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Modeling soil CO2 production and transport to investigate the intra-day variability of surface efflux and soil CO2 concentration measurements in a Scots Pine Forest (Pinus Sylvestris, L.)

Goffin, Stéphanie, Wylock, Christophe, Haut, Benoit, Maier, Martin, Longdoz, Bernard, Aubinet, Marc
Plant and soil 2015 v.390 no.1-2 pp. 195-211
Pinus sylvestris, carbon dioxide, carbon dioxide production, coniferous forests, forest soils, models, phloem, temporal variation, Germany
AIMED: The main aim of this study is to improve the mechanistic understanding of soil CO₂efflux (Fₛ), especially its temporal variation at short-time scales, by investigating, through modeling, which underlying process among CO₂production and its transport up to the atmosphere is responsible for observed intra-day variation of Fₛand soil CO₂concentration [CO₂]. METHODS: In this study, a measurement campaign of Fₛand vertical soil [CO₂] profiles was conducted in a Scots Pine Forest soil in Hartheim (Germany) and used to develop a model testing several hypotheses. A reference model taking into account a purely diffusive CO₂transport and a temperature-dependent CO₂production is compared to models with a more complex description of either CO₂production or CO₂transport. For transport, the introduction of advection and the dispersion is investigated. For the production, the emergent hypothesis of the phloem pressure concentration wave (PPCW) influence is tested. RESULTS: We show that intra-day variation of Fₛand [CO₂] is better represented when the more complex CO₂production expression is taken into account compared to the more detailed description of CO₂transport. CONCLUSION: We conclude that focus should be placed on the potential factors affecting the CO₂production, rather than on the transport process description.