《园林树木学西农-吉文丽》第二章

Chapter2Functionofwoodylandscapeplantsinurbangreening(3hours)Twoparts:1Environmentprotection2Greeningandbeautifyingenvironment,EnvironmentalprotectionfunctionofwoodylandscapeplantsImprovingenvironment(改善环境作用)Adjustingtemperature(调节温度)Increasingrelativehumid(提高湿度)Airpurification（吸收二氧化碳、放出氧气；吸收有毒气体阻滞烟尘；排放杀菌素）LightNoisepreventionProtectingenvironment（保护环境作用)Water-reserving,waterandsoilconservation(涵养水源、保持水土)windpreventionandsandfixation(防风固沙)Fireanddisasterprevention(防火、抗灾),CharacteristicsofurbanenvironmentLight：theradiantintensityoflightinurbanandvisibilityislowbecauseofagreatofdust。Temperature：agreatofheatcomingfromfactories,powerstationsandcarsmakesairtemperaturehigh.Moisture：Relativehumidinurbanenvironmentislowbecausethewaterdrainawayfromthedrainagesystem,althoughagreatofCloudCondensationNucleiandheavyprecipitationexistinurbanarea.Air：airpollutionheavy,O2low，CO2high。Noisepollution：heavy,Theeffectonadjustingtemperature调节温度,Comparisonoftheeffectonadjustingtemperatureamongcommonstreettrees(accordingtoWuYisstudyin1963，unit）SpeciesTinfulllightTinshadeT银杏刺槐40.035.54.5枫杨40.436.04.4悬铃木40.035.74.3白榆41.337.24.1合欢40.536.63.9加杨39.435.83.6臭椿40.336.83.5小叶杨40.336.83.5构树40.437.03.4楝树梧桐旱柳中槐40.337.72.6垂柳37.935.62.3,Thebiggerdifferenceoftemperaturebetweencanopyandatmosphere(T)willbe,thebettereffectofshadingwillbe.Theshadingeffectisproportionaltoshadingqualityandrange.Theshadingqualitymeanscrowndensity,leavesareaandopaque.遮荫效果与树种“荫质”即树冠密、叶面大而不透明的荫质优）优劣、荫幅大小成正比Thereasonsoftreedecreasetemperature:reflect20-25%ofsunlight;absorb30%ofsunlight;someofheatisabsorbedbywatertranspirationThedecreasedtemperatureisdifferentbetweensingletreeandpatchforest.Patchforestlowthetemperaturenotonlyunderthetree,butalsothetemperatureoutside.,WarmingeffectInwinter,treescanincreasethetemperaturearoundtreesbecausethetreeshavemanybranchesandtrunkwheremoreareaaccesstothesunlightthananopenspace.Tosumup,treeshavethefunctionofdecreasedTinsummerandincreasedTinwinter.Ofcause,decreasedTinsummerismoreimportantthanincreasedTinwinter.,WateraspectwaterpurificationIncreasingrelativehumidItismostimportantfortreestoimprovetheairhumidity.Forexample,amatureEucalyptusspeciesget4000kgwaterfromsoiltomeetitsgrowth.95%ofthewaterreleasedintotheatmospherebytranspiration.Thehumiditytheremaybe20timeshigherascomparetotheopenspace,evenhigherthanthesameareaofwater苏联科学家移伊万诺夫在莫斯科地区，在17的条件下所测定的各树木蒸腾速率结果(g/kg.h)如下：松树152忍冬252白蜡326桦木341榆树344栎树364扬树369美国槭388椴树390苹果530Reducingwatertablewetland-transpiration,AirpurificationO2releaseCO2absorptionthechemicalcompositionofearthsatmosphereisasfollows:Nitrogen(N2):78%;Oxygen(O2):21%;CarbonDioxide(CO2):0.03%;Plusothermiscellaneousgases,includingH2O.UrbanareaCO202,CO2500-700ppm.WhenCO2is500ppm,peoplewillfelluncomfortable;WhenCO2is2000-6000ppm,headache,highbloodpressure,vomiting;WhenCO2isat10%,peoplewilldie.,PlantsaretheregulatorofCO2andO2Inphotosynthesis,aplantcanproduce32gO2byabsorbing44gCO2.Theplantbreathesatthesametime,onlyuse1/20O2itreleased.,Broad-leaveforestperhectareeverydayabsorbs1000kgCO2andreleases730kgO2Anadultastheweightof75kgwillneed0.75kgO2andrelease0.9kgCO2everyday.Soonepersonneed10m2forestor50m2turfgrassor30-40m2greeningland.,Bytheyear2010,Chinasurbangreenareawillachievemorethan35%,greencoveragehasreached40%andabove,publicgreenareapercapitareachedmorethan10,thecitycenterdistrictpublicgreenareapercapitareachedmorethan6.Actually,thephotosynthesisofdifferenttreesisdifferent.TheCO2absorptionofbroad-leaveforestusuallyishigherthanneedle-leaveforest.,AbsorptionoftoxicgasesAtmosphericpollution,includingawiderangeoftoxicgases,mainlytoSO2,followedbyHFandCI2.Manywoodylandscapeplantshavetheabilityoftoxicgasesabsorption.SO2:OxidationSO2-highlytoxicSulfiteion-sulfateion(30timeslowertoxicity)SO2absorptionofdifferenttreesisdifferent:垂柳、加杨、榆树、构树、刺槐、海桐、枸桔、厚壳树、女贞等。