Impact of Land Use Change on Water-Related Ecosystem Services under Multiple Ecological Restoration Scenarios in the Ganjiang River Basin, China

Ecological restoration programs (ERPs) can lead to dramatic land use change, thereby affecting ecosystem services and their interaction. Determining the optimal ERPs is a crucial issue for ecological restoration in ecologically fragile regions. This study analyzed the impacts of land use change on four water-related ecosystem services (WESs), namely water yield, soil retention, water purification, and food production in the Ganjiang River basin, China during the past two decades. Then, trade-off and synergy between WESs were detected based on correlation analysis. Finally, to quantify the effect of ERPs on WESs, we comprehensively considered the types and intensity of ERPs and designed four categories of scenarios: returning farmland to forest (RFF) scenarios; planting forest (PF) scenarios; riparian forestland buffer (RFB) scenarios; and riparian grassland buffer (RGB) scenarios. Each category contains five scenarios of different intensities. The results showed that water yield, soil retention, and food production increased while water purification decreased from 2000 to 2020. The deterioration of water quality was mainly due to transitions from forestland to farmland and built-up land. Trade-offs only occurred between regulating services and provisioning services. Among all ecological restoration scenarios, only the RFF scenarios can significantly improve soil retention and water purification at the same time, although food production will decrease. Considering food security, returning farmland with a slope greater than 10 degrees to forestland was the optimal scenario in the study area. This study highlighted that both the type and intensity of ERPs should be considered in ecological restoration. This study can contribute to ecological restoration in the Ganjiang River basin and other subtropical mountainous regions.