Research paperSpatiotemporal variation of vegetation coverage before and after implementation of Grain for Green Program in Loess Plateau, China

Ecological restoration is an effective method for mitigating environmental degradation, controlling water loss, and diminishing soil erosion. Long-term ecological restoration projects are critical for sustainable regional economic and ecological development. To understand the ecological transition from 1982 to 2013 in the Loess Plateau (LP), this study analyzed the spatiotemporal variability of vegetation using the satellite-derived Normalized Difference Vegetation Index (NDVI) dataset, known as the third-generation Global Inventory Modeling and Mapping Studies (GIMMS3g) dataset. Furthermore, the relationships between NDVI, climate change, and the “Grain for Green” Program (GGP) were assessed. At the regional scale, the average growing season, spring, summer, and autumn NDVI showed a significant increase from 1982 to 2013, 1982 to 1999, and 2000 to 2013, most notably in the latter period. At the pixel scale, the average growing season, spring, summer, and autumn NDVI decreased from the southeast to the northwest LP during the three time periods. In most areas in the LP, this parameter increased during the three periods, especially in 2000-2013. Moreover, increasing precipitation resulted in an improvement in vegetation cover. The average NDVI in the growing season was positively (negatively) correlated with precipitation in the north (south) LP during 1982-2013. In terms of human activity, our results indicate a strong correlation between the cumulative afforestation area and NDVI for 1998-2013, with r = 0.73, n = 16, and P < 0.001.