Reconstruction of Soil Carbon Redistribution Processes along a Hillslope Section in a Forested Area

Abstract

The vertical distribution of soil organic carbon (SOC) with depth and its horizontal pattern is influenced by the topography and relief of the surface, due to lateral redistribution of soil material along slopes. Spatial and temproral variability of these changes is frequently due to human impacts on the landscape. In our study, the results of these processes were studied in detail in a small sub-catchment in a forested hillslope section using radiocarbon (14C) dating of SOC and embedded datable material (charcoal, artifacts) from soil profiles with colluvial accumulations. Events with accelerated material redistribution could be identified as an accumulation of a 40-cm-thick colluvial layer between cal BC 410–360 (2σ) and cal AD 430–580 (2σ). Later colluvial deposition resulted in thinner accumulations (cal AD 1120–1220 [2σ] 30 cm; cal AD 1810–1920 [2σ] 21 cm). As the earliest human impact, we found soil transformation from cal BC 1290–1130 (2σ). The depth-age model for SOC compiled according to the average SOC age and its depth showed different characteristics on middle-slope and down-slope position, with rates of 48.0 yr×cm–1 and 22.0 yr×cm–1 respectively, which indicates the importance of topographic position of soils in SOC redistribution processes.