Abstract:

Green plants absorb CO₂ from the atmosphere through photosynthesis, which is the main source of carbon (C) in terrestrial ecosystems. Quantifying the allocation of photosynthetic C between plants and soil systems is of great significance for clarifying the turnover and retention of C, and predicting the potential of vegetation and soil C pools in the context of climate change. The ¹³C stable isotope technology, with its accuracy and ease of operation, is widely used in C cycle research, and provides important technical support for exploring the characteristics of C allocation, soil microbial community structure, C utilization efficiency, and changes in CO₂ flux from soil C mineralization in plant soil systems. This article first introduces the development and labeling methods of ¹³C stable isotopes, mainly including ¹³C pulse (single and multiple) labeling, ¹³C continuous labeling, and how to determine of ¹³C abundance by planting C₃ plants in C₄ soil, and how to identify natural ¹³C abundance without changing vegetation conditions. Secondly, the application of this technology in C cycling in the plant microbial soil system is summarized, including the application of ¹³C isotope labeling in C allocation in the plant-soil system, the application of ¹³C natural abundance technology in tree growth rings and plant community level C cycling, and the formation and decomposition process of soil organic C. In terms of soil microorganisms, the application of ¹³C stable isotopes in microbial biomarkers such as phospholipid fatty acids, amino sugars, chip stable isotope probes, nano secondary ion mass spectrometry isotope imaging, fluorescence in situ hybridization nano secondary ion mass spectrometry technology is summarized. Then, the shortcomings of the ¹³C stable isotope method are summarized, namely, the high cost of ¹³C sample detection, inaccurate ¹³C abundance detection due to ¹³C fractionation, and high requirements for ¹³C abundance in combination with microbial marker technology. Finally, prospects for future research on ¹³C isotope tracing technology are proposed: in theory, it is necessary to explore the mechanisms of action and influence of ¹³C labeled substrates in C allocation, transformation, and fixation in the plant soil microbial system, and construct statistical and validation models; in terms of application, emphasis should be placed on interdisciplinary applications, combining geographic information systems, remote sensing and other geoscience technologies with ¹³C stable isotopes to promote research on the C cycle in terrestrial ecosystems from a broader and more comprehensive perspective.

Key words: ¹³C stable isotope labeling technology, terrestrial ecosystem, carbon cycle, soil organic carbon, microbial markers