4种抗生素对蚯蚓-污泥系统细菌群落结构的影响

蚯蚓可摄食污泥中的有机物,其肠道微生物群落在其分解过程中起着主要的作用。利用赤子爱胜蚓(Eisenia foetida)和人工湿地基质构建蚯蚓-污泥系统,添加氯霉素、四环素、链霉素和青霉素4种抗生素,研究不同抗生素对污泥和蚓粪的细菌群落结构的影响。采用高通量测序技术比较分析污泥和蚓粪的细菌多样性及群落结构变化。结果表明,外加抗生素能够导致污泥的Chao1和ACE指数降低,同时降低拟杆菌门和变形菌门的相对丰度,加入氯霉素和青霉素会增加厚壁菌门的相对丰度,降低酸杆菌门、放线菌门和绿弯菌门的相对丰度,加入四环素和链霉素则与之相反。蚓粪样品中,添加氯霉素和链霉素导致Chao1和ACE指数降低,而添加四环素和青霉素则导致Chao1和ACE指数升高,外加抗生素可降低拟杆菌门的相对丰度,增加放线菌门、变形菌门和疣微菌门的相对丰度。主成分分析(PCA)和聚类分析表明,氯霉素和青霉素对污泥细菌群落影响作用相似,四环素与链霉素效果类似;氯霉素对蚓粪群落结构的影响小于其他抗生素。研究结果显示,抗生素可影响污泥和蚓粪的细菌多样性及群落结构,不同抗生素对污泥和蚓粪的影响程度存在差异。

低山林地改植茶园对溪流大型底栖无脊椎动物群落的影响

受到低山林地改植茶园影响的溪流各水体理化指标数值都比参照溪流高1倍左右。与参照溪流相比,林地改植茶园对相邻溪流底栖动物群落结构的影响表现在节肢动物物种比例下降(47.54%),EPT丰富度和昆虫纲物种丰富度显著下降(P<0.05)。水体营养指标的升高可能是导致低山林地改植茶园溪流大型底栖无脊椎动物多样性下降的直接原因。低山茶林(茶园与溪流之间有成片林地间隔)对溪流影响小于低山茶园,说明沿岸带林地对减缓茶园对相邻溪流的生态影响有积极作用。低山茶园、低山茶林、农田和参照溪流3个季节的群落相似性的非度量多维尺度分析表明,溪流群落相似性主要与干扰类型密切相关,干扰对溪流底栖动物群落组成的影响要大于底栖动物群落组成的季节性变化。

香蕉秸秆不同还田模式对土壤微生物群落的影响

采用土壤室内培养的方法,以香蕉秸秆不同还田模式为试验唯一变量因素,设置3个处理(无秸秆还田CK;将香蕉秸秆覆盖到土壤表层,作为秸秆自然还田处理F;将土壤与香蕉秸秆彻底混合,作为秸秆掩埋还田处理T),分析香蕉秸秆不同还田模式下的微生物群落差异,以期揭示香蕉秸秆的不同还田模式对土壤微生物的影响。结果表明:T、F处理与CK处理相比,真菌门中Basidiomycota相对丰度分别增加1.3%和2.8%;细菌门中Acidobacteria相对丰度分别增加5.1%和1.1%,Actinobacteria的相对丰度分别增加1.9%和3.2%。处理间Fusarium相对丰度大小顺序为CK>F>T。处理间细菌群落的丰富度(SChao1)和多样性(HShannon)大小顺序均为T>F>CK,真菌群落并无明显差异。聚类分析表明,T处理土壤微生物群落结构与CK处理明显不同。主坐标分析和OTU数量分布结果表明,T处理土壤微生物群落结构与F处理相近。本研究结果显示,T处理增加了土壤细菌群落的丰富性与多样性,改变了土壤微生物的群落结构,同时提高了具有分解功能的微生物分类属的相对丰度,并显著降低了病原菌的相对丰度。

Elevational diversity of arrow bamboo (Fargesia spathacea) communities on Mount Shennongjia in Central China

