Dissolved carbon as a component of net biome productivity of major land use systems

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Atmosphere-based estimates of carbon (C) sequestration in terrestrial ecosystems are larger than land-based estimates, which is attributed to `missing fluxes¿ that are not accounted for in present analysis. The transfer of dissolved organic and inorganic C from terrestrial settings to the hydrosphere through soils might well explain the differences in estimates of C sequestration. However, studies of dissolved C fluxes are almost exclusively from temperate forest ecosystems and non of these studies related dissolved C fluxes to local estimates of C sequestration. Also, little is known about dissolved C export to the hydrosphere from soil under different land use. Our hypotheses are i) export of dissolved C from soils fills the gap between atmosphere-based and land-based estimates of C sequestration; ii) land use modifies fluxes of dissolved C from soils in the order arable land > grassland > deciduous forest > coniferous forest. These hypotheses will be tested by determining fluxes of dissolved C from soils in relation to estimates of net biome productivity of 13 sites of different land use