外文翻译.docx
- 文档编号:4835269
- 上传时间:2022-12-10
- 格式:DOCX
- 页数:5
- 大小:20.71KB
外文翻译.docx
《外文翻译.docx》由会员分享,可在线阅读,更多相关《外文翻译.docx(5页珍藏版)》请在冰豆网上搜索。
外文翻译
Physicalenvironmentoftheforestecosystem
Published:
August7,2010,1:
28pm
Updated:
October17,2011,12:
30pm
Author:
GeneLikens
TopicEditor:
WayneDavis
Physicalenvironmentssetthepotentialforbiologicaldevelopment.Variationinsolarenergy,seasonality,temperatureregimes,wind,water,soil,andfireplaysamajorroleindeterminingthespeciescomposition,structure,productivity,ratesandpatternsofvegetationchangeanditsresistancetoandresilienceafterdisturbance.
Ecologicalroleofsolarradiation
Solarradiationisthemajorsourceofenergyforlife.Itisnecessaryforexistenceofecosystemandmaintenanceofthefunction.Itsintensityaspassesthroughtheatmosphereandreachestheearth’ssurfacedeterminesthewater,airtemperatures,climates,andweatherpatternsintheworld.
Basicallysolarradiationiscomposedofthreeparts:
ultraviolet(UV),visiblelightandinfrared.UVbalancesthesynthesisthesynthesisanddecompositionoftheozonewhichabsorbsmuchofUVradiationfromthesun.UVradiationrestrainsthegrowthofplantsbydestroyingtheauxins(growth-regulatinghormones)thatcontrolthedivisionandenlargementoftheplantcells.Thepigmentsresponsibleforphotosynthesisabsorbradiationmostefficientlyintheviolet-blueandorange-redwavelengthswhicharepartsofthevisiblelights.Theecologicaleffectofthevisiblelights.Theecologicaleffectoftheinfraredistoenhancethetemperatureofplant,andisastimulustoelongationofstem.
Thelightintensityatwhichlevelrespiratorylossesareexactlyexactlybalancedbyphotosyntheticgainsiscalledthecompensationpoint(CP).AboveCP,therateofphotosynthesiscontinuestoincreaserapidlywithincreasinglightintensity,untillittleornofurtherincreasesinnetCO2fixation.Thatpointiscalledassaturationpoint(SP).CPsandSPsvaryconsiderablyamongdifferentspecies,amongdifferentindividualsofthesamespecies,amongdifferentpartsofasingleindividual,andevenjustunderdifferentenvironmentalconditions.GenerallyspeciesororgansthatgrowindeepshadehavelowerCPsandSPsthanthosegrowinfullsunlightdo.
Aplatgrownintheshadelooksdifferentfromanotherplantofthesamespecieshowevergrowninfullsunlight.Forexample,underhighlightintensities,seedlingrootbiomassmayincreaseasfastasorevenfasterthanstembiomass,butunderreducedlightintensities,mostofthenetbiomassproductionisinvestedinstemheightintensities,seedingrootbiomassmayinvestedinstemheightgrowth,thusincreasingthestemrootandheightdiameterratios.
Thesensitivityoforganismstothelengthofday-lengthiscalledphotoperiodism.Accordingtothereproductiveoftheindividual,photoperiodicresponsescanbeclassifiedintothreecategories:
short-dayorganisms,long-dayorganismsandday-lengthindifferent(day-neutral)organisms.Itsmajorroleisinregulatingtheonsetofreproductioninplantsandanimals,preparationfordormancy,thestartofmigrations,andtheseasonalchangeincoloroffurandfeathers.
Ecologicalroleoftemperature
Temperaturehasimportanteffectsonbiologyingrowth,metabolism,metabolism,number,reproduction,behavioranddistribution.
Insomegivenrangemetabolicandrespiratoryrateincreasewithtemperature,whichstimulatescelldivision,andleadstohighproductivity.Temperaturealsohasnegativeeffectsontheorganisms.Twoaspectsoftemperatureareresponsibleformostofthetemperature-relatedinjuriestoplants:
rapidchangeintemperatureandtheoccurrenceofunseasonaltemperaturessuchasfrost,rapidalteouseffectofhightemperaturesleadingtotheexcessivelossofmoistureandthestimulationofexcessiverespirationrate.
