Chin J Plant Ecol ›› 2022, Vol. 46 ›› Issue (12): 1497-1507.DOI: 10.17521/cjpe.2021.0390

Special Issue: 碳水能量通量

• Special feature: Ecosystem carbon and water fluxes in ecological vulnerable areas of China • Previous Articles     Next Articles

Coupling-decoupling of soil CO2 and CH4 fluxes and their responses to temperature in arid and semi-arid regions of China

YANG Meng(), YU Gui-Rui()   

  1. Synthesis Research Center of Chinese Ecosystem Research Network, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
    College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2021-11-01 Accepted:2022-03-11 Online:2022-12-20 Published:2023-01-13
  • About author:First author contact:

    *Contributed equally to this work (Yang M,; Yu GR,

  • Supported by:
    National Natural Science Foundation of China(31800406);National Natural Science Foundation of China(41991234)


Aims Arid and semi-arid regions are typical ecologically fragile areas, and they also have an important impact on global warming. Those regions are considered to be important CH4 sinks since most soils are under aerobic conditions. Studies have found that along with the increase of CH4 uptake velocity, the rate of CO2 emissions also has increased. This study was carried out to examine whether there is an offset phenomenon and under what environmental conditions it occurs.

Methods Based on the integration of soil greenhouse gas fluxes and relevant environmental data in arid and semi-arid regions of China, correlations between soil CO2 and soil CH4 fluxes, on seasonal and daily scales, were analyzed.

Important findings The results showed that there were three levels of soil CO2 and soil CH4 flux, i.e., synergy (positively correlated), offset (negatively correlated), and random (not correlated). Among which, the proportion of random relationships was the highest, on seasonal and daily scales 83% and 54%, respectively. Compared to water content and vegetation conditions, air temperature correlated with the correlations between the two fluxes more strongly, showing a quadratic relationship (the absolute values of correlation coefficients between fluxes decreased with increasing temperature). On a seasonal scale, the mean air temperature during the sampling period determined the correlations between the fluxes with an accuracy of 92%, and the air temperature threshold of flux coupling-decoupling was 12.5 °C. On the daily scale, the diurnal air temperature difference determined fluxes relationships with an accuracy of 79% and the temperature threshold of flux coupling-decoupling was 15.2 °C. In addition, when the soil was in the state of absorbing CH4 on a daily scale, the relationship between soil CH4fluxand soil CO2flux was positive in more cases. This phenomenon was difficult to explain by temperature alone. We speculate that a one-way coupling relationship between soil respiration and CH4 oxidation formed through O2 competition, that is, soil respiration would inhibit the CH4 oxidation by consuming O2, resulting in an increase in soil CO2 emissions and a decrease in CH4 absorption. The study suggests that coupling-decoupling of soil CO2 and CH4 fluxes might be driven by a mechanism of temperature regulation linked with oxygen competition regulation. Climate warming may cause decoupling of the two fluxes across space and time and increase the complexity of carbon cycles, thereby increasing the uncertainty of regional carbon flux estimations.

Key words: coupling-decoupling, soil CO2 flux, soil CH4 flux, temperature, arid and semi-arid region