计算机技术在群落表制作和群落分类中的应用

介绍利用MicrosoftFoxpro和Excel软件编写程序 ,实现法瑞学派植物群落分类方法中群落表制作各个步骤的新技术 ,说明了制表程序的运行流程 ,并规定了该程序所需要的数据格式。这一技术简化了传统制表过程。本文提供了一个利用此新技术对

基于根表真菌群落与病原菌鉴定探究‘宁杞5号’枸杞根腐病的发生机制

【目的】比较两种植区易感病品种‘宁杞5号’枸杞健康株和患病株的根表真菌群落组成和分离到的腐根真菌,明确‘宁杞5号’根腐病的病原菌,探究两种植区‘宁杞5号’根腐病的发生原因。【方法】采用高通量测序技术研究枸杞根表真菌群落的组成特征,采用组织分离法从两种植区枸杞腐根中分离腐根真菌,基于形态学和ITS、EF-1α基因序列对腐根真菌进行分类学鉴定,依据科赫法则进行致病性研究。【结果】两种植区‘宁杞5号’枸杞健康株和患病株之间的根表真菌群落组成均表现出明显差异,主要体现在患病后镰刀菌属(Fusarium)相对丰度升高,被孢霉属(Mortierella)相对丰度降低,伴随着Fusicolla和Pseudogymnoascus等未知类群丰度增加,而两种植区健康株根表真菌群落结构趋于一致。自QXBZ腐根分离到36株真菌,分别鉴定为尖孢镰刀菌(Fusarium oxysporum)、腐皮镰刀菌(F.solani)、红贝俄式孔菌(Earliella scabrosa)、立枯丝核菌(Rhizoctonia solani)和Penicillium pimiteouiense,自QTBZ腐根分离29株真菌,分别鉴定为尖孢镰刀菌、腐皮镰刀菌、红贝俄式孔菌、粉红黏帚菌(Clonostachys rosea)、P.pimiteouiense、新知镰刀菌(F.andiyazi)、桃色顶孢霉(Acremonium persicinum),其中腐皮镰刀菌的分离频率在两种植区均为最高,尖孢镰刀菌次之。回接实验确定腐皮镰刀菌、尖孢镰刀菌、新知镰刀菌和立枯丝核菌是‘宁杞5号’枸杞根腐病的病原菌,其中新知镰刀菌为新发现的枸杞根腐病病原菌。【结论】‘宁杞5号’根腐病发生主要与根表真菌群落结构改变以及病原菌种类密切相关,与种植区关系不大,F.solani、F.oxysporum、F.andiyazi和R.solani是‘宁杞5号’根腐病的病原菌。

群落排表分类的两种数学方法

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。

Effects of surface cracks on the rhizospheric microhabitat of Artemisia ordosica in subsidence area caused by coal mining

The effects of surface cracks caused by underground coal mining on microhabitat in the rhizosphere of Artem＆ia ordosias were studied based on field investigation and sample analysis. The results show that the amounts of microorganisms, enzyme activity and water content in soil vary with the biomass ofA. ordosias, and that the account exhibits in an order of large A. ordosias〉medium A. ordosias〉small A. ordosias. Surface cracks apparently decrease microbial quantities and enzymatic ac- tivities, and change the composition and structure of microbial community in the rhizosphere of A. ordosias. Surface cracks reduce water content and electrical conductivity, enhance the R/S （ratio of root and soil） of water content, electrical conductivity and pH value, and raise the content of Na and Pb in rhizosphere soil ofA. ordosicas, It can be concluded that the disturbance of underground coal mining on the microhabitat in the rhizosphere ofA. ordosica is obvious in the early days.