Furthermoretemperatureexertspowerfulinfluenceindeterminingthegeographicaldistributionoforganisms.Lowtemperaturesinthewintercanderangemetabolism,freezetissues,reducetheavailabilityofthefoodandwater,orcausemechanicalinjuries,whichcandeterminetheupperaltitudinalandpolewardextensionofspecies.Hightemperaturesinthesummerresultinthederangementofmetabolicprocesses,heatmortality,excessivelossofwater,highrespirationrate,andthereductionintheavailabilityofthefoodandwater.Inadequatedurationorintensityofwinterchillingwilllimitthelatitudinaloraltitudinalrangeofspeciesthatrequirechillingtobreakdormancyorstimulateflowering.
Ecologicalroleofwater
Wateristhematerialthatmakeslifepossible.Itactsasthemediuminwhichalllifeprocessesoccur.Itactsasatransportingsystempermittingnutrientuptakeformthesoil,movingmetabolitesaround,supplyingoxygen,removingwasterproducts,regulatingthetemperatureoforganisms,andsupportingandprotectingaquaticorganisms.Ithashigherspecificheatwhichgivesittheabilitytogreatlyreducetemperaturefluctuations.Moisturemaybetransferredfromairtolandinavarietyofways:
rain,snow,hail,dew,fogdrip,andrime.
Accordingtotheiradaptationstowaterstressplantscanbeclassified:
hydrophytes,mesophytes,andxerophtes.Watercaninfluencetheproductivityanddistributionofforestsandinturntheforestscaninfluencetheproductivityanddistributionofforestsandinturntheforestscaninfluenceprecipitationbyintercepting,redistributing,infiltratinginthesoil,evaporating,andtranspiration.
Ecologicalroleofwind
Windshaveawidevarietyofecologicaleffects.Theytransportthewatervaporfromoceanstothelandandthusensurethesupplyofrainfall.Windremovesthedustandorganicparticlesfromoneecosystemanddepositstheminanother,sometimestotheextentthatadeeplayerofloesssoildevelops.Itisanimportantmeansofdispersingpollen,seeds,andatmosphericpollutants.Whereashighwindscanuproottrees,erodesoil,anddestroyfarmandforestcrops.Windinfluencesevaporationandtranspirationandcanproducedesiccationdamageandeventhedeathofplants.
Ecologicalroleofsoil
Soilisthenaturallyoccurring,unconsolidated,mineralororganicmaterialattheearth’ssurfacewhichiscapableofsupportingtheplantgrowth.Itisacombinedresultofclimate,topography,andbiologicalprocessesactingongeologicalmaterialsoveraperiodoftime.Thetextureandstructureofsoilaredeterminanttowater,air,temperature,anddistributionoftherootsystem.Theacidityandalkalinityofsoil,organicmaterialandsoilmicrobecombiningallaboveinfluencetheavailabilityofnutrientsanduseefficiencyofplant,determinetheproductivityofforestseventually.
Ecologicalroleoffire
Fireisgenerallyanenvironmentalfactoroflowfrequencybutofconsiderablepotency.Forestfirecanbedividedintothreemajortypes:
groundfires,surfacefirescrownfires.Theallhavepotentialtoinducethechangeinorganicmatter,structure,porosity,moisture,andtemperatureinsoil.Inplants,firehasagreateffectontheanystageinaplantlife’sprocesses(vegetative,flowering,fruiting,anddormant).Asfarasecosystemisconcerned,firechangestheenergyflowandbiogeochemistrycycle.Thedegreetowhichpropertiesarealteredbyfiredependsonthefireintensity,fireseverityandfirefrequency.
FurtherReading
Brimblecombe,P.,Hara,H.,Houle,D.andNovak,M.,(eds.).2007.AcidRain–DepositiontoRecovery.Springer.420pages.
Driscoll,C.T.,etal.2001.AcidicdepositioninthenortheasternU.S.:
sourcesandinputs,ecosystemeffects,andmanagementstrategies.BioScience51(3):
180-198.
Jacobson,M.Z.2002.AtmosphericPollution:
History,Science,andRegulation.CambridgeUniversityPress,NewYork.399pages.
