The impact of landscape evolution on soil physics: Evolution of soil physical and hydraulic properties along two chronosequences of proglacial moraines
Abstract. Soil physical properties highly influence soil hydraulic properties which define the soil hydraulic behavior. Thus, changes within these properties affect water flow paths and the soil water and matter balance. Most often these soil physical properties are assumed to be constant in time and little is known about their natural evolution. Therefore, we studied the evolution of physical and hydraulic soil properties along two soil chronosequences in proglacial forefields in the Central Alps, Switzerland. One soil chronosequence developed on silicate and the other on calcareous parent material. Each soil chronosequence consisted of 4 moraines with the ages of 30, 160, 3000, and 10 000 years at the silicate forefield and 110, 160, 4900, and 13 500 years at the calcareous forefield. We investigated bulk density, porosity, the content of clay, silt, sand, and gravel as well as loss on ignition and hydraulic properties in form of retention curves and hydraulic conductivity curves. Samples were taken in three depths (10, 30, 50 cm) at six sampling sites at each moraine. Soil physical and hydraulic properties change considerably over the chronosequence. Particle size distribution shows a pronounced reduction in sand content and an increase in silt and clay content over time at both sites. Bulk density decreases and porosity increases during the first 10 millenia of soil development. The trend is equally present at both parent materials, but the reduction in sand and increase in silt content was more pronounced at the calcareous site. The organic matter content increases, which is especially pronounced in the top soil at the silicate site. With the change in physical soil properties and organic matter content the hydraulic soil properties change from fast draining coarse textured soils to slow draining soils with high water holding capacity, which is also more pronounced in the top soil at the silicate site. The dataset presented in this paper is available at the online repository of the German Research Center for Geosciences (GFZ, Hartmann et al. (2020b)). The dataset can be accessed via the link: http://pmd.gfz-potsdam.de/panmetaworks/review/f46bd4d822a0766a9c0baf356bc7e55644d65d62d7ab71527f5d80c35eed11e5 and will be published with the DOI specified under the link.