Soil organic carbon pool's contribution to climate change mitigation on marginal land of a Mediterranean montane area in Italy.

To evaluate the mitigation potential provided by the SOC pool, we investigated the impact of woody encroachment in the 0-30 cm depth of mineral soil across a natural succession from abandoned pastures and croplands to broadleaves forests on the central Apennine in Italy. In parallel, to assess the effect of the land use change (LUC) from cropland to pasture, a series of pastures established on former agricultural sites, abandoned at different time in the past, were also investigated. Our results show that woody encroachment on former pastures and croplands contributes largely to mitigate climate change, with an increase of the original SOC stock of 45% (40.5 Mg C ha-1 ) and 120% (66.5 Mg C ha-1 ), respectively. Also the LUC from croplands to pastures, greatly contributes to climate change mitigation trough a SOC increase of about 80% of the original SOC (45.9 Mg C ha-1 ). The management of abandoned lands represent a crucial point in the mitigation potential of agriculture and forestry activities, and particularly the role of the SOC pool. A policy effort should focus on minimizing the risk of speculative management options, particularly when the value of woody biomass become convenient to supply new energy systems allowing monetizing a long term forests productivity. In conclusion, despite both the land abandonment and the LUC can have a different impact on the SOC pool under different climatic conditions, these results can be useful to improve the SOC estimates in the National greenhouse gases Inventory at country level.