CO2, N2O and CH4 Emissions and C Storage in Eucalyptus Forests with Different Management Practices of Harvest Residues

Total or partial removal of eucalyptus harvest residues can influence the dynamics and the increase of fluxes of greenhouse gases. The objective of this study was to evaluate the impact of removal or maintenance of harvest residues practices in the CO2, N2O, and CH4 fluxes and C fixation in the soil-plant system. Before the experiment was set up, a eucalyptus forest was selected with 5 years and harvested using the harvester + forwarder system. After harvest, the coppicing system was adopted and three types of residue management were established: 1. maintenance of all harvest residues and litter from the previous rotation, 2. maintenance of litter from the previous rotation, and 3. removal of harvest residues and litter from the previous rotation. The soil gas flux was sampled 5 days before harvest and at 4 times (distributed along the dry and rainy seasons) over 22.3 months. To collect the gases, PVC chambers were allocated into the soil surface in the planting rows and interrows. Subsequently, the gas samples were analyzed by gas chromatography. To evaluate C inputs in the system, the quantity of C in the plants and soil surface layer (0-10 cm) were quantified at the end of the experiment (22.3 months). There was higher CO2 equivalent flux in the soil in the area with harvest residues and litter at 0.3 and 9.3 months after harvest, with no differences between the areas with removal of harvest residues + litter and maintenance of litter. CO2 equivalent fluxes were similar among all treatments at 15.8 and 22.3 months after harvest. Maintenance of harvest residues increases soil CO2, CH4, and N2O fluxes in the first months after harvest compared to the area with removal of residues or with only litter. However, no differences were observed in the treatments regarding to soil organic C content and C fixation in plant biomass.