Net Primary Productivity Increased on the Loess Plateau Following Implementation of the Grain to Green Program

Abstract

The spatio-temporal characteristics of net primary productivity (NPP) since implementation of the Grain to Green Program (GTGP) are important for understanding ecological restoration of the Loess Plateau in China. Here, we conduct spatio-temporal analysis of NPP using MODIS datasets (500 m, 8-day intervals) and VPM (Vegetation Photosynthesis Model) from 2000–2015. We found that NPP on the Loess Plateau increased significantly from 2000 to 2015 (p<0.05). Significant increases in NPP were observed in core areas of the GTGP, including northern Shaanxi and Luliang Mountain in Shanxi. NPP in alluvial plains decreased due to urban expansion into cropland. Significant increases in NPP from 2006–2010 were located north of the area of change in 2000–2005. NPP increased across three vegetation types and four slope gradients. In hilly-gully regions prone to soil erosion, such as central and southeastern parts of the Loess Plateau, obvious vegetation restoration was detected.