biomass and carbon stocks of vegetation in the marginal

Annals of Tropical Research 36[Supplement]:70-81(2014)© VSU, Leyte, Philippines

Correspondence : R.S. Come Address: CollegeofForestryandEnvironmentalScience,VisayasStateUniversity,Visca,BaybayCity,Leyte6521-AEmail:[email protected]

Biomass and Carbon Stocks of Vegetation in the Marginal Uplands in Inopacan, Leyte, Eastern

Visayas (Philippines)

Renezita S. Come, Marlito M. Bande, Manilyn Camutuhan, May Joy B. Alip and Rowela Porazo

CollegeofForestryandEnvironmentalScience,VisayasStateUniversity,Visca,BaybayCity,Leyte6521-A

ABSTRACT

Marginal uplands are characterized by unproductive soils and lowbiodiversity. These areas can be a good storage of carbon for climatechangemitigationifrehabilitationmeasureswillbedone.Thisstudywasconducted toquantify thebiomassandcarbonstorageofvariousplantspecies growing in the marginal uplands in Inopacan, Leyte. Samplequadrats measuring 2m x 2m were laid-out inside the one hectareexperimentalplotsestablishedinthesite.Variousspeciesofgrasses,herbsand shrubs were identified inside the quadrats. Using destructivesampling,biomassandcarboncontent in theabove-ground(stemsandleaves)andbelow-ground(roots)weredetermined. Soilsampleswerealsotakenforbulkdensityvalueandsoilorganiccarboncontent. Resultsshowedthatthevegetationwasdominatedbygrass,Imperatacylindrica andshrubsnamely:MelastomamalabathricumandChromolaenaodorata

-1 -1was2.34Mgha andtherootswas2.28Mgha .Carbonstoredinthestems-1 -1

andleaveswas1.05MgCha androotscontained1.03MgCha .Soilshold-1thehighestpercentageofcarbonwhichamountedto25.93MgCha .The

-1totalcarbonstocksinthemarginaluplandinInopacanwas28.01MgCha .

Keywords:biomass,carbonstocks,marginaluplands,soilorganiccarbon,InopacanLeyte

[email protected]

Typewritten text

DOI: 10.32945/atr36s5.2014

INTRODUCTION

ThePhilippinesisdescribedasacountrywithvasthillylands.Outofitstotallandareacoverof30millionhectares,halfarelocatedintheuplandsorareaswith18%slopeandabove.Theseareaswerepreviouslycoveredwith lush vegetation, mostly forests. However, through the years, thecountry has experienced a very fast deforestation rate. Many of theseuplandareasareconvertedfromonelandusetoanotheri.e.fromforesttoagricultural areas through shifting cultivation and, leaving themunproductiveafterbeingcultivatedforyears.Uplandareaswithnoorlessvegetation are described to be more prone to soil erosion due to itsbiophysicalcharacteristicsincludingruggedterrainandwithlessfertilesoil. In addition, soil erosion is the most widespread process of soildegradationinthePhilippines(Asioet.al.,2009).Thisconditionisabigchallengetoagriculturists,forestersandlandmanagerssinceallactivitiesin theuplandscouldaffect lowlandandcoastal resources.Theeffectofclimate changemayworsen these conditions in the uplandswhere 25millionFilipinoswhoarealsoconsideredas“poorestamongthepoor”areliving(FDC1985,WorldBank1989).

Countrywide, rehabilitation of many uplands and making themproductiveandecologicallysustainablehasbeenthepriorityformorethana century (Chokkalingam et.al., 2006). The government through theDepartment of Environment and Natural Resources (DENR) has lednationalreforestationprogramssuchastheNationalForestationProgramin1986,UplandDevelopmentProgram,LuntiangKalikasan,andrecently,the National Greening Program. These programs aimed to rehabilitategrassland areas in the uplands and regreening of lands under publicdomain.Otherapproachesincludingagroforestry,establishingtreefarms,and recentlybyadoptingorganic farming in theuplandswerealsoputforward.Inaddition,environmentalservicessuchascarbonsequestration,reductionofsoilerosion,waterconservationandwildlifehabitatarejustfewofthemanybenefitsthatwecouldderivefromrehabilitationoftheseunproductiveareas.

