Carbon balance and energy fluxes of a Mediterranean crop

This paper is based on the analysis of a long-term mass (carbon dioxide, hydrogen oxide) and energy (solar radiation) balance monitoring programme carried out during years 2010 and 2012 in an irrigated orange orchard in Sicily, using the Eddy Covariance (EC) method. Orange (Citrus sinensis L.) is one of the main fruit crops worldwide and its evergreen orchard may have a great potential for carbon sequestration, but few data are currently available. In the study, the role of the orchard system in sequestering atmospheric CO2 was analyzed, thus contributing to assess the carbon balance of the specie in the specific environment. Vertical energy fluxes of net radiation, soil heat, sensible heat and latent heat fluxes were measured at orchard scale by EC. A Bowen ratio-based method (BR) was proposed to resolve the lack of closure of the EC method to obtain reliable sensible and latent heat fluxes. Evapotranspiration (ET) values determined from the BR method were compared with up-scaled transpiration data determined by the sap flow heat pulse technique, evidencing the degree of correspondence between instantaneous transpirational flux at tree level and the micrometeorological measurement of ET at orchard level.