Remote sensing assessment of the ecological benefits provided by national key ecological projects in China during 2000–2019

We propose a theoretical framework for assessing the ecological benefits provided by key national ecological projects in China over the past 20 years. A dataset consisting of six primary indicators and nine secondary indicators of ecosystem structure, ecosystem quality, and ecosystem services for 2000–2019 was generated using ground survey and remote sensing data. Ecological benefits were quantitatively evaluated following the implementation of these projects in China. Areas with medium, relatively high, and high degrees of ecological restoration accounted for 24.1%, 11.9%, and 1.7% of the national land, respectively. Degrees of ecological restoration were higher in areas with greater numbers of ecological projects. Areas with relatively and absolutely high degrees of ecological restoration were mainly concentrated in the Loess Plateau, the farming–pastoral zone of northern China, the Northeast China Plain, and an area spanning the borders of Sichuan, Yunnan, Guizhou, Chongqing, and Hunan. The relative contributions of climatic factors and ecological projects to changes in vegetation net primary productivity were 85.4% and 14.6%, respectively, and the relative contributions of climatic factors and ecological projects to changes in water erosion modulus were 69.5% and 30.5%, respectively. The restoration potential of national vegetation coverage was 20%, and the restoration potential percentage of forest and grassland vegetation coverage was 6.4% and 23%, respectively. Climatic conditions can inhibit ecological restoration. Areas with relatively high and high degrees of ecological restoration were mainly distributed in areas with an average annual temperature greater than 0°C and annual precipitation greater than 300 mm. Therefore, the limitations associated with climate conditions require consideration during the implementation of national ecological projects. The implementation of combined measures should be emphasized, and the benefits of ecological investment funds should be maximized.