Nutrient cycling in deciduous forest ecosystems of the Sierra de Gata mountains: aboveground litter production and potential nutrient return

Abstract

Listen

Translate article

The potential nutrient return in a chestnut coppice (Castanea sativa Miller) over a period of 3 years (1991-1994) has been established and compared with the returns found in four deciduous oak (Quercus pyrenaica Wild.) forests (1990-1993) located in the Sierra de Gata mountains (central Spanish system). A convergence of abscission phenology patterns was observed among the different ecosystems studied, together with a delay in leaf fall at the warmest plot. This similarity is logical since the plots harbour the same deciduous species which are, however, subjected to climatological vari- ations. The chestnut coppice was found to be more productive than the oak forests, the amounts of leaves, branches, flowers and total litterfall being significantly greater. Statistical analysis showed a highly significant correlation between the chestnut coppice and the oak forest aboveground produc- tion, ranging between 0.82 and 0.96 for the leaves and between 0.72 and 0.89 for the total litter. In general, the leaf organs of the chestnut trees showed a higher concentration of bioelements than the oaks, with N and Ca predominant in the buds, Ca and Zn in the branches, K in the fruits, and above all Fe and Cu in the other plant remains. In all the forests studied, the potential nutrient supply fluc- tuated over the years and depended strongly on phenological factors; above all it was found to be gov- erned by the leaves, which contributed most to the return of mineral nutrients to the soil. The most marked potential nutrient return through the oak aerial organs occurred on the plot with the lowest rain- fall, particularly with respect to P and Ca. Considering all the forest plots, the general sequence of the amount of bioelements returning with the litterfall to the soil was as follows: with the exception of one oak plot (with an acid soil reaction and poor soil drainage), where the Mn return was higher than that of P owing to the high concentration of Mn in all the litter components. (© Inra /Elsevier, Paris.)