MICROBIAL ACTIVITY AND LEACHING DURING INITIAL OAK LEAF-LITTER DECOMPOSITION

The decomposition of oak leaf litter was studied by means of a litterb ag experiment in an oak forest in the Netherlands. The contribution of microbial activity and leaching to weight loss and element dynamics d uring the first 6 weeks of decomposition was investigated by means of frequent respiration measurements and extractions of the litter and by a qualitative comparison of throughfall and litter percolation water chemistry. The oak-leaf litter lost 9.3% of its initial dry weight dur ing the first 6 weeks. In total, 90% of this observed weight loss was explained by the processes studied. About 5.9% (64% of the total) of t his weight loss was attributed to microbial respiration and 0.5% (5%) to the loss of inorganic solutes. Leaching of dissolved organic compou nds was estimated to accouut for 2.0% (21%). The results indicated a f ast leaching of K and Cl out of the fresh litter during the first 2 we eks, while Mg, Fe, Mn, Si, ortho P, and dissolved organic N were relea sed at a much lower rate. At the same time, small amounts of H+, NH4and NO3- were retained in the litter.