173 Chapter 12 Afforestation and Reforestation: The Sicilian Case Study Juliane Rühl, Luciano Gristina, Tommaso La Mantia, Agata Novara and Salvatore Pasta © Springer-Verlag Berlin Heidelberg 2015 R. Valentini and F. Miglietta (eds.), The Greenhouse Gas Balance of Italy, Environmental Science and Engineering, DOI 10.1007/978-3-642-32424-6_12 Abstract In some regions of the world such as the Northern Hemisphere, the abandonment of agricultural land is one of the most widespread forms of land use change. In general, abandonment is followed by colonization by herbaceous and woody plants. Since the 1950s, wide areas of Southern Italy have been afforested for soil conservation improvement. In order to quantify the effects of agricultural abandonment and artificial afforestation on soil organic carbon (SOC), a dataset of 48 Sicilian sites has been analyzed. Because of their high environmental variabil- ity, these sites can be considered as representative of Southern Italy and in general of the Mediterranean basin. Soil samples were taken throughout all bioclimates in different successional stages (cultivated areas: orchards, cereal crops, herb-dom- inated plant communities, grasslands dominated by perennial grasses, garrigues and low shrublands, maquis, natural forests and in nearby artificially afforested sites (Pine plantations)). The study confirmed that SOC accumulation after agri- cultural abandonment depends on bioclimate: the highest SOC accumulation was recorded in the meso-mediterranean bioclimate, intermediate in the thermo-medi- terranean, and the lowest in the supra-mediterranean bioclimate. Data showed that for C sequestration in the soil, artificial afforestation is not convenient in compari- son to natural afforestation by spontaneous secondary succession processes. 12.1 Introduction In the Mediterranean region, lands cultivated since ancient times are today subject to two contrasting trends: intensification or abandonment. Since the 1950s, vast areas of Southern Italy have been afforested with the aim of soil conservation and J. Rühl · L. Gristina · T. La Mantia (*) · A. Novara · S. Pasta Agricultural and Forest Sciences Department, University of Palermo, Viale delle Scienze, Ed. 4, Ingr. H, 90128 Palermo, Italy e-mail: tommaso.lamantia@unipa.it