Vegetation coverage and carbon sequestration changes in China’s forest projects area

To achieve the ultimate goal of carbon neutralization by 2060 in China, increasing carbon sequestration has become more important. Based on satellite images, field observations and spatial econometric models, this study examined vegetation coverage and carbon sequestration changes during the period 2000–2020 in China’s eight forestry engineering projects area, analysed their correlation, and compared their response to climate change. The results show that there was a significant turning green trend in all regions. The NDVI with an increasing trend accounted for 68.5 % of the whole study area, which were widely distributed and especially significant in the south. The NDVI with a decreasing trend were more concentrated in the north. For NEP, 31.44 % of the total study area showed decreasing trend, which had a wide distribution and more concentrated in the south and the coastal regions of China. NEP under increasing trend were more obvious in the centre and north of China. In time series, 77.85 % of NDVI in the total study area positively correlated with NEP, with the average correlation coefficient of R = 0.51 (P > 0.05), and the higher positive correlations were more concentrated in the centre and north of China. For precipitation, 83.32 % and 65.31 % of the total area can promote the increase in NDVI and NEP, with the effect more obvious in the north. For temperature, about half of the total area showed a positive correlation, more obvious in the north, for both NDVI and NEP. Spatially, NDVI changes corresponded well with NEP for most vegetation types, for both precipitation and temperature. The few differences only appeared for broad-leaved forest and coniferous forest changes with average precipitation higher than 50 mm between 2000 and 2020. We draw the conclusion that turning green will increase carbon sequestration, the effect is more obvious in northern China.