Site description Mokré Louky (The „Wet Meadows“) is situated near the town of Třeboň (South Bohemia, Czech Republic) in the cadastral area of a man-made lake (Rožmberk fishpond, 5 km2). The water level is controlled by a system of ditches, which interconnect the man-made lakes (fishponds) in the whole region. The water level is fairly stable throughout the year (-0.2 – 0.2 m) owing to the water level control of the Rožmberk lake by the lake managers. In some years, spring and summer floods occur during snow melting and summer rains, respectively, depending on the current meteorological situation. The wet meadow is a sedge grass marsh, in which Carex gracilis (acuta) and Calamagrostis canescens were the dominant plant species till the long-lasting summer flood in 2002. Afterwards, Phalaris arundinacea took over and has since dominated over 50 % of the site, where the water level keeps below the soil surface for most time. Carex acuta keeps dominating the wetter part, where the water level is higher than the soil surface for most of the year. The part of the wetland, where the Eddy-covariance measurement site is situated in the unmanaged part of the wetland (unfertilized, unmown), about 0.5 km upstream from the Rožmberk lake. Though the site itself is not managed, the upstream part of the meadow is mown and fertilized by pretreated piggery sewage. The proceeding site eutrophication is indicated by the downstream expansion of Urtica dioica and other ruderal species. The study of nitrogen availability in comparison with an oligotrophic meadow site is in progress.The Eddy-covariance station was installed on the site in September 2004. The seasonal course of CO2 and water vapour has been measured during the vegetation season of 2005. Accompanying measurements include seasonal maximum aboveground biomass (in 2005), soil respiration (in 2005, 2006), primary production (2006) and preliminary measurement of photosynthetic CO2 exchange by leaves of dominant species (in 2005, repeated in 2006).