The Braunschweig Carbon Project: Atmospheric flux monitoring and free air carbon dioxide enrichment (FACE)

With respect to the predicted climate changes and the rise in the concentra tion of atmospheric CO2 it has become evident that the role of terrestrial ecosystems in the global carbon (C) turnover is not yet fully understood. T his is also true for C fluxes in agricultural ecosystems. As rising atmosph eric CO2 concentrations will directly affect plant photosynthesis, plant bi omass production and plant water relations and fluxes of other elements, it is of particular importance to predict the dynamics of C fluxes between th e atmosphere and agricultural canopies and the potential consequences for a groecosystems under future atmospheric CO2 conditions. Currently there are hardly any experimental approaches under real field conditions in crop rota tion systems to measure C fluxes at larger spatial scales and to simulate f uture CO2 scenarios. The Braunschweig Carbon Project is a combination of mi crometerological flux measurements of atmospheric trace gases and other air constituents and of a large scale free air carbon dioxide enrichment (FACE ) experiment. The project which is unique in the the combination of these t wo approaches is especially designed to meet the requirements of process an d landscape models and to contribute to the improvement and validation of m odels to predict the consequences of climate changes for agricultural ecosy stems. The present paper is a description of the structure and design of th e experiment.