Interactions between the Grain-for-Green Program and check dams increased vegetation carbon sequestration in the Yanhe basin, Loess Plateau

Vegetation carbon sequestration, usually expressed by net primary production (NPP), is an important ecosystem service (ES) to mitigate global warming. Multiple soil and water conservation projects (SWCPs) have been implemented to restore disturbed ecosystems on the Loess Plateau (LP), as one of the most eroded areas in the world. However, responses of NPP to the conservation projects are unclear due to trade-offs between NPP and other ESs. Herein, we quantified NPP and other key ESs (i.e., water yield, soil conservation, and crop production) and the spatio-temporal trade-offs among them, using RS/GIS techniques and ecosystem modelling in the Yanhe basin of the LP from 1990 to 2020. Furthermore, the structural equation model was used to quantify the impact of ecological restoration projects and programmes such as check dams, terraces, and the Grain-for-Green (GFG) on NPP. As shown by our results, NPP reached 457 t ha(-1) in 2020, which was twice what it was in 1990. Moreover, we found increasing trade-offs between NPP and other ESs at sub-basin scale. Specifically, 63% of NPP changes were explained by ESs and SWCPs. The combined action of check dams and GFG can promote NPP and balance trade-offs between NPP and other ESs, while terracing decreases NPP indirectly according to its specific soil and climate conditions. Overall, the main findings provide a better understanding of the interacting processes of multi-projects that influence vegetation carbon sequestration and the sustainable utilization of ESs in hill and gully regions of the LP.

Automated summary

This study quantified the changes in net primary production (NPP) and other key ecosystem services (water yield, soil conservation, and crop production) in the Yanhe basin of the Loess Plateau using RS/GIS techniques and ecosystem modeling. The results showed that NPP doubled from 1990 to 2020 and there were increasing trade-offs between NPP and other ecosystem services at the sub-basin scale. The combined action of check dams and the Grain-for-Green program promoted NPP and balanced the trade-offs, while terracing indirectly decreased NPP.