BGD Biogeosciences Discussions BGD Biogeosciences Discuss. 1810-6285 Göttingen, Germany 10.5194/bgd-7-9137-2010 Spatial and seasonal variability of heterotrophic and autotrophic soil respiration in a winter wheat stand Prolingheuer N. 1 Scharnagl B. 1 Graf A. 1 Vereecken H. 1 Herbst M. 1 Institute of Bio- and Geosciences, IBG-3: Agrosphere, Forschungszentrum Jülich, 52425 Jülich, Germany 15 12 2010 7 6 9137 9173 Copyright: © 2010 N. Prolingheuer et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://bg.copernicus.org/preprints/7/9137/2010/bgd-7-9137-2010.html The full text article is available as a PDF file from https://bg.copernicus.org/preprints/7/9137/2010/bgd-7-9137-2010.pdf

Soil respiration (<i>R</i><sub>s</sub>), the sum of respiration by soil organisms (<i>R</i><sub>h</sub>) and roots (<i>R</i><sub>a</sub>), is known to be highly variable in both, space and time. There is less information available about the behaviour of <i>R</i><sub>h</sub> and <i>R</i><sub>a</sub> in time and particularly in space. The objective of this study was to quantify the contribution of each component to the temporal and spatial variability of soil respiration in a winter wheat stand. We measured soil respiration from March to July 2009 by closed-dynamic chambers for 61 sampling points in a 50&times;50 m plot in a winter wheat stand close to Jülich, Germany. Each sampling point was equipped with a 7 cm soil collar to measure total <i>R</i><sub>s</sub> and a 50 cm soil collar to exclude roots and to measure <i>R</i><sub>h</sub> only. <i>R</i><sub>a</sub> was assumed to equal <i>R</i><sub>s</sub>&minus;<i>R</i><sub>h</sub>. Simultaneously, soil temperature and soil water content were measured in 6 cm depth. Biweekly the temporal development of the leaf area index was measured. On average, the heterotrophic contribution to <i>R</i><sub>s</sub> was 69% and thus higher than the autotrophic contribution. Seasonal changes of soil temperature and especially water content explained well the temporal variability of <i>R</i><sub>s</sub> (<i>r</i><sup>2</sup>=0.74) and <i>R</i><sub>a</sub> (<i>r</i><sup>2</sup>=0.80). Spatial variability of <i>R</i><sub>a</sub> was on average much higher (CV=88%) than the spatial variability of <i>R</i><sub>h</sub> (CV=30%). However, <i>R</i><sub>h</sub> was mainly randomly distributed in space, whereas <i>R</i><sub>a</sub> showed spatial autocorrelation. Spatial correlation and cross-variograms showed a significant spatial dependence of <i>R</i><sub>s</sub> on <i>R</i><sub>a</sub>. From our results we concluded that spatial variability of soil respiration in a winter wheat stand represented mainly the spatial variability of the autotrophic component.

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