sustainable agricultural land management practices

Tài liệu Opportunities to Reduce Greenhouse Gas Emissions through Materials and Land Management Practices docx

...  Carbondioxide(CO 2 )isabsorbedby land andvegetationthroughtheprocessofphotosynthesis.The netemissionsarenegative(sequestration)andsubstantial,offsettingapproximately884MMTCO 2 E,or approximately13%oftotalemissionsin2006. 114 Thecarbonsequestrationandstorageprovidedby land canbepreservedthough sustainable land management practices, andcanbeenhancedby restorationof land, suchasreforestationofcontaminated land.   Theemissionsestimateforthe land basedcarbonsinkisgivenbytheInventory.Specifically,Chapter7, Land Use, Land UseChange,andForestry,providesanassessmentofthenetGHGfluxresultingfrom theusesandchangesin land typesandforestsintheU.S.,includingnetemissionsfromforestland remainingforestland,croplandremainingcropland, land convertedtocropland,grasslandremaining grassland, land convertedtograssland,settlementsremainingsettlements,landfillyardtrimmings,and ... T on =Timeperiodoftransition,defaultis1yearforcarbonlosses AlthoughthisequationissimilartotheequationusedtoestimatecarbonlossesinDOM(seebelow),it isnotinaccordancewiththe2006IPCCGuidelines.Theguidelinesrecommendagreaterdegreeof disaggregationoflandusedatabyclimateandsoiltype.Theequationaboverepresentsa simplificationofthevariabilityofcarboncontentsinsoilthatexistsonregionalandnationalscales.The soilcarbonstockfortheoldlandusecategory(Cs o )wasbasedoninformationfordifferentecosystem typespresentedinthe2000IPCCreportonLandUse,LanduseChange,andForestry. 117 Thesoil carbonstockforthenewlandusecategoryofsettlements(Cs n )wasbasedonafractionofCs o .For forestlandandgrassland,thefractionwas0.5andforcropland,thefractionwas0.8.GuoandGifford (2002)observedthatlandusechangesofforestlandtocroplandandpasturelandtocroplandresulted insoilcarbondecreasesof42%and59%,respectively. 118 Theestimateforthisprojectassumesthat theconversionofforestlandorgrasslandtourbanlandisequivalenttoaconversiontocropland(bo removeexistingvegetationandcausesignificantsoildisturbance);therefore,GuoandGiffordswork supportsthiseffortsestimationofa50%lossassociatedwiththisconversion.Itisestimatedthatsoils underforestsorgrasslandswillloseapproximately50%oftheoriginalorganiccarbonwhenthelandis convertedtodevelopedland.Theselossesareaconsequenceofboththeremovalofsurfacesoils(to providesuitablebuildingfoundation)andnaturaloxidationwhenthesoilisgradedfollowingremoval ofthevegetativecover.Lossesfromcroplandsareonlyexpectedtobe20%becausethesesoilsalready undergoperiodictillageandthemajorityofnaturaloxidationwillalreadyhaveoccurred.Aliterature reviewforthisprojectdidnotidentifyotherstudiescomparabletoGuoandGifford(2002)that estimatedsoilcarbonlossesassociatedwithconvertingcroplandtourbanland.Therefore,the20%soil carbonlossestimatefordevelopmentofcroplandintourbanlandisbasedonbestprofessional judgment. th ...  Carbondioxide(CO 2 )isabsorbedby land andvegetationthroughtheprocessofphotosynthesis.The netemissionsarenegative(sequestration)andsubstantial,offsettingapproximately884MMTCO 2 E,or approximately13%oftotalemissionsin2006. 114 Thecarbonsequestrationandstorageprovidedby land canbepreservedthough sustainable land management practices, andcanbeenhancedby restorationof land, suchasreforestationofcontaminated land.   Theemissionsestimateforthe land basedcarbonsinkisgivenbytheInventory.Specifically,Chapter7, Land Use, Land UseChange,andForestry,providesanassessmentofthenetGHGfluxresultingfrom theusesandchangesin land typesandforestsintheU.S.,includingnetemissionsfromforestland remainingforestland,croplandremainingcropland, land convertedtocropland,grasslandremaining grassland, land convertedtograssland,settlementsremainingsettlements,landfillyardtrimmings,and ...

Ngày tải lên: 21/02/2014, 12:20

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Sustainable Land Management (SLM) Technologies and Approaches pot

Ngày tải lên: 23/03/2014, 08:21

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