Application of EPR Spectroscopy in Studies of Soils from Destroyed Forests

Abstract

The presented results show that significant changes have taken place in the structure of the humic acids in the soils affected by forest destruction. Regardless of the cause of forest removal: clear-cutting, a wildfire or a windstorm, its effect on soil humic acids was the same. The elemental analysis and the spectroscopic data (UV–Vis, EPR) indicate a higher content of aliphatic moieties and hence a lower degree of humification (higher parameter g of the radicals) of the organic matter extracted from the affected plots in comparison with the reference ones. Due to the slowing down of the humification processes, the soil organic matter extracted from the spruce forest on the disturbed plots is not as stable as the one taken from the reference plots. The results prove that semiquinone radicals present in humic acids are suitable indicators for tracking changes in the humified matter in the organic and mineral layers of forest soil under different management regimes in disturbed areas. Principally, the EPR method is an appropriate instrument which, through the detailed quantitative and qualitative determination of semiquinone radicals, makes it possible to track changes in the inner chemical structure of humic acids.