Countrywide, vast areas covered by Imperata cylindrica cover 35million hectares (Garrity et.al., 1997) and many of these areas needimmediaterehabilitationastheyarelocatedinwatersheds.Theseareasstoresandsequesterssignificantamountofcarbonfromtheatmosphere.However,duetothenatureofmanyspecieswhichcanbefoundintheseareas(i.e.fastturn-overrate),carboncannotbestoredforalongerperiod

71Biomass and Carbon Stocks of Vegetation in the Marginal Uplands

of time when compared to other land uses including plantations,agroforestry and second-growth forests. Hence, quantification of thestorageandsequestrationcapacityoftheseareasisimportantespeciallythatfewsimilarstudieshavebeenconductedinLeyte.Findingsmaybeusefulforagriculturists,foresters,farmersandlandmanagersandcouldserveasabaselinestudytocomparethecarbonstoragewhengrasslandsareconvertedintootherlandusesespecificallyinInopacan,Leyte.

OBJECTIVESOFTHESTUDY

ThestudygenerallyaimedtoquantifythecarbonstocksofgrasslandinthemarginaluplandsinInopacan,Leyte.Specificallythestudyaimedto:

1. Quantify the biomass and carbon stored in the above-ground

(stalksandleaves)andbelow-groundvegetation(roots);and

2.Determinethecarbonstorageinthesoil

MATERIALSANDMETHODS

StudySite

ThestudyareaissituatedinBarangayLinao,SitioBatuan,Inopacan,Leyte.Itisa5thclassmunicipalityintheprovinceofLeyteandoneoftheprovinces in Easter Visayas, Philippines (10°31'48"N 124°49'44"E). Climateischaracterizedwithrainfallthatisevenlydistributedthroughouttheyear(TypeIV).Thesitehasanaveragetemperatureof27°Cwithahighrelativehumidityof84%.Maximumelevationinthissitereached1,000masl(MunicipalProfileofInopacan,Leyten.d.).(Figure1).

Plotlay-outandSampling

Aonehectareexperimentalplotwasestablishedinthesiteownedbyaprivateindividual.Theareawasdividedinto25plotsmeasuring20mx20mandwasfurthersub-dividedinto16sub-plotsmeasuring5mx5m(Figure2).A total of twenty fourquadratsmeasuring2mx2mnestedwithin5mx5msub-plotswererandomlylaid-out.Allspeciesofgrasses,herbsandshrubsfoundwithinthequadratswereidentified.Also,usingdestructive samplingallplants containedwithin the randomly selectedquadratswereharvestedtogetthefreshweight.Sub-samplesweretakentothelaboratoryforoven-dryingat70°Cfor48hoursoruntilconstant

72Come et al.

weightwasattained.Inthesameplotswereabove-groundvegetationwasharvested, roots were collected up to one meter depth. Samples werewashed and sieved using 2mm wire mesh to separate them from theattachedsoil.Samemethodstheabove-groundvegetationwasappliedtodeterminethefreshweightandoven-driedweightofrootssamples. Core sampling method was used for determining bulk density.Animprovisedcanisterwithadimensionof5.4cmdiameterand6cmheightwasused.Samplesforbulkdensitywerecollectedwithinthefollowingsoildepth:0-10cm,10-30cm,30-50cmand50-100cm.Sampleswerecarefullytaken-out from the canister and placed in a sealed plastic. Thesewerebought to the laboratory foranalysis.Three (3) representative samplesweretakenfromeverydepth forsoilbulkdensitydeterminationwhilefour(4)samplesweretakenforsoilorganiccarbonanalysis.AnalysiswasdoneintheVisayasStateUniversity,BaybayCity,LeyteCentralAnalyticalLaboratory.


Figure1.LocationmapofthestudyareainSitioBatuan,Brgy.Linao,Inopacan,Leyte.

Figure2.Lay-outoftheonehectareexperimentalplots.

74Come et al.

DataAnalysis

Descriptive statistics including mean and standard deviation wasperformedforthisstudy.Inaddition,thefollowingformulawereusedintheanalysisandinterpretationofdata.

