Spatial–temporal change patterns of vegetation coverage in China and its driving mechanisms over the past 20 years based on the concept of geographic division

Based on the datasets of MODIS NDVI and SPOT VETGETATION NDVI from 1999 to 2018, this study has introduced the gravity centre model and time-lag analysis model to explore the spatial–temporal change patterns of the NDVI in China in different sub-regions and its response to climate factors. Results showed that: (1) In 1999–2018, there was an increasing trend in vegetation coverage in China on the whole, with a larger increase occurring in central south and northeast China. (2) The NDVIs of six land use types showed a similar change trend with temperature and precipitation with different time lags. (3) The maximum correlation coefficients between the NDVIs of different land types and climate factors appeared at Lag 0–1 (current month and previous one month) and Lag 0–2 (current month, previous one and two month), while the correlation coefficients were the lowest at Lag 3 (previous three month). (4) During the past twenty years, the gravity centres of the NDVI, temperature and precipitation moved northward as a whole with similar migration trajectories. These results could provide important decision supports for vegetation restorations and ecological protections in different sub-regions of China.