Impact of ecological restoration on ecosystem service trade-offs: Insight from karst desertification control

Ecological restoration programmes (ERP) contribute to greening and regulation service improvement. However, whether greening exacerbates the social-ecosystem trade-offs in a degraded ecoregion remains unclear. In this study, we chose South China karst, a global hotspot of greening (improvement of vegetation), as a case-study. First, we analyzed the degree of greening in different ecoregions and the contribution of landscape to greening during 2000-2020. Second, we investigated the relationship between greening and indicators (land use, gross domestic product [GDP], and population distribution) and explored the relationship between regulation and provision over time. The results showed that the degree of greening in different ecoregions was different, although ERP played a positive role in greening. The rapid greening in degraded ecoregion was relevant to net forest expansion (26.79% of the conversion area), while the slow greening in a non-degraded ecoregion was associated with net built-up land expansion (25.81% of the conversion area). Forest expansion in a degraded ecoregion increased out-migration and exacerbated the trade-off between greening and GDP reduction, regulation and provision. Our study found that weak service supply in degraded ecoregion limited farming income, which forced farmers to migrate for work and abandon slopeland. In conclusion, the combination of retiring land and emigrating for work triggers land functional transformation and aggravates social-ecosystem trade-offs, but agroforestry can mitigate these trade-offs. Despite there are limitations in the quantification of population migration, it still provides new insight for the next stage of ERP.