简介：在每个分解阶段的森林土壤性质上的崽秋天和它的效果在热带季风被调查三种植园(7年的相思树种植园，15年的相思树种植园和18年的混合种植园)和从孟加拉国的Chittagong多山的区域的一个自然森林(Sitapahar森林)的气候的条件。结果证明有机物的全部的累积与种植园年龄增加了，与年度累积率的减少伴随。在一样的植被类型以内，有山上的显著地改变的腐植质(p≤0.05)的新鲜、部分分解的垃圾的器官的累积放，在底部斜坡上是最高的并且在森林里向山顶逐渐地减少。在土壤有机物的累积的反向的趋势在15年的相思树auriculiformis种植园，燃料木头在哪儿收集了被显示出。在7年、15年的相思树和18年的混合宽广离开的种植园，全部的有机物生产由组成评价新鲜，在土壤的部分并且完全分解的垃圾以及合并有机物是2554.31，705.79和1028.01kg·h−1·a−1,分别地，并且从新鲜垃圾的相应贡献是38.23，19.40和30.48kg·h−1·a−1,分别地。在三种植园和自然森林，在一般水准上，新鲜垃圾组成了32.45%，部分与腐植质13.50%分解了垃圾并且合并了在有0.90厘米的吝啬的崽厚度的土壤54.56%全部的有机物生产的有机物。土壤酸味随有机物的分解舞台的增加增加了。

简介：Determiningthephysicalandmechanicalpropertiesofsoilanditsbehaviorforengineeringprojectsisessentialforroadconstructionoperations.Oneofthemostimportantprinciplesinforestroadconstruction,whichisusuallyneglected,istoavoidmixingorganicmatterwithroadmaterialsduringexcavationandembankmentconstruction.Thecurrentstudyaimedtoassesstheinfluenceoforganicmatteronthephysicalpropertiesandmechanicalbehaviorsofforestsoilandtoanalyzetherelationbetweentheamountoforganicmatterandthebehaviorofforestsoilasroadmaterial.Atypicalsoilsamplefromthestudyareawascollectedbesideanewlyconstructedroadbed.Thesoilwasmixedwithdifferentpercentagesoforganicmatter(controltreatment,5,10,and15%bymass)anddifferenttestsincludingAtterberglimits,standardcompaction,andCaliforniabearingratio(CBR)testswereconductedonthesedifferentsoilmixtures.Theresultsshowedthatsoilplasticityincreasedlinearlywithincreasingorganicmatter.Increasingtheorganicmatterfrom0%(control)to15%resultedinanincreaseof11.64%oftheplasticlimitand15.22%oftheliquidlimitafterdryingat110℃.Also,increasingtheorganicmattercontentreducedthesoilmaximumdrydensityandincreasedtheoptimummoisturecontent.Increasingtheorganicmatterfrom0to15%resultedinanincreaseof11.0%oftheoptimummoisturecontentandadecreaseof0.29g/cm3ofthemaximumdrydensity.OrganicmatterdecreasedtheCBR,whichisusedastheindexofroadstrength.Adding15%organicmattertothesoilresultedinadecreaseoftheCBRfrom15.72to4.75%.Therewasasignificantdifferencebetweenthetwodryingtemperatures(60and110℃)forthesameorganicmattermixtureswithlowerwatercontentvaluesafterdryingat60℃.Theresultsrevealedtheadverseinfluenceoforganicmatteronsoilengineeringpropertiesandshowedtheimportanceoforganicmatterremovalbeforeexcavationandfillconstruction.

简介：Background:Thelargepotentialofthesoilorganiccarbon(SOC)pooltosequesterCO2fromtheatmospherecouldgreatlyamelioratetheeffectoffutureclimatechange.However,thequantityofcarbonstoredinterrestrialsoilslargelydependsuponthemagnitudeofSOCmineralization.SOCmineralizationconstitutesanimportantpartofthecarboncycle,andisdrivenbymanybiophysicalvariables,suchastemperatureandmoisture.Methods:Soilsamplesofapineforest,anoakforest,andapineandoakmixedforestwereincubatedfor387daysunderconditionswithsixtemperaturesettings(5°C,10°C,15°C,20°C,25°C,30°C)andthreelevelsofsoilmoisturecontent(SMC,30%,60%,90%).TheinstantaneousrateofmineralizedSOCwasperiodicallyandautomaticallymeasuredusingaLi-CorCO2analyzer.BasedonthemeasuredamountofmineralizedSOC,carbonfractionswereestimatedseparatelyviafirst-orderkineticone-andtwo-compartmentmodels.Results:Duringthe387dayincubationexperiment,accumulativemineralizedcarbonrangedfrom22.89mgcarbon(C)·g-1SOCat30°Cand30%SMCforthemixedforestto109.20mgC·g-1SOCat15°Cand90%SMCfortheoakforest.Mineralizedrecalcitrantcarbonvariedfrom18.48mgC·g-1SOCat30°Cand30%SMCforthemixedforestto104.98mgC·g-1SOCat15°Cand90%SMCfortheoakforest,andcontributedatleast80%tototalmineralizedcarbon.Conclusions:Basedontheresultsofthisexperiment,thesoilorganicmatterofthepurebroadleavedforestismorevulnerabletosoilmicrobialdegradationinnorthernChina;mostoftheamountofthemineralizedSOCderivedfromtherecalcitrantcarbonpool.Labilecarbonfractionconstitutesonaverage0.4%ofSOCacrossthethreeforesttypesandwasrapidlydigestedbysoilmicrobesintheearlyincubationstage.SOCmineralizationmarkedlyincreasedwithsoilmoisturecontent,andcorrelatedparabolicallytotemperaturewiththehighestvalueat15°C.Nosignificantinteractionwasdetectedamongthese

简介：Plantationsofeucalyptsasshort-rotationtreecropsarerapidlyexpandingintropicalandsub-tropicalregions,includingsouthernChina,wherethesoilsareacidicandavailablephosphorus(P)islimited.Weinvestigatedseedlinggrowth,drymatteraccumulation,andthedynamicsofphotosyntheticrateandchlorophyllcontentofsevenEucalyptusspecies/hybrids(E.dunnii,E.grandis,E.grandis×E.camaldulensis,E.urophylla×E.camaldulensis,E.urophylla×E.tereticornis,E.grandis×E.tereticornis,E.urophylla×E.grandis)inresponsetodifferentlevelsofPsupply(0,6,12and18mg?kg-1KH2PO4).ThephotosyntheticrateandthechlorophyllcontentsignificantlydeclinedasthePsupplydeclinedinalmostalinearfashionforallspeciesasthePstressperiodextended.IntheabsenceofPsupply,heightgrowthofseedlingsofallspecieswassignificantlyimpaired,whilerootcollardiametergrowthandwholeplantdrymatteraccumulationwasnotaffectedbythelevelofPsupplyinmostofthespecies.Significantinter-speciesvariationsingrowth,drymatteraccumulationandphotosyntheticrateinresponsetoPsupplyweredetected.EucalyptusdunniihadthelowestgrowthperformanceacrossalllevelsofPsupplywhileE.urophylla×E.tereticornisshowedsuperiorgrowthperformance.Fromapracticalpointofview,E.urophylla×E.tereticornisissuggestedasacandidatehybridforplantingonslightlyP-deficientsitesinsouthernChinawhileE.dunnii,beingaslow-growingspecies,isnotsuitableforshort-rotationplantation.OnplantationsiteswhereseverePdeficiencyexists,Pfertilizationneedstobeconsideredtoboostrapidgrowthofseedlingssoastomeetthemanagementobjectivesofshort-rotationplantation.

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%.