Ecological patterns and comparative nutrient dynamics of natural and agricultural mediterranean-type ecosystems.

An agricultural watershed, situated on an island of the Aegean archipelago, was studied in order to gain insight into the structure and the design of a typical terrestrial ecosystem of the Mediterranean region. Fieldwork was focused on the comparative study of seasonal patterns of inorganic nutrients, organic nitrogen, and erosion over the most abundant vegetation types of the area, such as olive groves, maquis, and wetlands. Nutrient losses via the pathway of erosion were provided by the determination of nutrient concentrations in runoff sediments. Results showed that nutrient levels are higher and more susceptible to rapid changes in the zones that host agricultural activities and animal husbandry. The behavior of nitrogen and phosphorus showed remarkable stability in the maquis, where dynamic processes were mainly affected by soil erosion, which led gradually to land degradation, especially on sloping terrains. The aim of this study was to form the basis for the quantification of the interconnections within the Mediterranean-type ecosystems and to conceptualize their operational properties.