桉樹對土壤肥力影響

1、桉樹對土壤肥力的影響1桉樹的相關(guān)概述relatedoverviewoftheeucalyptus1.1桉樹簡介eucalyptusintroduction桉樹是桃金娘科桉樹屬的總稱，屬常綠喬木。樹皮粗厚而宿存或平滑而年年脫落，有揮發(fā)性芳香油，同松樹、楊樹一起成為全球最速生、經(jīng)濟(jì)價(jià)值最大、生態(tài)和社會(huì)效益最高的三大樹種。一百多年前我國開始引種桉樹，初期只是小規(guī)模的引種試驗(yàn)或觀賞性質(zhì)的樹種；近年來桉樹人工林的規(guī)模迅速發(fā)展，國內(nèi)總的種植面積已達(dá)154萬公頃,僅次于印度和巴西，主要分布在兩廣地區(qū)、云貴川地區(qū)、福建和海南等長江以南地區(qū)。Thefloorboardoftheeucalyptusismyrta

2、ceaeeucalyptus,evergreentrees.Barkthickandpersistentorsmoothandlossyearafteryear,haveavolatilebalmyoil,becometheworldsfast-growingwithpine,poplar,theeconomicvalueofthethreelargestandmostecologicalandsocialbenefits.EarlyonehundredyearsagobegantointroductionofeucalyptusinChina,onlysmall-scaleintroduct

3、ionexperimentorornamentalqualitytreespecies;Thesizeoftherapiddevelopmentofeucalyptusplantationinrecentyears,domestictotalplantingareaof1.54millionhectares,issecondonlytoIndiaandBrazil,aremainlydistributedinareas,YunGuiChuanareasofguangdong,fujianandhainanregionsouthoftheYangtzeriver.桉樹用途eucalyptuspu

4、rposes桉樹的經(jīng)濟(jì)效益比較客觀,主要用在以下方面:第一個(gè)重要的用途就是纖維材,桉樹造紙廣泛的應(yīng)用在我國江淮一帶的紙漿廠,桉樹纖維材還可以用于生產(chǎn)纖維板和刨花板,近年來華南的纖維板廠正逐步建立和完善并正向環(huán)保型纖維板生產(chǎn)方向發(fā)展;第二桉樹是質(zhì)量上成外部美觀的家具裝飾用材,多用于高檔次的建筑物和室內(nèi)裝飾,不但質(zhì)量好,而且十分美觀;第三桉油是用途良好的醫(yī)藥和香料原料,其中史密斯桉、直桿藍(lán)桉、亮果桉等是產(chǎn)油較高的樹種。最后桉樹在園林綠化和生態(tài)林建設(shè)方面的應(yīng)用十分廣泛。Theeconomicbenefitsofeucalyptusismoreobjective,mainlyusedinthefoll

5、owingaspects:thefirstisimportantusefibermaterial,eucalyptusiswidelyusedinpaperpulpmillofjianghuaiareainourcountry,eucalyptusfibrematerialcanalsobeusedforproductionoffiberboardandparticleboard,fiberboardfactoryinsouthChinainrecentyearsisgraduallyestablishandperfectandisenvironmentallyfriendlyfiberboa

6、rdproductiondirection;Secondonthequalityofeucalyptusisintoexternalbeautifulfurniture,decorationmaterialusedinhigh-gradebuildingandinteriordecoration,notonlyofgoodquality,andverybeautiful;Thirdeucalyptusoilisusegoodrawmaterialmedicineandspices,includingeucalyptus,straightrodSmithiseucalyptusglobulus,

7、brightfruitsuchaseucalyptusoilhightreespecies.Finallyeucalyptusinlandscapingandtheapplicationoftheconstructionofecologicalforestisveryextensive.桉樹的影響theinfluenceofeucalyptus桉樹人工林大面積發(fā)展可能會(huì)導(dǎo)致土地肥力衰退,這種衰退主要表現(xiàn)在兩方面:一方面桉樹因其速生性,其生長過程需要由土地供給大量的養(yǎng)分,因而對土壤肥力的消耗較大;另一方面,桉樹林地的管理方式不科學(xué),如不論土壤條件,改變了土壤結(jié)構(gòu),減少了地表的植被覆蓋,進(jìn)而導(dǎo)致林

