分分析(PCA)等数量分类方法划分群丛时存在的一些问题,主要表现在数量分类结果与传统分类单位的对应关系不能达到协调一致,无法判断是否划分到了群丛的水平.最后提出了群丛划分方法的展望:数量方法是基础,特征种(组)是及其数量特征是关键.  相似文献   

2.
景观分类的研究进展与发展趋势   总被引:2,自引:0,他引:2  
景观分类既是景观结构、过程和功能研究的基础,又是开展景观评价、规划、保护和管理的前提条件,直接影响景观研究结果的精度和实用性.本文综述了国内外景观分类系统、理论、方法体系等,总结了目前研究中存在的主要问题和不足.同时系统介绍了LANMAP、MUFIC等景观分类体系.最后指出基于功能结构形态分类思想以及综合考虑景观分类实用目的、景观功能、景观结构、自然地理因子、人类活动的干扰强度等多种因素的定性和定量综合分类方法是未来该研究领域的发展方向;综合运用地学图件、3S技术、数学定量模型、计算机人工智能、专业学科知识等多种方法以提高景观分类体系的科学性和分类结果的精度水平,将是未来景观分类研究的重点和发展趋势.  相似文献   

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Relationship between species in the genus Rosa, section Pimpinellifoliae   总被引:1,自引:0,他引:1  
The morphology of twelve species of Rosa is described and similarities between these species are assessed. Possible origins of the tetraploid species from diploid species are indicated on grounds of comparative morphology.
The wild origins of living and herbarium specimens are given in order to supplement published data on geographical distribution.
Meiosis in pollen mother cells, viability of pollen grains at anthesis and ability to set seed was studied in several F1 hybrids: no indication of complete or even partial sterility was found. Reproductive isolation is therefore unlikely to be maintained by reduced fertility of interspecific hybrids.
Three species are reduced to synonymy with three other species, being retained as subspecific taxa. Two species are transferred from section Pimpinellifoliae to section Cinnamomeae.  相似文献   

6.
A Newly Revised Classification of the Protozoa*   总被引:1,自引:0,他引:1  
SYNOPSIS The subkingdom Protozoa now includes over 65,000 named species, of which over half are fossil and ~ 10,000 are parasitic. Among living species, this includes ~ 250 parasitic and 11,300 free-living sarcodines (of which ~ 4,600 are foraminiferids); 1.800 parasitic and 5,100 free-living flagellates: ~ 5,600 parasitic “Sporozoa” (including Apicomplexa, Microspora, Myxospora, and Aseetospora); and ~ 2,500 parasitic and 4,700 free-living ciliates. There are undoubtedly thousands more still unmamed. Seven phyla of PROTOZOA are accepted in this classification—SARCOMASTIGOPHORA. LABYRINTHOMORPHA, APICOMPLEXA, MICROSPORA, ASCETOSPORA, MYXOSPORA, and CILIOPHORA. Diagnoses are given for these and for all higher taxa through suborders, and representative genera of each are named. the present scheme is a considerable revision of the Society's 1964 classification, which was prepared at a time when perhaps 48,000 species had been named. It has been necessitated by the acquisition of a great deal of new taxonomic information, much of it through electron microscopy. It is hoped that the present classification incorporates most of the major changes that will be made for some time. and that it will be used for many years by both protozoologists and non-protozoologists.  相似文献   

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Previous classification of the Disinae has been based almost entirely on floral morphological data. These data are critically assessed by various methods to determine to what extent they support a classification resolved to sectional level. The variation in the characters relative to the sections and genera is mapped, homologies are established by careful morphological observation and ontogenetic studies, and finally hypotheses of homology are tested by congruence in several cladistic analyseS. It is found that although floral morphology allows the recognition of some groups, for others the results are ambiguouS. Floral morphological data are clearly inadequate to establish the taxonomy of the Disinae on a sound footing.  相似文献   

9.
群落排表分类的两种数学方法   总被引:6,自引:0,他引:6  
张金屯 《植物研究》1994,14(2):179-185
本文描述两种执行群落排表分类的数学方法:X2分类法和信息熵分类法,并以德国西北部草地数据为例进行了应用和分析。结果表明这两个方法都是有效的群落排表分类方法,它们所排的群落表可直接地反映群落类型和种类组成之间的关系,体现了Braun-Blanquet传统排表法的特点。  相似文献   