Pigment characterization for the 2011 bloom in Qinhuangdao implicated "brown tide" events in China

A large-scale bloom occurred from May to June in 2011 in sea area near Qinhuangdao of the Bohai Sea, leading to huge damage of the scallop culture industry. Similar blooms have been observed in this region for three years. The causative species of the bloom, which dominated the phytoplankton community with the maximum cell density around 109 cell/L, could not be identified with morphological features due to the small cell size （-2 μm）. A pigment analytical method was then adopted to analyze the pigment profile of the phytoplankton samples collected from the blooming sea area. It was found that pico-sized （〈2 μm）, nano-sized （2-20 μm）, and bulk phytoplankton samples had similar pigment profile, representing the pigment signature of the bloom-causative species. The major pigments detected included 19-butanoyloxyfucoxanthin （But-fuco）, fucoxanthin （Fuco）, diadinoxanthin （Diad） and chlorophyll a （Chl a）, and high content of But-fuco was the most significant characteristics of the phytoplankton samples. Based on the pigment composition and content, the bloom-causative species could be tentatively identified as pelagophyte, ＂type 8＂ group of haptophyte, or silicoflagellate. Some unique features of the bloom, such as the extremely high cell density, small-sized and But-fuco containing cells, occurring in early summer, and the feeding-cessation effects on scallops, suggest it be a ＂brown tide＂ event similar to those reported in the east coast of the United States of America. The recurrent ＂brown tide＂ events and their dramatic impacts on the shellfish mariculture industry in QirLhuangdao need close attention in the coming years.

Bacterial diversity in surface water of the Yellow Sea during and after a green alga tide in 2008

From May to August 2008, a large "green tide", consisting of the alga Ulva (Enteromorpha) prolifera, occurred in the Yellow Sea, China, affecting the local marine ecosystem and human activities. We investigated the influence of the green tide on the microbial community in the surface seawater, at four sites from July to August 2008, using bacterial 16S rRNA gene clone libraries. We sequenced 228 clones of unique patterns identified by restriction fragment length polymorphism (RFLP) techniques. The results show that 228 sequenced clones fell into six bacterial phyla:Proteobacteria, Bacteroidetes, Cyanobacteria, Verrucomicrobia, Actinobacteria, and Planctomycetes. Alphaproteobacteria (33%), Gammaproteobacteria (25%), Bacteroidetes (23%) and Cyanobacteria (9%) dominated the assemblage. Comparison between samples collected in July (during the tide) and those collected in August (after the tide) showed that, in the microbial community, diversities of Alphaproteobacteria and Cyanobacteria increased after the tide, while those of Gammaproteobacteria and Bacteroidetes decreased. These results indicate that the green tide influenced the growth of some bacteria, and provide information for further studies on the interactions and relationships between U. prolifera and the bacterial community. This study suggests that microbial community analysis is a good approach to monitoring green tides.

Molecular Characterization of Sulfate-Reducing Bacteria Community in Surface Sediments from the Adjacent Area of Changjiang Estuary

Sulfate-reducing bacteria(SRB),which obtain energy from dissimilatory sulfate reduction,play a vital role in the carbon and sulfur cycles.The dissimilatory sulfite reductase(Dsr),catalyzing the last step in the sulfate reduction pathway,has been found in all known SRB that have been tested so far.In this study,the diversity of SRB was investigated in the surface sediments from the adjacent area of Changjiang Estuary by PCR amplification,cloning and sequencing of the dissimilatory sulfite reductase beta subunit gene(dsr B).Based on dsr B clone libraries constructed in this study,diversified SRB were found,represented by 173 unique OTUs.Certain cloned sequences were associated with Desulfobacteraceae,Desulfobulbaceae,and a large fraction(60%) of novel sequences that have deeply branched groups in the dsr B tree,indicating that novel SRB inhabit the surface sediments.In addition,correlations of the SRB assemblages with environmental factors were analyzed by the linear model-based redundancy analysis(RDA).The result revealed that temperature,salinity and the content of TOC were most closely correlated with the SRB communities.More information on SRB community was obtained by applying the utility of Uni Frac to published dsr B gene sequences from this study and other 9 different kinds of marine environments.The results demonstrated that there were highly similar SRB genotypes in the marine and estuarine sediments,and that geographic positions and environmental factors influenced the SRB community distribution.