Borderline Variations of Desertification and Grassland over China Viewed from NDVI 0\^12

After discussing and comparing desertification index and rainfall, the NDVI index 0\^12 was used as the dividing borderline between desertification and degenerated grassland. The changes of the borderline in China were qualitatively discussed in recent 20 years. Results showed that NDVI was a perfect index that used to divide the desertification and degenerated grassland area. The 200 mm isohyet corresponds to the \{isoline\} of NDVI 0\^12. The desertification area has been extended since 1998 in the north area from the Yellow River, and the most change locates in the transition zone between agriculture and pasture.