TheSO2absorptionofdeciduoustreesusuallyishigherthanevergreentrees,evenmoreneedle-leavetrees.,HF：HFpoisoningeffectonthehumanbody,20timesmoreeffectivethansulfurdioxideon.NotfewtreespecieshavehighlyabilityofHFabsorption.柑橘类可以吸收较多的氟化物而不受害。象泡桐、梧桐、大叶黄杨、紫薇、女贞、银桦、乌桕、蓝桉等也是抗HF的树种。,CI2吸收CI2能力较强而且抗性也强的树种有：悬铃木、泡桐、刺槐、女贞、银桦等，还有旱柳、臭椿、赤扬、水蜡、卫矛、忍冬也是净CI2的较好树种。Pb悬铃木、石榴、刺槐、女贞、大叶黄杨等。Hg夹竹桃、棕榈、樱花、桑、大叶黄杨、八仙花等。,DustblockTheairintheurbanareaandthefactoriesandmines,inadditiontoharmfulgases,stillcontainsalotofdust.Thedustoftencanleadtoeyes,skinorrespiratorydisease.TheairdustcanbeblockedbyTreesbranchesandleaves,thenwashedawaybyrainwater.Theabilityofblockingdustoftreesspeciesisdifferent.Thetreeswithdensecrown,roughfoliageorfurryfoliagehavehighabilityofblockingdust.E.g.构树、榆树、朴树、木槿、刺楸等。,ReleasingSpinosadThenumberofbacteriaindowntownareais7timesmorethanthatinparkarea.OneofthemuchlessbacteriareasonsismanyplantsreleasedSpinosad(orphytoncide).E.g.桉树、肉桂、柠檬,etc.canreleasearomaticoilwhichhastheabilitytokillbacteria.黑核桃、桉类、悬铃木、紫薇、柑橘类,phytocide.各类林地的减菌作用不一样，松树林、柏树林及樟树林减菌能力强，可能与它们的叶子能散发某些挥发性物质有关。,ImprovinglightThelightisverydifferentbetweenparkandstreetinsummer.Inthepark,thereareabout20-25%lightoftheleafreflectance;35-75%lightabsorbedbythecrown;5-40%lightprojectedthroughtheforestcanopy.Thereforethereislowlightinthepark.Plantabsorblightbandismainlyredandorangelightandblue-violetlight,reflectedlightisgreen,sointermsofopticalquality,forestandlawnhavealargenumberofgreenwavelengthsoflight.Thisgreenlightinparkismuchmorecomfortablethanthelightinthestreets,squares,andisgoodforeyes.Especially,greenlightmakespeoplefeelcomfortable,refreshingandquietinsummer.,ReducingnoiseNoiseisakindofenvironmentalpollution.Urbandwellersalwayssufferfromgreaterlevelsofnoisepollutionthanotherareas.Ifnoiseexceeded70decibels,itwillbeharmfultopeopleThenoisealwaysexceeded70decibelsindowntownarea,thatiswhyprohibitcarhorninmanycities.Combinationoftreeandshrubsmayreducenoise.Accordingtoameasurementin1976,theresultsasfollow:,12mwidePlatanusacerifolia(悬铃木)canreduceover3-5decibelsthananopenspace.20mwidemixtureofstreettrees（e.g.雪松、杨树、珊瑚树、桂花plantedinarow,respectively）canreduce5-7decibelsthananopenspace.A30mwideMiscellaneousforest（以枫香为主，林下空虚）reduced8-10decibelsthanopenspace；18mwideforestbeltof圆柏、雪松（Lushfoliage,evenfromtoptobottom）reduced9decibels;45mwide悬铃木youngtreesreduced15decibels.4mwidehedgewallofdensefoliage（由椤木、海桐各一行组成）reduced6decibels.,Usuallytreeswithlowbranch,densecrown,lowcrown,lushfoliagehavegoodnoisereductioneffects.树木分枝底、树冠低、叶多、多枝、树冠紧密者减噪音效果好。Goodnoisereductiontrees:乔木类-雪松、柏、龙柏、水杉、悬铃木、梧桐、垂柳、云杉、山胡桃、鹅掌楸、柏木、臭椿、樟树、榕树、柳杉、栎树等。小乔木及灌木-珊瑚树、椤木石楠、海桐、桂花、女贞等。,SoilerosionpreventionWhenitrains,thecrowncanretain15-40%rainfall.Ifitrainsheavily,somerainfallwillfallintothelitterUnderheavyrain,rainfellonthelitterlayer,andthelittercanabsorb5-10%rainfall,othersisslowlyabsorbedbysoil.Ifitisalargeandintenserainfall,thesoilcannotabsorballtherainfall.Theremainingwaterunderthelayermayformrunoff,andthewaterisclear,anddidnottakesoilaway.,Differentspecieshavedifferentinterceptionrate.Generally,thetreeswithLushfoliageandroughfoliagehavehighinterceptionrate。Needle-leavetreebroad-leavetreeShade-toleranttreespeciesheliophilousspecies,Forthepurposeofwaterconservation,weshouldselectthesetreeswithlargedensecrown,highcrowndensity,highrainfallinterceptionrate,highshade-tolerance,easilyformedsuperabsorbentlitter.Deeperandwiderrootsystemisoneofthechoices.Deeprootsisbenefitsforsoilreinforcementandslopestabilizationandalsohelpfulforwaterinfiltratingintodeepsoil(e.g.tree:柳、槭、胡桃、枫杨、水杉、云杉、冷杉、圆柏等乔木;shrub:榛、夹竹桃、胡枝子、紫穗槐;vine:紫藤、南蛇藤、葛藤、蛇葡萄),WindbreakandSand-FixationIfwindbreaksiswide,thick,itwillbesignificantforthewindspeedreduction.Shelterbeltplantedindesertareareducedsoilerosionandincreasedsandfixation.Theeffectsofshelterbeltarerelatedtospeciesselectedandmannerplant