The hysteresis response of soil CO2 concentration and soil respiration to soil temperature
[1];
- Wuhan University (China). State Key Laboratory of Water Resources and Hydropower Engineering Science, College of Water Resources and Hydropower Engineering; Tsinghua University, Beijing (China). State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering; Duke Univ., Durham, NC (United States). Nicholas School of the Environment
- Duke Univ., Durham, NC (United States). Nicholas School of the Environment and Department of Civil and Environmental Engineering
- Duke Univ., Durham, NC (United States). Nicholas School of the Environment
- Monash University, Clayton, Victoria (Australia). Department of Civil Engineering
- Stockholm Univ. (Sweden). Department of Physical Geography and Bolin Center for Climate Research
- Tsinghua University, Beijing (China). State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering
Diurnal hysteresis between soil temperature (Ts) and both CO2 concentration ([CO2]) and soil respiration rate (Rs) were reported across different field experiments. However, the causes of these hysteresis patterns remain a subject of debate, with biotic and abiotic factors both invoked as explanations. Here, to address these issues, a CO2 gas transport model is developed by combining a layer-wise mass conservation equation for subsurface gas phase CO2, Fickian diffusion for gas transfer, and a CO2 source term that depends on soil temperature, moisture, and photosynthetic rate. Using this model, a hierarchy of numerical experiments were employed to disentangle the causes of the hysteretic [CO2]-Ts and CO2 flux Ts (i.e., F-Ts) relations. Model results show that gas transport alone can introduce both [CO2]-Ts and F-Ts hystereses and also confirm prior findings that heat flow in soils lead to [CO2] and F being out of phase with Ts, thereby providing another reason for the occurrence of both hystereses. The area (Ahys) of the [CO2]-Ts hysteresis near the surface increases, while the Ahys of the Rs-Ts hysteresis decreases as soils become wetter. Moreover, a time-lagged carbon input from photosynthesis deformed the [CO2]-Ts and Rs-Ts patterns, causing a change in the loop direction from counterclockwise to clockwise with decreasing time lag. An asymmetric 8-shaped pattern emerged as the transition state between the two loop directions. Lastly, tracing the pattern and direction of the hysteretic [CO2]-Ts and Rs-Ts relations can provide new ways to fingerprint the effects of photosynthesis stimulation on soil microbial activity and detect time lags between rhizospheric respiration and photosynthesis.
- Research Organization:
- Duke Univ., Durham, NC (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- SC0006967; FG02‐95ER6208
- OSTI ID:
- 1454926
- Journal Information:
- Journal of Geophysical Research. Biogeosciences, Vol. 120, Issue 8; ISSN 2169-8953
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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