Above-GroundandBelow-GroundBiomass

Biomassvaluesforgrass,shrubsandherbswerecalculatedusingthefollowingformula:

Equation1

ODW(g)=TFW—(TFW*(SFW–SODW))

SFW

Where:ODW=Oven-DryWeightTFW=TotalFreshWeightSODW=sampleoven-dryweight


Tocalculatethecarbonstorageinplants:

Equation2

TotalC=Biomass*carboncontentofplanttissue(weused45%asDefaultvalue)

Soil

Equation3

-3Bulkdensity(gcm )=

Thedryweightofsoilandcarbonstockwascomputedusingthefollowingformulae:

Equation4

Soilmassatspecifieddepth(Mg)=Bulkdensityatspecifieddepth(Mg-3 2m )x10,000m xdepth(m)

Soilorganiccarbonstocks(Mg)

Equation5

-1TotalSOC(MgCha )=

Dryweightofsoil(g)

Volumeofthecanister(cc)

soilmassatspecifieddepth(Mg)x%organiccarbonatspecifieddepth

100

76Come et al.

RESULTSANDDISCUSSION

Speciescomposition.Resultsfromthisstudyshowedthatthestudyareaismainlydominatedbycogon(Imperatacylindrica)with16.09%ofthetotal vegetation. Cogon is characterized as very flammable, and theiroccurrenceindicatesthattheareahasanacidicsoil.Thiswasfollowedbyshrubspeciesnamely:hantotoknaw(Melastomamalabathricum),hagonoy(Chromolaema odorata) andmalagabon or kukug banug (Elephantopusspecatus)wereallofthemcomprisedperspecies.Otherplantspeciesthatare present in the area includes mani-mani (Desmodiumtriflorum),bugang/talahib (Saccharum spontaneum), bario-bario (Piperaduricum),malacogon,cropslikecamote,cassava,pineappleandbanana.Also, fewtreesofGmelinaarboreawereobserved in thearea,however,treesareplantedoutsidetheonehectarestudyplot.Atotalof25plantspecieswereidentifiedinthestudysite(Table1).

Abovegroundbiomassandcarbonstocks.Thecomputedbiomassofthe-1abovegroundpartofthegrasslandareahasatotalof2.34Mgha .Itranges

-1from0to0.50Mgha .Thisresultwasverydependenttothekindofspeciesthatwerefoundintheplotandhowmuchthesamplesthatwereabletotakefromtheplot(Pulhin,2008).Forexample,inplot18therewereonly3species of grass that were collected. This is because plot 18 has beencultivated forcropplantationpurposes.On theotherhand,plot11hasmore10speciesofgrassandithasthehighesttotalfreshweightwhichis

-17.94 Kgha The total carbon storage of above-ground vegetation has.-1amountedupto1.05Mgha .

Belowgroundbiomassandcarbonstocks.Rootbiomasshasatotalof-1 -1

2.28Mgha . Value ranges from 0.01 to 0.30Mgha . The result can beexplainedbythehighamountofrootsthatweretakenfromtheplots.The

-1carbon storage of the roots has a total of 1.03Mgha (Figure 3). Rootbiomassisalmosthassimilaramounttothebiomassintheabove-groundvegetation.Thisisduetoitsrootssysteminwhichgrasshasashortlengthofrootsanditcannotholdcarbonforlongerperiodoftime,comparedtotherootsystemoftreeswhichcanpenetratedeeperandhaslongerlength,soithasmorecapacitytostoredcarbonforlongtime.

AsstatedbyLugoandBrown(1992)inasystembiomasshasdifferentvalues, in which resulted from the different degrees of anthropogenicactivity and other natural disturbances. A grassland area with higher


biomassdensitiesmeansitsexperiencinglesserdisturbances.Whileiftheareahave lowerbiomassdensities thatmeans it is experiencinghigherdisturbancesuchasfrequentburningofthegrasses.

Likewise,manyfactorscouldaffectthebiomassandcarbonstorageofvegetationandoneofthatistheweather,whichisthewetanddryseason.Biomass and carbon storage in rainy season is indeedgreater than thebiomassandcarbonstoragethatisbeingaccumulatedduringsummer.Forin rainy season the grassland vegetation is faster to regenerate, hencehigherbiomassisexpected.Inaddition,carbonstorageduringthisseasonis also greater because its result is very dependent to the amount ofbiomassgathered.

