Litter layer and mineral soil were oven-dried at 60 °C to constant weight. The mineral soil was sieved at 2 mm to remove rock fragments that, however, were not found at both sites. Soil pH was measured potentiometrically in deionised water (1:5 w/v), a day after wetting to allow reaching chemical equilibrium. Litter layer and mineral soil aliquots finely ground in a ball-mill were used to determine total C and N by a Perkin Elmer 2400 CHNS Analyser. Mineral soil gently disaggregated in a mortar and sonicated for 10 min was submitted to dichromate oxidation as reported in Bird and Gröcke (1997). Briefly, 40 mL of 0.1 M K2Cr2O7/2 M H2SO4 were added to 400 mg of sample. The oxidation was performed for 6 h in a thermal bath at 60 °C, checking each hour to detect possible premature saturation of the solution, which is revealed by its green colour. If this occurred, the treatment had to be repeated with higher amount of sulfochromic solution. The residue of the oxidation was recovered by centrifugation at 6000 g for 15 min and rinsed various times with deionised water, until the solution was colourless. The residue was then dried at 60 °C and its C content measured by the CHN Analyser.