Vertical root distribution characteristics of Amorpha fruticosa on southern Mu Us Sandy Land

60-year,35-year,28-year and 6-year old Amorpha fruticosa growing on southern Mu Us Sandy Land were sampled using the total strain mining method.Aboveground morphological characteristics,soil moisture, root biomass,specific root length,root fraction,root volume,root surface area and root length density were studied to reveal the ecological adaptability of A.fruticosain a sandy habitat.Results indicated that with increasing soil depth,the root biomass,root volume and root surface area of A.fruticosaof all ages declined exponentially in the formY=ae-bx.Root extinction coefficient analysis showed that roots were concentrated close to the soil surface.Parameters of root distribution showed different degrees of correlation:Soil moisture was significantly correlated with above ground biomass,root biomass,and specific root length.Soil moisture was also positively related to root surface area.The root distribution parameters,moisture control factor and framework factor,were confirmed by principal component analysis.With increasing years,A.fruticosa did not show an aging phenomenon since its roots had the ability to self-thin and update constantly,adapting to the changes in the environment.