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6 - Nitrogen processes in terrestrial ecosystems
- from Part II - Nitrogen processing in the biosphere
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- By Klaus Butterbach-Bahl, Karlsruhe Institute of Technology, Per Gundersen, University of Copenhagen, Per Ambus, Risø DTU National Laboratory for Sustainable Energy, Jürgen Augustin, Leibniz-Centre for Agricultural Landscape Research, Claus Beier, Risø DTU National Laboratory for Sustainable Energy, Pascal Boeckx, Ghent University, Michael Dannenmann, University of Freiburg, Benjamin Sanchez Gimeno, CIEMAT, Spain, Andreas Ibrom, Risø National Laboratory for Sustainable Energy, Ralf Kiese, Karlsruhe Institute for Technology, Barbara Kitzler, Federal Research and Training Centre for Forests, Robert M. Rees, Scottish Agricultural College, Keith A. Smith, University of Edinburgh, Carly Stevens, Open University, Timo Vesala, University of Helsinki, Sophie Zechmeister-Boltenstern, Federal Research and Training Centre for Forests
- Edited by Mark A. Sutton, NERC Centre for Ecology and Hydrology, UK, Clare M. Howard, NERC Centre for Ecology and Hydrology, UK, Jan Willem Erisman, Gilles Billen, Albert Bleeker, Peringe Grennfelt, Hans van Grinsven, Bruna Grizzetti
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- Book:
- The European Nitrogen Assessment
- Published online:
- 16 May 2011
- Print publication:
- 14 April 2011, pp 99-125
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- Chapter
- Export citation
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Summary
Executive summary
Nature of the problem
Nitrogen cycling in terrestrial ecosystems is complex and includes microbial processes such as mineralization, nitrification and denitrification, plant physiological processes (e.g. nitrogen uptake and assimilation) and physicochemical processes (leaching, volatilization). In order to understand the challenges nitrogen puts to the environment, a thorough understanding of all these processes is needed.
Approaches
This chapter provides an overview about processes relating to ecosystem nitrogen input and output and turnover. On the basis of examples and literature reviews, current knowledge on the effects of nitrogen on ecosystem functions is summarized, including plant and microbial processes, nitrate leaching and trace gas emissions.
Key findings/state of knowledge
Nitrogen cycling and nitrogen stocks in terrestrial ecosystems significantly differ between different ecosystem types (arable, grassland, shrubland, forests).
Nitrogen stocks of managed systems are increased by fertilization and N retention processes are negatively affected.
It is also obvious that nitrogen processes in natural and semi-natural ecosystems have already been affected by atmospheric Nr input.
Following perturbations of the N cycle, terrestrial ecosystems are increasingly losing N via nitrate leaching and gaseous losses (N2O, NO, N2 and in agricultural systems also NH3) to the environment.