Temporal variation of soil CO2 emission in different land uses in the Caatinga

CO2 is an important gas for the biological cycle, as it plays a fundamental role in regulating the planet's temperature. Modifications in ecosystems promote an imbalance in carbon dynamics, causing more significant release into the atmosphere. The Caatinga biome, a dry forest type, has been anthropized since before the beginning of Brazil's colonization. Knowledge about the consequences of this anthropization in carbon stock changes in the soil is still scarce. This work aimed to evaluate the soil CO2 efflux in preserved and degraded sites in the Caatinga. CO2 emissions were collected in the field using an Infrared Gas Analyzer at four sampling points in the dry and rainy seasons of 2017. Texture, reactivity, nutrient content, and soil porosity were measured. Base saturation and texture were similar in the preserved and degraded sites. Preserved sites have higher C, N, P, and available water contents. Emission of CO2 increased with available water after rain events. Temperature, soil moisture, and land use influenced CO2 efflux, indicating the complexity of understanding the phenomenon. Degraded sites registered lower C stock and CO2 influx as an indication of desertification.