HR: 17:35h
AN: H24D-06    [Abstracts]
TI: Soil water content and temperature induced spatial structure of heterotrophic respiration at field scale
AU: * Herbst, M
EM: m.herbst@fz-juelich.de
AF: ICG-4, Forschungszentrum Juelich GmbH, Leo-Brand Str., Juelich, 52428, Germany
AU: Prolingheuer, N
EM: n.prolingheuer@fz-juelich.de
AF: ICG-4, Forschungszentrum Juelich GmbH, Leo-Brand Str., Juelich, 52428, Germany
AU: Graf, A
EM: a.graf@fz-juelich.de
AF: ICG-4, Forschungszentrum Juelich GmbH, Leo-Brand Str., Juelich, 52428, Germany
AU: Huisman, J A
EM: s.huisman@fz-juelich.de
AF: ICG-4, Forschungszentrum Juelich GmbH, Leo-Brand Str., Juelich, 52428, Germany
AU: Weihermueller, L
EM: l.weihermueller@fz-juelich.de
AF: ICG-4, Forschungszentrum Juelich GmbH, Leo-Brand Str., Juelich, 52428, Germany
AU: Vanderborght, J
EM: j.vanderborght@fz-juelich.de
AF: ICG-4, Forschungszentrum Juelich GmbH, Leo-Brand Str., Juelich, 52428, Germany
AU: Vereecken, H
EM: h.vereecken@fz-juelich.de
AF: ICG-4, Forschungszentrum Juelich GmbH, Leo-Brand Str., Juelich, 52428, Germany
AB: Heterotrophic soil respiration is known to be highly variable in space and time. The spatial structure of this carbon dioxide flux strongly depends on the spatial pattern of soil water content and energy fluxes at the boundary layer between soil and atmosphere. The goal of this study was to determine the spatial variability of soil respiration, soil water content and soil temperature and their inter-relations at field scale. We simultaneously measured soil CO₂ efflux, soil water content and soil temperature at 48 locations within a 14 by 14 m field plot under different soil and meteorological conditions. We measured an overall mean CO₂ efflux of 2.4 g C m^-2 d^-1 for the bare soil, associated with a coefficient of variation of 32 %. The observed data was also analysed with geostatistical means including cross-semivariograms. For the scale under investigation we detected a mean correlation length of 2.5 m for soil respiration. Further we found a high structural semivariance of CO₂ efflux for wet soil conditions, which is attributed to the effect of limited diffusion within the soil. The correlation length of the cross-semivariance between to soil water content and soil temperature is 5.9 and 3.3 m, respectively. From multiple regression we determined a higher influence of soil water content on the variance of soil respiration than for soil temperature, whereas the mean of soil respiration depended rather on soil temperature than on water content. Sequential Gaussian simulations were able to reproduce the spatial structure of the measured soil respiration.
DE: 0402 Agricultural systems
DE: 0428 Carbon cycling (4806)
DE: 1866 Soil moisture
DE: 1878 Water/energy interactions (0495)
DE: 3252 Spatial analysis (0500)
SC: Hydrology [H]
MN: 2007 Fall Meeting