CO2 emission and its relation to soil temperature, moisture, and O2 absorption in the reforested areas of Cerrado biome, Central Brazil

Aims To characterise the temporal variability in soil CO2 emissions (FCO2), soil O-2 influx (FO2), soil water content (SWC), and soil temperature (Ts) and their relations in long-term reforested areas (30 years of conversion) in an Oxisol, Cerrado biome, Brazil. Methods The following land-use changes (Luces) were evaluated: pine (PI), eucalyptus (EU), and native species (NS) reforested areas. The molar ratio between FCO2 and FO2 (respiratory quotient, RQ) was calculated to better understand the process of soil metabolism. Results Soil CO2 emission was 28% less in PI than in the other LUCs. A model including Ts, SWC, and FO2 could explain 91 and 62% of the FCO2 temporal variability in NS and PI, respectively. The total FCO2 (November 2015 to May 2016) were 11.26, 10.99, and 7.97 Mg ha-1 for EU, NS, and PI areas, respectively (p < 0.05). The SWC, but not Ts, influenced the temporal variation of FCO2. The first two principal components accounted for 69.32% of the total variability, and two groups distinguished mainly on the basis of soil chemical attributes. Conclusions Temporal variations of FCO2 in reforested areas in the Cerrado were influenced by edaphoclimatic conditions. Soil carbon stock was influenced by the type of forest and litter on the ground. FO2 was similar in all LUCs studied. The results indicate that RQ of >1 is associated with the effect of root system-mediated soil respiration. Our results suggest that LUCs influence soil carbon input and output-soil carbon dynamics-by changing soil attributes.