LAUSR

The karst critical zone is an essential component of the carbon (C) pool, constituting the global C cycle. It is referred to as one of the “residual land sink” that remains largely indeterminate. Karst area (2.2×107 km2) comprises 15% of the world’s land area, and karst area comprises 3.44×106 km2 of area in China. Due to the complexity of karst structure and its considerable heterogeneity, C sequestration rate estimations contain large inaccuracies, especially in relation to the different methods used in calculations. Therefore, we reevaluated rock weathering-related C sink estimations in China (approximately 4.74 Tg C yr–1), which we calibrated from previous studies. Additionally, we stipulated that more comprehensive research on rock-soil-biology-atmosphere continuum C migration is essential to better understand C conversion mechanisms based on uncertainty analyses of C sink estimations. Moreover, we stressed that a collective confirmation of chemical methods and simulated models through a combined research effort could at least partially eliminate such uncertainty. Furthermore, integrated C cycling research need a long-term observation of the carbon flux of multi-interfaces. The enhanced capacity of ecosystem C and soil C pools remains an effective way of increasing C sink. Karst ecosystem health and security is crucial to human social development, accordingly, it is critical that we understand thresholds or potential C sink capacities in karst critical zones now and in the future.