How can massive ecological restoration programs interplay with social-ecological systems? A review of research in the South China karst region

Exploring the cost-effective pathways for restoring ecosystems is a fundamental aspect for scientific communities and policy-makers aiming for a sustainable future. The South China karst region has experienced severe environmental degradation because of unsustainable management practices in this vulnerable social-ecological context. However, it has also become one of the most stunning areas following its remarkable vegetation recovery over recent decades as a result of large-scale ecological restoration programs. There is an extensive body of literature focusing on how ecological restoration programs have altered the degraded environment in this region. By searching and comparing the published peer-reviewed articles, we reviewed the studies related to the effects of ecological restoration programs from the point of view of ecological, socio-economic, and integrated social-ecological impacts, as well as influencing factors and restoration approaches. We found independent evidence to support that large-scale ecological restoration programs increased biomass and carbon sequestration since 2000 across this region. The farmers' livelihoods have spontaneously transited from agriculture into forestry or non-farming sectors without financial compensation or incentive schemes, which coincided with a positive correlation between the implementation of ecological restoration programs and poverty alleviation. However, due to a lack of clear "before and after" comparisons, many studies have indirectly determined the impacts of ecological restoration with non-negligible uncertainties. In addition, considering the critical interactions between belowground and aboveground processes in karst regions, special attention should be given to the selection of tree species and restoration measures according to different bedrock types. In the future, to better understand the impacts of ecological restoration on social-ecological systems, research could be advanced by considering data access, context-based analysis, measurement-targeted assessment, and cross-scale integration.