Data of chemical elements extractable fractions concentrations in forest litter horizons of Retisols in the Smolenskoye Poozerie National Park

Data on changes of proxies and chemical elements extractable fractions concentrations of forest soils litter horizons at different stages of reforestation are presented. The following stages of natural reforestation have been identified within the Smolenskoye Poozerye National Park Biosphere Reserve: agrocenosis, meadow, forests with the age of the tree stand <30, 35-60, 70-80, 80-110, 90-130, 110-135 years. In Albic Retisols (Loamic), the differentiation of soil proxies was studied: pH, total organic carbon (TOC), grain size fractions, TC, TN, available P, K, as well as easily-exchangeable, hardly-exchangeable, bound with complexes, Fe-Mn (hydr)oxides fractions of 28 chemical elements.