Temporal and Spatial Variation of Land Use and Vegetation in the Three-North Shelter Forest Program Area from 2000 to 2020

The Three-North Shelter Forest Program Area (TNSFPA), covering the three subregions of Northwest, North and Northeast China, is an important green ecological barrier in northern China. Research on spatiotemporal variation of land use and vegetation in this area can help us understand the evolution of vegetation recovery. Based on MODIS image data, we built a dataset including land use/cover, annual and seasonal vegetation coverage and vegetation productivity in the TNSFPA from 2000 to 2020, then analyzed their spatiotemporal dynamics' characteristics and further explored the driving factors. The results demonstrate that 90.05% of land area in the TNSFPA remained unchanged from 2001 to 2020. The area of barren decreased, whereas the area of all other land use types increased. From 2000 to 2020, the vegetation coverage generally presented a spatial pattern of high in the east and low in the west, and the interannual fluctuation of high coverage area was small. More than 90% of the TNSFPA had an increasing vegetation coverage (0.41%center dot a(-1)), with the change rates of 0.51%center dot a(-1), 0.54%center dot a(-1) and 0.37%center dot a(-1) in Northeast, North and Northwest China, respectively. The spatial distribution of vegetation productivity was generally consistent with the vegetation coverage, and the interannual fluctuation in areas with low productivity was small. The area with an increasing vegetation productivity (3.41 gC center dot m(-2)center dot a(-1)) occupied 51.66% of the TNSFPA, mainly in the basic stable state and significantly increased state. The change rates in Northeast, North and Northwest China were 7.34 gC center dot m(-2)center dot a(-1), 6.72 gC center dot m(-2)center dot a(-1) and 2.10 gC center dot m(-2)center dot a(-1), respectively. The vegetation coverage and productivity were positively correlated with climate factors, and the correlation with precipitation is significantly higher than that with temperature. The ecological protection and restoration activities in the TNSFPA have accelerated the recovery of the vegetation ecosystem. Meanwhile, the rapid growth of population has led to the acceleration of urbanization. The intensification of the interaction between humans and land has led to the reclamation and development of barren, which has a great impact on the small-scale vegetation ecosystem.