8、地土壤水分下滲量減少和水土流失的嚴(yán)重問題。Couldleadtowidespreaddevelopmentofeucalyptusplantationlandfertilitydecline,thedeclineismainlymanifestedintwoaspects:ontheonehand,eucalyptusbecauseitsspeedis,thegrowthprocessoflandsupplyhastobealotofnutrients,thusfortheconsumptionofsoilfertility;Eucalyptusforest,ontheotherhand,th

9、emanagementisnotscience,suchaswhethersoilconditions,changethesoilstructure,reducedthesurfacevegetationcover,leadingtoreducedthevolumeofforestlandsoilwaterinfiltrationandtheseriousproblemofsoilerosion.土壤肥力2thesoilfertility土壤肥力的界定definitionofsoilfertility土壤是林業(yè)生產(chǎn)的首要因素,常以N、P、K和有機(jī)質(zhì)等養(yǎng)分的含量來衡量土壤肥力的高低。土壤肥力是土

10、地生產(chǎn)力的基礎(chǔ),土壤肥力是土壤為植物生長提供營養(yǎng)和環(huán)境條件的能力,是土壤基本性質(zhì)的綜合體現(xiàn)。蘇聯(lián)土壤學(xué)家威廉士對土壤肥力的定義是:“土壤在植物生活的全過程中同時(shí)又不斷地供給植物以最大量的有效養(yǎng)分及水分的能力”;現(xiàn)代學(xué)者孫波、陳金林等人將土壤肥力定義為:“內(nèi)外在因素（光照、溫度與土壤物理?xiàng)l件等）都適合特定植物生長時(shí),土壤以適當(dāng)?shù)牧亢推胶獾谋壤蜻@種植物供應(yīng)養(yǎng)分的能力。”Soilisthefirstfactorofforestryproduction,oftennutrientssuchasN,P,Kandorganicmattercontenttomeasurethelevelofsoilfer

11、tility.Soilfertilityisthebasisoflandproductivity,soilfertilityistheabilitytoprovidenutrientsforplantgrowthandenvironmentalconditions,istheintegratedembodimentofsoilbasicproperties.SovietsoilscientistWilliamJamestothefertilityofsoilisdefinedas:soilinthewholeprocessofplantlifeandcontinuallysupplyplant

12、swiththemostlargeamountsofavailablenutrientsandmoisturecapacity;Sunbo,modernscholarsChenJinlinetal.Soilfertilityisdefinedas:absurdismfactors(light,temperatureandsoilphysicalconditions,etc.)isfitforaparticularplantgrowth,soilintheappropriateamountandbalancetheproportionoftheabilitytosupplynutrientsto

13、theplant.土壤肥力評價(jià)指標(biāo)thesoilfertilityevaluationindex一般來說土壤肥力與健康的診斷主要有描述土壤健康的描述性分析和定量研究的分析性指標(biāo),具有定量單位的分析性指標(biāo)是學(xué)術(shù)研究中評價(jià)土壤肥力的主要標(biāo)準(zhǔn),分析性指標(biāo)主要包括物理指標(biāo)、化學(xué)指標(biāo)和生物指標(biāo),在評價(jià)土壤肥力時(shí)根據(jù)不同的土壤和評價(jià)目的,選擇性的對指標(biāo)進(jìn)行取舍組合。學(xué)者研究調(diào)查指出合理評價(jià)土壤肥力應(yīng)該參考以上指標(biāo)進(jìn)行綜合測量。Ingeneralthesoilfertilityandhealthdiagnosisismainlydescribethesoilhealthydescriptiveanalysi

