((Nutrient cycling and soil processes in terrestial ecosystems : specific nature of Mediterranean ecosystem and its implications for the soil-plant relationship))

Mediterranean ecosystems are classically regarded as nutrient-poor ecosystems. Nutrient availability for plants depends on several complex and interacting mechanisms. First, nutrient availability will depend on leaf and root litterfall and other nutrient inputs processes (such as nutrient stemflow and throughfall). Plant strategies for nutrient conservation in their tissues will determine the litter quality, the decomposition rate, and finally the equilibrium between mineralization and immobilization in the microbial biomass. Secondly, nutrient availability for plant will depend on soil climatic conditions. As compared with other ecosystems, Mediterranean ecosystems are exposed to frequent and short drying-rewetting cycles. Under these conditions, rapid nutrient immobilization likely occurs, and the possibility of dissolved organic nitrogen uptake by plants, as observed in other nutrient-poor ecosystems, remains largely unexplored. Increasing atmospheric nitrogen deposition, and changes in soil temperature and humidity as consequence of Global Change emerge new nutritional scenarios for Mediterranean ecosystems