Dynamic Changes of Net Primary Productivity and its Response to Temperature and Precipitation in China

River basins are important natural and geographical units on the land surface that witness intense human activities. This paper shows that: (1) the Net Primary Productivity (NPP) values in the Inland River and the Yellow River Basins were below the national average. (2) The NPP showed a general decreasing trend in all river basins, while the proportion of NPP increased in inland river area and the southwest river area; the NPP in the Yellow River Basin was slightly higher, which might be explained by the increasing amounts of glacial meltwater due global warming. This indicates lower impact of human activities and the possible implementation of ecological and protection projects. (3) The hydrothermal conditions in the Pearl River Basin and the Songliao River Basin were relatively abundant and balanced. Moreover, the hydrothermal conditions in the southeast river area were not balanced and vegetation showed a demand for heat. On the contrary, in the other six river basins, vegetation showed a demand for water.