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Biogeosciences An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
04 Apr 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Biogeosciences (BG) and is expected to appear here in due course.
Modelling the diurnal and seasonal dynamics of soil CO2 exchange in a semiarid ecosystem with high plant-interspace heterogeneity
Jinnan Gong1, Ben Wang1,2, Xin Jia1,2, Wei Feng2, Tianshan Zha2, Seppo Kellomäki1, and Heli Peltola1 1School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland
2Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
Abstract. This study represents a first attempt to model the diurnal and seasonal dynamics of soil CO2 exchange (FS) in a dryland ecosystem with a high plant-interspace heterogeneity. The modelling used an integrated process-based approach, in which the CO2 production, transport and surface exchanges (e.g. biocrust photosynthesis, respiration and photodegradation) are considered simultaneously. The model was parameterized and validated with multivariate data measured during year 2013–2014 in a semiarid shrubland ecosystem in Yanchi, northwestern China. We also investigated the sensitivity of simulated FS to a set of stand-specific parameters and investigated the relative contribution of different flux components. The model explained reasonably well the two-year dynamics of FS measured from a non-crusted and two lichen-crusted plots. Simulations showed that the temporal pattern of FS could deviate from that of the total CO2 production from rooting-zone soil. Such deviations could be explained by the variations of CO2 dissolution and the CO2 exchanges of biocrust during wetting-drying cycles, and the root uptake and transport of dissolved CO2. Moreover, the FS was spatially sensitive to the plant-interspace differences and the variations in root biomass, soil organic matter and pH. These results emphasized that, the processes beyond autotrophic and heterotrophic respirations and the heterogeneities of soil at plant-interspace can strongly affect the FS dynamics and their climatic sensitivities. Such variability should be carefully considered in extrapolation of findings from chamber to ecosystem level and from seasonal to inter-annual scales. Based on this work, our model can serve as a useful tool to simulate FS dynamics in dryland ecosystems.

Citation: Gong, J., Wang, B., Jia, X., Feng, W., Zha, T., Kellomäki, S., and Peltola, H.: Modelling the diurnal and seasonal dynamics of soil CO2 exchange in a semiarid ecosystem with high plant-interspace heterogeneity, Biogeosciences Discuss.,, in review, 2017.
Jinnan Gong et al.
Jinnan Gong et al.


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