Influence of pine and spruce admixture in European beech stand on some properties of organic and humic horizons of dystric arenosols and the intensity of biological turnover

The aim of the study has been to assess the influence of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies) admixture in European beech (Fagus sylvatica) stand on some properties of organic and humic horizons of Dystric Arenosols and the intensity of biological turnover. The studies were conducted in northern Poland in Łysomice Forest Subdistrict (Forest District Leśny Dwór, Regional Directorate of State Forest Szczecinek). Significant differences in some properties of examined soil horizons were noticed between the stands. About 3-times higher stocks of organic matter in ectohumus were found in beech-pine and about 2-times in beech-spruce in relation to pure beech stand. Higher stocks of soil organic matter recorded in beech-pine and beech-spruce stands may result from the influx of coniferous litter and reduction of the intensity of biological turnover. The stocks of organic matter in A horizons were slightly higher in beech stand. Lower values of pH in O and A horizons were found in mixed stand in relation to pure beech. The concentration of nitrogen was comparable in both stands. It can be assumed that spatial variability of the stocks of nitrogen was strongly related to spatial diversity of soil organic matter stocks.