越冬橘园蜘蛛群落多样性研究   总被引：2，自引：0，他引：2  

王智 《果树学报》2002,19(6):433-435

通过系统调查,湖南省邵阳市越冬橘园蜘蛛群落共有12科22属28种,其中斑管巢蛛(Clubionareichlini)和美丽蚁蛛(Myrmarachaefarmicaria)为优势种。异质性大的越冬橘园蜘蛛群落的多样性指数、丰富度和个体总数均大于异质性小的越冬橘园,越冬橘园蜘蛛群落的多样性指数大小主要由群落物种丰富度和个体总数决定,与均匀度大小无关。  相似文献   

Strong functional stability of soil microbial communities under semiarid Mediterranean conditions and subjected to long-term shifts in baseline precipitation     

《Soil biology & biochemistry》2014

We investigated the effect of soil microclimate on the structure and functioning of soil microbial communities in a Mediterranean Holm-oak forest subjected to 10 years of partial rain exclusion manipulations, simulating average drought conditions expected in Mediterranean areas for the following decades. We applied a high throughput DNA pyrosequencing technique coupled to parallel measurements of microbial respiration (R_H) and temperature sensitivity of microbial respiration (Q₁₀). Some consistent changes in the structure of bacterial communities suggest a slow process of community shifts parallel to the trend towards oligotrophy in response to long-term droughts. However, the structure of bacterial communities was mainly determined by short-term environmental fluctuations associated with sampling date (winter, spring and summer) rather than long-term (10 years) shifts in baseline precipitation. Moreover, long-term drought did not exert any chronic effect on the functioning of soil microbial communities (R_H and Q₁₀), emphasizing the functional stability of these communities to this long-term but mild shifts in water availability. We hypothesize that the particular conditions of the Mediterranean climate with strong seasonal shifts in both temperature and soil water availability but also characterized by very extreme environmental conditions during summer, was acting as a strong force in community assembling, selecting phenotypes adapted to the semiarid conditions characterizing Mediterranean ecosystems. Relations of climate with the phylogenetic structure and overall diversity of the communities as well as the distribution of the individual responses of different lineages (genera) to climate confirmed our hypotheses, evidencing communities dominated by thermotolerant and drought-tolerant phenotypes.  相似文献   

黄土高原亚高山草地退化对土壤种子库的影响     

牛瑞芳  吴铁航  柴宝峰 《草地学报》2021,29(5):972-981

本试验对黄土高原亚高山草地不同退化程度下土壤种子库的物种组成、种子密度、分布特征以及影响因素进行了研究。结果表明,研究区地上植物有31种,分属于14科、25属;种子库植物有32种,分属于14科、31属;种子库的83.45%都分布于浅层土壤中（0~5 cm）。随着草地退化程度的加重,地上植被和地下种子库中多年生植物的比例减少,种子库密度与丰富度都显著下降（P<0.001）;极度退化样地的地上一年生植物增多,物种组成与地下种子库相似;轻度和中度干扰的样地中,地上植物与种子库的物种的组成具有显著差异（P<0.01）。总之,亚高山草地退化对土壤种子库产生了较大的影响,其中土壤pH与水分是影响种子库密度与丰富度主要的环境因素。极度退化草地种子库密度极低,地上植被靠自然更新很难恢复,需人工辅助。  相似文献   

农民生计多样性影响因素调查分析 ——以丰都县为例     

金晓霞  郭岭  刘秀华 《中国农学通报》2007,23(8):619-619

丰都县农民生计多样性在整个西部地区比较具有代表性，但对于影响农民生计多样性的因素一直缺乏实证研究。该次调查采用参与性农村评估法（PRA），对丰都县名山镇（两汇口、古家店、鹿鸣寺）、社坛镇（三桥、德盛、干坛）、武平镇（殷家坝、坝周村）的农民生计方式及影响农民生计多样性的因素进行调查研究。研究表明，影响农民生计多样性的因素大致包括：自然资源、环境、人力资本、物质基础、社会关系、国家政策等方面  相似文献   

克隆文库分析红树林土壤中放线菌的多样性     

谢晴宜  屈直  马海霞  洪葵 《热带作物学报》2012,33(8):1466-1470

直接提取8个红树林土壤的总DNA,用放线菌门的特异性PCR引物进行扩增,通过构建16S rRNA文库,测序及系统发育分析,获取新颖放线菌菌株.结果发现,有酸微菌亚纲(Acidimicrobidae) (30.2％)、放线菌亚纲(Actinobacteridae) (68.0％)、红蝽菌亚纲(Coriobacteridae)(1.1％)和去腈基菌亚纲(Nitriliruptoridae)( 0.7％)成员,没有红色杆菌亚纲( Rubrobacteridae)成员.仙农指数和Chao1物种多样性指数(Schao1)表明,红树林土壤样品中含有丰富的放线菌多样性.以16S rDNA基因的相似率≥97％作为临界点,45.1％可能代表新候选种(candidate species)(未培养、分离).本研究为进一步获取新颖的红树林放线菌资源提供了基础.  相似文献   

Plant monocultures produce more antagonistic soil Streptomyces communities than high-diversity plant communities     