10.
ZHU Hua 《Plant Diversity》2007,29(4):377-387
Xishuangbanna of southern Yunnan is a region of extremely interest to biologists and also a hotspot for biodiversity conservation . It is located in a transitional zone from tropical Southeast Asia to temperate East Asia biogeographically. The present paper reviewed vegetation types of Xishuangbanna and suggested a revised classification system based on theupdated study results over the last two decades . By combining physiognomic and floristic characteristics with ecological performances and habitats , the primary forest vegetation in Xishuangbanna can be organized into four main vegetation types: tropical rain forest, tropical seasonal moist forest, tropical montane evergreen broad-leaved forest and tropical monsoon forest. The tropical rain forest can be classified into two subtypes , i. e. tropical seasonal rain forest in the lowlands and tropical montane rain forest on higher elevations. The tropical seasonal rain forest in this region shows similar forest profile and physiognomic characteristics to those of equatorial lowland rain forests and is a type of world tropical rain forest. Because of conspicuous similarity on floristic composition , the tropical seasonal rain forest in Xishuangbanna is a type of tropical Asian rain forest . However , since the tropical seasonal rain forest occurs at the northern edge of tropical SE Asia, it differs from typical lowland rain forests in equatorial areas in maintaining some deciduous trees in the canopy layer , fewer megaphanerophytes and epiphytes but more abundant lianas and more plants with microphyll . It is a type of semi-evergreen rain forest at the northern edge of the tropical zone . The tropical montane rain forest occurs in wet montane habitats and is similar to the lower montane rain forests in equatorial Asia in floristic composition and physiognomy . It is a variety of lower montane rain forests at the northern tropical edges of tropical rain forests . The tropical seasonal moist forest occurs on middle and upper limestone mountains and is similar to the tropical montane evergreen broad-leaved forest of the region in physiognomy, but it differs from the latter in floristic composition. The monsoon forest in Xishuangbanna is a tropical deciduous forest under the influence of a strong monsoon climate and is considered to be a transitional vegetation type between tropical rain forest and savanna in physiognomy and distribution. The tropical montane evergreen broad- leaved forest is the main vegetation type in mountain areas . It is dominated by the tree species of Fagaceae , Euphorbiaceae , Theaceae and Lauraceae in majority. It differs from the tropical montane rain forests in lack of epiphytes and having more abundant lianas and plants with compound leaves . It is considered to be a distinct vegetation type in the northern margin of mainland southeastern Asia controlling by a strong monsoon climate, based on its floristic and physiognomic characteristics.  相似文献   

11.
An ecological classification of surface waters in the Netherlands is presented. This classification is based on literature data and the authors opinions concerning the habitat range of macroinvertebrate taxa. Water types were defined by key factors. Taxa were assigned to these water types and provided with a characterizing weight. The list may be a useful tool in the ecological management of waters.  相似文献   

12.
The family-group classification of conodonts presented in the revised edition of the Treatise on Invertebrate Paleontology, Part W, Supplement 2, Conodonta, published in 1981, is shown to contain errors with regard to the International Code of Zoological Nomenclature. The classification lacks a concise philosophical and methodological foundation and exhibits very poor conceptualization of the taxa it recognizes. The classification is analyzed and discussed in terms of, among Linnkan taxonomists, generally accepted objectives and conventions with regard to the internal structure and phylogenetic message of a hierarchical natural classification. The obvious errors in terms of the ICZN are pointed out and corrected. As a demonstration of an alternative approach, a classification of the superfamilies Prioniodontacea, Hibbardellacea, and Icriodontacea is presented.  相似文献   

13.
Variation in foliar trichomes in Croton (Euphorbiaceae) is reviewed, and the terminology clarified by redefinitions and illustrations of terms. Evolution of trichome types appears to proceed from branched (stellate or fasciculate) hairs to simple and dendritic ones. A systematic enumeration characterizes the trichome morphology in 36 of the 40 sections, with citation of the 120 species examined.  相似文献   

14.
Often we encounter a misunderstanding based on the assertion that the criterion of air quality is excluded from studies into meteorology and climatology. In contrast to this, it must be stressed that the admixtures and pollutants pertaining to air quality criteria belong to the atmosphere and therefore, of course, to the field of meteorology, and due to their possible effects also to human biometeorology. A normal weather forecast should include data concerning the concentrations of ozone, nitrogen dioxide, and other substances. Biometeorological weather classifications should also include mention of air quality rather more than previously. For instance, the classification after Bucher used in Germany is referred to and supplemented with respect to air quality. Analogous relationships hold true for the global classification of climates. As an example, the well-known classification after Koeppen is supplemented according to air quality.  相似文献   

