Spatiotemporal Evolution of NPP in Sandy Land of China's Seasonal Freezing-Thawing Typical Region

Based on the data set of AVHRR GIMMS, TERRA/AQUA MODIS NDVI, and climate data from 1982 to 2018, CASA model, GIS spatial analysis, and mathematical statistics were used to study the changing law in the category of time and space, spatial distribution, and the correlativity between the NPP and meteorological factors in the sandy land of China's Seasonal Freezing-Thawing Typical Region. The results showed that the average annual NPP value of vegetation in the growing season of the sandy land from 1982 to 2018 fluctuated between 217.65-356.61 gC/m2a, showing an obvious seasonality and a significant increase. The spatial distribution of NPP in the sandy land in the near 37a is significantly different. There are significant seasonal differences in vegetation responses to temperature, precipitation, wind speed, evaporation, and other meteorological factors in different regions. The increase of vegetation cover in sandy land of China's Seasonal Freezing-Thawing Typical Region is controlled by regional atmospheric circulation and human dynamics.