Evolution and determinants of ecosystem services: insights from South China karst

The South China Karst (SCK), the world's largest contiguous karst region, has undergone severe ecological degradation associated with the interaction of fragile natural attributes and human activities. Understanding the causes of changes in ecosystem services (ES) is essential to prevent and control ecosystem degradation and support sustainable development. However, existing studies have not comprehensively explored the impact of natural systems and human activities on karst ES and have failed to consider their spatiotemporal heterogeneity. Here, we used regression analysis to study the spatiotemporal evolution of ES in diverse landscapes (karst and non-karst) of SCK and the impact of human activity on them. Random forest regression and geographically weighted regression analysis were used to explore the key factors and driving forces in different landscape ES. The results show that from 1982 to 2018, ES, such as soil conservation (+8.12%), net primary productivity (+21.14%), carbon storage (+0.86%), nitrogen export (-5.89%), and phosphorus export (-1.46%), were improved, mainly due to re-greening and rewilding, which optimizes the structure of the ecosystem. However, large-scale afforestation led to a decrease in water yield (-13.23%). Urban development worsened habitat quality (-0.50%) and biodiversity (-1.91%). With the intensification of human activities, ES in the karst region showed lower maintenance capacity than in non-karst regions. The study found that the driving factors of ES varied with the differing landscapes. Population distribution in the karst region was the biggest threat to ES, whereas farming in the non-karst region was the main ES threat in this region. In these regions, the improvement in vegetation coverage was helpful in plant-carbon sequestration, and the increase of precipitation increased water yield. Importantly, we found that biodiversity maintenance plays a crucial role in ES. Nature-based solutions combined with proper management strategies can counter ecosystem degradation and help achieve sustainable development.