Chin J Plant Ecol ›› 2022, Vol. 46 ›› Issue (12): 1523-1536.DOI: 10.17521/cjpe.2021.0427

Special Issue: 稳定同位素生态学 碳水能量通量

• Review • Previous Articles     Next Articles

Progress in the theory, hypothesis and application of the methods measuring soil CO2 flux gradient

WANG Jing-Yuan1, WEI Jie1,*(), WEN Xue-Fa1,2   

  1. 1Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
    2College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
  • Received:2021-11-22 Accepted:2022-05-21 Online:2022-12-20 Published:2023-01-13
  • Contact: *WEI Jie(weijie@igsnrr.ac.cn)
  • Supported by:
    National Natural Science Foundation of China(41830860);National Natural Science Foundation of China(42077302)

Abstract:

Soil respiration is mainly composed of the CO2 released from atmosphere-soil interface and change of CO2 stored in the soil. Understanding the production and migration of CO2 in the soil is essential for measuring the carbon cycle in terrestrial ecosystems. The flux gradient method calculates soil CO2 flux by measuring the diffusion-driven CO2 concentration gradient and diffusion coefficient. The flux of soil CO2 and its stable carbon isotopes composition (δ13C) at different depths can be calculated based on Fickʼs law. The amount of CO2 released from soil and the amount of CO2 stored in different soil layers can thus be measured. The underground soil CO2 (13CO2 and 12CO2) concentration is mainly controlled by pore tortuosity, the depth of root distribution, microbial activity and total soil CO2 production. The underground CO2 transmission process is mainly controlled by the CO2 concentrations, porosity and water content at different depths of the soil. These physical, chemical and biological features of the soil are key factors affecting the application of the soil flux gradient method, and directly determine the precision and accuracy of soil CO2 and its δ13C flux calculation. The gradient method is a useful complement to the chamber method, which can clarify the process of production and migration of soil CO2 at different depths and thus the impacts on the release and storage of soil CO2, elucidating the contribution of soils at different depths to CO2 release and uncovering the underlying environmental and physical mechanisms.

Key words: flux gradient method, CO2 concentration gradient, diffusion coefficient, CO2 flux, δ13C flux