NUTRIENT POOLS TO THE SOIL THROUGH ORGANIC MATTER IN SEVERAL CASTANEA SATIVA MILL. COPPICES OF MOUNTAINOUS MEDITERRANEAN CLIMATE AREAS

Nutrient cycling is of basic importance for sustainability of forest ecosystems, various aspects of which were studied in six Castanea sativa Mill. coppices near Salamanca (Spain), Catania (Italy) and Montpellier (France). Best regression equations for the above-ground tree biomass were obtained by applying the allometric regression method: Y = aX^b (Y = total above-ground biomass; X = DBH) and the following regression equations were calculated: Spain stand, tree biomass = 0.066 (DBH)^2.628; Italian stands, tree biomass = 0.137 (DBH)^2.247; French stand, tree biomass = 0.118 (DBH)^2.336. Litterfall was highly correlated with stand age. In the two younger coppices, the amounts of organic matter reaching the soil were small compared to the four older stands. There were also significant differences in the amounts between younger and older plots. The nutrient-use efficiency index values (proportional resorption) as applied to the six studied stands suggest that translocation of N, P, K, Ca, Mg varies in relation to each stand.