简介:陶渊明深受老庄哲学的影响,在时局动荡之际选择了归隐,把自己的注意力转向大自然,把田园自然风光作为自己的精神归宿.陶渊明的文章蕴含着丰富的自然思想,其中以《桃花源记》和《桃花源记(并诗)》最具特色.他所建构的桃花源社会,体现了其“质性自然”之内涵,表达了人生具有“自然”的天性.陶渊明“质性自然”含有“真”与“朴”二重性,反映了他寻求真、朴的自然观.陶渊明在庄子自然无为思想影响下,用“委运顺化”思想实行自然无为之道,因而选择回归山林与躬耕田园以顺应其本性.陶渊明用自然景色表达他的自然心境,将“渔人”形象与自然相结合,体现了身心与自然融为一体的和谐,说明其向往桃源的生活.陶渊明用“渔人忘路而入桃花源”来说明“忘”的境界,“忘路”意味着摒弃世俗争竞,乃至于功利思辨.因此,他所构筑的桃花源成了一个融自然美、人情美、身心美于一体的生态体系,体现了“物物而不物于物”的“新”自然境界,表达了陶渊明对社会与人生的思考.“新”自然境界是对现实生活和感性经验的超越,实现了心境与自然相统一,体现了天地人和谐共生的境界.
简介:TheimpactsofelevatedtemperatureandCO2onyoungsilverbirch(BetulapendulaRoth)saplingsafter0,25,50or75%artificialdefoliationwereassessedbymeasuringplantheightanddrymassofabovegroundcompartmentsandrootsandvariousmorphologicalandphysiologicalvariables.Defoliationeitherincreasedordecreasedplantgrowthdependingontheseverityofdamageandtheclimatictreatment.At21Cand400mgL-1CO2,defoliatedplantswerenotabletocompensateforthelostfoliage,butgrowthcompensationandadaptationtothechangedconditionsweregreater;growthofyoungdefoliatedsilverbirchsaplingsincreased,whichledtoincreasedheightandatendencytoenhancefinalabovegroundandrootbiomassandleafnitrogenandcarboncontentcomparedtothenondefoliatedcontrols.Nevertheless,theshort-termeffectofthedifferentclimaticconditionsdidnotresultinasignificantovergrowthofdefoliatedplants.AslightincreaseintemperatureandCO2werethemostacceptableconditionsfordefoliatedplants;however,a4CincreasewithcorrespondinglyhigherCO2wasmorestressfulasshownbylessgrowthinheightandbiomassallocationtoleaves,stemsandroots.Thefindingsfromthepilotexperimentaremoreapplicabletoyoungbirchtrees,butstressonyoungtreesmaybereflectedinfuturetreegrowth.
简介:SiberianmothDendcrolimussuperanssibiricusTschetw.isthemainimportantinsectpestnotonlyinSiberianconiferoustaiga,butitoftenformsfociofmassreproductioninlarchstandsintheRussianFarEast.ThisarticlehasdescribedoutbreaksoftheSiberianmothandotherinsectpestssince1960tillnow.
简介:Background:Thispaperexploredthelong-term,ceteris-paribuseffectsofpotentialCO,fertilizationontheglobalforestsector.BasedonthefindingsofNorbyetal.(PNAS2005,102(50))aboutforestresponsetoelevated[CO_2].Methods:ForestproductivitywasincreasedintheGlobalForestProductsModel(GFPM)inproportiontotherising[CO.,]projectedintheIPCCscenarioA1B,A2,andB2.Projectionsoftheforestareaandforeststockandoftheproduction,consumption,prices,andtradeofproductsrangingfromfuelwoodtopaperandpaperboardwereobtainedwiththeGFPMforeachscenario,withandwithoutCO_2fertilizationbeginningin2011andupto2065.Results:C02fertilizationincreasedwoodsupply,leadingtolowerwoodpriceswhichinturninducedmodestlowerpricesofendproductsandhigherglobalconsumption.However,productionandvalueaddedinindustriesdecreasedinsomeregionsduetotherelativecompetitiveadvantagesandtothevaryingregionaleffectsofCO_2fertilization.Conclusion:ThemaineffectofCO,fertilizationwastoraisetheleveloftheworldforeststockin2065by9to10%forscenariosA2andB2andby20%forscenarioA1B.Theriseinforeststockinducedbyfertilizationwasinpartcounteractedbyitsstimulationofthewoodsupplywhichresultedinlowerwoodpricesandincreasedharvests.
简介:主要通过对比观测与SiB2模拟的吉林通榆农田和草地样地的感热通量、潜热通量、CO2通量和气温来检测独立版简化生物圈模式的数值模拟能力。在模拟中,农田和草地代表半干旱区2种典型的地表覆盖类型,它们的全年冠层高度和叶面积指数都处于变化当中,在非生长季地表裸露,而在生长季,冠层高度农田可达2m,草地可达0.8m,对应的叶面积指数分别可达4.2和2.4。SiB2模型模拟用观测值为初始场,以半小时气象观测为驱动场。对2003年的模拟和观测的比对研究表明:在生长季模式具有很好的模拟小时时间尺度的潜热、感热和CO2通量及地表气温的能力;(2)模式模拟土壤热通量可能偏大;(3)模拟的逐日潜热、感热和CO2通量及地表气温可用合理地反映全年的季节变化。