Abstract: In order to study the results of soil productivity maintenance measurements,soil nutrient,soil enzyme activities and soil microbes of intercropping forestland,soil replacing(replacing sand with fertile farming soil) forestland and cultivar-alternated forestland were measured in the field along the Shu River in Juxian County in Shandong Province.The results showed that in soil-replaced forestland,the DBH and the height of stands increased significantly,and soil nutrient,the activities of urease,peroxidase,polyphenol and the number of soil microbes were improved,bacteria,fungi,actinomyces increased 1.55,2.05,1.24 times compared with CK.Soil organic matter,available N,available K,the activities of soil urease,peroxidase,polyphenol,the amount of soil microbes of cultivar-alternated forestland increased,and bacteria,fungi,actinomyces increased 3.18～23.91,3.40～28.71,0.71～2.80 times respectively.Intercropping was beneficial to soil organic matter,available P,available K,trace element Fe,Mn,the activities of soil enzyme,the amount of soil microbes.And bacteria,fungi,actinomyces increased 1.38～3.39,1.28～7.73,0.79～3.11 times respectively,the DBH and the height of stands increased 15.25%～37.84%,8.17%～29.12% respectively.

Key words: poplar plantation, continuous cropping, soil productivity maintenance