云南苍山火烧迹地不同恢复期地表蜘蛛群落多样性

为了解云南苍山针阔混交林火烧迹地恢复过程地表蜘蛛群落多样性变化,于2009年1月份-2009年12月份,运用陷阱法,以“空间序列代替时间序列”,调查了苍山森林火干扰后不同恢复期样地(火干扰后2、10、18、23、33a和对照样地)地表蜘蛛多样性.研究结果表明,(1)物种组成及相对多度:不同恢复期随着恢复时间的增加优势类群更替趋势明显;(2)多样性:恢复1Oa样地地表蜘蛛群落多度显著大于其他恢复期(P＜0.05),而不同恢复期地表蜘蛛物种多样性却没有显著差异;(3)群落相似性:PCoA相似性分析将地表蜘蛛群落发展过程划分为火烧后2a、火烧后10a和火烧后18-33a 3个阶段;(4)指示物种:西菱头蛛Sibianor sp.1等是阶段1的指示物种,格氏狼蛛Lycosa grahami等是阶段2的指示物种,花蟹蛛Xysticus sp.2等是阶段3的指示物种,弱蛛Leptoneta sp.1等是对照的指示物种.火干扰改变了苍山针阔混交林原有的地表蜘蛛群落多样性;指示物种对生境的选择能够反映出不同恢复阶段地表环境变化;5个不同恢复时期火烧迹地中恢复最久的火烧迹地地表蜘蛛群落仍没有完成恢复,说明云南苍山火迹地地表蜘蛛的恢复需要30a以上.     

大兴安岭火烧迹地恢复初期土壤微生物群落特征

对大兴安岭兴安落叶松2003年重度和中度火烧迹地以及未过火样地的土壤微生物群落进行了考察,旨在揭示火烧迹地恢复初期土壤微生物群落变化特征。研究结果表明火烧迹地土壤养分(全氮、全碳、土壤有机质、有效氮)和土壤水分与未过火对照样地存在显著差异;火烧迹地土壤微生物量碳氮、微生物代谢活性以及碳源利用能力均显著高于对照样地;但火烧迹地与对照样地土壤微生物群落结构指标土壤微生物量碳氮比(MBC/MBN)以及多样性指数没有显著差异。相关分析结果表明:土壤微生物量、代谢活性和碳源利用能力与土壤养分指标(全碳、全氮、速效氮、有机质)和土壤水分含量有显著相关性。主成分分析的结果表明火烧与否是火烧样地与对照样地土壤微生物对碳源利用能力差异的原因。所有样地土壤微生物群落真菌比例较高,可能与该地区土壤酸碱度有关(pH=4.12—4.68)。经过6a的恢复,重度和中度火烧迹地的土壤养分和水分、土壤微生物群落的生长、代谢、以及群落多样性仍存在差异,但均不显著,表明此时火烧程度对土壤微生物群落的影响已很微弱。     

不同类型茶园昆虫、蜘蛛群落结构分析

应用多样性指数,排序和聚类分析方法研究了不同生态环境和防治处理的茶园昆虫,蜘蛛群落结构,结果表明：在生态控制的茶园,由于完全不使用化学农药,昆虫和蜘蛛的丰富度,多样性指数,均匀度均较大。综合防治的茶园次之一。而主要依靠化学防治的茶錾,丰富度减少,多样性指数和均匀度降低,经常出现害虫暴发成灾的现象。     

兴安落叶松林不同强度火烧迹地土壤微生物群落特性研究

通过选取大兴安岭岭北部的兴安落叶松林重度、轻度火烧迹地以及为过火样地,运用磷脂脂肪酸分析方法（PLFAs）,研究了火烧对0~5和5~10 cm土层的土壤理化性质和土壤微生物群落的结构特征的影响,并探讨了火烧当年土壤微生物群落生物量和群落结构的变化规律与影响因素。研究结果表明：0~5和5~10 cm土层的土壤pH、全钾、有效磷、黏砂比等土壤理化指标受到了火烧的显著性影响;不同火烧程度对微生物类群的生物量有影响,但不显著;重度火烧迹地的土壤微生物的群落结构指标革兰氏阳性菌/革兰氏阴性菌（G+/G-）以及真菌/细菌（F/B）与轻度和未过火样地具有显著差异。RDA分析指出,G+/G-受土壤含水量影响最大,F/B受pH影响最大。说明在火烧迹地的当年,土壤水分和pH是影响土壤微生物群落结构的最重要因素。     