Altitudinal changes in species richness, species diversity, species evenness, life-form spectrum, and community structure of arrow bamboo (Fargesia spathacea) were studied within 11 plots from 1 500 m to 2 600 m asl on Mount Shennongjia in Central China. From the lowest plot (1 680 m) to the highest one (2 570 m), vascular plants declined from 30 to 7 species, following a linear model ofY=55.99-1.83X (d.f.=9,F-value=48.64,r 2=0.84,P<0.001); species diversity, reduced from 3.13 to 1.78, following a linear model ofY=4.67–0.10X (d.f.=9,F-value=22.82,r 2=0.72,P=0.001); species evenness varied from 0.83 to 0.99, but presented little relationship to the altitude (r=0.112,P=0.742). In the life-form spectra, with the increase of altitude, the percentage of annual plants (r=0.60), underground bulb perennials (r=0.40), and big trees (r=0.35) tended to increase; shrubs (r=?0.52) and middle-sized trees (r=?0.45) tended to decline; perennial grasses (r=0.04) and semi-shrubs (r=0.03) were not strongly related to the altitudinal gradient. Arrow bamboo communities could be classified into five groups: bamboo under evergreen broad-leaved forest, under deciduous broad-leaved forest, under temperate coniferous forest, under cold-temperate coniferous and mixed forest, and pure bamboo community.

A Comparative Study of Fish Assemblages Near Aquaculture, Artificial and Natural Habitats

Habitat plays a critical role in regulating fish community structure. Using the data collected from a monthly trammel net survey in Ma'an archipelago off the east coast of China, we evaluated impacts of five different habitats(artificial reefs, mussel farms, cage aquaculture, rocky reefs and soft bottom) on fish assemblages. This study suggests that artificial reefs(AR) have significantly higher species richness, abundance and diversity than mussel farms(MF) or soft bottom(SB) habitats during most seasons, and that fish taxa in the AR habitats are similar to those in the rocky reef(RR) habitats. Two different fish assemblage patterns were revealed in the study area using non-metric multidimensional scaling ordination: an assemblage dominated by reef fishes(especially by Scorpaenidae species) in AR, RR and cage aquaculture(CA) habitats and an assemblage dominated by Sciaenidae species in MF and SB habitats. We suggest that reef fishes play a key role in differentiating fish community structures in the study area. Although few differences in fish abundance and diversity were found between the CA and SB habitats, a more diverse age structure was observed in the CA habitats. A much more complex fish assemblage and enhanced population of local species were established as a result of the presence of both floating and fixed artificial structures, probably through improved survival rates.

Understory vascular plant community assembly in relation to time-since-fire and environmental variables in a Chinese boreal forest

Understanding the response of understory vegetation to fire disturbance is vital to biodiversity conservation and management of boreal forests. We surveyed understory vascular plant richness and composition, and measured related environmental variables along a toposequence within three successional stages, initial （3 years post-fire）, early （13 years post-fire） and late （〉1oo years post-fire） successional stages. Using permutation multivariate ANOVA and nonmetric multidimensional scaling, we analyzed how understory species richness and composition change as time-since-fire proceeds, and their correlative relationships with environmental variables. Species richness and composition showed significant differences among the three successional stages. Understory species richness and abundance were significantly associated with time-since-fire, topographic position, elevation and organic layer depth. Among these variables, time-since-fire had the strongest effect and topographic position was the second major factor on affecting understorycommunity assembly. In overwhelmed the effects addition, time-since-fire of soil pH in the initial successional stage and gravimetric soil moisture in early and late successional stages on understory species composition

Influence of a large dam on the longitudinal patterns of fish assem- blages in Qingyi Stream

