Developments in deriving critical limits and modeling critical loads of nitrogen for terrestrial ecosystems in Europe Wim de Vries, Hans Kros, Gert Jan Reinds, Wieger Wamelink, Janet Mol, Han van Dobben, Roland Bobbink, Bridget Emmett, Simon Smart, Chris Evans, Angela Schlutow, Philipp Kraft, Salim Belyazid, Harald Sverdrup, Arjen van Hinsberg, Maximilian Posch, Jean-Paul Hettelingh Alterra-rapport 1382, ISSN 1566-7197 Uitloop 0 lijn 20 mm 15 mm 10 mm 5 mm 0 15 mm 0 84 mm 0 195 mm Developments in deriving critical limits and modeling critical loads of nitrogen for terrestrial ecosystems in Europe 2 Alterra-rapport 1382 Developments in deriving critical limits and modelling critical loads of nitrogen for terrestrial ecosystems in Europe Wim de Vries Hans Kros Gert Jan Reinds Wieger Wamelink Janet Mol Han van Dobben Roland Bobbink Bridget Emmett Simon Smart Chris Evans Angela Schlutow Philipp Kraft Salim Belyazid Harald Sverdrup Arjen van Hinsberg Maximilian Posch Jean-Paul Hettelingh Alterra-rapport 1382 Alterra, Wageningen and CCE, Bilthoven 2007 ABSTRACT Vries, Wim de, Hans Kros, Gert Jan Reinds, Wieger Wamelink, Janet Mol, Han van Dobben, Ronald Bobbink, Bridget Emmett, Simon Smart, Chris Evans, Angela Schlutow, Philipp Kraft, Salim Belyazid, Harald Sverdrup, Arjen van Hinsberg, Maximilian Posch, Jean-Paul Hettelingh, 2007. Developments in deriving critical limits and modeling critical loads of nitrogen for terrestrial ecosystems in Europe. Alterra, Alterra-rapport 1382, 206 pp.; 42 figs.; 24 tables.; 9 Annexes, 287 refs. Keywords: nitrogen deposition, air pollution, biodiversity, critical load, critical limit, biogeochemical models, terrestrial ecosystems, forests. This collaborative report of Alterra and the Coordination Center for Effects (MNP-CCE), in co- operation 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. ISSN 1566-7197 This report is available in digital format at www.alterra.wur.nl. A printed version of the report, like all other Alterra publications, is available from Cereales Publishers in Wageningen (tel: +31 (0) 317 466666). For information about, conditions, prices and the quickest way of ordering see www.boomblad.nl/rapportenservice © 2007 Alterra P.O. Box 47; 6700 AA Wageningen; The Netherlands Phone: + 31 317 474700; fax: +31 317 419000; e-mail: [email protected] No part of this publication may be reproduced or published in any form or by any means, or stored in a database or retrieval system without the written permission of Alterra or CCE. Alterra assumes no liability for any losses resulting from the use of the research results or recommendations in this report. 4 Alterra-rapport 1382 [Alterra-rapport 1382/March 2007] Contents Preface...................................................................................................................................... 7 Summary .................................................................................................................................. 9 1 Introduction .................................................................................................................. 13 1.1 Background of the report ................................................................................. 13 1.2 Aim of the report............................................................................................... 16 1.3 Contents of the report ...................................................................................... 16 2 Adverse impacts of elevated nitrogen deposition on terrestrial ecosystems and empirical critical nitrogen loads: an evaluation................................................. 17 2.1 Introduction........................................................................................................ 17 2.2 Plant species diversity........................................................................................ 19 2.3 Soil quality and forest nutrition ....................................................................... 27 2.4 Other impacts..................................................................................................... 36 2.4.1 Faunal species diversity 36 2.4.2 Ground water quality 39 2.5 Evaluation of the presented critical loads ...................................................... 40 3 Modelling approaches for the derivation of critical nitrogen loads for plant species diversity impacts.............................................................................................. 45 3.1 General approach............................................................................................... 45 3.2 The SMART2-SUMO-MOVE/NTM model................................................ 47 3.3 The MAGIC-SUMO-GBMOVE model........................................................ 56 3.4 The BERN model.............................................................................................. 64 3.5 The ForSAFE-VEG model.............................................................................. 73 3.6 Comparison of modelling approaches and data requirements.................... 80 4 Critical nitrogen limits: evaluation of currently used values and possible updated values for use in critical load assessments ................................................. 85 4.1 Evaluation of currently used critical nitrogen limits..................................... 85 4.2 Assessment of updated critical nitrogen limits in soil solution................... 89 4.2.1 Critical N concentrations in view of plant species diversity impacts 89 4.2.2 Critical N concentrations in view of a differentiation between undisturbed and “leaky” forest sites 95 4.2.3 Critical N concentrations in view of forest root growth and impacts on foliar N contents 96 4.3 Evaluation of present and updated critical nitrogen limits.......................... 98 5 Discussion, conclusions and recommendations ....................................................101 5.1 Discussion.........................................................................................................101 5.2 Conclusions ......................................................................................................104 5.3 Recommendations ...........................................................................................106 Literature..............................................................................................................................109 Alterra-rapport 1382 5 Annexes 1 Calculation of critical loads for nitrogen with the SMART2 steady state model............................................................................................................................133 2 Description and validation of the SUMO model predicting vegetation succession ....................................................................................................................139 3 Prediction and validation of soil and vegetation changes with the dynamic MAGIC-GBMOVE model.......................................................................................153 4 Calculation of critical loads for nitrogen and acidity with the SMB –BERN steady state model.......................................................................................................161 5 Prediction of vegetation changes with the dynamic BERN model.....................169 6 ssessment of individual responses functions in the ForSAFE-VEG model .....175 7 Prediction and validation of vegetation changes with the dynamic ForSAFE-VEG model...............................................................................................185 8 Parameterization of response functions for plant groups in the ForSAFE- VEG model .................................................................................................................197 9 Derivation of critical nitrogen concentration limits used in the present mapping manual..........................................................................................................203 6 Alterra-rapport 1382 Preface This report is the result of a collaborative project between Alterra and the Coordination Centre for Effects (CCE), including comments and texts from international experts. It presents an overview of: - Adverse impacts of elevated nitrogen deposition on terrestrial ecosystems and related empirical critical nitrogen loads (Chapter 2). - Modelling approaches for the derivation of critical