"Soil respiration is expected to make a major contribution to C cycle feedbacks in a changing climate, but the magnitude of these feedbacks are highly uncertain. One of the most important shortcomings is that soils must be viewed as spatially heterogeneous and dynamic systems at the landscape scale if we are to understand soil biogeochemistry and soil carbon cycling in particular. Consequently, improving our understanding of (i) the vertical and lateral translocation of SOC by erosion as well as its stability and (ii) the coupled effects of land use change on SOC 3 dimensional distribution becomes an important issue. In this study, we aim to couple soil respiration experiments at depth and empirical and process-based spatial models to meet these objectives. This must allow us to predict the temporal evolution of SOC at the landscape scale within a 3 dimensional context.
First, parameters of the SOC depth distribution model of Meersmans et al. (2009) will be modeled as function of time, slope position variables and land use change type. The results of these empirical modeling will be compared with dynamical process-based models results, such as SPEROS-C. In order to separate the effects of erosion and land use change on SOC, we intend to study the later on profiles in equilibrium (i.e. non eroded and constant land use) and on sites characterized by changed land use and/or erosion. Secondly, the stability of organic matter at different depths in soil profiles from both eroded and depositional areas will be investigated by measuring CO2 production in incubation experiments. To refine the 3 dimensional estimation of SOC dynamics at the landscape scale the output of these first two work packages will be incorporated in existing process based C profile models (i.e. Roth C based) and spatially explicit models (i.e. SPEROS-C). In addition we aim to upscale the land surface scheme JULES by developing methods to integrate the outcomes of our study in this large scale ES model."
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