Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 2 1 2005 10.5194/bg-2-15-2005 http://www.biogeosciences.net/2/15/2005/ http://www.biogeosciences.net/2/15/2005/bg-2-15-2005.html http://www.biogeosciences.net/2/15/2005/bg-2-15-2005.pdf 15 26 2005-02-17 The carbon budget of terrestrial ecosystems at country-scale – a European case study I. A. Janssens A. Freibauer B. Schlamadinger R. Ceulemans P. Ciais A. J. Dolman M. Heimann G.-J. Nabuurs P. Smith R. Valentini E.-D. Schulze Department of Biology, Universiteit Antwerpen, Belgium Max-Planck-Institute for Biogeochemistry, Jena, Germany Joanneum Research, Graz, Austria Laboratoire des Sciences du Climat et de l’Environnement, Gif sur Yvette, France Department of Geo-Environmental Sciences, Free University Amsterdam, The Netherlands Alterra, Wageningen, The Netherlands European Forest Institute, Joensuu, Finland School of Biological Sciences, University of Aberdeen, UK Department of Forest Science and Environment, University of Tuscia, Italy We summed estimates of the carbon balance of forests, grasslands, arable lands and peatlands to obtain country-specific estimates of the terrestrial carbon balance during the 1990s. Forests and grasslands were a net sink for carbon, whereas croplands were carbon sources in all European countries. Hence, countries dominated by arable lands tended to be losing carbon from their terrestrial ecosystems, whereas forest-dominated countries tended to be sequestering carbon. In some countries, draining and extraction of peatlands caused substantial reductions in the net carbon balance. <br /><br /> Net terrestrial carbon balances were typically an order of magnitude smaller than the fossil fuel-related carbon emissions. Exceptions to this overall picture were countries where population density and industrialization are small. It is, however, of utmost importance to acknowledge that the typically small net carbon balance represents the small difference between two large but opposing fluxes: uptake by forests and grasslands and losses from arable lands and peatlands. This suggests that relatively small changes in either or both of these large component fluxes could induce large effects on the net total, indicating that mitigation schemes should not be discarded a priori. <br /><br /> In the absence of carbon-oriented land management, the current net carbon uptake is bound to decline soon. Protecting it will require actions at three levels; a) maintaining the current sink activity of forests, b) altered agricultural management practices to reduce the emissions from arable soils or turn into carbon sinks and c) protecting current large reservoirs (wetlands and old forests), since carbon is lost more rapidly than sequestered.