Revegetation projects significantly improved ecosystem service values in the agro-pastoral ecotone of northern China in recent 20 years

摘要

Revegetation is a conventional approach used for ecological protection and restoration projects, especially in the agro-pastoral ecotone of northern China (AENC). However, for this ecologically vulnerable area, the changes in land use and ecosystem service values (ESV) resulting from revegetation projects have received little attention and have not been fully elucidated. In this study, based on a rapid valuation tool-the benefit transfer method modified by the biomass factor (net primary productivity, NPP)-we assessed the ESV of the AENC at multiple-time scales by designing land scenarios related to local revegetation projects. The results showed that forestland expansion (+697 thousand ha) and grassland shrinkage (-650 thousand ha) dominated the land use change in the AENC in 2000-2018 and indirectly resulted in a net increase of US$8.18 billion in total ESV, in which reveg-etation projects generated nearly 1.5 million ha of new vegetated land and a corresponding US$6.86 billion in ESV (83.83% of the total increase). For future revegetation, the returning-farmland-to-forestland scenario exhibited a greater potential with increases of 5.66 million ha of forestland and US$65.20 billion in ESV to be provided. Over-all, revegetation projects improved the ESV of the AENC in the last two decades because of the pronounced ex-pansion in forestland of high ESV at the expense of the reductions in farmland and grassland, and this trend will be led continually by the Grain for Green Project in the future through the rapid assessment based on the modified benefit transfer method. Specifically, more investments and attention must be directed to the protec-tion and restoration of grassland and wetland ecosystems.