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1.
分支系统学简评   总被引:1,自引:0,他引:1  
冷琴  周巍 《古生物学报》1997,36(1):122-131
分支系统学简评冷琴(中国科学院南京地质古生物研究所,南京210008)周巍(南京市玄武区花园路,南京210037)1前言分支(支序)系统学(Cladistics,Cladisticsystematics),又称系统发育分类学(phylogenetic...  相似文献   

2.
庐山土壤微生物类群及酶活特性   总被引:3,自引:0,他引:3  
庐山土壤微生物类群及酶活特性陆杨森,熊金莲,张明(安徽农学院,合肥230036)MicrobialGroupsandEnzymeActivityinSoilofLushanMountain¥LuYangsen;XiongJinlian;ZhangMing(AnhuiAgriculturalCollege,Hefei230036).ChineseJournalofEcology1993,12(5):25-28。ThetotalnumberofmicrobesvariesindifferentsoiltypesofLushanMountain,beingthehighest(1.2×10 ̄9numbersgdrysoil)inmountainousyellowbrownsoil.Theecologialdistributionofvariousmicrobialgroupsindifferentsoiltypesissimllar。Bacteriaismorethanactinomycesandfungi.Nonitrifyingbacte-riacanbefoundInsollsofLushanMountai  相似文献   

3.
生物统计的各种检验方法和使用条件概述   总被引:3,自引:0,他引:3  
生物统计的各种检验方法和使用条件概述房继明刘来福(北京师范大学生物学系,100875)(北京师范大学数学系,100875)AnOutlineofTestingMethodsandConditionsinBiologicalStatistics¥Fan...  相似文献   

4.
生态网络分析的研究进展   总被引:6,自引:0,他引:6  
生态网络分析的研究进展韩博平(厦门大学生物系,361005)ProgressesontheAnalysisofEconetwork¥HanBoping(BiologyDepartment,XiamenUniversity,Xiamen361005);ChineseJournalofEcology,1993,12(6):41-45.Econetworkisastructuralmodelwhichisusedtosimulatetheflowofmaterialandenergyinecosystem。Theanalysisofeconetworkisthetheoryandmethodstoanalyzetheflowbehaviorandfeatureofmaterialandenergyineconetwork,itincludestheanalysisofflowfeature,informationindices,stochasticpro-cess,trophiclevelandsensitivity.Areviewissystematicallygiven.Keywords:econetwork  相似文献   

5.
丘陵地区农户生态系统演替分析   总被引:2,自引:1,他引:1  
丘陵地区农户生态系统演替分析曹凑贵(华中农业大学,武汉430070)EvolutionaryAnalysisonHousekoldEcosysteminHIIIyRegions¥CaoCougui(CentralChinaAgriculdturalUniversity,Wuhan430070).ChineseJournalofEcology,1993,12(2):53-54.Thecharacteristicsofdifferenttypehouseholdecosystemsandtheirevolutionarycorrelationsareanalyzedusingfuzzyclusteringandsystemsyntheticevolutionmethods,Thecauseanddirectionofagriculturaldevelopmentinhillyregionsarerevealedandsuggestionsondevelopingeco-agriculturalconstructioninlowerproductivehillyregionsaremade.Keywords:ho  相似文献   

6.
棉花无蜜腺性状抗棉铃虫及红铃虫效果研究郑冬官,方其英(安徽农业大学合肥2300336)郑厚今(安徽省农业厅,合肥230001)Resistanceofcottonnectarilesscharactertobollwormandpinkbollwor...  相似文献   

7.
珍稀濒危植物青钩栲种群数量特征研究   总被引:20,自引:2,他引:18  
提出自适应种群增长新模型S=exp(aln^2(1+ce^-rt)+βln(1+ce^-et)+γ),该模型包融了Logistic模型、Smith模型、Gompertz模型、崔-Lawson模型、张-Logistic模型和刘-Logistic模型,运用遗传算法适应新模型进行参数估计,拟合青钩栲种群增长规律比其它种群增长模型更符合青钩栲群种的实际增长趋势,说明新模型具有一定的实用价值。  相似文献   

8.
生态学的发展阶段及其特点   总被引:3,自引:0,他引:3  
生态学的发展阶段及其特点吴兆录(云南大学生态学与地植物学研究所,昆明650091)Developmentstagesofecologyandtheircharacteristics.¥WuZhaolu(InstituteofEcologyandGeo...  相似文献   