Using seasonally collected data(2009-2010) from 15 sampling sites that represent first- to fifth-order streams within the Qingyi watershed,we examined the spatio-temporal patterns of fish assemblages along two longitudinal gradients to explore the effects of a large dam on fish assemblages at the watershed scale.No significant variation was observed in either species richness or assemblage structure across seasons.Species richness significantly varied according to stream order and gradient.Dam construction appeared to decrease species richness upstream substantially,while a significant decrease between gradients only occurred within fourth-order streams.Along the gradient without the large dam,fish assemblage structures presented distinct separation between two neighboring stream orders,with the exception of fourth-order versus fifth-order streams.However,the gradient disrupted by a large dam displayed the opposite pattern in the spatial variation of fish assemblages related with stream orders.Significant between-gradient differences in fish assemblage structures were only observed within fourth-order streams.Species distributions were determined by local habitat environmental factors,including elevation,substrate,water depth,current discharge,wetted width,and conductivity.Our results suggested that dam construction might alter the longitudinal pattern in fish species richness and assemblage structure in Qingyi Stream,despite the localized nature of the ecological effect of dams.

Floristic and structural analysis of the woodland vegetation around Dello Menna,Southeast Ethiopia

Floristic composition and vegetation structure were described for the woodland vegetation around Dello Menna, Bale zone, southeast Ethiopia. A total 50 （20 m ×20 m） quadrats were sampled to identify and describe plant community types, species diversity, richness and evenness and to relate the identified plant community types with some environ- mental factors and describe the population structure of woody plant species. In each quadrrat, data on species identity, abundance, height and Diameter at Breast Height （DBH） of woody plant species, altitude and slope were recorded. Vegetation classification was performed using PC - ORD software package. Sorensen＇s similarity coefficient was used to detect dissimilarities among communities. Shannon - Wiener diversity index, species richness and Shannon＇s evenness were computed to de- scribe species diversity of the plant community types. Results show that a total of 171 vascular plant species representing 53 families were re- corded. Fabaceae is the dominant family represented by 13 genera and 26 species （15%） followed by Asteraceae, Lamiaceae and Anacardiaceae with eight species each （4.6%）. Based on the results of vegetation classi- fication, three plant communities （Dalbergia microphylla community, Grewia bicolar- Acacia brevispica community, and Combretum molle- Combretum collinum community） are recognized and described. Species richness, diversity and evenness varied among the plant communities.Species richness and diversity exhibit a bell - shaped pattern along alti- tude. Species turn over among communities more or less follow altitud- inal gradients. Tukey＇s pairwise comparison of means among the plant community types shows significant variations in altitude, implying that altitude is one of the most important factors determining the distribution of plant communities. The community Dalbergia microphylla type exhibits the highest species richness and diversity. Analysis of population structure of the dominant species reveals various patterns. Future research directions and recommendations are suggested for the sustainable utilization.

Characteristics of bird communities between slope and valley in natural deciduous forest, South Korea

Bird communities were surveyed in natural deciduous forest of both slope area and valley area at Mt. Gyebangsan (3740 30 N, 12830 1 E), Gangwon Province, South Korea in winter, spring, summer and autumn from September 2000 to November 2001. The investigating results showed that there existed differences in the bird species composition, richness, bird species diversity, guild structure between slope area and valley area, and the vertical forest structure, especially coverage of understory, and diameter at breast height (DBH) distribution also had significant difference between the two study areas. The differences in habitat structure between the areas are very likely to have influences on how birds used the available habitat.

