HR: 10:35h
AN: B32B-02    [Abstracts]
TI: Unravelling nitrogen deposition effects on carbon cycling in forests
AU: * Luyssaert, S
EM: Sebastiaan.Luyssaert@ua.ac.be
AF: UAntwerpen, Universiteitsplein 1, Wilrijk, 2610, Belgium
AU: * Luyssaert, S
EM: Sebastiaan.Luyssaert@ua.ac.be
AF: Oregon SU, College of Forestry, Corvallis, OR 97331-5752, United States
AU: Inglima, I
AF: SUNaples, Via Vivaldi 43, Caserta, 81100, Italy
AU: Ceulemans, R
AF: UAntwerpen, Universiteitsplein 1, Wilrijk, 2610, Belgium
AU: Ciais, P
AF: LSCE, Orme des Merisiers, Gif-sur-Yvette, 91191, France
AU: Dolman, H A
AF: VUAmsterdam, VUA, Amsterdam, 1081HV, Netherlands
AU: Grace, J
AF: UEdinburgh, School of GeoSciences, Edinburgh, EH9 3JN, United Kingdom
AU: Hollmén, J
AF: Helsinki UT, PO Box 5400, Helsinki, 02015 TKK, Finland
AU: Law, B E
AF: Oregon SU, College of Forestry, Corvallis, OR 97331-5752, United States
AU: Matteucci, G
AF: CNR-ISAFOM, Via Cavour 4, Rende, 87036, France
AU: Papale, D
AF: UTuscia, Forest Science and Environment, Viterbo, 01100, Italy
AU: Piao, S L
AF: LSCE, Orme des Merisiers, Gif-sur-Yvette, 91191, France
AU: Reichstein, M
AF: Max Planck Biogeochemistry, PO Box 100164, Jena, 07701, Germany
AU: Schulze, E D
AF: Max Planck Biogeochemistry, PO Box 100164, Jena, 07701, Germany
AU: Sulkava, M
AF: Helsinki UT, PO Box 5400, Helsinki, 02015 TKK, Finland
AU: Tang, J
AF: Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL 60022, United States
AU: Janssens, I A
AF: UAntwerpen, Universiteitsplein 1, Wilrijk, 2610, Belgium
AB: Nitrogen (N) limitation constrains forest productivity over large areas. Where N is suboptimal, provision of N through fertilization or atmospheric deposition stimulates gross primary productivity (GPP) directly or by enabling forests to benefit from increased atmospheric CO₂. Nitrogen deposition also enhances carbon sequestration, but the mechanisms via which this stimulation occurs have so far not been unravelled. Here we analyze observations from 133 forests to decipher how it influences the fate of the absorbed carbon. We find that N-deposition stimulate GPP which, in turn, results in an increase in biomass production (NPP). Whilst the increase in woody biomass production is proportional to the increase in GPP, a disproportional high amount of carbon is used for the production short-lived tissues such as roots and foliage, thereby increasing carbon-inputs to the soil. Nitrogen deposition also strongly retarded heterotrophic respiration and the associated carbon-losses from the soil. Thus, N-deposition strengthened the CO₂ sink in the boreal and temperate regions, which are typically N-limited. A future shift in N-deposition towards tropical regions will not necessarily result in a similar increased sink-strength, because these regions are typically not N-limited but suffer from phosphorus, potassium and molybdenum deficiencies.
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0469 Nitrogen cycling
SC: Biogeosciences [B]
MN: 2007 Fall Meeting