Botanical Studies (2010) 51: 223-236. ECOLOGY Characteristics and pedogenesis of podzolic forest soils along a toposequence near a subalpine lake in northern Taiwan Shih-HaoJIEN1,Sen-PoWU2,Zueng-SangCHEN3,Tsai-HueiCHEN4,andChih-YuCHIU1,* 1BiodiversityResearchCenter,AcademiaSinica,Taipei11529,Taiwan 2ScienceandTechnologyPolicyResearchandInformationCenter,NationalAppliedResearchLaboratories,Taipei10622, Taiwan 3DepartmentofAgriculturalChemistry,NationalTaiwanUniversity,Taipei10617,Taiwan 4TaiwanForestryResearchInstitute,Taipei10066,Taiwan (ReceivedFebruary17,2009;AcceptedSeptember2,2009) ABSTRACT. Podzolicsoilsarecommonlyfoundundercypressforestsinthesubalpineregionofnorthern Taiwanwheretheclimaticconditionsarecoldandhumid.Toposequentialchangefromsummittolakeshore along a subalpine lake (Lake Jialo) was selected to evaluate the influence of high soil moisture conditions on vegetationandpedogenicprocesses,andtoclarifythemechanismofpodzolization.Alongthistoposequence, thepodzolizationprocessoccursatalllandscapesitesexceptfortheoneatthelakeshore.Organically- complexedFeandAlarethedominantformsintheBshorizonsatsummitandfootslopesites.Thefulvic acidscomplexFeandAlandtranslocatethelatterdownwardsintotheBshorizons.Theplacichorizonin soilsatthefootslopeisdominatedbyamorphousFeoxides.Formationofplacichorizonsismainlyattributed toperchedwater,whichiscausedbyheavyrainfallandseasonallyhighlakewaterlevelbetweentheAEand Bs horizons. This situation causes Fe reduction and translocation to lower parts of the soil profile, resulting in formationofaplacichorizonbetweenEandBshorizons.Thesoilstowardsthelakeshorearecharacterized byincreasingdominanceofhydromorphicprocessoverpodzolization.However,althoughthepodzolization process occurs, the studied soils cannot be classified as Spodosols. High clay and crystalline Fe oxide contents derivedfromparentmaterialsretardthemobilityoforganically-complexedmetalcationsandthusslowdown thepodzolizationprocessandformationofspodichorizonsinthisarea. Keywords: Fulvicacids;Placichorizon;Podzolicsoils;Podzolization. INTRODUCTION enriched)horizon(McKeagueetal.,1983).Theterm “podzolicsoil”inthispaperisappliedtoPodzol-likesoils Podzolsoccurmainlyincoolandhumidclimates withableachedeluvialhorizonandFeorAlilluviated underforestsofconiferousvegetationwithmediumto horizons,whicharenotexpressedwellenoughtobe coarsetexture(Lundströmetal.,2000).Thevegetation classified as Spodosols or Podzols. and climate conditions are critical factors to influence the Some alpine or subalpine areas of tropical and formationofpodzolicsoils.Thesesoilsareusuallyfound subtropicalclimaticregionsprovidesimilarandsuitable inborealandtemperateregions(BuurmanandJongmans, environments for podzolization. Hence, small and specific 2005;Saueretal.,2007),andpodzolizationisamajor areaswithPodzolsarealsofoundinsomesubalpineareas processofsoilgenesisintheseregions.Theclassical ofperhumidtropicalandsubtropicalregions(Hseuetal., viewofpodzolizationisthatAlandFearereleasedvia 2004;Saueretal.,2007;Schaweetal.,2007).Taiwanis weatheringintheeluvialEhorizonandtranslocatedto locatedinthetropicsandsubtropics,butcoldandhumid theBhorizonfurtherdowninthesoilprofile.Podzols