9.
河西走廊农户生态系统农田能流和物流数量特征的研究   总被引:6,自引:0,他引:6  
河西走廊农户生态系统农田能流和物流数量特征的研究李发弟(甘肃农业大学畜牧系,兰州730070)QuantintiveCharacteristicsofEnergyFlowandNutrientCyclingofFarmlandinaFarmEcosysteminHexiCorridor¥LiFadi(DepartmentofAnimalHusbandry,GansuAgriculturalUnitversity).ChineseJour-nalofEcology,1993,12(6):37-40.Quantitativecharacteristicsofenergyflowandnutrientcyclingoffarmlandsubsysteminafarmecosys-teminHexiCorridorwerestudied.Theresultsshowedthatthedeflreeofopening,inputandoutputwerehigh,theratioofoutputtoinputofsubsidyenergy,nitrogenandphosphorusofthefarmlandsubsy  相似文献   

10.
DynamicChangesofβTubulinduringtheResumptionofMeiosisofMouseOocyteLIUHui;(刘辉)CHENDa-yuan;(陈大元)(StateKeyLaoboratoryofReproducti...  相似文献   

11.
We investigated the influence of environmental parameters and spatial distance on bacterial, archaeal and viral community composition from 13 sites along a 3200-km long voyage from Halifax to Kugluktuk (Canada) through the Labrador Sea, Baffin Bay and the Arctic Archipelago. Variation partitioning was used to disentangle the effects of environmental parameters, spatial distance and spatially correlated environmental parameters on prokaryotic and viral communities. Viral and prokaryotic community composition were related in the Labrador Sea, but were independent of each other in Baffin Bay and the Arctic Archipelago. In oceans, the dominant dispersal mechanism for prokaryotes and viruses is the movement of water masses, thus, dispersal for both groups is passive and similar. Nevertheless, spatial distance explained 7–19% of the variation in viral community composition in the Arctic Archipelago, but was not a significant predictor of bacterial or archaeal community composition in either sampling area, suggesting a decoupling of the processes regulating community composition within these taxonomic groups. According to the metacommunity theory, patterns in bacterial and archaeal community composition suggest a role for species sorting, while patterns of virus community composition are consistent with species sorting in the Labrador Sea and suggest a potential role of mass effects in the Arctic Archipelago. Given that, a specific prokaryotic taxon may be infected by multiple viruses with high reproductive potential, our results suggest that viral community composition was subject to a high turnover relative to prokaryotic community composition in the Arctic Archipelago.  相似文献   

12.
Savannas are spatially diverse, variable and are susceptible to high rates of disturbance from fire and herbivory. There is significant interest in woody cover dynamics in relation to disturbance regimes. Less effort has been devoted to understand processes that drive tree community composition. In this study, tree species composition data collected at the landscape scale in the Serengeti were used to identify key environmental factors driving variation in species composition. A system of 38 plots clustered within 10 sites spanning the mean annual precipitation (MAP) gradient was used to assess the relative role of bottom‐up (precipitation, soil nutrients and soil texture) vs. top‐down factors (fire and elephant herbivory) on tree community composition. We developed candidate models relating tree species composition (based on multivariate community analysis) to different combinations of plot‐level environmental covariates. Results suggest that tree community composition is largely driven by MAP and is associated with elephant population density. Strikingly, we found no evidence that fire influences species compositional turnover. In a second analysis, we used structural equation model (SEM) to explore the possible direction of association between elephant density and tree species composition. We compared a model that included elephant effects on composition to one that included community composition effects on elephant density. Results suggest that variation in elephant population density across space is more likely to drive tree community composition and not vice versa. We propose that precipitation and herbivory, rather than fire, determine tree species composition in Serengeti Acacia tree community.  相似文献   

13.
Vegetation species composition and structure are known to affect taxonomic composition and life‐history characteristics of arthropod communities. Soil conditions alter vegetation composition and structure, and thus, soils have indirect effects on arthropods. Whilst grassland management affects soil properties, and hence vegetation, the direct effects of soil on arthropod communities within the sward are less clear. We used a long‐term hay meadow experiment to assess both direct and indirect effects of various fertilizer regimes on arthropod community composition and feeding guilds. Arthropods were sampled via pitfall traps and sweep nets and then analysed using principal components and redundancy analyses (RDA) to determine relationships between soil properties, vegetation community, forage quality and arthropod community. Vegetation community composition, measured by the first vegetation principal component, was used as a constraining variable in partial RDA, to estimate direct effects of soil on the arthropods. Variance partitioning quantified the relative roles of vegetation and soil on the arthropod community. Our results indicate that available soil nitrogen and carbon–nitrogen ratios are important determinants of arthropod community composition. Once the effects of the vegetation were removed, it was found the soil acidity and the available potassium altered arthropod community composition. Further research is required to determine the mechanisms by which these soil properties affect arthropod communities.  相似文献   