《Soil biology & biochemistry》2013

Plant–soil feedbacks are important to productivity and plant community dynamics in both natural and managed ecosystems. Among soil bacteria, the Streptomyces possess particularly strong antagonistic activities and inhibit diverse plant pathogens, offering a clear pathway to involvement in plant–soil feedbacks. We hypothesized that feedback effects and the ability of individual host plant species to foster antagonistic Streptomyces populations may be modified by the richness of the surrounding plant community. To test this, we collected soil associated with four different plant species (two C4 grasses: Andropogon gerardii, Schizachyrium scoparium; and two legumes: Lespedeza capitata, Lupinus perennis), grown in communities that spanned a gradient of plant species richness (1, 4, 8, 16, or 32 species). For each of these soils, we characterized the potential of soil Streptomyces to antagonize plant pathogens, using an in vitro plate assay with indicator strains to reveal inhibition. We cultivated each plant species in each conditioned soil to assess feedback effects on subsequent plant growth performance. Surrounding plant richness modified the impacts of particular plant species on Streptomyces antagonistic activity; A. gerardii supported a higher proportion of antagonistic Streptomyces when grown in monoculture than when grown in 32-spp plant communities, and L. capitata supported more strongly antagonistic Streptomyces when grown in 4- or 32-spp plant communities than in 8-spp plant communities. Similarly, the feedback effects of particular plant species sometimes varied with surrounding plant richness; aboveground biomass production varied with plant species richness for A. gerardii in L. perennis-trained soil, for L. capitata in A. gerardii-trained soil, and for L. perennis in L. capitata-trained soil. Streptomyces antagonist density increased with overall Streptomyces density under low but not under high plant richness, suggesting that plant diversity modifies selection for antagonistic phenotypes among soil Streptomyces. This work highlights the complexity of feedback dynamics among plant species, and of plant–microbiome interactions in soil.  相似文献   

Scale dependence of tree abundance and richness in a tropical rain forest,Malaysia   总被引：5，自引：0，他引：5  

He  Fangliang  LaFrankie  James V.  Song  Bo 《Landscape Ecology》2002,17(6):559-568

Abundance and richness are the two fundamental components of speciesdiversity. They represent two distinct types of variables of which the formerisadditive when aggregated across scales while the latter is nonadditive. Thisstudy investigated the changes in the spatial patterns of abundance andrichnessof tree species across multiple scales in a tropical rain forest of Malaysiaandtheir variations in different regions of the study area. The results showedthatfrom fine to coarse scales abundance had a gradual and systematic change inpattern, whereas the change in richness was much less predictable and ahotspot in richness at one scale may become acoldspot at another. The study also demonstrated that differentmeasures of diversity variation (e.g., variance and coefficient of variation)can result in different or even contradictory results which further complicatedthe interpretation of diversity patterns. Because of scale effect the commonlyused measure of species diversity in terms of unit area (e.g.,species/m²) is misleading and of little use in comparing speciesdiversitybetween different ecosystems. Extra care must be taken if management andconservation of species diversity have to be based on information gathered at asingle scale.This revised version was published online in May 2005 with corrections to the Cover Date.  相似文献   

新疆库尔勒市区草坪植物多样性研究     

熊炜 《牧草与饲料》2007,1(4):31-36

在室内外调查研究的基础上，应用生物多样性基本原理，首次论述了库尔勒市区草坪植物区系、染色体遗传、生活型、生态型、植物景观和资源植物的多样性及其质量特征。结果表明，库尔勒市区草坪植物的多样性，在植物物种组成上，以人工栽培和引种为主，本土杂草为辅；在地理成分上，以本土地理成分为主，外引地理成分为辅；在染色体组型上，以单染色体组型为主，多染色体组型为辅；在生活型组成上，以木本植物为主，草本为辅；生态类型组成上，以中生为主，旱生为重要组成部分，湿、水生为补充；在植物景观组成上，以2、4、5要素景观为主，1、3要素景观为辅；在资源植物构成上，以环境和生产类为主，食用和特殊类为辅。  相似文献   

贵州威宁黄牛线粒体DNA D-loop区全序列分析     

刘若余  杨公社  夏先林  刘培琼  张明忠  雷初朝 《中国牛业科学》2006,33(1):14-16

为了解贵州威宁黄牛的遗传多样性及遗传背景，我们分析测定了19个个体线粒体DNA D-loop区序列。结果检测到8种单倍型，7种为普通牛血统的单倍型，1种为瘤牛血统的单倍型，表明威宁黄牛同时受普通牛和瘤牛的影响。本研究同时构建了19个威宁黄牛个体的系统发生树，结果发现它们明显分为普通牛血统单倍型组和瘤牛血统单倍型组两组。  相似文献   

大青叶樱桃根际微生物种群结构及其变化动态   总被引：3，自引：0，他引：3  

于翠  吕德国  秦嗣军  杜国栋  刘国成 《果树学报》2007,24(3):298-302

利用选择性培养基,对2年生大青叶樱桃(Cerasus pseudocerasus)根际微生物进行了分离、鉴定和分类,分析了不同物候期根际微生物种群结构的变化。结果表明,从大青叶樱桃根际分离纯化获得的细菌分别属于15个属,以芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)为主;放线菌属于链霉菌属的6个类群,以白色类群(Albosporus)、黄色类群(Flavus)为主;真菌以镰刀菌(Fusarium)和木霉属(Trichoderma)为主。不同生育期根际微生物种群结构不同,落叶期根际细菌种群结构最丰富,萌芽期最少。  相似文献