Phospholipid fatty acids(PLFAs)can be used as biomarkers for qualitative and quantitative analyses of soil microbial community diversity.In this study,we collected soil samples at 10-cm intervals to a depth of 1 m from Robinia pseudoacacia,Caragana korshinskii and Medicago sativa plantations with different ages(R.pseudoacaciaof 10,15,25 and 40 years;C.korshinskiiof 38,42 years;M.sativaof1,10,20 and 30 years)in a loess area and analysed the soil microbial community structure by PLFA analysis.1)The results sh...