climaticconditionswereprevailinginalpineandsubalpine typicallyhavethreetofourmajorhorizons,includinga forestareas.Thesetropicalorsubtropicalforestareas dark-colored, organicsurfacehorizon(O);ableached withaltitudeshigherthan1,900m,highprecipitation eluvialhorizon(E);andareddish,brownishorblackish (≥ 3,000 mm year-1)anddominantconiferousvegetation illuvialhorizonenrichedinamorphousmaterials(Bhs), aresuitablefortheformationofUltisols,Spodosolsand whichmaybedifferentiatedintoanupperBh(primarily podzolicsoils(Chenetal.,1989,1995;Liuetal.,1994; humus-enriched)andlowerBs(primarilysesquioxide Lietal.,1998;Hseuetal.,1999;LiuandChen,2004;Wu andChen,2005). *Correspondingauthor:E-mail:[email protected]. 224 Botanical Studies, Vol. 51, 2010 Published studies on soil genesis in tropical and informationisavailableonassociatedsoilsnearsubalpine subtropicalmountainforestssuggestpodzolizationand lakesandtheeffectsoffluctuatingwaterlevelsofthe hydromorphismasdominantsoilformingprocesses(Hseu lake. In addition, there are no reports on the influence of etal.,2004;WuandChen,2005;Schaweetal.,2007). differentfractionsofsoilorganicmatter,whichwould Thesesoilformingprocessesareaffectedbydifferent enableunderstandingthetranslocationofmetalcations kindsofvegetation,compositionofsoilorganicmatter, inpodzolicsoilsinthesealpineandsubalpineforests. claycontents,crystallineFeoxidesanddifferentmoisture Therefore,weaimtoevaluatethepedogenicprocesses regimes(Wangetal.,1989;LiuandChen,1991;Kaiser andpodzolizationprocessinpodzolicsoilsalonga andZech,2000;Lundströmetal.,2000;Stutteretal., toposequencenearasubalpinelake,andtoevaluatethe 2007).ÁlvarezArteagaetal.(2008)foundPodzol-like influence of soil forming factors on podzolization process soilsinmontanecloudforestsintropicalareas,which inthesesoils. resultedfromintensiveweatheringandleaching,spodic materialformation,andgleyzationprocesses,evenin MATERIALS AND METHOIDS heavy-textured soilsandhydromorphicsoils,butthese soilswerenottypicallySpodosolsorPodzols.Theyalso Soils and environmental conditions indicatedthatthepedogenesisofPodzolsinmontane Taiwanislocatedinthetropicsandsubtropics,but cloudforestsisnotverystableandmightbealteredeasily theclimateiscoldandhumidinthealpineandsubalpine by slight modification of soil forming factors. Spodosols forestregionsoftheisland’sCentralRidge.Thestudy orpodzolicsoilswithheavytexturearefoundinthe was conducted in the Jialo Lake area (about 24°28΄26˝ N, alpineandsubalpineforestregionsofcentralandnorthern 121°28΄42˝ E) on Jialo Mountain in northeastern Taiwan Taiwan(Chenetal.,1989;1995;Lietal.,1998).Liu (Figure1).JialoMountainbelongstothephysiographic andChen(1991)suggestedthatthehighclaycontents regionoftheCentralRidgeinTaiwan.Thismountainwas inalpineforestregionsincentralTaiwanslowdownthe formedbytectonicupliftduringMioceneandismainly podzolizationprocessbecauseofpoordrainageandlow composedofsandstone,shaleandslate(Ho,1986).At mobilityoforganicmatterinsoilpedons. least18lakesaredistributedinthissubalpineregion.In Inadditiontopodzolicsoils,soilswithplacichorizons thetyphoonseason,thelakesincreaseinsize,andseveral arefoundinsubalpineforestregionswithperhumid smalllakesmaycombineintoafewlargelakes.The