祁连山青海云杉林不同海拔梯度土壤水分动态变化研究.docx
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祁连山青海云杉林不同海拔梯度土壤水分动态变化研究.docx
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祁连山青海云杉林不同海拔梯度土壤水分动态变化研究
ResponseRelationshipbetweentheSeasonalFreezing-ThawingProcessofSoilandSpatialFactorChangesintheDayekouBasinoftheQilianMountains
Abstract
[Objective]Inthisstudy,theinfluenceandresponserelationshipbetweentheseasonalfreezing-thawingprocessofsoilandthespatialfactorchangesinthemanagementandutilizationofwaterresourceprocesseswereexplored.
[Methods]Themonitoringequipmentinthisstudywasarrangedatdifferentaltitudes,gradients,andslopedirections,suchasthetypicalforestsampleareaintheDayekouBasinoftheQilianMountains.Thespatialvariationcharacteristicsoftheseasonalfreezing-thawingprocessofthesoilwereanalyzed,andaregressionmodelwasestablished.
[Results]
(1)Theresultsofthisstudydeterminedthattherateofthesoil’sfreezingincreasedwiththealtitudeinatrendofvolatility.However,therateofthethawingofthefrozensoilwasfoundtohaveanoppositetrend.Thevariationdegreeofthefreezing-thawingprocessincreasedwiththealtitudeinatrendofvolatility.Theendtimeoftheapproximatesoilfreezingwithaltitudeincreasedinavolatilitytrendaheadofschedule.However,theoppositewasobservedinthethawingrateofthefrozensoil;
(2)Therateofthesoil’sfreezingunderthemossesofthespruceforestatanaltitudeof3,028mwasfoundtobethelowest.However,inthesub-alpinescrubforestatanaltitudeof3,300m,amaximuminthespatialorderingwasobserved,withanaverageof1.9cm·d-1.Thethawingrateofthefrozensoilinscrub-spruceforestatanaltitudeof3,300mwasfoundtobeminimal.However,inthesunnyslopegrasslandatanaltitudeof2,946m,amaximuminthespatialorderingwasobserved,withanaverageof1.5cm·d-1.Inthespatialorderingofthevariationdegreeoftheprocessoffreezing-thawingwithanaverageof1.2,thescrub-grasslandatanaltitudeof2,518mwasfoundtobethelowest,andthescrub-spruceforestatanaltitudeof3,195mwasalsolow;(3)ThesoilfreezingbeganonapproximatelyOctober20th,andtherateofsoilfreezinggraduallybecamereduced.Thearrivaltimeofthefrozensoilofupto150cmindepthinsub-alpinescrubforestwasfirstobservedatanaltitudeof3,028m.However,thescrub-spruceforestatanaltitudeof3,100mdidnotbecomefrozenuntilapproximatelyJanuary12thonaverage.Then,thethawingrateofthefrozensoilincreasedgradually.Theendtimeofthethawingwasearliestobservedinthesunnyslopegrasslandatanaltitudeof2,946m.However,thescrub-spruceforestatanaltitudeof3,100mwasfoundtobethelasttothaw,andaveragedapproximatelyJuly27th.Theaveragedurationsofthefreezingandthawingofthesoilwere77and121days,respectively,andtheaveragedurationoftheentireprocessoffreezing-thawingwas199days;(4)Thisstudy’sestablishedregressionmodelsofthedurationtimesoffrozensoil’sthaw,andtherateoffrozensoil’sthaw,allpassedtheRtestofgoodnessoffit,Ftestofvariance,andttest.
[Conclusions]Thecharacteristicsoftheseasonalfreezing-thawingprocessofthesoilwiththespatialchangeswereseasonal.However,thecharacteristicsunderthedifferentspatialfactorinfluenceswerenotthesame.
Keywords:
freezing-thawing;spatialfactor;seasonalfrozensoil;DayekouBasinoftheQilianMountains
Thefrozenearthchangesarethemainresearchcontentofacryosphere,andthefreezing-thawingprocessofsoildirectlyaffectsbasinrunoff.Itisknownthat,withinabasin,thefreezing-thawingprocessofsoiltendstobesensitivetospatialchanges.Therefore,inordertoexplorethebasinrunoffprocess,thespatialvariationattributesofthefreezing-thawingprocessofsoilshouldbeconsidered(Niuetal.,2014;Zhangetal.,2012).Oneofthemostimportantanddifficultproblemsinfrozenearthresearchisthedeterminationofthespatialchangesofthefrozenearth,especiallythoseonabasinscale(Wangetal.,2014).Thepreviousresearchregardingthespatialchangesoffrozenearthhasmainlyconcentratedonthreeaspects.Oneaspectistheassumptionofthefutureclimatescenarios,consideringthatplateauregionsaregenerallywarmingwiththesameamplitude,andpermafrostdegradationisknowntooccurnotonlyontheedgeofthepermafrostzone,butalsoaroundthevalleythawingarea,andthehighplainswampinthepermafrostregions(Lietal.,1999;Nanetal.,2004;NelsonFEetal.,2002).Thesecondaspectisthespeculationofthespatialchangesofthepermafrostinthelimitedareasusingthedrillingorcuttingdataatlimitedpoints(Wang,2010).Thethirdaspectofmainresearchcontentisthespatialchangesofthepermafrost,ortheseasonalfrozensoilintheQinghai-TibetPlateau(Wang,2008).Theseresearchresultshaveimportantacademicandapplicationvalues.However,therehavebeenfewerexperimentsconductedregardingthemassivemeasureddataofthespatialvariationfactorsonabasinscalewhichcanbeutilizedforthestudyingofthefreezing-thawingprocessofsoil.
