Vegetation change in the south of China after Grain-for-Green
In the wake of the severe Yellow River drought in 1997 and massive Yangtze River flooding in 1998, the Chinese government launched a huge progressive project, “Grain-for-Green (Sloping Land Conversion Programs)” in 1999, to promote afforestation and reforestation to reduce surface runoff and consequent soil erosion at nationwide. It is of great importance to understand how vegetation has changed over the ten years since the project as well as its effects on the vegetation dynamics in the south of China which is the major distribution area of forest in China. In this study, we used the Enhanced Vegetation Index (EVI, MODIS-1km) and climate data to analyze the vegetation dynamics and its driving forces in the south of China from 2000 to 2009. And ground-truth observation and household interview were carried out for verification of satellite-based results.
EVI trend analysis shows that 18.83% of the study area significantly increased and 3.97% significantly decreased in EVI value (p<0.05). Based on Global Land Cover 2000 (GLC2000) and Shuttle Radar Topography Mission（SRTM）data, cropland with significant EVI increases was mainly distributed on slopes greater than 25 degrees and had been altered to forest, shrub and rangeland much. While neither annual average temperature nor annual precipitation showed significant influences on the changes of vegetation during the period from 2000 to 2009 in this region. By referencing government statistical data and launching field observations, we show that the “Grain-for-Green” project significantly improved vegetation cover in the south of China. This study displays a complete picture of vegetation change during the past ten years and helps provide a direction for the re-vegetation in the south of China in the future.