[Effect of the Grain for Green Program on Ecosystem Services in Northern Shaanxi, China]

This study quantitatively evaluated ecosystem services of carbon storage （CS）, water yield （WY）, soil conservation （SC）, and food supply （FS） in northern Shaanxi and assesses the implementation areas and types of the Grain for Green Program （GFGP）. It examined the impact of GFGP on ecosystem services in northern Shaanxi from the perspectives of spatio-temporal patterns, hot spot distribution, trade-offs and synergies. The results indicated： ① From 2000 to 2020, CS, WY, SC, and FS in northern Shaanxi increased by 19.16 million t （2.63%）, 1 156.11 million m³ （51.35%）, 344.21 million t （26.31%）, and 5.10 million t （60.48%）, respectively. The cumulative implementation area of GFGP reached 4 538.25 km², with cropland-to-forest, cropland-to-grassland, and barren-to-forest/grassland accounting for 22.71%, 73.46%, and 3.83% of the total, respectively. ② In the project implementation areas, the increases in CS and SC were significant, while the increase in WY was relatively small, and FS showed a declining trend. Distinct differences were observed in ecosystem service changes among different types of implementation areas of GFGP. ③A trade-off relationship was observed between most ecosystem services in northern Shaanxi, which gradually weakened from 2000 to 2020, with relatively weaker trade-off relationships observed within the project implementation areas of GFGP. ④ The areas providing multiple ecosystem services in northern Shaanxi significantly increased, with cropland-to-forest playing a prominent role in promoting the emergence of multiple-hot-spots, while barren-to-forest/grassland effectively eliminated zero-hot-spot. ⑤ Future efforts in northern Shaanxi should focus on enhancing the sustainability of food provisioning and alleviating water resource shortages. Strategies should be classified based on the actual situation of ecosystem services, utilizing barren-to-forest/grassland to reduce areas lacking ecosystem services and promoting the synergistic development of multiple ecosystem services through cropland-to-forest.