Estimate of mass and energy fluxes over grapevine using eddy covariance technique

The impacts of weather on carbon storage in tree and vine crops are inadequately investigated because of the small area planted in comparison to the large extent of forest ecosystems. In the last decade, the eddy covariance technique (EC) has become a standard for estimating carbon and water vapor exchanges in all international flux networks. EC is a direct measurement of the upward and downward fluxes that uses high frequency measurements of vertical component of the wind speed and scalars. This study assessed the energy budget components and carbon and water vapor fluxes in two vineyards in Italy. An EC system was used to monitor 15-min values of carbon dioxide (Fc), water vapor (LE), and sensible heat (H) fluxes above the vegetation. Flux data were taken in August of 2002 in Tuscany, Italy, and in July of 2003 in Sardinia, Italy. In addition, net radiation (Rn) and soil heat flux (G) data were collected. The results of the energy balance closure indicated good accuracy of the data set. Rn was partitioned more toward H and less toward ëE most of the time, depending on weather conditions and irrigation applications. The daytime Fc values ranged between -8 and -15 ìmol CO2 m-2s-1. The daily net C budget was in about 2.14 g m-2 d-1 in Tuscany and 4.32 g m-2 d-1 in Sardinia showing that the vineyards were sinks for C.