大巴山北坡垂直带土壤特性及系统分类   总被引：1，自引：1，他引：0  

赵允格  李岗  邵明安 《山地学报》2000,18(5):415-421

通过野外考察与室内分析相结合,对大巴山北坡不同海拔高度的土壤特性进行研究,确定了各剖面的诊断层和诊断特性及其在系统分类中的位置。结果表明大巴山北坡各垂直带土壤在系统分类中可划归２个土纲的６个土类,系统分类中土壤的分类位置与发生分类位置并不具有简单的一一对应的关系。  相似文献   

A multimetric-index approach using fisheries data to assess fish assemblage structure in relation to salinity gradient in a tropical West African estuary     

J Kantoussan  JM Ecoutin  R Laë  OT Thiaw  L Tito de Morais 《African Journal of Marine Science》2018,40(2):175-185

This study examines the effects of increasing salinity on fish assemblage structure in the Casamance Estuary, Senegal, using a series of indices. The study data were derived from commercial fishery surveys conducted between April and July 2005. Analysis of within-trophic-group diversity in the Casamance Estuary shows a significant drop in the diversity of apex predators in the upper, more saline reaches of the estuary. By contrast, primary consumers adapted well to salinity changes and exhibited higher taxonomic diversity in the upper reaches of the estuary than in the lower reaches. The findings also indicate decreases in average sizes of the landed species and the trophic levels among fish catches in the direction of the upper reaches. However, the catch per unit effort (CPUE) was globally higher in the upstream area of the estuary as compared with the downstream area. This increasing CPUE trend from the lower towards the upper reaches is attributed to (i) the high primary productivity in the upper Casamance Estuary; (ii) the increasing abundance of euryhaline fish species in an upstream direction; and (iii) ‘telescoping’ of the food chain through the presence of mostly herbivorous fishes in the upper reaches. Such a situation likely facilitated high fish production in the upstream area of the estuary, though multimetric indices indicated unfavourable living conditions for many fish taxa in this area.  相似文献   

黄河口鱼类群落分类学多样性的研究   总被引：2，自引：2，他引：0  

王娇  张崇良  薛莹  任一平  徐宾铎 《海洋学报》2018,40(4):86-95

根据2013-2014年在黄河口水域进行的7个航次的鱼类资源底拖网调查数据，应用分类多样性指数分析了黄河口水域鱼类群落生物多样性的时空变化。黄河口鱼类主名录的平均分类差异指数△+理论平均值为75.5。2013-2014年调查中，该水域共捕获鱼类51种，隶属10目、27科、43属，以鲈形目、鲱形目和鲉形目鱼类居多。本次调查中鱼类群落分类多样性指数△和分类差异指数△*月变化范围分别为39.98~65.48和59.15~75.54，均表现为夏季月份最高，春、秋季月份次之，冬季最低。除春季月份外，其他月份鱼类平均分类差异指数△+均显著低于黄河口鱼类主名录的△+理论平均值。不同月份中平均分类差异指数△+也呈现一定的空间变化，夏、秋季月份绝大部分站位平均分类差异指数处于95%置信范围内，春、冬季月份个别站位的平均分类差异指数显著低于理论平均值，这与这些站位绝大多数种类集中在鲈形目有关。黄河口水域鱼类分类学多样性具有明显的时空变化，鱼类资源衰退，应加强该水域鱼类资源养护和多样性保护。  相似文献   

我国高山土壤分类研究的进展     

高以信 《山地学报》1990,(1)

在回顾了我国高山土壤分类后,概述了高山土壤的诊断层和诊断特性,阐述了土壤分类命名原则,提出了新的高山土壤分类系统以及涉及这些土壤的土纲及其以下级别的检索。  相似文献   

Environmental drivers of phytoplankton crops and taxonomic composition in northeastern Antarctic Peninsula adjacent sea area     

Yubin Feng  Dong Li  Jun Zhao  Zhengbing Han  Jianming Pan  Gaojing Fan  Haisheng Zhang  Ji Hu  Haifeng Zhang  Jiaqi Wu  Qiuhong Zhu 《海洋学报(英文版)》2022,41(1):99-117

The ecosystem of the sea region adjacent to the Antarctic Peninsula is undergoing remarkable physical and biological changes, in the context of global warming. However, understanding of the dynamics of phytoplankton taxonomic composition in this marginal ice zone remains unclear. In this study, seawater samples collected from 36 stations in the northeastern Antarctic Peninsula were analyzed for nutrients and phytoplankton pigments.Combining with CHEMTAX analysis, remote sensing data, and physico...  相似文献   

