SOC sampling and analysis
In each plot, one soil core was extracted with a 5 x 5 cm probe at 0-20 cm soil depth. Carbon content of the fine earth was determined by the elemental auto-analyzer. The organic C fraction was determined by subtracting inorganic C in the carbonates from the total C. Soil organic carbon stocks (SOC) in the upper 20 cm soil layer were then estimated taking into account the organic C concentration in the sample and its bulk density, and subtracting the coarse particle (> 2 mm) content, following GarcĂ­a-Pausas et al. (2007). See Rodriguez et al. 2020 for further details about SOC sampling and determination.