简介：在在东方的种类和土壤因素之间的植物种类和关系的分发Gurbantunggut沙漠的中央部分被学习提供更多的卓见进植物群并且越过沙漠的各种各样的部分在植被决定差别。双向簇分析证明在区域的植被能被划分成三个组，第一个组被灌木种类，Ephedraprzewalskii和草种类统治，主要在扁平的根据和轻轻的斜坡的区域的Carexphysodes；第二个组被C统治。physodes，Artemisiasongorica和A。主要沙沙丘和第三个组的斜坡上的xerophytica被灌木种类统治，主要沙沙丘的顶上的Haloxylonpersicum。在植物密度在之间没有差别组织1和2，但是在组3有重要减少。不到植被组3的土壤水比在其它，二个组根本玷污深度的低得多。EC，有机物，全部的P和可溶的Na，Ca和Mg与土壤水很同样变化了。正规通讯分析(CCA)令人满意地在区域估计了种类土壤关系。植物种类的分发强烈与水内容，有机物，EC和营养素的土壤因素被相关。在三把CCA斧子解释的种类出现的变化是大约70%，显示一些解释地点变量可以在我们的学习参数外面存在。土壤质地被建议在未来研究被包括改进CCA的解释。

简介：Xiangshanbayisanarrowsemi-closedbayandsituatedonthenorthwesterncoastoftheEastChinaSea.Overpastdecades,ithasbecometoamajorbaywithintensivehumanactivities,denseurbanizedarea,andpoorwaterquality.Theaimofthispaperwastorevealtheecologicalstatusthroughtheelucidationofthespeciescomposition,abundance,biomassanddiversityofmacrobenthosinthisbay.SixintertidalsectionsweresurveyedfromJanuary2007toNovember2008quarterly.SectionsTG,HDandXHarelocatedinthethreeinnerbays,sectionsQJandWSarelocatednearthethermalpowerplants,andsectionXXislocatedattheouterpartofXiangshanBay.Greatvariationsinmacrobenthoscommunitywereindentified,andthespeciescompositionofthecommunityinthepresentstudyshowedthedominanceintheorderofmolluscs(bivalvesandgastropods),crustaceansandothers,andonlyfewPolychaetawererecorded.Onlythreedominantspecies,Littorinabrevicula,Ilyplaxtansuiensis,andCerithideacingulatawerecollectedinallthesections,andatotalof19dominantspecieswererecordedonlyinonesection.Two-wayANOVAanalysesofabundanceindicatedthatthereweresignificantdifferencesamongsectionsorseasons.Shannon-Wienerdiversityindex(H’)haditsmaximum(2.45)insectionQJ,andminimum(1.76)insectionTG.Multipleirregulark-dominanceplotsclearlyshowedthatthestudyareawaspollutedandthemacrobenthoscommunitywasunderstress.WeconcludethatthemacrobenthosofXiangshanBayhavebeendisturbedbyhumanactivities,especiallyattheinteriorbay.

简介：Background:Coarsewoodydebris(CWD)isanimportantelementofforeststructurethatneedstobeconsideredwhenmanagingforestsforbiodiversity,carbonstorageorbioenergy.Tomanageiteffectively,dynamicsofCWDdecompositionshouldbeknown.Methods:Usingachronosequenceapproach,weassessedthedecompositionratesofdownedCWDofFagussylvatica,PiceaabiesandPinussylvestris,whichwassampledfromthreedifferentyearsoftreefallandthreedifferentinitialdiameterclasses(>10–≤20cm,>20–≤40cm,>40cm).Samplesoriginatingfromwindthrowsin1999werecollectedalongatemperatureandprecipitationgradient.Basedonthedecayclassandassociatedwooddensities,logvolumeswereconvertedintoCWDmassandCcontent.Logfragmentationwasassessedoveroneyearforlogsegmentsofintermediatediameters(>20–40cm)after8and18yearsofdecomposition.Results:Significantlyhigherdecompositionconstants(k)werefoundinlogsofF.sylvatica(0.054year~(-1))thaninP.abies(0.033year~(-1))andP.sylvestris(0.032year~(-1)).However,masslossofP.sylvestrisoccurredmainlyinsapwoodandhencekforthewholewoodmaybeoverestimated.DecompositionratesgenerallydecreasedwithincreasinglogdiameterclassexceptforsmallerdimensionsinP.abies.About74%ofthevariationinmassremainingcouldbeexplainedbydecompositiontime(27%),treespecies(11%),diameter(17%),theinteractiveeffectsbetweentreespeciesanddiameter(4%)aswellasbetweendecompositiontimeandtreespecies(3%)andarandomfactor(siteandtree;9.5%),whereastemperatureexplainedonly2%.Woodfragmentationmayplayamoreimportantrolethanpreviouslythought.Here,between14%and30%ofthedecompositionrates(forthefirst18years)wereattributabletothisprocess.Carbon(C)density(mgC·cm~(-3)),whichwasinitiallyhighestforF.sylvatica,followedbyP.sylvestrisandP.abies,decreasedwithincreasingdecaystagetosimilarvaluesforallspecies.Conclusions:Theapparentlackofclimateeffectsondecompo