15.
景观生态分类概念释义及研究进展   总被引:1,自引:0,他引:1  
景观生态分类通过建立等级分类系统,能够全面反映一定区域景观的空间分异和组织关联,揭示其空间结构与生态功能特征,是景观生态评价和规划管理的基础.本文首先对景观生态分类的概念进行剖析,然后从分类系统的制定及对分类因子选择的发展进程、分类方法的改进和创新、景观生态类型制图及应用领域等方面阐述国内外景观生态分类的进展和现状,并在总结以前研究存在不足的基础上,进一步指出今后景观生态分类研究的重点和发展趋势.
Abstract:
Landscape ecological classification (LEC), through establishing hierarchical classifi-cation system, can comprehensively reflect the spatial heterogeneities and their associations of definite regional landscape,, and reveal its spatial structural characteristics and ecological func-tions, being the basis of landscape evaluation, landscape planning, and landscape management. In this paper, the concept of LEC was paraphrased, and the research progress of LEC was reviewed and analyzed from the aspects of framing classification systems, selecting indices, im-proving classification methods, mapping landscape ecotypes, and applications. The problems of LEC research and its development trend were pointed out.  相似文献   

16.
《Engineering in Life Science》2017,17(12):1254-1263
The proposed work aims at designing a classification system for automatic identification of A. muelleri species, grown as a potential cash crop in many Asian countries, from the DNA fingerprints of Amorphophallus genus. Four sets of 48 DNA fingerprints belonging to 37 species of the Amorphophallus genus, developed with the help of four different primers are considered for the experiment, with an objective to identify only the fingerprints of the species of interest. A second experimental setup deals with the automatic classification of species containing high amounts of glucomannan from the same set of DNA fingerprints of the Amorphophallus genus. For each set of 48 DNA fingerprints generated with a specific primer, the DNA fingerprints are preprocessed to extract a 42 dimensional feature vector which is used to generate a k‐Nearest Neighbor based classifier based on the Leave One Out Cross Validation protocol. Final classification based on outputs from individual classifiers constructed with respect to the four different primers is performed according to a n‐star consensus strategy. The n‐star consensus predicts species A. muelleri with cent per cent accuracy while it predicts species containing glucomannan with a more modest accuracy of 81.25%.  相似文献   

17.
城市森林分类探讨   总被引:22,自引:0,他引:22  
介绍了城市森林的含义 ,城市森林的分类现状 ,阐明城市森林分类的必要性和紧迫性 ,在此基础上提出城市森林分类的原则和依据 ,确定了城市森林的 4级分类单位 :城市森林类、城市森林亚类、城市森林组和城市森林型 ,最终将城市森林分为附属庭院林、道路林、风景游憩林、生态公益林和生产经营林 5个城市森林类 ,共 16个城市森林亚类。并就有关城市森林分类提出几点建议。  相似文献   

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Classification of microorganisms on the basis of traditional microbiological methods (morphological, physiological and biochemical) creates a blurred image about their taxonomic status and thus needs further clarification. It should be based on a more pragmatic approach of deploying a number of methods for the complete characterization of microbes. Hence, the methods now employed for bacterial systematics include, the complete 16S rRNA gene sequencing and its comparative analysis by phylogenetic trees, DNA-DNA hybridization studies with related organisms, analyses of molecular markers and signature pattern(s), biochemical assays, physiological and morphological tests. Collectively these genotypic, chemotaxonomic and phenotypic methods for determining taxonomic position of microbes constitute what is known as the ‘polyphasic approach’ for bacterial systematics. This approach is currently the most popular choice for classifying bacteria and several microbes, which were previously placed under invalid taxa have now been resolved into new genera and species. This has been possible owing to rapid development in molecular biological techniques, automation of DNA sequencing coupled with advances in bioinformatic tools and access to sequence databases. Several DNA-based typing methods are known; these provide information for delineating bacteria into different genera and species and have the potential to resolve differences among the strains of a species. Therefore, newly isolated strains must be classified on the basis of the polyphasic approach. Also previously classified organisms, as and when required, can be reclassified on this ground in order to obtain information about their accurate position in the microbial world. Thus, current techniques enable microbiologists to decipher the natural phylogenetic relationships between microbes.  相似文献   

20.
链孢囊放线菌及其相关菌的数值分类研究   总被引:4,自引:0,他引:4  
对链孢囊菌属的28株放线菌和4株气丝可形成孢囊的放线菌进行了形态、生理生化特性、生长条件、抗生素敏感性、抗菌谱等107项试验测定。根据Ssm相似性系数及平均链锁聚类方式,借助于电子计算机对这些菌株进行了比较。结果表明,11株国际公认的链孢囊菌属的标准菌和一株已知的链孢囊菌与供试未知菌,在59%的水平上归为一群。通过数值分类把所比较的菌株在77%水平上区分为不同的表观群,为进一步的分子分类学研究和种的鉴定提供了依据。  相似文献   

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