Net primary productivity and its spatiotemporal patterns in Loess Plateau during 1981-2000

Based on the GLO-PEM simulated data, net primary productivity (NPP) and its spatiotemporal patterns in Loess Plateau were studied from 1981 to 2000. Our research indicated that the distribution of annual NPP in Loess Plateau was obviously different from east to west and from south to north. The average of annual total NPP is 0.15PgC, with an annual increasing rate of 0.01%. NPP decreased in most parts of Loess Plateau, with the largest decrease in the southeast of Shanxi Province and northeast of Loess Plateau, But it increased in the area along the boundary between Shaanxi Province, Inner Mongolia Province and Lanzhou Basin in the west of Loess Plateau, The early 1990s (1991-1995) is the time with fastest NPP increase. The variation of NPP is different seasonally. It decreased mostly in winter, with an annual rate of 0.57%, and increased with an annual rate of 0.51% from April to May.