Contribution of the litter and superficial soil layer to N2 fixation, denitrification and N2O and CH2 emissions in a Pinus laricio Poiret forest (Sila mountains, Italy)

N2 fixation (ARA), denitrification (acetylene block) and N2O and CH4 emissions were measured throughout the year in a Pinus laricio Poiret forest in Sila Mountains (Southern Italy) on a subacid sandy shallow soil on granite. Both litter and superficial soil layers (0-5 cm) showed similar levels and annual patterns of activities. Soil metabolic activity (CO2 evolution) was very low in the dry period as well as during winter. ARA showed the highest level in the spring (20.5 μmol m-2 3h-1 in May) and lower level in fall and winter. Denitrification was negligible from April to September but reached high values during fall and winter with a peak (2.48 μmol N2O m-2 3 h-1) for litter in December. N2O and CH4 emissions showed a pattern very similar to that observed for denitrification. The data presented are the first ones for mediterranean coniferous forest.