Application of Infrared Spectroscopy Techniques for Identification of Ancient Vegetation and Soil Change on Loess Areas

The discussion on the formation of Chernozems still has no consensus, and one of the outstanding questions is the type of the vegetation that supported the persistence of these soils in Central Europe over the Holocene period. The transformation of Chernozems and related soil types may be clarified by paleoenvironmental studies, which integrate different investigation techniques and proxy data. We propose a procedure based on infrared reflectance spectroscopy of soil organic matter, that presumably contains specific fingerprints from land use and plant cover. A database of spectra for 337 samples representing vegetation classes (grassland, woodland and arable) and loess soil types (Chernozem, Phaeozem, Luvisol) was created to build a mathematical model, which allows to identify the origin of buried soils with unknown history. The comparison confirmed the applicability of both near-infrared and mid-infrared spectroscopy, with higher statistical affinity of MIR. A clear disjunction of land use/vegetation classes was proven and allowed reliable association of the samples from buried soils with grassland/woodland and episodes of arable land use, followed by prevailing forest vegetation after burial. The findings are consistent with proposed models in Poland and Czechia, and confirm the potential of spectroscopy techniques in identification of soil types and their evolution.