Bulkdensityandsoilorganiccarbon.Thebulkdensitiesofthesoilinall-1 -1sampledplotsrangedfrom0.30gcc to0.70gcc .Plot7containsboththe

lowestandhighestbulkdensityofthesoil.Itwasnotedthatalloftheplots-1havebulkdensitiesof >0.90gcc ,whichindicatesthatsoilbulkdensities

derivedfromthegrasslandisstillcompactedandlessdisturbed.ThisfitsthetypicalcharacteristicofgrasslandareasinthePhilippineswhereinhighsoilbulkdensityindicatesthatsiteisdisturbed(Pulhin,2008).

-1Soilorganiccarbon(SOC)rangedfrom16.61to30.34MgCha foundinvarious soil layerswhere sampleswere taken.On the otherhand, bulk

-1densityrangedfrom1.05to1.22gcc (Table2).Carbonstorageinsoilsatvariousdepthsingrasslandsshowednopatternandtheaveragewas25.93

-1MgCha .Resultsofthestudyshowedthatsoilholdsthehighestamountofcarbon.ThecarbonstoredthatwasderivedfromthisstudyisalmosthalftotheresultsofstudiesthatwereconductedinLeyte,whichhaveacarbon

-1densityvalueof52.70Mgha (Lasco,et.al.2000).

Table2.Samplebulkdensityandcarbonstorageofthesoil.

Totalcarbonstorageofgrassland.Overall,theone-hectaregrassland-1storedthetotalcarbonstocksof28.01Mgha .Variouscarbonpoolsinclude

-1soilswith25.93Mgha ,above-groundbiomass (stemsand leaves)with-1 -11.05Mgha and below-ground biomass (roots) with 1.03Mgha . Soil

stores the highest amount of carbon while above-ground and below-

Soil Layers BD (g cc-1) C (MgCha-1) 0-10cm 1.05 16.61± 2.15 10-30cm 1.22 25.90±9.11 30-50cm 1.07 20.91±13.96 50-100cm 1.14 30.34±22.39

Common Name Scientific Name Family Name Classification No. Of occurrence

N=86

Frequency (%)

Cogon Imperata cylindrica Pocaeae Grass 14 16.28 Hantotoknaw Melastoma malabathricum Melastomataceae Shrub 11 12.79 Hagonoy Chromolaema odorata Asteraceae Herb 11 12.79 Malagabon Elephantopus specatus Ateraceae Herb 11 12.79 Mani-mani Desmodium triflorum Fabaceae Herb 5 5.81 Fern Neptirolepis tirsutula Dryopteridaceae Fern 4 4.65 Daat Scleria sphaecocarpa - - 4 4.65 Carabao grass Paspalum conjugatum Poaceae Grass 3 3.49 Baryo-baryo Piper aduricum Piperaceae Herb 3 3.49 Makahiya Mimosa pudica Fabaceae Herb 3 3.49 Dysmodium Desmodium ovaliforium Fabaceae Herb 2 2.33 Bugang/Talahib Saccharum spontaneum Poaceae Grass 2 2.33 Cotton-cotton Desmodium ovaliforium - - 2 2.33 Malagabon Elephantopus tomentosus Asteraceae Herb 1 1.16 Gabon Blumea balsamifera Asteraceae Herb 1 1.16 Alibangbang Piliostigma sp. Fabaceae Tree 1 1.16 Malacogon Ǽ � - 1 1.16 Mini-mani mani Alysicarpus sp. Fabaceae Herb 1 1.16 Kadena de Amor Antigonon leptopus Polygonaceae Vine 1 1.16 Dawa-dawa Pancum maximum Poaceae Grass 1 1.16 Batung-batong Calopogonium mucunoides Fabaceae Herb 1 1.16 Amorseco Chrysopogon aciculatus Poaceae Grass 1 1.16 Bukot-bukot Centella sp. Apiaceae Herb 1 1.16 Unidentified grass Ǽ � Grass 1 1.16 Total 86 100

Table1.Description,numberofoccurrenceandfrequencyofplantspeciesinthestudysite.Com

e e

t al.

