Arctic soil development on a series of marine terraces on Central Spitsbergen, Svalbard: a combined geochronology, fieldwork and modelling approach
Soils in Arctic regions currently enjoy significant attention because of their potentially substantial changes under climate change. It is important to quantify the natural processes and rates of development of these soils, to better define and determine current and future changes. Specifically, there is a need to quantify the interactions between various landscape and soil forming processes that together have resulted in current soil properties. Soil chronosequences are ideal natural
... l natural experiments for this purpose. In this contribution, we combine field observations, luminescence dating and soil-landscape modelling to test and improve our understanding about Arctic soil formation. Our field site is a Holocene chronosequence of gravelly raised marine terraces in central Spitsbergen. <br><br> Field observations suggest that soil-landscape development is mainly driven by weathering, silt translocation, aeolian deposition and rill erosion. Spatial soil heterogeneity is mainly caused by soil age, morphological position and depth under the surface. Substantial organic matter accumulation only occurs in few, badly drained positions. Luminescence dating confirmed existing radiocarbon dating of the terraces, which are between ~ 3.6 and ~ 14.4 ka old. Observations and ages were used to parameterize soil landscape evolution model LORICA, which was subsequently used to test the hypothesis that our field-observed processes indeed dominate soil-landscape development. Model results indicate the importance of aeolian deposition as a source of fine material in the subsoil for both sheltered beach trough positions and barren beach ridge positions. Simulated overland erosion was negligible. Therefore, an un-simulated process must be responsible for creating the observed erosion rills. Dissolution and physical weathering both play a major role. However, by using present day soil observations, relative physical and chemical weathering could not be disentangled. Discrepancies between field and model results indicate that soil formation is non-linear and driven by spatially and temporally varying boundary conditions which were not included in the model. Concluding, Arctic soil and landscape development appears to be more complex and less straight-forward than could be reasoned from field observations.