Disentangling the relative and cumulative impacts of diverse policies on food- and water-related ecosystem services and their trade-offs in ecologically fragile areas

Land use/land cover (LULC) changes driven by diverse policies in arid ecologically fragile areas have sizeable impacts on agricultural production and water-related ecosystem services (ESs) and their trade-offs. However, the relative and cumulative impacts of diverse policies on ESs and their trade-offs in different periods are still unclear and need further differentiation. The western Jilin Province, China was taken as a case study, and actual LULC conversions associated with policy implementation rules were selected to disentangle the relative and cumulative impacts of diverse policies on food- and water-related ESs and their trade-offs in the historical (2000-2010) and recent (2010-2020) periods. Policies that have the greatest impact on ESs trade-offs at county scale in different periods were further identified. The results showed that food production improved the most (203.50%), but habitat quality (-7.79%) and water purification (-7.61%) decreased the most in the food security plan (FSP) during 2000-2020. Habitat quality improved the most (3.73%) in the river-lake connection program (RLCP), and water purification improved the most (3.85%) in the Grain for Green (forest) program (GFGP). The impact of diverse policies on ESs in the historical period was generally greater than that in the recent period. The cumulative impact of the ecological protection and restoration improved all ESs. While the saline-alkali land amelioration program (SLAP) mitigated most ES trade-offs in the historical period, all ecological protection and restoration policies enhanced most ES trade-offs in the recent period. Policies that have the greatest impact on ESs and their trade-offs varied over time. The SLAP and RLCP have immense potential to improve ESs and their trade-offs. This study can serve as a reference for future agricultural development and ecological protection and restoration strategies in arid areas.