Comparison of N, C and GHG budgets from European forests, wetlands and agricultural land

In order to advice on mitigation of N and GHG pollution in present and future climates it is important to have detailed knowledge of the nitrogen and carbon transformations and flow into and out of the system. Such knowledge was obtained through intensive measurements over a 4.5 year period from 13 locations representing the dominant climate zones (Boreal to Mediterranean, continental to maritime) and ecosystems (forest, grassland, arable, wetland) of Europe and was funded by the EU project 'Nitroeurope'. Nitrogen inputs as precipitation, dry and aerosol deposition and on some sites fertilisation; C and N transformations in soil, litter and vegetation; and gaseous export as NH3, NO, N2O, CH4 and CO2 and NO3 leaching and harvest were measured, using the same common protocol, at appropriate high temporal and spatial frequency. Soil type, climate and landuse influenced the flow of nitrogen and carbon. Nitrogen cycles in remote, unpolluted areas (i.e the boreal forest in Finland) are almost closed, whereas intensive, high N input agricultural fields are hotspots of pollutants, N2O and NO3 (i.e. grazed grassland in Scotland). Greenhouse gas budgets are dominated by CO2 sequestration for almost all sites. Sequestration rates were, however reduced by large N2O emissions from intensively managed grasslands and large CH4 emissions from rice paddies and boreal wetlands. Temporal and inter-annual variations and the importance of this data set to the modelling community and application beyond Europe will be discussed