14、sandquantitativeanalysisoftheindicators,withthequantitativeanalyticalindexoftheunitisthemainstandardofevaluationofsoilfertilityintheacademicresearch,analyticalindicatorsmainlyincludephysical,chemicalandbiologicalindicators,accordingtodifferentsoilandwhenevaluatethesoilfertilityevaluationpurpose,sele

15、ctivelytochoosecombinationindex.Scholarsresearchpointsoutthatthereasonableevaluationindexofsoilfertilityshouldrefertotheabovecomprehensivemeasurement.桉樹對土壤肥力的影響Threeeucalyptusimpactonsoilfertility對土壤物理性質(zhì)的影響impactonsoilphysicalproperties土壤容重大小能夠反映土壤的通透性以及根系伸展的阻力狀況,土壤容重容重大小在很大程度上影響著植物根系的生長、土壤動(dòng)物和微生物的活動(dòng)

16、。土壤水分是土壤物質(zhì)轉(zhuǎn)化和代謝的重要因素,土壤中的毛管水可以移動(dòng),對于植物是最有效的水分,很大程度影響著植物的生長發(fā)育;經(jīng)過筆者實(shí)地定期調(diào)查顯示在同一層級的桉樹人工林地,隨著樹齡增長,土壤的容重逐漸減少,而土壤的最大持水量有所增加;土壤孔隙主要包括毛管孔隙和非毛管孔隙,其中毛管孔隙將細(xì)小土粒排列形成小的孔隙,有利于土壤水分被毛管引力吸持,因此這種孔隙決定了土壤的蓄水性;非毛管孔隙則是由較大土粒疏松排列形成的,這類孔隙對水分吸持力較小,進(jìn)入孔隙的水分會(huì)很快淋失,其決定了土壤的通氣性和排水情況。筆者實(shí)地定期調(diào)查在同一層級的桉樹人工林地,隨著樹齡的增長,土壤的孔隙度逐步增加,改善了土壤的通氣條件,但

17、是隨著土層深度的增加,土壤通氣良好的狀況逐漸降低。綜上所述,桉樹人工林的大規(guī)模種植可以在一定程度上改良土壤的容重、土壤的含水量以及土壤的孔隙度,但是這種對土壤物理性質(zhì)的改善程度是需要進(jìn)一步驗(yàn)證的。Sizecanreflectthepermeabilityofsoilandsoilbulkdensityrootsstretchingresistancecondition,soilbulkdensitysizetoalargeextentaffectthegrowthofplantroots,soil,animalandmicrobialactivity.Soilmoistureisanimpor

18、tantfactorofsoilmaterialandmetabolic,capillarywatercanbemovedfromthesoil,toplantisthemosteffectivemoisture,greatlyaffectplantgrowthanddevelopment;Throughfieldsurveyonaregularbasisatthesamelevelofeucalyptusplantationforest,alongwiththeagegrowth,soilbulkdensitygraduallydecreased,andsoilmaximummoisture

19、capacityincreased;Soilporosityismainlyincludingcapillaryporosityandcapillaryporosity,capillaryporositywillfinesoilparticlesarrangementformsmallpore,isbeneficialtosoilwaterbycapillaryforceholding,sotheporedeterminesthewaterstorageofsoil;Thecapillaryporesareformedfromlargesoilgrainloosearrangement,suc

20、hporosityonthemoistureholdingforceissmall,intotheporewaterwillsoonleaching,determiningthesoilairpermeabilityanddrainage.Theauthorfieldsurveysonaregularbasisatthesamelevelofeucalyptusplantationforest,asthegrowthoftheage,soilporosityincreasedgradually,theimprovedsoilaerationconditions,butwiththeincrea

21、seofsoildepth,soilaerationgoodconditiongraduallyreduced.Tosumup,thelarge-scalecultivationofeucalyptusplantationcantoacertainextent,improvesoilbulkdensity,soilwatercontentandsoilporosity,buttheimprovementonsoilphysicalpropertiesisneedfurthervalidation.對土壤化學(xué)性質(zhì)的影響impactonsoilchemicalproperties土壤中的氮是植物生