简介：象Wolbachia那样的繁殖寄生虫在节肢动物之中是极其普遍的并且能在他们的主人的繁殖和健康上有大影响。未被发现的感染能因此使集中于繁殖隔离的主人行为，复制，健康，和度的方面的大量研究的结果惊讶。这个潜在的问题被有货模型系统果蝇melanogaster的调查Wolbachia感染的发生的工作已经加重了。这里，我们调查进一步通常使用的模型节肢动物的实验室股票的一个范围，特别集中于面粉甲壳虫Triboliumcastaneum和Triboliumconfusum，豇豆象鼻虫Callosobruchusmaculatus和相关种类(翘目：Tenebrionidae和Bruchidae)。这些种类是普遍的存储了产品害虫因此有共生者的感染的知识进一步在通知biocontrol措施有潜在的使用。甲壳虫与3个已知的微生物引起的繁殖寄生虫为感染被估计：Wolbachia，立克次休属微生物，Spiroplasma。有一些这些微生物的感染在一些股票学习了的实验室被发现，尽管全面感染是相对稀罕的。多半在这些或另外的种类和以前的研究的类型发现感染最被假装的后果被讨论。

简介：Background:Prosopisspecieshavebeenintroducedtomanyareasoutsidetheirnativerangetoprovidebenefitstolocalcommunities.SeveralProsopisspeciesandtheirhybrids(hereafter"mesquite")have,however,becomenaturalisedandinvasiveandnowgeneratesubstantialcosts.Managementoptionsarelimitedbecauseofthecomplexconflictsofinterestregardingbenefitsandcosts.Managementpoliciesandstrategiesmusttakeaccountofsuchconflicts,butfurtherinsightsareneededonthedimensionsofusesandimpactsbeforesuchinformationcanbeusefullyapplied.CurrentpolicyinSouthAfricaallowsforthegrowthanduseofmesquiteinoneprovince,butnotinotherswhereitscontrolismandatory.Wereportonastudytoquantifythedirectuseandperceptionsofnon-timberforestproducts(NTFPs)frommesquiteandnativetreesinSouthAfrica.Methods:Semi-structureshouseholdinterviewswereconductedwithvariousstakeholdergroupstoidentifywhattreeproductsareused,toascertainamountsusedaswellastogaugeperceptionsofnaturalresourceusebetweendifferenttreespeciesanduseovertime.Results:Thedirecthouseholdusevalueofnativetreeswashigherthanthatofmesquite,andlocalstakeholdersattachedgreatervaluetoproductsfromnativetreesthanfrommesquite.Therefore,nativetreesareandwillstillbepreferentiallyharvested,andmesquiteisunlikelytoofferprotectiontonativespeciesbyprovidinganalternativesourceofproducts.Mesquitepodsdo,however,providevaluableadditionalresources(fodderandmedicinalproducts).Theuseofbothnativetreesandmesquiteisdecreasingastheincomesofpoorerhouseholdsriseandasalternativeenergysourcesbecomeavailable.Thebenefitsandrelianceonmesquitearenotashighaspreviouslyassumedandtheimpactsfrommesquiteinvasionscreatelargeproblemsforlocalcommunities.Conclusion:Thisstudyprovidesfurtherevidencethattheimpactsofmesquiteexceedthebenefits,lendingsupportforapolicytoreducenegat

简介：Background:Mostcurrentapproachesinforestscienceandpracticerequireinformationaboutstructureandgrowthofindividualtreesratherthan-orinadditionto-sumandmeanvaluesofgrowthandyieldatforeststandlevelasprovidedbyclassicexperimentaldesigns.Byinventingthewheeldesign,Nelderprovidedthepossibilitytoturntotheindividualtreeasbasicinformationunit.Suchtrialsprovidevaluableinsightsintothedependencyofgrowthonstanddensityatparticularsites.Methods:Here,wepresentanextensionoftheoriginaldesignandevaluationbyNelder.(i)WeestablishedNelderwheelsalonganenvironmentalgradientthroughEuropeinatlanticclimateinBelgiumandGermany,MediterraneanclimateinItaly,continentalclimateinHungaryaswellasonhighlandclimateinMexico.SuchdisjunctNelderwheelsalonganenvironmentalgradientcanberegardedandanalysedasatwo-factordesignwiththefactorsofsiteconditionandstanddensity.(ii)WepresentanadvancedstatisticalapproachtoevaluatedensitydependentgrowthdynamicsoftreesplantedinformoftheNelderdesign,whichconsidersspatio-temporalautocorrelation.(iii)Weprovetheusefulnessofthemethodsinimprovingecologicaltheoryconcerningdensityrelatedproductivity,trade-offsbetweenfacilitationandcompetition,andallometricrelationsbetweensizevariables.Results:FirstevaluationsbasedonremeasuredNelderwheelsinoak(QuercusroburL.)showasizegrowthdifferentiationduringthefirstobservationperiod.Inparticular,heightgrowthisacceleratedunderhighercompetitionindicatingfacilitationeffects.Wedetectfurthermoreahighvariabilityinallometricrelations.Conclusions:Theproposeddesign,methods,andresultsarediscussedregardingtheirimpactonforestpractice,modelbuilding,andecologicaltheory.WeconcludethattheextendedNelderapproachishighlyefficientinprovidingcurrentlylackingindividualtreelevelinformation.