78


Figure3.TotalstocksinthevariouscarbonpoolsinthestudyareainInopacan,Leyte

IMPLICATIONSANDRECOMMENDATIONS

ImportantbaselinedataonthecarbonstoragecapacityofgrasslandsinmarginaluplandsinInopacan,Leytewasderivedfromthisstudy.Resultsshowedthatsoilisanimportantcarbonpoolandhashighercapacitytostorecarbonthanabove-groundandbelow-ground(roots)pools. Sincegrasslandsareknowntohavehighturn-overrateduetotheirnatureandpronetoburningandgrazing,carboncannotbestoredforalongerperiodof time compared to other land uses including agroforestry and treeplantations. It is therefore recommended that marginal uplands inInopacan be converted intomore productive and diverse ecosystem inorder to maximize the benefits of the areas both ecologically andeconomically. Further studies including quantification of carbon in

groundvegetationstoredmoreorlessthesameamountofcarbon.Soilsareknowntostoremoreorganiccarbonandholdsitforalongerperiodoftime.Inaddition,thecapabilityofthesoiltostoresoilorganiccarbonisbeinginfluenced by the following factors: (1)mean annual precipitation; (2)degree of forest disturbance; (3) extent of land use change (Lugo andBrown,1993).ItwascitedbyPulhin(2008)thatinordertoenhancesoilsequestrationthefollowingstrategiesmustbedone.(1)reduceerosionthrough reforestation; (2) improving soil fertility; (3) reduce shiftingcultivation;(4)removemarginallandsfromagriculturalproduction;(5)retainingforestlitteranddebris(Lascoetal.,2000).

different grassland communities is also recommended. Carbon stocksassessment of marginal uplands during rainy season could also beconductedtocomparetheresultsofthisstudy.Otherimportantspeciesofgrasses,shrubsorherbsmightbepresentduringthisseasonwhichwerenotdocumentedduringtheconductofthisstudy.

REFERENCES

ASIOV.B.,JAHN,R.,PEREZ,F.O.,NAVARETTE,I.A.ANDABIT,S.M.JR.2009.AReview of Soil Degradation in the Philippines. Annals of TropicalResearch31(2):69-94.

CHOKKALINGAM,U.,CARANDANG,A.P.,PULHIN,J.M.,LASCO,R.D.,PERAS,R.J.andTOMA,T.,2006.OneCenturyofForestRehabilitationinthePhilippines: Approaches, outcomes and lessons. SMK Grafika DesaPutera,Jarakta,Indonesia.132pp.

FORESTRYDEVELOPMENTCENTER (FDC). 1985. A critical look at theupland livelihoodprograms in thePhilippines.PolicyPaperNo.16.Forestry Development Center, College of Forestry and NaturalResources,UniversityofthePhilippinesLosBaños.

GARRITY,D.P.,SOEKARDI,M.,vanNOORDWIJK,M.,delaCRUZ,R.,PATHAK,P.S.,GUNASENA,H.P.,vanSO,M.N.,HUIJUN,G.andMAJID,N.M.1997.The Imperata grasslands of tropical Asia: area, distribution andtypology.AgroforestrySystems,36:3-29.

LASCO,R.D.,J.S.LALES.,M.T.ARNUEVO.,I.Q.GUILLERMO.,DEJESUS,A.C.,

MEDRANO, R., BAJAR, O.F. and MENDOZA, C.V. 2000. ProceedingsWorldGeothermalCongress2000.Kyushu-Tohoku,Japan,May28-June10,2000.Pp.6.

LUGO,A.E.andS.BROWN.1992.TropicalForestasSinksofAtmosphericCarbon.ForestEcologyandManagement.,54:239-255.

LUGO,A.E.andBROWN.1993.ManagementofTropicalSoilsasSinksorSources of Atmospheric Carbon. Plant and Soil. Kluwer AcademicPublishers.Netherlands.149:27-41.

Come et al.80

MunicipalProfileofInopacan,Leyten.d.pp.53.

PULHIN, F. 2008. Carbon storage of the grassland areas of IkalahanAncestral Domain, Nueva Viscaya, Philippines. Published by WorldAgroforestrySystem.Bogor,Indonesia.WP32:p32.

QUIMIO, J. 1996. Grassland Vegetation in Western Leyte, Philippines.Doctoraldissertation,FreibergUniversityinGermany.

WORLD BANK. 1989. Philippines, environment and natural resourcesmanagement study: aWorld Bank country study. TheWorld Bank,Washington,D.C.,USA.


biomass and carbon stocks of vegetation in the marginal

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