Litter Decomposition as a Source of Active Phosphates in Spruce and Beech Mountainous Forests Affected by Acidification

In this contribution, results from a short-term litter bag experiment are presented. Beech leaves and spruce needles were placed in polyamide bags, and then inserted between litter and fermentation horizons for the period April to November 2013. Each type of litter was placed under the same corresponding forest type. Three litter bags were sampled each month. Water extractable contents of cations or anions were determined by means of ion chromatography and ICP-OES. Weight loss, pH and total chemical composition of litter were also investigated.We observed a greater release of the majority of water extractable cations and anions from beech litter compared to spruce litter. However, we observed a higher amount of available PO43− from spruce needles in comparison to more nutrient rich beech leaves. We expect that availability of PO43− is controlled mainly by the high amount of major cations (Ca2+ and Mg2+) and probably Al3+. An excess of these cations probably leads to phosphate precipitation under beech forest. In contrast, the production of dissolved ions by spruce litter does not significantly vary during the biologically active period of the year.