Nutrient release dynamics in decomposing leaf litter in two Mediterranean deciduous oak species

Abstract

The release and dynamics of macronutrients from decomposing leaf litter were determined for two deciduous oak species: one in Spain, Quercus pyrenaica, growing on a humic Cambisol (Sol brun forestier) and the other in France, Q lanuginosa, on a rendsic Leptosol (Rendzine). The same processes were studied after leaf-litter exchanges between the French stand and a Spanish stand. Nylon litter bass (1 mm2 mesh), containing 10 g of leaves, were placed in five stands (four in Spain and one in France) and collected every 2 months when they were weighed and analysed for N, P, Ca, Mg and K. The mean amount of nutrients in the decomposing leaves decreased over the 36-month period. The four Q pyrenaica stands were classified into two groups involving different nutrient release processes, without any relation to yearly litterfall. For the Q lanuginosa stand, the results obtained were similar to those for one of the Q pyrenaica groups. Similar nutrient release processes occurred in the litter-bags collected from native stands and after exchanges between the two species, with a quick release of K, followed by Mg and P. Higher Ca accumulation was noted for the Q pyrenaica litter as compared to Q lanuginosa litter. For N, the results were very different between the two species and the two locations.