The heterogeneity in spatial-temporal scale of the net primary productivity(NPP) and ecological service value was studied to keep a healthy ecological system of cultivated land by using methods related to the ecological system service and productivity assessment.The changes in NPP and the unit area value of ecological service were not distinct with the total increasing from 1997-2005.The spatial distribution of NPP and ecological service value was very obvious and divided into the lower value in the northwe...