热带次生林、旱稻种植地和火烧迹地土壤节肢动物群落结构特征及季节变化

通过模拟刀耕火种过程 ,对刀耕火种前后的次生林、旱稻地 (第 2年 )和火烧迹地 (火烧后直接撂荒地第 2年 )土壤节肢动物群落结构特征及季节变化进行了调查研究。结果显示 :3块样地土壤节肢动物群落的优势类群组成相同 ,均为蜱螨目、膜翅目和弹尾目 ,但不同生境样地中各优势类群所占群落总数的比例不同 ,并且 3样地常见和稀有类群的组成差异较大 ;土壤节肢动物类群数、个体数和 DG多样性指数表现为次生林高于其它 2块样地 ,而旱稻地和火烧迹地则无较大差异 ,但一些类群在旱稻地、火烧迹地的数量分布与次生林具有差异 ,且在土壤层的表现较为突出 ;3块样地土壤节肢动物群落具有较好相似性 ,其中旱稻地与火烧迹地达到极相似水平 (D、DS>0 .9)。3种不同类型生境土壤节肢动物群落在类群数、个体数和多样性指数的季节变化总体呈现出雨量少的干季或雨季初末期高于雨量最大的雨季中期 ,与当地降雨量和气温变化有密切关系 ,同时各样地土壤节肢动物群落因生境条件不同及人为活动干扰强弱而形成各自的季节消长特点。研究表明刀耕火种后的旱稻种植对土壤节肢动物群落的恢复和发展在一定限制条件 (面积、周围次生林和坡度 )下无破坏性影响 ,但植被改变、农事活动等对直接撂荒地和旱稻地土壤节肢动物群落的季节消长产生     

武汉天河机场地区蜘蛛群落及多样性研究

１９９９年７月－１０月对天河机场地区４种生境的蜘蛛资源进行了调查,蜘蛛群落有１２科３４属５２种。研究结果表明：群落的优势种为三突花蛛、锥腹肖蛸、茶色新园蛛、斜纹猫蛛、食虫沟瘤蛛、纵条蝇狮;不同生境、不同季节,群落结构组成不同;丰富度、多样性指数、均匀度、优势度不同;４种生境中的蜘蛛群落相似性很小。这主要与植被类型、密度等直接有关,另外也受农事活动的影响。     

不同林型兴安落叶松林火烧迹地物种组成及多样性研究

以内蒙古大兴安岭兴安落叶松林火烧迹地为研究对象,采用分层取样的方法对群落中植被进行了调查,分析比较了3种不同林型兴安落叶松林群落恢复过程中物种组成及多样性的差异。结果表明:不同林型兴安落叶松林群落各层α多样性指数总体表现为草本层灌木层乔木层。不同林型兴安落叶松林火烧迹地群落恢复12年后,草本层的Simpson和Shannon-Wiener指数均小于对照样地并呈现出草类-兴安落叶松林杜香-兴安落叶松林杜鹃-兴安落叶松林的趋势,而在灌木层则各指数均大于对照样地并呈现出草类-兴安落叶松林杜鹃-兴安落叶松林杜香-兴安落叶松林的趋势。     

张家口土壤蜘蛛群落结构及多样性研究

1996年8月中旬,在张家口地区4种生境中共捕获土壤蜘蛛461头,隶属于12科54种(属)。研究表明:4种生境中的土壤蜘蛛群落相似性很小,群落结构组成不同,丰富度、多样性指数、均匀度、优势度也不同。植被类型、疏密程度是影响群落结构的主要生态因子,农事活动是另一个重要影响因素。     

武汉地区油菜和蚕豆田内蜘蛛群落多样性的初步分析

用五种多样性指数及均匀度指数对武汉市油菜和蚕豆田内蜘蛛群落进行了比较,讨论了多样性指数的生态学意义及其判别力,探讨了其物种多样性值的行为变化,分析测定了油菜及蚕豆田内蜘蛛群落多样性的时间格局。并讨论了群落多样性与丰盛度、均匀度及其与群落稳定性的关系。结果表明:采用Shannon—Weaver指数较为合适。     

