Microfibrilangle(MFA)inChinesefirwastestedbyX-raydiffractionapparatusandcalculatedbycomputersoftware.Theresultswereasfollows:MFAwascontrolledstronglybyinheritance,andtherewasnosignificantdifferenceinMFAamonginterspecies,juvenileandmaturewood.Inthelongitudinal,MFAreduceswiththeheightrisingfrom0to5.5m,especiallyintheheightsfrom0to1.5m.ThevaluesofMFAarenearlyconsistencefrom1.5to7.5m.Thevariationrangewasbetween10.82oand12.57ofrom1.5to7.5m,R2ofpowerequationachieved0.9321,andanalysisofvarianceindicatedthatthevariationofMFAwasnotsignificantfrom1.5to7.5m.TheageofthetreeshadanimportantinfluenceonMFA,consequently,thedifferenceinMFAwassignificantamongannualringsinradial,whichwasmaximalinnearpithandreducedrapidlyfromthepithtosapwood,anditsdeclinetendencywasslowbeyondtheninthannualring.MFAreachedminimumvalueatthe15thannualring,andthedifferencereachedmorethan20oandR2ofbinomialequationachieved0.7556.
