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.)

Abstract

34Aimed: 35 The main aim of this study is to improve the mechanistic understanding of soil CO 2 efflux 36 (F s ), especially its temporal variation at short-time scales, by investigating, through modeling, 37 which underlying process among CO 2 production and its transport up to the atmosphere is 38 responsible for observed intra-day variation of F s and soil CO 2 concentration [CO 2 ]. 39Methods: 40In this study, a measurement campaign of F s and vertical soil [CO 2 ] profiles was conducted in 41 a Scots Pine Forest soil in Hartheim (Germany) and used to develop a model testing several 42 hypotheses. A reference model taking into account a purely diffusive CO 2 transport and a 43 temperature-dependent CO 2 production is compared to models with a more complex 44 description of either CO 2 production or CO 2 transport. For transport, the introduction of 45 advection and the dispersion is investigated. For the production, the emergent hypothesis of 46 the phloem pressure concentration wave (PPCW) influence is tested. 47Results: 48We show that intra-day variation of F s and [CO 2 ] is better represented when the more 49 complex CO 2 production expression is taken into account compared to the more detailed 50 description of CO 2 transport. 51Conclusion: 52We conclude that focus should be placed on the potential factors affecting the CO 2 53 production, rather than on the transport process description 54This is the preprint version of a manuscript that has been published in Plant and Soil 2015

2D profiles of CO 2 , CH 4 , N 2 O and gas diffusivity in a well aerated soil: measurement and Finite Element Modeling

“…In 2009 two parallel access trenches (0.8 m depth, 1.2 m length, 0.5 m width) were dug with a separation of 2 m. Holes for gas sampling tubes were drilled through the soil between the trenches (Goffin et al, 2014;Goffin et al, 2015;Parent et al, 2013). A 1.5 m long gas-permeable sampling tube (Accurel PPV8/2, Membrana, Wuppertal, Germany) was installed into each of these holes and the trenches were refilled.…”

A multi‐layer, closed‐loop system for continuous measurement of soil CO2 concentration

“…While manual or automated soil chambers (Pumpanen et al, 2004) are the most common methods to measure soil-atmosphere CO 2 exchange under field conditions, the flux-gradient approach, based on solid-state CO 2 sensors, to measure soil CO 2 concentrations at different soil depths is getting more attention (Tang et al, 2003;Davidson et al, 2006;Maier and Schack-Kirchner, 2014;Goffin et al, 2015). The flux-gradient approach applies Fick's law to vertical profiles of soil trace gases like CO 2 to calculate vertical fluxes of gas within soils, including the efflux from soil, and to vertically partition the production or consumption of gas into different soil layers, based on a time series of gas concentrations at different soil depths and the level of gas diffusivity in the soil (Freijer and Leffelaar, 1996).…”

Relationship between root water uptake and soil respiration: A modeling perspective

“…Mechanistic models have been developed for CO 2 production and transport to adequately describe vertical gaseous diffusion and dispersion as a function of soil water content and temperature [ Patwardhan et al , ; Simunek and Suarez , ; Fang and Moncrieff , ]. These models have been calibrated and validated against experimental data [ Suarez and Simunek , ; Moncrieff and Fang , ; Goffin et al , ], have been coupled to soil water and temperature models at catchment scale [ Welsch and Hornberger , ; Riveros‐Iregui et al , ], and have been combined with experimental data of soil moisture, soil temperature, and air‐phase soil CO 2 concentrations to estimate soil CO 2 production and surface efflux [ Hirano et al , ; Chen et al , ; Jassal et al , ; Daly et al , ; Liang et al , ; Latimer and Risk , ].…”