Effect of slope position on soil particle-size distribution in young glacial landscape (Łyna River valley, NE Poland)

Abstract

AbstractThe aim of this paper was to characterize soil particle-size distribution (PSD) of in the middle part of young glacial Łyna River valley in relation to parent materials, soil forming processes and slope position. The study comprised rusty soils, arenosols, clay-illuvial soils, colluvial and alluvial soils located in four slope position: summit / midslope, footslope / toeslope, upper and lower part of floodplain. In order to describe the sedimentological environment and possible heterogenity of the soil formations, sedimentological and granulometric indices were calculated. The relationships between soil fractions in A horizons and environmental variables (slope position and depth of A horizon) were determined using principal component analysis (PCA).The studied soils were poorly sorted with various values of skewness of granulometric distribution (symmetrical, fine and very fine skewed) and kurtosis (mainly very leptokurtic). The value of mean grain diameter was decreasing with slope position which may suggest high dynamics and energy of sedimentological environment in the middle part of Łyna River valley. The analysis of granulometric indices revealed that colluvial deposits were the most homogenous and alluvial formations were the most heterogenous. The results of the statistical analysis showed a positive correlation of the amounts of clay and silt fractions with depth of A horizons. The factor responsible for variability of these fractions was the position on the slope. The A horizons in soils located at the summit and footslope had the highest amounts of sand fractions. While significant increase in the share of finer fractions in soils located in the floodplain was noted.