Soil CO2 flux measurements in vineyard ecosystem

Many recent studies on climate change indicate the soil as a major source for atmospheric CO2. Oxidation of soil organic matter and the respiration of plant roots produce the soil CO2 and the efflux rate to the atmosphere depends on the concentration gradient and aerodynamic resistance. Knowledge of soil respiration rate from cultivated ecosystems is important for determining the role of these ecosystems in the global carbon balance. This paper presents the results from short-term measurements conducted in two Italian vineyards with different characteristics. Soil respiration rates were measured using soil chambers in an open-system configuration. Fluxes of CO2 were measured along transects between rows approximately every four hours by sealing the chambers over the collars. Higher differences were found in relation to spatial location of chambers than to time of the day. Soil tillage showed a very important influence in relation to amount of CO2 released from soil. Root distribution and activity explains the variability of soil respiration between chambers. CO2 flux was little affected by soil temperature except when the soil was wet. The observed variability indicates that correct measurements of soil CO2 efflux require an adequate number of samples and a good sample distribution.