简介:以杭州曲院风荷景点为研究对象,以历史文献为线索,结合山水画、版画、照片、测绘图等图像资料,梳理其景观格局变迁历程,分析演变中景物间的联系,并对各时期园林发展情况进行总结。将其发展历程划分为南宋麯院时期、元代至明代衰落时期、清代更址重建时期及中华人民共和国成立至今的公园化时期。认为清康熙年间曲院的迁址与更名是景点发展的重要转折点,这一举动既使古老的景名得以延续,又使景点有了新的内涵和发展空间。园林建筑与环境的营造围绕"曲"这一主题展开,代表人工的"曲院"与代表自然的"风荷"体现了该景点人工建筑与自然景物并重的审美主旨。通过分析整理历史图像资料对于今人了解古代园林变迁有重要帮助。
简介:Globalwarmingisoneofthehottestenvironmentproblems.OneofthereasonsisthesharpincreaseofCO2inatmosphere.Soilrespirationinforestecosystemsaccountsto60%-90%oftotalecosystemrespirationandisthereforeoneofthekeycomponentsoftheglobalCcycle.Thispapersummarizeddifferentresponsesofsoilrespirationtoforestmanagementmeasures,anddescribedtherelevantresearchesathomeandabroadontheeffectofmanagementmeasureslikeharvesting,forestfertilization,soilimproving(Liming),litterremoval,andprescribedburningonsoilrespiration.
简介:FieldexperimentswerecarriedoutwithricevarietyofShenong91ofshortculmsanderectpaniclestostudynutrientcontentsinhigh-yiedldingriceplantsandtoincreasericeyieldbyappropriatefertilization.Nitrogen,phosphorus,potassium,magnesium,zinc,manganese,ironandcoppercontentsinriceplantsvariedwithdifferenttreatmentfactors.Therelationshipbetweenthenutrientcontentsandtreatmentfactorscouldbesimulatedusingamultiplequadraticequation.Thenutrientcontentsinplantsshouldbeappropriateforhigh-yieldingrice.Ifthemeannutrientcontentinriceplantsproducuing11tha^-1ormoreofgrain(uj)wassetasthestandardvalueandthestandarddeviation(σj)wassetastherangeofvariation,thenutrientcontentinhigh-yieldingriceplantsshouldbeμj±1.99σj.Riceleavesweresensitivetothenutrientelements.Heavynitrogendressingincreasedthecontentofnitrogeninriceplants.Sparsetransplantingalsoincreasednitrogencontent,Improperapplicationofnitrogen,phosphorusandpotassiumcouldaffectthenutrientcontentsanddecreasethegrainyield.
简介:AccordingtothecultivatingpracticeofLarixolgensispulpplantation,IRR(Internalrevenuerate)andNPV(Netpresentvalue)weretakenastwoeconomicindicestostudytheeffectofcultivationmeasurementsoneconomicbenefitofLarixolgensispulpforest.Theresultsshowedthattheeconomicbenefitofthistypeofforestiscloselyrelatedtorotationandsiteclass.Highereconomicbenefitcouldbeobtainedwhentherotationisshorterandsiteclassishigher.Theplantingdensityalsohadanobviousinfluenceoneconomicbenefit.Onthebaseofassuringsurvivalrateandconservingrate,thelessthefeeusedinsoilpreparationandyounggrowthtendingis,thehighertheeconomicbenefitis.Theinfluenceofdeterminedsixcultivationmeas-uresoneconomicbenefitinsequencewastherotation-siteclass-density-managementfeelevel-younggrowthtendingin-tensity-soilpreparationmethods.
简介:EcosystemdegradationoccursinparallelwithdesertificationprocessinsandyareasofNorthChina.ThevastsandyareasinNorthChinaarecharacterizedwithflexibleenvironmentsandfragileecosystemsaswellasintensivehumanactivities.DuetotheannualprecipitationgradientdecreasesfromeasttowestinNorthChina,thewholesandyregionfallsinto3mainclimaticzones:add,semi-addanddrysub-humidzones.Theecosystemsineachtypeofclimaticzonesaredifferentinclimaticconditions,humanactivities,culturaldimensions,vegetationcovers,landscapes,andcausesandprocessesofecosystemdegradation.Therefore,themosteffectiverehabilitationmeasuresofdegradedecosystemsindifferenttypesoftheclimaticzonesarealsodifferent.Forthearidsandyareas,vegetationrehabilitationofdegradedecosystemsneedstobecompletelyclosed,assistingwithartificialmeasures,suchasplantation,irrigationorothers.Forsemi-addsandyareas,theeffectivemeasuresofvegetationrehabilitationofdegradedecosystemsincludeincreasingofproportionofforestsandrangelandsandlimitationofreclamation;reducingthecarryingcapacityoflivestockonunitareaofrangelandsandgrowthoffodderplants;andplantationonthelowlandsbetweensanddunes.Forthedrysub-humidareas,themosteffectivemeasureisenclosureofdegradedecosystemscombinedwithplantation,andinsomecases,juststopusesbygrazingorreclamation.