Letters to Nature

Nature 404, 861-865 (20 April 2000) | doi:10.1038/35009084; Received 12 January 2000; Accepted 3 March 2000

Respiration as the main determinant of carbon balance in European forests

R. Valentini1, G. Matteucci1, A. J. Dolman2, E.-D. Schulze3,4, C. Rebmann3,4, E. J. Moors2, A. Granier5, P. Gross5, N. O. Jensen6, K. Pilegaard6, A. Lindroth7, A. Grelle8, C. Bernhofer9, T. Gr|[uuml]|nwald9, M. Aubinet10, R. Ceulemans11, A. S. Kowalski11, T. Vesala12, |[Uuml]|. Rannik12, P. Berbigier13, D. Loustau14, J. Gu|[eth]|mundsson15, H. Thorgeirsson15, A. Ibrom16, K. Morgenstern16, R. Clement17, J. Moncrieff17, L. Montagnani18, S. Minerbi19 & P. G. Jarvis17

  1. University of Tuscia, Department of Forest Environment and Resources, I-01100 Viterbo, Italy.
  2. Alterra, PO Box 47, 6700 AA Wageningen, The Netherlands.
  3. Max-Planck-Institut f|[uuml]|r Biogeochemie, D-07745 Jena, Germany.
  4. Former address: Lehrstuhl f|[uuml]|r Pflanzen|[ouml]|kologie, Universit|[auml]|t Bayreuth, D-95440 Bayreuth, Germany.
  5. Centre de Recherches de Nancy, Unit|[eacute]| d|[rsquo]|Ecophysiologie Foresti|[egrave]|re, Equipe de Bioclimatologie, F-54280 Champenoux, France.
  6. Risoe National Labouratory, DK-4000 Roskilde, Denmark.
  7. Lund University, Department of Physical Geography, Box 118, SE-221 00 Lund, Sweden.
  8. SLU, Department for Production Ecology, Faculty of Forestry, PO Box 7042, S-7042 Uppsala , Sweden.
  9. TU Dresden, Institut f|[uuml]|r Hydrologie und Meteorologie , D-01737 Tharandt, Germany.
  10. Unit|[eacute]| de Physique, Facult|[eacute]| Universitaire des Sciences Agronomiques de Gembloux, B-5030 Gembloux , Belgium.
  11. Department of Biology, University of Antwerpen, Universiteitsplein 1, B-2610 Wilrijk, Belgium.
  12. Department of Physics, PO Box 9, FIN-00014, University of Helsinki, Finland.
  13. Unit|[eacute]| de Bioclimatologie, INRA Bourdeaux, BP 81, F33883 Villenave d|[rsquo]|Ornon Cedex, France.
  14. Unit|[eacute]| de Recherches Foresti|[egrave]|res, INRA Bourdeaux, BP 45, F33611 Gazinet, France.
  15. Agricultural Research Institute, Department of Environmental Research, Keldnaholti, 112, Reykjavik , Iceland.
  16. Georg-August Universit|[auml]|t, Institut f|[uuml]|r Bioklimatologie , B|[uuml]|sgenweg 2, D-37077-G|[ouml]|ttingen , Germany.
  17. University of Edinburgh, Institute of Ecology and Resource Management, Edinburgh EH9 3JU, UK.
  18. University of Padova, Department of Land and Agro-Forestry Systems, Agripolis, I-35020 Legnaro , Padova, Italy. Autonomous Province of Bolzano, Forest Services, I-39100 Bolzano, Italy.

Correspondence to: R. Valentini1 Correspondence and requests for materials should be addressed to R.V. (e-mail: Email: rik@unitus.it).

Carbon exchange between the terrestrial biosphere and the atmosphere is one of the key processes that need to be assessed in the context of the Kyoto Protocol1. Several studies suggest that the terrestrial biosphere is gaining carbon2, 3, 4, 5, 6, 7, 8, but these estimates are obtained primarily by indirect methods, and the factors that control terrestrial carbon exchange, its magnitude and primary locations, are under debate. Here we present data of net ecosystem carbon exchange, collected between 1996 and 1998 from 15 European forests, which confirm that many European forest ecosystems act as carbon sinks. The annual carbon balances range from an uptake of 6.6 tonnes of carbon per hectare per year to a release of nearly 1 t C ha -1 yr-1, with a large variability between forests. The data show a significant increase of carbon uptake with decreasing latitude, whereas the gross primary production seems to be largely independent of latitude. Our observations indicate that, in general, ecosystem respiration determines net ecosystem carbon exchange. Also, for an accurate assessment of the carbon balance in a particular forest ecosystem, remote sensing of the normalized difference vegetation index or estimates based on forest inventories may not be sufficient.