22、長發(fā)育所需要的營養(yǎng)元素之一氮元素的供應(yīng)容量反映土壤的總體水平,其中堿解氮體現(xiàn)了一定時(shí)期內(nèi)N素的供應(yīng)情況,調(diào)查顯示桉樹林地的土壤全N和水解N隨著林齡的增加而逐漸減少,對同一林齡的土壤隨土壤層次的增加全N、水解N含量逐漸降低。與對照（混交林）相比,桉樹人工林的土壤全N、水解N含量均小于混交林含量。ofnitrogeninthesoilisoneofthenutrientsneededforplantgrowthanddevelopmentreflectstheoveralllevelofsoilnitrogensupplycapacity,thealkalinehydrolysisnitrogen

23、embodiesthesupplysituationofNelementincertainperiodoftime,accordingtoasurveyofeucalyptuswoodlandsoiltotalNandhydrolyticNdecreasegraduallyalongwiththeincreaseofforestage,onthesameplantationageofsoilwithsoillayersincreasedtotalN,hydrolyticNcontentgraduallydecreased.Comparedwiththecontrol(mixed),eucaly

24、ptusplantationsoiltotalN,hydrolyticNcontentwerelessthanthemixedcontent.磷對于植物生長具有很大的營養(yǎng)生理功能植物所需要的磷主要來自土壤,然而土壤有效磷只占全磷量的極小部分,有效磷和全磷量之間并沒有相關(guān)性,因此土壤全磷量并不是土壤磷素供應(yīng)水平衡量指標(biāo)。實(shí)地調(diào)查結(jié)果顯示,對于同一層級的土壤全磷量隨著林齡的增加逐漸減少,同一樹齡的土壤隨土壤層次的增加也逐漸降低;而對有效磷量的影響并不明顯。phosphorusforplantstogrowverynutritionphysiologicalfunctionofphosphorusm

25、ainlyfromplantsneedsoil,however,availablesoilphosphorusaccountsforonlysmallpartoftheamountoftotalphosphorus,effectivephosphorusandtotalphosphorusamountisnocorrelationbetween,sothequantityofsoiltotalphosphorusisnotmeasurethesoilpsupplylevel.Fieldsurveyshowsthatforthesameleveloftotalphosphoruscontenti

26、nsoilincreasedwiththeincreaseofforestagegraduallydecreases,withtheincreaseofthesoillayersofthesoilisofthesameoldgraduallyreduce;Andaffectsthequantityofeffectivephosphorusisnotobvious.鉀的調(diào)節(jié)催化作用加速了植物對二氧化碳的同化促進(jìn)碳水化合物的轉(zhuǎn)移以及蛋白質(zhì)的合成,鉀素增強(qiáng)植物的抵抗力,是植物生長必須營養(yǎng)元素之一。鉀素能增強(qiáng)植物的抗病力,土壤中的速效鉀是鉀素的現(xiàn)實(shí)供應(yīng)指標(biāo)。調(diào)查顯示,速效鉀和全鉀的含量隨著林齡的增加遞

27、減明顯,這表明桉樹的生長對土壤全鉀和速效鉀的均顯著影響。theregulationofpotassiumcatalystacceleratedtheplantassimilationofco2promotesthetransferofcarbohydrateandproteinsynthesis,potassiumenhanceplantresistance,isoneofmustnutrientelementsforplantgrowth.Potassiumcanenhancethediseaseresistanceofplants,andthesoilavailablekisthereal

28、ityofpotassiumsupplyindicators.Accordingtothesurvey,rapidly-availablepotassiumandtotalpotassiumcontentisdiminishingwiththeincreaseofforestage,suggestingthatthegrowthofeucalyptusonsoiltotalpotassiumandavailablepotassiumhavesignificantinfluence.雖然土壤中微量元素的含量僅有萬分之幾,對植物正常生長發(fā)育起著不可忽視的作用直接影響到有機(jī)體的代謝過程;微量元素主要

