Multi-scale analysis of soil erosion and its impact on soil organic carbon storage in agricultural landscapes

The dynamic and stability of the soil organic carbon (C) reservoir are currently receiving attention in the context of global change. The aim of this thesis was to improve our understanding of the effects of soil redistribution on C dynamics. For this, a multi-scale analysis covering different aspects of the C/Soil redistribution continuum has been conducted. The presented work particularly focused on (i) the identification of controls on C dynamics and C distribution patterns along geomorphic gradients in landscapes affected by soil redistribution, (ii) the different C stabilization mechanisms and (iii) the role of the mineral phase in stabilizing C. A global assessment of the importance of agricultural soil erosion for C dynamics revealed the significance of soil redistribution for carbon studies. It was further demonstrated that it is mandatory to consider various environmental processes to predict C accurately, especially in deeper soil layers. A significantly higher mean residence time for buried C at depositional positions was observed, compared to non-eroding and eroding positions. This resulted from the physical protection of C associated with microaggregates and silt-sized particles. The chemical and mineralogical soil components involved in stabilizing C at various depths, slope positions and fractions differed significantly. Current rates of soil erosion and the associated rejuvenation of soils at eroding sites and burial of soil at depositional sites provide a temporally limited local net sink for atmospheric C by stabilizing C with minerals.(GEOG 3) -- UCL, 201