Quantifying the biodiversity and ecosystem service outcomes of karst ecological restoration: A meta-analysis of South China Karst

Decades of restoration efforts have greened South China Karst, the largest and most concentrated karst area in the world. However, it is unknown whether and how the observed increase in vegetation coverage could enhance biodiversity and the provision of ecosystem services (ES). In this study, we performed a meta-analysis of 108 studies with 6505 observations to quantify the influence of karst ecological restoration on biodiversity and ES provision and to uncover key factors that may influence restoration outcomes. We found that restored karst lands on average provided 29 % and 18 % higher biodiversity and ES than degraded karst lands, respectively, but 14 % and 29 % lower than intact reference karst lands. However, the outcomes of karst ecological restoration were mediated by restoration strategy, vegetation type, and restoration age. Natural restoration actions often had more positive effects on biodiversity and ES than reconstructive restoration actions. Karst restoration outcomes also increased with the progress of vegetation succession and increasing restoration age. Furthermore, ES outcomes were positively correlated with biodiversity outcomes, demonstrating the importance of incorporating the biodiversity-ecosystem functioning relationship into karst restoration actions. Overall, our study suggests that karst ecological restoration has substantial potential to improve biodiversity and the provision of ES, but restoration outcomes are context-dependent. These findings may inform evidence-based decision making for biodiversity conservation and sustainable development in karst regions, especially with the UN Decade on Ecosystem Restoration 2021-2030 underway.