14.
Although climate change is acknowledged to affect population dynamics and species distribution, details of how community composition is affected are still lacking. We investigate whether ongoing changes in bird community composition can be explained by contemporary changes in summer temperatures, using four independent long‐term bird census schemes from Sweden (up to 57 yr); two at the national scale and two at local scales. The change in bird community composition was represented by a community temperature index (CTI) that reflects the balance in abundance between low‐ and high‐temperature dwelling species. In all schemes, CTI tracked patterns of temperature increase, stability or decrease remarkably well, with a lag period of 1–3 yr. This response was similar at both the national and local scale. However, the communities did not respond fast enough to cope with temperature increase, suggesting that community composition lags behind changes in temperature. The change in CTI was caused mainly by changes in species’ relative abundances, and less so by changes in species composition. We conclude that ongoing changes in bird community structure are driven to a large extent by contemporary changes in climate and that CTI can be used as a simple indicator for how bird communities respond.  相似文献   

15.
Understanding how environmental fluctuations affect the stability of populations and communities is complex, for example, because direct effects of environmental variability on populations may be modified and propagated across communities by species interactions. One way to explore and further understand these complexities is via a factorial manipulation of community composition and environmental conditions. Using laboratory based aquatic microcosms we manipulated environmental fluctuation by creating two environments; one with variable light and one with constant light. Within these environments, community composition was manipulated by constructing communities from all possible combinations of three species that vary in their reliance on light for growth (an autotroph: a diatom completely reliant on light, a heterotroph: a Paramecium species not reliant on light, and a mixotroph: a Paramecium species somewhat reliant on light). Community composition was predicted to affect populations and communities by introducing and altering competitive interactions between species and affecting the degree of niche differentiation between species. We found that population stability was predominantly influenced by an interaction between community composition and environmental variability, whereby the effect of environmental variability synergistically combined with effects of community composition to reduce population stability. Covariance of populations was determined by an interaction between community composition and environmental variability, though this did not result from the effect of niche differentiation between species. Species interactions drove correlations between population biomass and the environment which otherwise did not exist. Our results demonstrate the complex and interrelated effects of abiotic and biotic factors on population and community stability, and suggest the need to consider aspects of community composition when predicting the impact of environmental fluctuations.  相似文献   

16.
Plants are known to influence belowground microbial community structure along their roots, but the impacts of plant species richness and plant functional group (FG) identity on microbial communities in the bulk soil are still not well understood. Here, we used 454‐pyrosequencing to analyse the soil microbial community composition in a long‐term biodiversity experiment at Jena, Germany. We examined responses of bacteria, fungi, archaea, and protists to plant species richness (communities varying from 1 to 60 sown species) and plant FG identity (grasses, legumes, small herbs, tall herbs) in bulk soil. We hypothesized that plant species richness and FG identity would alter microbial community composition and have a positive impact on microbial species richness. Plant species richness had a marginal positive effect on the richness of fungi, but we observed no such effect on bacteria, archaea and protists. Plant species richness also did not have a large impact on microbial community composition. Rather, abiotic soil properties partially explained the community composition of bacteria, fungi, arbuscular mycorrhizal fungi (AMF), archaea and protists. Plant FG richness did not impact microbial community composition; however, plant FG identity was more effective. Bacterial richness was highest in legume plots and lowest in small herb plots, and AMF and archaeal community composition in legume plant communities was distinct from that in communities composed of other plant FGs. We conclude that soil microbial community composition in bulk soil is influenced more by changes in plant FG composition and abiotic soil properties, than by changes in plant species richness per se.  相似文献   