TheQilianMountainislocatedonanintersectionofthreeplateaus(i.e.theQinghai-Tibet,InnerMongolia-XinjiangandLoessPlateaus),andhaveaveryimportantgeographicpositioninnationalforesthydrologyandecologyresearch.Acombinationofthesoil’sfreezing-thawinghydrologicprocessasaninevitablehydrologicalphenomenoninthisregion,andtheinsufficientrelatedresearch,hasmadeitverynecessarytocarryoutrelatedresearchinthisregion.DuringtheresearchregardingthespatialchangesofthefrozensoilintheQilianMountainsorupstreamoftheHeiheRiver,seventhermometerboreholeswereusedtosetthermometertubesforgroundtemperaturemonitoringforthepurposeofstudyingthefrozensoildistributioncharacteristics(Wang,2008).Morethan40yearsoftemperatureandsoiltemperaturedataatadepthof5cmfrom11meteorologicalstationswereadoptedtosystematicallystudythemonthlyseasonalfrozensoildistributionfrom2000to2009,alongwiththespatiotemporalvariationcharacteristicsofthefreezingprobability(Peng,2013).Basedonanelevation-responsemodel,thehigh-resolutionelevationdata(DEM),longitudedata,latitudedata,annualaverageairtemperature(MAAT),andverticallapseratedata(VLRT)wereappliedforanumericalsimulationofthefrozenearthdistributionintheQilianMountainsduringthelast40years(Zhang,2014).RelatedresearchhasalsobeenconductedintheSidalong,Binggou,andPailugouBasinsoftheQilianMountainsbytheGansuResearchInstituteofWaterConservationForestintheQilianMountains(Wang,2001;Chang,2001;Jin,2011;Niuetal.,2014).Thisresearchfocusedonthehydrologicalandinter-annualchangecharacteristicsofthefreezingandthawingprocessofsoil.
Insummary,therewerefewexperimentalresultsavailabletosetthedensersampleplotsandfrozensoiltubesinthebasinforthelong-termfieldmonitoringofthefrozensoilchanges.Therewasalsoonlyasmallamountofdataregardingthechangesinthespatialfactorssuchasaltitude,slopegradient,slopedirection,andcrowndensityfactors,bywhichtostudythefreezing-thawingprocessofsoil.Accordingly,themonitoringdevicesweresetintypicalsampleplotswithdifferentelevations,slopegradients,slopedirections,andforeststandsthroughouttheentirebasintoobtainthedataforthisstudy.Thespatialvariationcharacteristicsofthesoil’sfreezingandthawingprocesseswereanalyzedtofurtherresolvethestandstructureofthebasin,alongwithitsfunctionmechanismofwaterconservation,whichprovidedascientificbasisandreferencefortheecologicalhydrology.
1.Studyarea
TheQilianMountainsarelocatedattheintersectionoftheQinghai-Tibet,InnerMongolia-XinjiangandLoessPlateaus.Thismountainrangeisclassifiedasoneof50nationallyimportanteco-functionareas,andoneof25keyeco-functionareasbytheNationalEcologicalFunctionRegionalizationandtheNationalMajorFunctionAreaPlanning,andtherebypresentsaveryimportantecologicalniche.TheDayekouBasin(38°16'-38°33'N,100°13'-100°16'E)belongstotheZhongshanclimatezoneoftheQilianMountains,andextendseasttoMazongliang,westtoXigouliang,northtoZhengnangou,andsouthtoPailugou.ThisbasinoriginatedfromYeniuMountains,SunanCounty.Sixlargerbranches,namelyDongcha,Xicha,Toutangou,Xigouliang,GuantaigouandShengou,convergeattheDayekouReservoir,withanareaof80km2,andcontrol98%ofthebasincatchmentarea,whichindicatesatypicalclosedbasin(asshowninFig.1).Duetogreatelevationvariationintervalsinthebasin,thehydrothermalconditionsdisplaylargedifferencesintheformofvegetationandsoiltypes,aswellasverticalandhorizontalgradientdifferences.Fromthelowesttohighestaltitudes,thevegetationtypescanbedescribedasmountaindesert,mountaingrassland,mountainforestgrassland,subalpinemeadow,andmountainsnowvegetation.Thesoiltypesincludemountainsierozem,mountainchestnutsoil,mountaingraycinnamonicsoil,subalpineshrubmeadowsoil,andalpinefrostdesertsoil.Amongallofthesoils,themountaingraycinnamonicsoilandthesub-alpineshrubmeadowsoilarethesoilsinvolvedinforestgrowth,andaredistributedintheregionswithaltitudesof2,400to3,300mand3,300to4,000m,respectively.Amongtheedificatories,theQinghaiPiceacrassifoliaisdistributedaspatchesorstripsontheshadedandhalf-shadedslopes,ataltitudesbetween2,400and3,300minthetestarea,staggeredwithgrasslandonthesunnyslopes.TheQilianSibinaprzewalskiisdistributedassmallblocksonthesunnyandhalfsunnyslopes.Theshrubswhichare
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- 祁连山 青海 云杉 不同 海拔 梯度 土壤 水分 动态 变化 研究