Impact of Scots pine admixture in European beech stand on dissolved organic carbon and nitrogen leaching from organic and humic horizons of Dystric Arenosols in northern Poland

Abstract

The effect of Scots pine admixture in European beech stand on the leaching of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate nitrogen (NO3-N) and ammonium nitrogen (NH4-N) from organic and humic horizons of Dystric Arenosols was studied in northern Poland in 2008-2009. Three zero-tension lysimeters under organic and humic horizons were installed in pure beech and mixed pine-beech stands. Water samples were collected after each rainfall, measured volumetrically, filtered and analysed. In each sample pH and concentrations of DOC, DON, NH4-N and NO 3-N were analysed. Stronger acidification of leachates was observed in mixed stand compared to pure beech. About twice higher concentration of DOC and its fluxes per unit area were determined in mixed stand. The fluxes of DOC from unit mass of soil were less varied. In general, lower concentrations of DON, NH4-N and NO3-N as well as fluxes of the components (calculated in mg·kg-1DM·year-1 and mg·m-2·year-1) were observed in mixed stand.