中国南方喀斯特地区碳循环研究进展

中国南方喀斯特地区碳循环路径与过程基本清晰,与其他陆地生态系统明显不同,呈现出鲜明的区域特色:雨热同季、地质构造背景与碳酸盐岩可溶性的耦合,导致碳酸盐岩中大量封存的碳重新进入生态系统碳的循环;二元三维结构中地下空间CO_2具体动态变化性,可视为次级碳库,影响生态系统碳的循环过程;陆生植物、水生植物均有利用HCO_3~-碳源进行光合作用的新途径;发现了碳酸盐岩快速的风化作用与水生植物生物碳泵的耦合机制,喀斯特作用碳汇效应得以确证。但是,中国南方喀斯特地区碳循环的研究还存在明显不足:喀斯特作用碳汇量的估算受到气候变化、土地利用变化的正负机制、外源酸等多因素的挑战,还具有很大的不确定性;植被、土壤与岩石、地下空间次级碳库、大气、大气降水存在复杂的多界面作用过程,碳的通量及迁移转化机制仍不明确。未来研究应重视:针对喀斯特地区特点的新研究方法、技术的研发;喀斯特关键带理念的统领;联网长期观测;模型的集成与创新。

A Review of Research Progress and Future Prospective of Carbon Cycle in Karst Area of South China

The carbon cycle and its processes in the karst area of South China, distinct from other terrestrial ecosystems, are basically clear and show distinctive regional characteristics. The coupling of tectonic background of rain and hot seasons and geomorphic rejuvenation to the solubility of carbonate rocks leads to a large number of carbon sequestration from carbonate rocks re-entering the ecosystem carbon cycle. The dynamic variation of CO₂ in the underground space with a binary three-dimensional structure can be regarded as secondary carbon pool, which affects the carbon cycle of the ecosystem. Terrestrial and aquatic plants have the power to use HCO₃^- carbon source for new ways of photosynthesis. It was found that the coupling effect of carbonate fast weathering and bio-carbon pump on aquatic plants, and the carbon sequestration effect of karst was confirmed. However, there are obvious shortcomings in the carbon cycle study in karst areas of South China. The estimation of carbon sequestration under karst function is challenged by many factors, such as climate change, positive and negative mechanisms of land use change, and exogenous acid. It has also great uncertainties. There are complex multi-interface processes in vegetation, soil, rock, subsurface carbon pool, atmosphere and precipitation. The mechanism of carbon flux and migration is still unclear. Future research should pay more attention to new research methods and technologies aiming at the unique features of karst morphology, the concept of karst critical zone, the long-term observational network, and integration and innovation of karst simulations.