Abstract: The soil is the carriers of land ecosystem,which supports all kinds of human activities.It is inevitable that human being activities will influence the ecosystem when they exploiting what they need,which in turn affect the state of the ecosystem and its function to serve humankind.It is one of the main functions of an ecosystem to produce primary products.Based on GIS and employing the data of the third land use in Loess Plateau of northern Shaanxi,the paper estimated the service function change of the system resulting from the change of land use.The results showed that the ecosystem service function value of regional NPP in 1996 increased by 1.17?10⁸ yuan than that in 1986,which that in 2001 increase by 3.37?10⁸ yuan than that in 1986.It suggested that measures of reforesting and restoring grass,preventing the landscape broken and the expansion of urbanization were effective to enhance the service function of local ecosystem.

Key words: Leaf decomposition, Tilia amurensis, Broad-leaved Korean pine forest