Processes and patterns in natural ecosystems

The aboveground biomass, litterfall and its accumulation, litter weight loss due to decomposition, N return and seasonal leaf N dynamics and nutrient pools in relation to soil properties may be performed in different forest ecosystems in order to better understand the recycling of elements associated with the turnover of organic matter. The leaves were found to accumulate a qualitatively important fraction of mobile nutrients as compared with their low percentage in total above-ground biomass (3%). Nutrient management seems to be related to the availability for the trees of elements such as phosphorus and potassium. Nutrients present in lower amounts are recycled through the plant-soil system in much higher proportions than other nutrients present in greater amounts in the soil. The parent material mostly affects the soil content of assimilable Ca and P, on the other hand, the climate (mostly rainfall) affects the organic matter content, total N, the cation exchange capacity and the percentage of base saturation of the soil epipedons of the forest ecosystems.