Abstract
In the aftermath of the severe droughts and floods at the end of the 20th century, the Chinese government launched several ecological restoration projects, including the Natural Forest Protection Program in 1998 and the Grain-for-Green Program in 1999, to promote afforestation and reforestation to reduce surface runoff and consequent soil erosion nationwide. However, it is still unclear how vegetation has changed in southern China since the launch of these programs. In this study, we used the MODIS Enhanced Vegetation Index (EVI) to analyze the vegetation cover dynamics in southern China from 2000 to 2009 and evaluate the resulting effects of controlling soil erosion. Our observations indicate that 5.3% of the study area significantly increased and 0.98% significantly decreased in EVI value (p < 0.05). The spring EVI had largest increase in space. The conversions of croplands on steep slopes to forests resulting from national policies led to significant increases in EVI. The increase in EVI was not driven by annual average temperature and annual precipitation. By referencing ecological restoration statistical data and field observations, we showed that ecological restoration programs significantly improved vegetation cover in southern China. Increase in the area of farmland-converted forestlands has reduced soil erosion based upon monitoring sediment yields at hydrologic stations in the Yangtze River. This study displays the spatial patterns of trend in vegetation growth since the beginning of the 21st century in southern China and highlights the important role of China’s afforestation program.
Highlights
Water loss and soil erosion have been deteriorating China’s environment and economy for a long time [1]
We develop a top-down framework using the 250 m resolution MODIS Enhanced Vegetation Index (EVI) dataset through the incorporation of 30 m resolution Landsat TM/ETM+ images to study the vegetation dynamics and its driving forces in southern China from 2000 to 2009, during which the major restoration projects were implemented
Significant increases in EVI account for 5.3% of the entire study area from 2000 to 2009 (p < 0.05), mainly found in the eastern part of southern China
Summary
Water loss and soil erosion have been deteriorating China’s environment and economy for a long time [1]. In the wake of the huge damage caused by these natural calamities, the Chinese central government launched several ecological restoration projects since the late 1990s to promote afforestation and reforestation and reduce surface runoff and soil erosion nationwide, including the Natural Forest Protection Program (NFPP) Project launched in 1998, as well as the Grain-for-Green Program(GGP) in 1999 [4]. Many studies of these restoration projects and their resulting effects have been conducted at local scales, especially in the Loess Plateau of China [5,6,7,8]. There is a lack of conclusive evidence that these managed practices positively influence vegetation cover and, consequentially, the control of soil erosion in southern China due to the complex interactions among climate, ecological, social and economic factors [9, 10]
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