17.
Enzyme-mediated decomposition of soil organic matter (SOM) is controlled, amongst other factors, by organic matter properties and by the microbial decomposer community present. Since microbial community composition and SOM properties are often interrelated and both change with soil depth, the drivers of enzymatic decomposition are hard to dissect. We investigated soils from three regions in the Siberian Arctic, where carbon rich topsoil material has been incorporated into the subsoil (cryoturbation). We took advantage of this subduction to test if SOM properties shape microbial community composition, and to identify controls of both on enzyme activities. We found that microbial community composition (estimated by phospholipid fatty acid analysis), was similar in cryoturbated material and in surrounding subsoil, although carbon and nitrogen contents were similar in cryoturbated material and topsoils. This suggests that the microbial community in cryoturbated material was not well adapted to SOM properties. We also measured three potential enzyme activities (cellobiohydrolase, leucine-amino-peptidase and phenoloxidase) and used structural equation models (SEMs) to identify direct and indirect drivers of the three enzyme activities. The models included microbial community composition, carbon and nitrogen contents, clay content, water content, and pH. Models for regular horizons, excluding cryoturbated material, showed that all enzyme activities were mainly controlled by carbon or nitrogen. Microbial community composition had no effect. In contrast, models for cryoturbated material showed that enzyme activities were also related to microbial community composition. The additional control of microbial community composition could have restrained enzyme activities and furthermore decomposition in general. The functional decoupling of SOM properties and microbial community composition might thus be one of the reasons for low decomposition rates and the persistence of 400 Gt carbon stored in cryoturbated material.  相似文献   

18.
There is growing interest in understanding the linkages between above- and belowground communities, and very little is known about these linkages in tropical systems. Using an experimental site at La Selva Biological Station, Costa Rica, we examined whether plant diversity, plant community composition, and season influenced microbial communities. We also determined whether soil characteristics were related to differences in microbial communities. Phospholipid fatty acid (PLFA) composition revealed that microbial community composition differed across a plant diversity gradient (plots contained 1, 3, 5, or over 25 species). Plant species identity also was a factor influencing microbial community composition; PLFA composition significantly varied among monocultures, and among three-species combinations that differed in plant species composition. Differences among treatments within each of these comparisons were apparent in all four sampling dates of the study. There was no consistent shift in microbial community composition between wet and dry seasons, although we did see significant changes over time. Of all measured soil characteristics, soil C/N was most often associated with changes in microbial community composition across treatment groups. Our findings provide evidence for human alteration of soil microbial communities via the alteration of plant community composition and diversity and that such changes are mediated in part by changes in soil carbon quality.  相似文献   

19.
Quantifying the role of spatial patterns is an important goal in ecology to further understand patterns of community composition. We quantified the relative role of environmental conditions and regional spatial patterns that could be produced by environmental filtering and dispersal limitation on fish community composition for thousands of lakes. A database was assembled on fish community composition, lake morphology, water quality, climatic conditions, and hydrological connectivity for 9885 lakes in Ontario, Canada. We utilized a variation partitioning approach in conjunction with Moran's Eigenvector Maps (MEM) and Asymmetric Eigenvector Maps (AEM) to model spatial patterns that could be produced by human‐mediated and natural modes of dispersal. Across 9885 lakes and 100 fish species, environmental factors and spatial structure explained approximately 19% of the variation in fish community composition. Examining the proportional role of spatial structure and environmental conditions revealed that as much as 90% of the explained variation in native species assemblage composition is governed by environmental conditions. Conversely on average, 67% of the explained variation in non‐native assemblage composition can be related to human‐mediated dispersal. This study highlights the importance of including spatial structure and environmental conditions when explaining patterns of community composition to better discriminate between the ecological processes that underlie biogeographical patterns of communities composed of native and non‐native fish species.  相似文献   

20.
The research of a generation of ecologists was catalysed by the recognition that the number and identity of species in communities influences the functioning of ecosystems. The relationship between biodiversity and ecosystem functioning (BEF) is most often examined by controlling species richness and randomising community composition. In natural systems, biodiversity changes are often part of a bigger community assembly dynamic. Therefore, focusing on community assembly and the functioning of ecosystems (CAFE), by integrating both species richness and composition through species gains, losses and changes in abundance, will better reveal how community changes affect ecosystem function. We synthesise the BEF and CAFE perspectives using an ecological application of the Price equation, which partitions the contributions of richness and composition to function. Using empirical examples, we show how the CAFE approach reveals important contributions of composition to function. These examples show how changes in species richness and composition driven by environmental perturbations can work in concert or antagonistically to influence ecosystem function. Considering how communities change in an integrative fashion, rather than focusing on one axis of community structure at a time, will improve our ability to anticipate and predict changes in ecosystem function.  相似文献   

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