29、由酶、維生素和生長激素等組成的成分。在桉樹人工林的實(shí)地調(diào)查中顯示,林地土壤微量元素的含量呈現(xiàn)遞減趨勢,其中有效Fe和有效Mn的含量在0-20cm土層處隨著林齡的增加而減少,然而不同樹齡的土壤有效Fe含量變化不顯著;有效Cu的含量在40-60cm土層處的含量無明顯變化,而其余土層的含量均隨林齡的增加而減少而有效Zn的含量在土層的并無明顯變化。熱風(fēng)爐總之,桉樹人工林的生長對土壤有效微量元素有一定的影響。althoughthecontentoftraceelementsinsoil,onlyveryfewtotheplantnormalgrowthanddevelopmentplaysaconsid

30、erableroledirectlyinfluencesthemetabolismoforganismsprocess;Traceelementsismainlycomposedofenzymes,vitaminsandgrowthhormone,etc.Fieldsurveyineucalyptusplantation,woodlandsoiltraceelementcontentpresentatendencyofdecreasing,theeffectivecontentofFeandMnin020cmsoillayerincreasedwiththeincreaseofforestag

31、edecreased,soileffectiveFecontentindifferenttreeage,however,changeisnotsignificant;EffectivecontentofCuin40to60cmsoillayerhasnoobviouschangeincontent,whiletherestofthecontentofsoildecreasewiththeincreaseofforestage;Andeffectivezinccontentinsoilandnoobviouschange.Tosumup,thegrowthofeucalyptusplantati

32、ononthesoileffectivetraceelementshaveacertaineffect.3.3對土壤生物性質(zhì)的影響3.3impactonsoilbiologicalproperties土壤微生物是森林生態(tài)系統(tǒng)的重要組成元素它在土壤中的含量和活動(dòng)狀況反映了土壤肥力,也是土壤中生物活性的具體體現(xiàn)。調(diào)查顯示桉樹林地土壤微生物以細(xì)菌居多,且桉樹林地土壤中的微生物含量隨著林齡的增長而減少其中細(xì)菌和放線菌在同一林齡40-60cm土層含量最多,20-40cm土層處含量最少,這可能與根系分布狀態(tài)有關(guān)系。而同一樹齡真菌的含量0-20cm土層處含量最多,而40-60cm土層處土壤微生物數(shù)量最少,這

33、種分布狀態(tài)與土層腐殖質(zhì)含量相關(guān);行星齒輪減速機(jī)soilmicroorganismsisforestecologicalsystemisanimportantelementofitscontentandactivityinthesoilreflectthesoilfertility,andalsotheembodimentofthesoilbiologicalactivity.Eucalyptusforestlandsoilmicrobesinthemajoritywithbacteria,accordingtothesurveyandeucalyptusforestlandsoilmicrob

34、escontentalongwiththeincreaseofforestageandreduce;Ofbacteriaandactinomycetesinthesameforestage40to60cmsoillayercontent,mostcontentofatleast20-40cmsoillayer,whichmayhaverelationswithrootsystemdistribution.Overthesameoldfungiin020cmsoillayeratmost,and40-60cmsoillayersoilmicrobialquantityminimum,thisdi

35、stributionstateassociatedwiththesoilhumuscontent;土壤酶是土壤中具有生物活性的蛋白質(zhì),有助于土壤中的物質(zhì)轉(zhuǎn)化酶活性高低是土壤肥力的衡量指標(biāo)之一。滴灌帶調(diào)查分析結(jié)果表明:蛋白酶過氧化氫酶、脲酶在桉樹人工林土壤的不同層次之間有著顯著影響;其中過氧化氫酶不同林齡之間達(dá)到了顯著差異,而脲酶不同林齡之間并無顯著性差異;即桉樹林的生長降低了土壤蛋白酶、過氧化氫酶有較大的影響而對土壤脲酶、磷酸酶的影響較小。rainfalldistributionon10-12soilenzymeisproteinwithbiologicalactivityinthesoil,tothematerialtransformationinsoilenzymeactivityisoneoftheindicatorsofsoilfertility.Investigationandanalysisresultsshowedthatth