Jenkins,J.C.,etal.2007.AcidRainintheAdirondacks:
anEnvironmentalHistory.CornellUniversityPress.246pages.
Kuylenstierna,J.C.I.,etal.2001.Acidificationindevelopingcountries:
ecosystemsensitivityandthecriticalloadapproachonaglobalscale.Ambio30:
20-28.
Lane,C.N.,(ed.).2003.AcidRain:
OverviewandAbstracts.NovaSciencePublishers,NewYork.
Likens,G.E.,etal.1972.AcidRain.Environment14:
33-40.
Seinfeld,J.H.,andPandis,S.N.2006.AtmosphericChemistryandPhysics:
FromAirPollutiontoClimateChange,SecondEdition.J.Wiley,NewYork.
Likens,G.E.&Bormann,F.H.1995.BiogeochemistryofaForestedEcosystem.Springer-Verlag,NewYork.159pages.
Likens,G.E.,etal.1996.Longtermeffectsofacidrain:
responseandrecoveryofaforestedecosystem.Science272:
244-246.
Likens,G.E.,T.J.Butler,andD.C.Buso.2000.Long-andshort-termchangesinsulfatedeposition:
effectsofthe1990CleanAirActAmendments.Biogeochemistry.(52)1:
1-11.
Likens,G.E.,F.H.Bormann,andN.M.Johnson.1972.Acidrain.Environment14:
33-40.
森林生态系统的自然环境
自然环境影响着生物的发生和发展。
太阳能量、季节、温度区域、风、水、土壤和火的变化对物种的组成、物种的结构、物种的生产力、植物变化率和变化类型以及物种对干扰的阻力和弹力都起着决定性作用。
太阳辐射
太阳辐射是生命能量的主要来源,是生态系统存在和维持的必要条件。
太阳辐射在穿过大气到达地表的过程中影响着整个世界的温度、水以及气候类型。
太阳光主要是由紫外线、可见光和红外线三部分组成。
由太阳发射出的大部分紫外线都被大气中的臭氧吸收,与此同时,紫外线也使臭氧的合成和分解过程达到平衡。
紫外线还通过破坏控制细胞分裂的生长素(生长调节荷尔蒙)来抑制植物的生长。
光合色素能够吸收可见光中活性最强的红光、橙光和蓝光、紫光。
红外线的生态作用主要是提高植物体温度,促进植物茎的延长和伸张。
当植物的呼吸作用的消耗量与光合作用的合成量持平时的光照强度称光补偿点(CP)。
达到CP后,光合速率随光照强度的增加而迅速增长,直到C02固定量不再增加,此时的光照强度称为光饱和点(SP)。
不同种之间、同种不同个体之间、个体不同部分之间以及在不同的环境下,CP和SP的变化是非常大的。
一般来说,生长在庇荫环境下的种或器官要比生长在全光条件下的种或器官低。
生长在庇荫条件下的植物与生长在全光条件下的同种其他植物个体的外貌上有很大差异。
例如,在强光下,幼苗的根生长量增长与茎生长量一样快过或更快,而当光强减弱时,大部分的净生长量用于茎的高生长上,因此茎语根和高与周长的比值会增加。
植物和动物对日照长度变化的反应称光周期性。
按照个体繁殖行为对光周期反应,可将它们分为三种类型:
短日照植物、长日照植物和中日照植物。
光周期的主要作用是调节动植物进入繁殖期,准备休眠,开始迁徙,和季节性地改变皮毛和羽毛的颜色。
温度因子
温度对植物的生长、新陈代谢、数量、繁殖、行为和分布具有重要的作用。
黄化现象是光与形态建成的各种关系中最极端的典型例子,黄化是植物对黑暗环境的特殊适应。
光合作用饱和点。
一定范围内,光合作用的效率与光强成正比,但到达一定强度光合效率不会再增加,若继续增加光强,光合效率下降,这点谓之饱和点。
在一定范围内,随着温度的升高,细胞分裂会加快,代谢和呼吸的速率都会增加,从而会使生产力提高。
温度对动植物同样也有不利影响。
温度造成植物伤害的原因主要表现在两个方面:
一个方面是温度迅速变
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 外文 翻译