摘要
Forestshavebeenexpandingovertypicalsavannasitesforthepast3000yearsintheNeotropics.Suchinvasioncanproduceaseriesofenvironmentalmodificationsontypicalsavanna;however,itremainsunclearhowmodificationsinsoilproperties,causedbytheencroachmentofwoodyspecies,facilitatetheexpansionofforestecosystemsunderdystrophicconditions.HereweexaminedchemicalandmicrobiologicalchangesassociatedwithtreeencroachmentinoxisolsofaNeotropicalSavannaatAssisEcologicalStation,SoutheasternBrazil.Wepredictedthattreeencroachmentcausedbytypicalforestspecieswouldcausesignificantchangesinthechemicalandmicrobiologicalpropertiesofsavannasoils.SoilsweresampledatAssisEcologicalStation,fromsavannasitesdifferingintreeencroachment（typical,denseandforestedsavanna）causedbydecadesoffireexclusion.Weanalysedvegetationleafareaindexandleaflittervolumedepositedinthestudiedplotsandchemical（pH,organicmatter,P,K,Ca,Mg,Al,NO3-,NH4+）andmicrobiological（microbialCbiomassanddehydrogenaseactivity）propertiesofsoilsunderdistinctencroachmentconditions.Mostsoilchemicalpropertiesdidnotchangealongthetreeencroachmentgradient;however,totalP,soilorganicmatter,soilmicrobialCanddehydrogenaseactivityincreasedfromtypicalsavannatoforestedsavanna.Thechangesinsoilorganicmatteranddehydrogenaseactivitywerecorrelatedwiththevaluesofleafareaindexandlittervolumealongtheencroachmentgradient.Ourresultsdemonstratethatforestspeciescanincreasecarbonandphosphorussuppliesintropicalsavannasoils.
出版日期
2016年05月15日（中国期刊网平台首次上网日期，不代表论文的发表时间）