带状采伐对毛竹林土壤细菌群落结构及多样性的影响

【目的】研究带状采伐后毛竹(Phyllostachys edulis)林土壤细菌群落结构及多样性的变化,认识带状采伐对毛竹林土壤生态系统的影响,为利用带状采伐实现毛竹林规模化经营提供指导。【方法】对毛竹林进行不同宽度(3、9、15 m)的带状采伐,25 d后采集样地内土壤样品,采用Illumina MiSeq高通量测序技术分析土壤细菌特定基因片段V3-V4区域,鉴定菌种类群,预测细菌功能,并结合7种土壤养分指标(有机质、全氮、全磷、全钾、碱解氮、有效磷、速效钾)的测定结果,探讨带状采伐对毛竹林地土壤细菌群落及土壤养分的影响。【结果】随着采伐宽度的增加,土壤有效磷、全钾、速效钾含量降低,土壤有机质、全氮、碱解氮含量先增后降。适当采伐可以提高土壤肥力,但采伐宽度超过一定限度后,土壤肥力降低,速效养分含量减少。不同带状采伐对毛竹林土壤中细菌类群的丰度、多样性、均匀度的影响各不相同;3 m采伐宽度的毛竹林地内土壤细菌群落丰富度最高,且物种分布最均匀,随着采伐宽度的增大,其毛竹林地内的细菌群落丰富度和物种均匀度均降低,当采伐宽度超过9 m时,群落间的物种组成变化差异减小。带状采伐后变形菌门(Proteobacteria)相对丰度增多,酸杆菌门(Acidobacteria)、绿湾菌门(Chloroflexi)相对丰度减少,这3种菌门同放线菌门(Actinobacteria)一起占据着毛竹林带状采伐土壤细菌群落种的主要地位,对土壤中碳(C)、氮(N)元素固定及其他养分的转化分解发挥着重要的作用。带状采伐后土壤细菌群落代谢通路中最重要的是碳水化合物代谢和氨基酸代谢,说明带状采伐后土壤细菌的优势功能主要集中在C、N两种元素的固定和转化。【结论】毛竹林带状采伐对土壤细菌群落结构及多样性产生显著影响,3 m宽度的带状采伐能够增加细菌类群的丰度、多样性、均匀度以及土壤养分含量,当采伐宽度增大,上述各项指标降低;综合分析表明带状采伐后土壤微生物类群主要参与C、N元素的固定和转化的相关功能通路。

合肥市草坪春季节肢动物群落结构研究

通过对合肥市内最常见的三种草坪,黑麦草、高羊茅和麦冬草坪的节肢动物群落结构系统调查:共调查到物种33种属于32个科,有昆虫纲、蛛形纲、唇足纲、腹足纲。昆虫纲中有8目23个科。蛛形纲有5个科。共调查5次,其中5月31号调查个体数是为最多1500头。草坪节肢动物群落多样性指数最大2.1551。均匀度最大为是0.7078。优势集中度最小0.1882。本研究对此群落多样性进行系统调查,并对出现这种现象的原因进行分析。

Species turnover drives grassland community to phylogenetic clustering over long-term grazing disturbance

Aims Grazing exerts profound effects on grassland ecosystem service and functions by regulating species composition and diversity,and structuring community assembly worldwide.However,adaptions of phylogenetic diversity and phylogenetic community structure to long-term grazing disturbance remain poorly studied,especially for ecosystems distributed in extreme environments.Methods Here,we conducted an experiment with multigrazing intensities to explore the impacts of grazing disturbance on plant phylogenetic diversity and community structure in an alpine grassland of the Tibetan Plateau.Important Findings Grazing disturbance enriched plant species richness(SR),and stimulated species turnover from regional species pool,consequently changing community species composition.Under low intensities,grazing exerted no obvious effects on phylogenetic diversity and community structure,whereas communities changed from overdispersion to clustering under high grazing intensity.High grazing intensity resulted in stronger environmental filtering,which consequently selected those species with high resilience to grazing disturbance.The observed clustering structure was associated with the colonizing species which were closely related to resident species,and locally extinct species,and distantly related to residents.At the plant functional trait level,high grazing intensity increased species colonization largely by altering the effect of root depth on species colonization compared to light grazing.Our results highlight that solely utilization of SR and diversity cannot fully represent grassland communities responses to grazing.The effects of species turnover on community phylogenetic diversity and structure are entailed to be explored in the future grazing studies.

