Spatial heterogeneity of organic carbon stock in soil profiles of a peri-urban Mediterranean forest ecosystem

Soil organic carbon (SOC) is essential for ensuring soil health and fertility, supporting key soil functions and related ecosystem services such as stabilization of soil structure and regulation of nutrient and water cycles. Moreover, SOC represents the largest terrestrial organic C reservoir but remains the largest source of uncertainty in future C cycle projections. In this context, Mediterranean areas show a high potential for C sequestration, but strictly dependent by anthropogenic pressure and changes in land use and climate. The amount, the spatial distribution, and the quality of soil organic matter, also evaluated through C and N stable isotopes, depend on transformation processes due to microbial activity. We applied a multidisciplinary approach to study C and N pools in the peri-urban Mediterranean forest of Castelporziano (Rome, Italy), a class 1 ecosystem station of the ICOS network (IT-Cp2) equipped with an eddy covariance tower measuring net ecosystem C fluxes. In the main site, several ecosystem types (e.g., holm oak, stone pine, Mediterranean scrub) and 14 soil profiles have been characterized and collected from a physical, chemical, isotopic, and spectroscopic point of view. Data will be discussed through an integrated approach to clarify the SOC dynamics in soil profile to deeper insight the processes of C stock and resilience of Mediterranean forest ecosystems. Results showing soil spatial heterogeneity may also help refining ICOS protocols for soil CO2 flux measurements which are very sensitive to the displacement of soil automatic chambers within each control point surrounding the eddy covariance tower.