简介:Settingmonitoringtransectinthemiddleandshallowwaterarea(altitude156-172m)inThreeGorgesreservoirhydro-fluctuationbelttoresearchthechangingcharacteristicsofthecontentsofN,P,K,pHandorganicmatterofthesoilwhichexperiencedtheinfluenceoffluctuationthefirsttime.Theresultsshowedthatbytheinfluenceofwaterlevelfluctuating,contentsofsoilN,P,K,pHandorganicmatterhadreducedindifferentsoillayersinhydro-fluctuationbelt.TheavailableNdecreasedby41.53%-59.87%,availablePdecreasedby5.26%-36.76%,availableKdecreasedby3.55%-45.56%,totalNdecreasedby9.52%-40.00%,totalPhadnochangegenerally,totalKhaddecreasedalittle,contentoforganicmaterialdecreasedby7.62%-37.83%%,pHvalueturnedtoneutral,changedby1.73%-9.58%.
简介:Leafshapesarenotonlytheusefulindicatorsinplanttaxonomy,butalsotheimportantfactorsaffectingenergyandmaterialexchangeinleaves.Inthispaper,wecollectedandscannedtheleavesofNitrariatangutoruminDengkouofInnerMongoliaAutonomousRegion(themeanannualprecipitation145mm)andMinqinofGansuProvince(themeanannualprecipitation115mm)andN.sphaerocarpainDunhuang,andthenanalyzedleafshapeparameterswithImage-ProPlus6.0imageprocessingsoftwareandleafδ13CvaluesintheisotopelaboratoryoftheChineseAcademyofForestry.Theresultshowedthat:1)asleafareaincreasedwithincreasingwateravailabilitytheincreasesintheleaflengthandwidthwereasynchronously;2)withthesameleafwidth,the1eavesofN.tangutorumandN.sphaerocarpaweresignificantlylongerinhighwateravailableconditions;and3)althoughthereweresignificantlydifferencesinwateravailabilitybetweenDengkouandMinqin,aswellasbetweenthebottomandmiddleofthealluvialfanneartheEastLakeinDunhuang,theleafδ13CvaluesofN.tangutorumorN.sphaerocarpaweresimilarindifferentwaterconditions(P>0.05).Ourresultssuggestedthattheratioofleafperimetertoareawouldbeanimportantfactorwhichlinkedleafshapetoplantwaterphysiology.Duringgrowingprocedureofleafarea,leaflengthincreasewaspriortoitswidthtoalleviatethereductioninratioofperimetertoareaandmaintainwateruseefficiencyoftheplant.
简介:ThehistoricaltransitionoftimberdistributionpatterninChinawaspresentedfirstlywithmainpartsoftimberflowsinChina,whichincludedtimbermarkets,timbertransportsystemandregulationsoftimbertransport.BasedontheoverviewontropicaltimberflowsinChina,thetradeflowsoftropicaltimberfromproductionandimportsoftropicaltimbertoexportoftropicaltimberproductswereanalyzedbyvividillustrations.Atthesametime,problemsintimbertradeflowsinChinawereanalysedintheend.
