Assessing organic carbon stock at scale profile in forest soils of Calabria (Southern Italy)

Understanding the amount of carbon content stored in forest soils may help to quantify their contribution in climate change mitigation. The main objective of the study was assessing soil organic carbon (SOC) stock at profile scale in a forest area of Calabria region and analysing the relationship between SOC stock and soil texture, soil type and landscape position. Twenty-eight soil pedons were collected in all physiographic units of the study area and were described and classified according to USDA classification. All mineral horizons were sampled and analysed for SOC, bulk density and soil texture. Moreover, the organic horizon (O) was sampled and SOC concentration was determined. Finally, the SOC stock along the soil profiles was calculated. The results showed that the soils belonged to Inceptisol and Entisol orders and were from shallow to moderately deep. SOC values of O horizon ranged from 217.0 g kg-1 to 369.8 g kg-1 with a mean value of 284.9 g kg-1. In the mineral horizons, SOC ranged from 1.0 to 132.2 g kg-1 with a mean value of 39.8 gkg-1. The mean value of total SOC stock for all the profiles was 160.9 Mg ha-1. The mean SOC stock was 4.8 Mg ha-1 for the organic horizons and 156.2 Mg ha-1 for the mineral horizons. Soil texture, soil types and landscape features controlled SOC stock with higher values recorded in flat areas than on steep slopes. SOC stock was typically lower for Entisols than Inceptisols and for loamy sand soils than loamy soils.