climate.Aplacichorizonisrelativelyimpermeableto originofthesesmalllakesisnotclearsofar.Theymight waterandplantroots.ItoccursinsomeSpodosolsasa bePleistoceneglacialgeomorphologicalfeatures(Cuiet thin,wavyorconvolutedhorizonthatmaytransgress al.,2002;Hebenstreiteal.,2006;Carcailletetal.,2007). severalsubhorizons(McKeagueetal.,1968).Insome JialoLake,thelargestlakeamongthesesubalpinelakes, regions,itoccurswithinorimmediatelybelowthealbic about300mlongand150mwide,isclosetothestudy Ehorizon(SoilSurveyStaff,1975).Placichorizonsare area.Theelevationsofthestudiedsitesfromlakeshore usuallyassociatedwithperudictoaquicsoilmoisture tosummitareabout2,250-2,300mabovesealevel,the regimesincoastalregions(McKeagueetal.,1983). meanannualairtemperatureis10°Candtotalannual However,insubalpineareaswithperhumidconditions precipitationis3,200mm.Thehighrainfallinthetyphoon inTaiwanInceptisolswithplacichorizonsarefoundthat season(fromJulytoNovember)canresultinaperiodic resultfromperchedwater(Hseuetal.,1999;2004;Wu fluctuation of the lake water level between the footslope andChen,2005).Furthermore,theparentmaterialsof andlakeshoresitesinthestudyarea.ForestsofTaiwan thesubalpineforestareasofTaiwanaremainlyshaleand falsecypress(ChamaecyparisformosensisMatsum)and slate,whichareeasilyweatheredtoafinersoiltexture. willowfir(CryptomeriajaponicaHassk.)aredominant Thefine-texturedsoilsimplythatwaterslowlyflows intheupperpartsoftheslopeandextendtothelower intooroutofthesoilbodyandleadstoalternationof boundaryofforestatthefootslopesite;bushesofyushan reducedandoxidizedconditions,whichisoneofthe cane(Yushanianiitakayamensis)coverthelowerpartof importantfactorsforthegenesisofplacichorizonsin theslope,whichistheupperlineofthelakewaterlevel Taiwan(Claydenetal.,1990;Hseuetal.,1999,2004; ofinundationintherainyseason.Grasslanddominatedby WuandChen,2005).Thegenesisofplacichorizonsis silvergrass(MiscanthustransmorrisonensisHayata)forms quitedifferentfromthepodzolizationprocess(Conryet thevegetationatthetoeslope,followedbyaquaticplants al.,1996;Hseuetal.,1999).Spodichorizonsfeaturethe (Schoenoplectusmucronatus)atthelakeshoreandswamp processesofaccumulationoforganiccarbon,aluminum, regions.Thesloperangesfrom0to5%onthesummit,5 withorwithoutFe,accordingtotheUSDASoilTaxonomy to10%atthefootslope,and10to15%atthetoeslopeand (SoilSurveyStaff,1999). inthelakeshorearea. Recently,thetranslocationofdifferentextractable Foursoilpedonswithclayeytexturewereselected Fe,AlandMnhasbeenstudiedinalpineorsubalpine alongthetopographyfromthesummittothelakeshore Spodosolsorpodzolicsoilsinsubtropicalareas(Chenet ofJialoLake(Figure1).Ineachsite,apitwasexcavated al.,1989,1995;Lietal.,1998;Hseuetal.,1999,2004; formorphologicalfeaturedescriptionaswellascollection LiuandChen,2004;WuandChen,2005),butlittle ofsoilsamplesaccordingtostandardprocedures(Soil JIEN et al. — Podzolic forest soils nearby subalpine lake 225 Figure 1.ThelocationofthestudyareaandthefourpedonsalongthetoposequencenearJialoLakeinnortheasternTaiwan.(LS: lakeshore;TS:toeslope;FS:footslope;SU:summit;HWT:highwatertableoflake;LWT:lowwatertableoflake). Survey Staff, 1993). Soil pedons were classified according method)wasperformedtodeterminethecontentsoffree