火烧迹地柽柳灌丛资源岛特征及植被的自然恢复

干旱半干旱地区灌丛资源岛特征及形成机制多有报道,但资源岛土壤对群落稳定性与火烧迹地植被的自然恢复作用尚不明确。以酒泉盐碱地柽柳灌丛地火烧3年后,自然恢复的柽柳(Tamarix ramosissima)及其冠下草本群落为研究对象,构建柽柳枯立株体量指数(SSI, Shrub Size Index)和恢复力综合指数,探讨了资源岛特征与植被恢复、冠下草本群落多样性的关系,量化不同大小柽柳灌丛的恢复力稳定性。结果表明:(1)在不同SSI的柽柳枯立株下土壤有机质和含水率明均显高于灌丛间地,形成了明显的资源岛特征。土壤有机质最大值出现在0—10 cm土层,中灌丛的肥力积聚效果最明显。(2)土壤主要以中性盐为主,在0—40 cm土层,灌丛区域土壤可溶性盐低于冠外,呈明显的盐谷特征,中灌丛的盐谷分布最为明显。(3)随着枯立株SSI的增大,柽柳新生枝条的数量及其高度均有所增大,冠下植物的高度、盖度、密度和地上植物量也明显高于灌丛间地,且灌丛越大恢复效果越明显。(4)灌下植物Simpson指数、Shannon-Wiener指数、Margalef指数和Pielou指数随着枯立株SSI的增大均先降后升,多样性...     

Multi-scale analysis of butterfly diversity in a Mediterranean mountain landscape: mapping and evaluation of community vulnerability

This paper is an attempt to outline a protocol for animal diversity census and evaluation aimed for areas in view of landscape planning of territories of hundred square kilometres and more, that may work utilising different faunal groups and be anyway useful at various scales. Many papers are addressed to elaborate tools for landscape planning starting from biodiversity evaluation and butterflies are often utilised because of their sensitivity to landscape modifications. In this work, the biodiversity evaluation has been performed using three hierarchically linked landscape units at micro-, meso- and macroscale. Being species diversity values often inadequate to define the conservation interest of a landscape portion, more importance has been given to which species compose the species assemblages. A community vulnerability Index was coded and used for evaluating potential consequences of human disturbance on butterfly assemblages. Forty-four year samples were gained by visual census in the Sila Greca, Southern Italy, on an area of approximately 520 square kilometres. During 5 years work, 2,535 specimens and 94 species were recorded, equal to 75.8% of the whole Calabrian fauna. Four vulnerability levels have been established and used for mapping butterfly assemblage vulnerability in the area, starting from a vegetation map. Species richness was found somewhat contradictory at micro-scale, where the community vulnerability Index gives a sounder approach. S diversity gives a more reliable picture of naturalness at meso-scale, a level we identified with the “ecotope”. At this more “geomorphic” scale level, biological functions reflected by butterfly assemblages revealed to be clearly linked to seral processes. Similarity analysis results show that the ecotope species richness, here called “eta-diversity”, could be an useful measure of zoological landscape (faunation) potentialities.     

火干扰对云南苍山地表蜘蛛群落生活型组成及季节动态的影响

为揭示不同蜘蛛类群对火干扰的敏感程度及蜘蛛群落外貌对环境变化产生的响应, 本文选取苍山针阔混交林2007年火烧迹地作为调查样地, 以无火烧记录的样地为对照, 运用陷阱法调查地表蜘蛛群落生活型及季节动态。研究结果显示: (1)火烧迹地中朱氏狂蛛(Zelotes zhui)(相对优势度 DV' =33.03)、晨豹蛛(Pardosa chionophila) (DV'=22.53)和西菱头蛛一种(Sibianor sp.1)(DV'=8.75)占明显优势; 而对照样地中龙隙蛛一种(Draconarius sp.2) (DV'=63.50)占绝对优势; (2)火烧迹地的定居型蜘蛛相对多度为25.82%, 显著少于游猎蜘蛛(P<0.001); 而对照样地的定居型蜘蛛相对多度为92.07%, 显著高于游猎蜘蛛(P<0.001); (3)火烧迹地地表蜘蛛优势类群随季节更替明显, 在夏季和冬季多度为低谷期; 对照样地优势类群稳定, 为漏斗蛛科蜘蛛。研究表明, 火干扰改变了苍山针阔混交林地表蜘蛛群落生活型组成, 降低了定居型蜘蛛的相对多度和地表蜘蛛群落的季节稳定性。     

Influence of fine woody debris on spider diversity and community structure in forest leaf litter