SCALAR VARIATION AND NODAL ACCESSIBILITY IN THE CHINESE RAILROAD NETWORK     

《The Professional geographer》2013,65(4):388-392

The effect of varying the scalar value in a powered connectivity matrix upon the measurement of nodal accessibilities is illustrated by reference to the railroad network in China. The degree of influence is demonstrated by estimating the effect of scalar variation on a model which is designed to predict the relative accessibility of thirty-nine cities within the network.  相似文献   

厦门海域鱼类群落分类学多样性的研究   总被引：5，自引：2，他引：3  

黄良敏  谢仰杰  李军  张雅芝  王家樵 《海洋学报》2013,35(2):126-132

根据厦门海域鱼类种类组成历史资料和调查资料,系统整理了厦门海域的鱼类总名录和现有名录,并应用分类学等级多样性指数和分类差异变异指数分析了厦门海域鱼类群落分类学多样性的时空变化。结果表明:厦门海域有记录鱼类共649种;现有鱼类有331种,隶属2纲22目90科181属,其中软骨鱼纲共5目9科9属15种,辐鳍鱼纲共17目81科172属316种。厦门海域鱼类总名录的等级多样性指数Δ+和分类差异变异指数Λ+分别为79.267和220.96;现有鱼类群落分类多样性指数Δ+和分类差异指数Λ+分别为77.504和245.34。分类多样性指数Δ+在冬、春季较高,秋季次之,而夏季最低;而分类差异指数Λ+夏季较高,秋季次之,冬春季较低。秋季和冬季鱼类组成的相似度最高,其次为夏季,最后为春季。与历史总名录相比,厦门海域的现有鱼类群落分类学范围较小,生态幅变窄,群落稳定性较差。  相似文献   

Taxonomic diversity of fish assemblages in the Changjiang Estuary and its adjacent waters     

SHAN Xiujuan  JIN Xianshi  YUAN Wei 《海洋学报(英文版)》2010,29(2):70-80

Taxonomic diversity of fish assemblages in the Changjiang Estuary(Yangtze River Estuary) and its adjacent waters was analyzed based on bottom trawl surveys carried out by R/V Beidou in June,August and October 2006.Four groups of fishes were identified for each survey by the twoway indicator species analysis(TWIA).Taxonomic distinctness,species richness and phylogenetic diversity were used to detect changes in taxonomic structure of fish assemblages.Most dominant fish species mainly belonged to Perciformes,Pleuronectiformes,Clupeiformes,Scorpaeniformes and Tetraodontiformes.Species richness in offshore waters of the survey area was higher than that in the other area.The average taxonomic distinctness value(AvTD,△+ ) of each fish assemblage was close to the average taxonomic distinctness of master list in the Changjiang Estuary(79.9),and had a positive correlation with species richness and Shannon diversity index(H ).A negative correlation was found between variations in taxonomic distinctness(VarTD,Λ + ) and traditional diversity indices,which were caused by fish species component that led to longer average path lengths among species.Taxonomic diversity index(△) had the similar results with species richness,H ,Simpson diversity index(D) and Pielou's evenness index(J ).VarTD also kept stable,which further certificated that fish assemblages and ecological environment were in equilibrium.Taxonomic distinctness index(△* ) was relatively stable in most of fish assemblages,and had higher values in some fish assemblages for a few absolutely dominant species.The present study showed that fish community formed new equilibrium stability in 2006 in the Changjiang Estuary when compared with those in the corresponding months of annual survey from 1985 to 1986.And AvTD in each sampling station was lower than AvTD of master list in the Changjiang Estuary,so some ecological niches were absent in each sampling stations from taxonomic or phylogenetic relationships,these would be helpful to stock natural resource and maintain ecological equilibruim of fish assemblages.  相似文献   

Diversity and Adaptations of Immature Diptera in Semiaquatic Habitats at Shorelines of Hypersaline Lakes in the Crimea,with a Brief Review of Diptera in Mineralized Bodies of Water     

Andrey PRZHIBORO 《《地质学报》英文版》2014,88(Z1):98-100

正The order Diptera(Insecta)is one of animal groups most successful in the colonization of mineralized shallow aquatic and semiaquatic environments.At the same time,the taxonomic composition of Diptera,their role in  相似文献   

普通球粒陨石的物理和岩石学性质及其分类参数     

王道德  王桂琴 《地球化学》2011,40(1):35-44

不同球粒陨石群的物理和岩石学性质,包括球粒的平均大小、球粒结构类型、复合球粒、带火成边球粒及含硫化物的比例、化学组成及矿物学特征等可用以划分球粒陨石的化学-岩石类型和小行星类型,这些性质提供了不同球粒陨石群有用的分类参数及其形成环境的信息.由于不同球粒陨石群的△17O与日心距离存在有相关关系,因此,依据不同球粒陨石群形...  相似文献