Developments in deriving critical limits and modelling critical loads of nitrogen for terrestrial ecosystems in Europe

This collaborative report of Alterra and the Coordination Center for Effects (MNP-CCE), in cooperation with various participants of the International Cooperative programme on Modelling and Mapping (ICP-MM) includes: 1. A summarizing overview of adverse nitrogen deposition effects on terrestrial ecosystems in terms of impacts on plant species and faunal biodiversity, forest nutrient status in relation to impacts on soil and solution chemistry and on ground water quality. 2. An overview of integrated dynamic biogeochemical models with plant species diversity models, that allow the assessment of critical loads and target loads of nitrogen in view of plant species diversity impacts. 3. A review of currently used critical limits for N concentrations in soil solution and derivation of new critical limits, based on field (literature) data and integrated soil vegetation models, that can be used in the computation of critical loads by steady state soil models. This updated knowledge of N effects, critcal N load methodologies (integrated models) and critical N limits a can contribute to a more appropriate data submission on critical N loads by the National Focal Centres to the CCE, specifically in view of biodiversity impacts, to be used for support of the UNECE and EU air pollution policies.