Resource enrichment combined with biomass removal maintains plant diversity and community stability in a long-term grazed grassland

Aims Long-term heavy grazing reduces plant diversity and ecosystem function by intensifying nitrogen(N)and water limitation.In contrast,the absence of biomass removal can cause species loss by elevating light competition and weakening community stability,which is exacerbated by N and water enrichment.Hence,how to maintain species diversity and community stability is still a huge challenge for sustainable management of worldwide grasslands.Methods We conducted a 4-year manipulated experiment in six long-term grazing blocks to explore combination of resource additions and biomass removal(increased water,N and light availability)on species richness and community stability in semiarid grasslands of Inner Mongolia,China.Important Findings In all blocks treated with the combination of resource additions and biomass removal,primary productivity increased and species richness and community stability were maintained over 4 years of experiment.At both species and plant functional group(PFG)levels,the aboveground biomass of treated plants remained temporally stable in treatments with the combination of N and/or water addition and biomass removal.The maintenance of species richness was primarily caused by the biomass removal,which could increase the amount of light exposure for grasses under resource enrichment.Both species asynchrony and stability of PFGs contributed to the high temporal stability observed in these communities.Our results indicate that management practices of combined resource enrichment with biomass removal,such as grazing or mowing,could not only enhance primary productivity but also maintain plant species diversity,species asynchrony and community stability.Furthermore,as overgrazing-induced degradation and resource enrichment-induced biodiversity loss continue to be major problems worldwide,our findings have important implications for adaptive management in semiarid grasslands and beyond.

The influence of terrain age and altitude on the arthropod communities found on recently deglaciated terrain

Climate warming has been more pronounced in the Arctic than elsewhere, resulting in a recent rapid glacial retreat. Over 85% of the Almajallojekna glacier has disappeared over the last 115 years and it is one of the fastest retreating glaciers in Sweden. In 2011 and 2012, at 18 sites in the vicinity of the remaining glacier network, we sampled arthropods and related the species richness, abundance and proportion of herbivores to altitude （ranging from 824 to 1,524 m.a.s.1.） and the age of the site （ranging from 0 to 〉 115 years）. Temperature was measured at six sites and the average annual air temperature ranged from -3.7℃ to 1.1℃. In total, we recorded 3,705 arthropods from 117 species in nine different taxonomic groups. The most abundant and species-rich group was Coleoptera （1,381 individuals, 41 species） followed by Araneae （1,050 individuals, 15 species） and Macrolepidoptera （732 individuals, 17 species）. Only at lower altitudes did the abundance and species richness of arthropods increase with increasing age of the site. The results were consistent among the studied taxonomic groups and when controlling for sam- piing intensity using two different approaches. The proportion of herbivores decreased with increasing age of the site and with increasing altitude. Clearly, altitude appears more important than the age of the site and, at higher altitudes, abundance, species richness and herbivory are low [Current Zoology 60 （2）： 203-220, 2014].

Impact of forest fire on soil seed bank composition in Himalayan Chir pine forest

Aims To explain how plant community copes with a recurring anthropogenic forest fire in Himalayan Chir pine forest,it is important to understand their postfire regeneration strategies.The primary aim of the study was to know:(i)how fire impact soil seed bank composition and(ii)how much soil seed bank composition differs with standing vegetation after the forest fire.Methods Soil samples were collected from burned and adjoining unburned sites in blocks using three layers down to 9 cm depth immediately after a forest fire and incubated in the net-house for seedling emergence.Same sites were revisited during late monsoon/early autumn season to know the species composition of standing vegetation recovered after a forest fire.Important Findings Soil contained viable seeds of>70 species.The average seed bank density was 8417 and 14217 seeds/m^(2) in the burned and unburned site,respectively.In both sites,it decreased with increasing soil depth.Overall fire had no significant impact on seed density;however,taking individual layers into consideration,fire had a significant impact on seed density only in the uppermost soil layer.The species richness of soil seed bank and standing vegetation was 73 and 100,respectively(with 35 shared species),resulting in a similarity of about 40%.In contrast,>80%species in soil seed bank was found similar between burned and unburned sites.Further,there were no significant differences in species richness of standing vegetation in burned(87 spp.)and unburned(78 spp.)sites.Our results showed that fire had an insignificant impact on soil seed bank composition and restoration potential of a plant species from seeds.The understory herb and shrub plant community’s ability to form a fire-resistant viable soil seed bank and capable to recover in the postfire rainy season,explains how they reduce the risk of recurring fire damage in maintaining their population.