Spatial—temporal pattern of GIMMS NDVI and its dynamics in Mongolian Plateau

The physical geography of Mongolian Plateau plays an important role in the East Asian climate ecology system. In this research, GIMMS NDVI, the third generation of NDVI dataset, was processed using the MVC method first, then the spatial-temporal patterns of GIMMS NDVI in Mongolian Plateau during 1982-2003 was investigated, and the transect from Tariat to Xilin Gol was also selected to analyze the NDVI dynamic processes in detail. The results demonstrated that: (1) the general spatial distribution pattern of NDVI showed a clear spatial differentiation. The high value pixels were mainly distributed in the east and north of Mongolian Plateau with forest and meadow steppe land cover, while the low value pixels were mainly distributed in the west and centre part of Mongolian Plateau with desert and Gobi land cover. However, the annual NDVI variability was relative small either in the high-covered regions (i.e. forest, forest steppe, and meadow steppe) or in low-covered regions (i.e. steppe desert, desert and Gobi), while the region with typical steppe normally had higher annual NDVI variability. (2) During 1982-2003, the dynamic evolution process of NDVI in Mongolian Plateau also showed an evident spatial differentiation. About 12.4% of total area featured a significant increase, 4.8% of total area featured an increase but without significance, and 9.3% of total area featured decrease without significance. The other part, about 73.5% of total area, had no obvious change. The NDVI increased significantly in the South-East, South and of Mongolian Plateau, while it decreased in the North-East and North of Mongolian Plateau. Further, the NDVI-increased regions were those typical steppe and farming-pastoral regions before, while the NDVI-decreased regions were those well-covered forest, forest steppe and meadow steppe regions before.