简介:为解决竹子种子长期保存问题,以马来龙竹、云南龙竹、巨龙竹、金平龙竹、麻竹、长节勒竹、云南箭竹、棉花竹、爪哇巨竹、大泰竹、笻竹、方竹和毛竹13种竹子的成熟种子为材料,通过研究不同低温、低温下不同储存时间、不同含水量、不同发芽设施和不同基质对种子发芽率的影响,来判断竹子种子保存的适合条件。结果表明:1)除笻竹和方竹的种子外,大多数竹种的种子在低温储存5个月内,随着温度由10℃逐渐降低到-16℃,种子发芽率会有不同程度的增高;2)在-16℃条件下,随着储存时间的延长,种子发芽率会有所下降;3)种子含水量会在很大程度上影响种子的发芽率,含水量超过在一定临界值,随着含水量的增加,种子发芽率会显著下降;4)选择不同的种子发芽设施也会影响种子发芽率,生产中宜选用具有微喷灌条件的温室进行育苗;5)在无菌红土、黑土和蛭石这3种基质中,蛭石是竹子播种育苗的适宜基质。
简介:Inaviewofnaturalconditionsofestablishingnaturereserve,anindexsystemwaspreparedforquantitativeassessmentonstatusofendangeredspecies,andthusdegreeofendangeredspeciesinTibetwasevaluated.Takingasub-ecozoneasbasicunit,top5animalsand1plantwithhighEaswellasthenumberofspeciesineachunitwereenumerated;andthedegreeoflandutilizationwasfiguredout.Afterward,weselected6coefficients,assignedweight,andframedformulatoreckonproportionofnaturereserve,thusanareaofnaturereserveineachsub-ecozonewasobtained.In5schemesofweightassignment,aschemewithmediumareaofnaturereservewasselected.Allsub-ecozoneswereclassifiedinto4gradespriorconservation,1wasingradeA,2ingradeB,2ingradeC,and11ingradeD.Totalplannedareawasapproximately365135km2,about48834km2smallerthantheactualareaof413969km2,ratioofnaturereserveinTibetdiminishesfrom34.4%to30.38%.Basedon3factorsofhumandisturbance,ratioofbuffer-experimentalzoneinproposednaturereservewascalculated.Itwasdemonstratedthatexistingsizeofnaturereservesisexcessiveonthewhole,andtheirdistributionisnotreasonableentirely.Thesizeofnaturereservesin3sub-ecozonesofnorthernChangtangshoulddecrease,anddecrementofareaisapportionedamongother13sub-ecozoneswhichshouldincreasenaturereserve.HeterogeneityofregionaldistributionofrarespeciesinTibetisquiteobvious,soproposedareadistributionofnaturereservesismorescatteredthantheexisting.
简介:在P下面在P缺乏的allophanic土壤在磷(P)部分变化。在壶用扫帚(CytisusscopariusL.)和毒麦(Loliummultiflorum)种的radiata幼苗被学习在以在根围决定导出施肥料的P的命运的·g−1,玷污的0,50,和100μg的率的三倍的过磷酸钙的申请以后的14个月。Pfertiliser的申请增加了NaOH-Pi,NaOH-Po,和H2那么4-P在土壤的i集中,但是减少residual-P集中。resin-Pi集中,在这土壤极其低,1~3μg·g−1),仍然是一样。增加的fertiliserP的多数然而在NaOH-Pi部分(40%49%)。这由于在这土壤(92%)的高P固定。第二最高的P恢复在NaOH-Po部分(7%19%)。在以0μg·g−1,的率的P缺乏的状况或增加下面NaOH-P在radiata根围土壤的i集中在体积土壤和草根围土壤是比那低的。这可能在释放了一些在根围修理到土壤的P的P缺乏的条件下面由于由根和mycorrhiza的更高的盐生产,它需要在未来研究被测试。
简介:TheratesofsoilNmineralizationatsoildepthsof0-15,15-30,30-45and45-0cmandmoistureregimesweremeasuredatthreesand-fixationplantationsofPinussylve.strisvar.mongolicabylaboratoryaerobicincubationmethod.TheresultsshowedthataverageratesofsoilnetN-mineralizationacrosssoildepthvariedfrom1.06to7.52mg~kg1.monthqatsoildepthsfrom0to60cm.Statisticalanalysesindicatedthattheeffectsofdifferentsoildepths,moisturesandtheirinteractionsonnetN-mineralizationratesweresignificant(P<0.05).ThenetN-mineralizationratessignificantlydecreasedwithincreasingsoildepthsandatdepth0-15cmaccountedfor60.52%ofthatatdepthof0-50cm.TherewasnodifferenceinsoilnetN-mineralizationratesbetweenhalfandfully-saturatedwatertreatments,howevertheseratesweresubstantiallyhigherthanthatwithoutwatertreatment(P<0.05).ThefactorsinfluencingNmineralizationprocesshavetobestudiedfurtherinthesesemiaridpineecosystems.