Dissolved organic matter( DOM) is a crucial component of soil organic matter and is attracting more attention. It plays an important role in global C / N cycling,and mediates many soil processes. As a small but active organic matter pool,the structural and chemical characteristics of DOM have recently been considered to be sensitive indicators of soil fertility. In many areas of southern China in the 1960's,many natural broad-leafed forests were transformed into productive plantations,in which soil fertilit...