NitroEurope IP: The nitrogen cycle and its influence on the European greenhouse gas balance. Fourth Annual Activity Report to the European Commission

The NitroEurope IP – or NEU for short – addresses the major question: What is the effect of reactive nitrogen (Nr) supply on net greenhouse gas budgets for Europe? The objectives are to: 1. establish robust datasets of N fluxes and net greenhouse-gas exchange (NGE) in relation to C-N cycling of representative European ecosystems, as a basis to investigate interactions and assess long-term change, 2. quantify the effects of past and present global changes (climate, atmospheric composition, land-use/land-management) on CN cycling and NGE, 3. simulate the observed fluxes of N and NGE, their interactions and responses to global change/land-management decisions, through refinement of plot-scale models, 4. quantify multiple N and C fluxes for contrasting European landscapes, including interactions between farm-scale management, atmospheric and water dispersion, and consideration of the implications for net fluxes and strategies, 5. scale up Nr and NGE fluxes for terrestrial ecosystems to regional and European levels, considering spatial variability and allowing assessment of past, present and future changes, 6. assess uncertainties in the European model results and use these together with independent measurement/inverse modelling approaches for verification of European N2O and CH4 inventories and refinement of IPCC approaches. These objectives are met by a programme that integrates: 1) an observing system for N fluxes and pools, 2) a network of manipulation experiments, 3) plot-scale C-N modelling, 4) landscape analysis, 5) European up-scaling and 6) uncertainty and verification of European estimates. Cross-cutting activities address management, databases, training & dissemination. NEU will advance the fundamental understanding of C-N interactions at different scales and deliver: process-based models, landscape-level assessments, European maps of C-N pools, Nr fluxes and NGE, and independent verification of GHG inventories, as required under the Kyoto Protocol