Exploitation of forests for biofuel results in variable amounts of fine woody debris (FWD) being left on the forest floor. Such practices have the potential to affect the diversity and taxonomic composition of litter-dwelling organisms. The ability to predict the consequences of harvesting biofuel will be strengthened by knowledge of how variation in FWD affects litter organisms in non-harvested forests. A field experiment with three treatments [Control (no manipulation), FWD Removal, and FWD Addition] was carried out in replicated open plots in an unexploited forest in order to determine how the amount of fallen FWD affects the abundance, diversity and community composition of spiders, selected because of their importance as predators in the leaf-litter food web. Manipulation of FWD started in August, and by the following July total spider density in the FWD Addition treatment was 1.6× that of FWD Removal plots. Spider density in FWD Removal plots was 30% lower than the Control treatment, with no statistically significant difference between Control and FWD Addition. Manipulating FWD had no statistically significant effects on standard indices of spider diversity. However, multivariate community-level analyses revealed statistically significant differences in spider community structure between the FWD Removal and FWD Addition treatments. Two dominant genera of web builders contributed the most to this effect of manipulating FWD. Our results, and the findings of studies of woody debris in younger forests, suggest that the relatively small effects of FWD in our field experiment may reflect the age of the forest, with effects on the fauna likely being larger in forests younger than the one we studied.     

Illumina-based analysis of microbial community diversity

Microbes commonly exist in milieus of varying complexity and diversity. Although cultivation-based techniques have been unable to accurately capture the true diversity within microbial communities, these deficiencies have been overcome by applying molecular approaches that target the universally conserved 16S ribosomal RNA gene. The recent application of 454 pyrosequencing to simultaneously sequence thousands of 16S rDNA sequences (pyrotags) has revolutionized the characterization of complex microbial communities. To date, studies based on 454 pyrotags have dominated the field, but sequencing platforms that generate many more sequence reads at much lower costs have been developed. Here, we use the Illumina sequencing platform to design a strategy for 16S amplicon analysis (iTags), and assess its generality, practicality and potential complications. We fabricated and sequenced paired-end libraries of amplified hyper-variable 16S rDNA fragments from sets of samples that varied in their contents, ranging from a single bacterium to highly complex communities. We adopted an approach that allowed us to evaluate several potential sources of errors, including sequencing artifacts, amplification biases, non-corresponding paired-end reads and mistakes in taxonomic classification. By considering each source of error, we delineate ways to make biologically relevant and robust conclusions from the millions of sequencing reads that can be readily generated by this technology.     

Molecular community analysis of microbial diversity

New technologies that avoid the need for either gene amplification (e.g. microarrays) or nucleic acid extraction (e.g. in situ PCR) have recently been implemented in microbial ecology. Together with new approaches for culturing microorganisms and an increased understanding of the biases of molecular methods, these techniques form the most exciting advances in this field during the past year.     

Secondary succession after fire in a Mediterranean dwarf-shrub community

Abstract. Changes in vegetation composition after fire in a Sarcopoterium spinosum dwarf-shrub community on phosphorus-deficient terra rossa soil overlying limestone were studied over a 10-yr period. Herbicide application and phosphate fertilizer were combined to provide a range of initial conditions for recovery. The site was undisturbed during the growing season in winter but was grazed by cattle in summer. Encroachment rate of S. spinosum was mainly a function of the density of viable buds on plants that survived the fire and/or the shrub control treatments. This, together with the very low rate of shrub establishment from seed set a short-to-medium term limit to the attainable cover of S. spinosum. The leguminous shrub Calycotome villosa appeared only in the third year after the fire, apparently from seed. After shrub control, the encroachment rate of C. villosa was low, even after 9 yr. On the other hand, where no herbicide was applied, and with the cessation of goat grazing, C. villosa became increasingly prominent, to the extent that by the 8th year after the fire, it inhibited the continued expansion of S. spinosum. Phosphorus nutrition tended to reduce the cover of S. spinosum because of its stimulating effect on the predominantly leguminous herbaceous vegetation. C. villosa also appeared to benefit from greater phosphorus availability, despite greater competition from the annual vegetation. These findings show that, depending on the context, secondary succession after fire can take different courses. Whereas the combined effect of herbicide control and P-enrichment cannot prevent shrub encroachment, it can slow down the rate of succession for more than a decade, despite the presence of ample shrub seed sources in the area.     

Molecular diversity of spider venom

Spider venom, a factor that has played a decisive role in the evolution of one of the most successful groups of living organisms, is reviewed. Unique molecular diversity of venom components including substances of variable structure (from simple low molecular weight compounds to large multidomain proteins) with different functions is considered. Special attention is given to the structure, properties, and biosynthesis of toxins of polypeptide nature.