Dinamica delCarbon Sinkin una cronosequenza agro-forestale mediterranea: caratterizzazione delle frazioni di sostanza organica

The study on the impact of different land uses on soil organic matter fractions have important implications for the identification of sustainable land management practices, and for the development of actions finalized to the soil carbon sequestration and, thus, to mitigate climate change processes. The study was carried out in a area representative of Mediterranean agro-forestry systems, located in the North-Eastern Sardinia on Palezoic intrusive rocks (granites). In the area, homogeneous for the ecological potential, seven land uses were compared: tilled vineyard, intercropped vineyard, forage annual crops two beneath the oak trees or not, pasture beneath the oak trees or not and oak forest. The aim of this study was to evaluate the impact on soil organic matter quality and stability of different land use types in an agro-forestry area by determining: i) humic and no humic SOM fractions, their elemental composition and their infrared spectroscopy patterns; ii) water-extractable organic matter (WEOM), particulate SOM (POM-free and POM-occluded) and mineral associated SOM (M-OM) and their elemental composition; iii) SOM quality and stability indices and soil quality classes in relation to land use. Differences among land uses for SOM fractions, composition and stability demonstrated that the most conservative land uses within an agro-forestry system under Mediterranean semi-arid conditions seemed to be those associated to pastoral activities and to the presence of oak trees.