title: Respiration as the main determinant of carbon balance in European forests.
abstract: 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 Protocol. Several studies suggest that the terrestrial biosphere is gaining carbon, 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.
authors.affiliation: University of Tuscia, Department of Forest Environment and Resources, Viterbo, Italy. rik@unitus.it
authors.forename: R
authors.initials: R
authors.lastname: Valentini
authors.forename: G
authors.initials: G
authors.lastname: Matteucci
authors.forename: A J
authors.initials: AJ
authors.lastname: Dolman
authors.forename: E D
authors.initials: ED
authors.lastname: Schulze
authors.forename: C
authors.initials: C
authors.lastname: Rebmann
authors.forename: E J
authors.initials: EJ
authors.lastname: Moors
authors.forename: A
authors.initials: A
authors.lastname: Granier
authors.forename: P
authors.initials: P
authors.lastname: Gross
authors.forename: N O
authors.initials: NO
authors.lastname: Jensen
authors.forename: K
authors.initials: K
authors.lastname: Pilegaard
authors.forename: A
authors.initials: A
authors.lastname: Lindroth
authors.forename: A
authors.initials: A
authors.lastname: Grelle
authors.forename: C
authors.initials: C
authors.lastname: Bernhofer
authors.forename: T
authors.initials: T
authors.lastname: Grünwald
authors.forename: M
authors.initials: M
authors.lastname: Aubinet
authors.forename: R
authors.initials: R
authors.lastname: Ceulemans
authors.forename: A S
authors.initials: AS
authors.lastname: Kowalski
authors.forename: T
authors.initials: T
authors.lastname: Vesala
authors.forename: U
authors.initials: U
authors.lastname: Rannik
authors.forename: P
authors.initials: P
authors.lastname: Berbigier
authors.forename: D
authors.initials: D
authors.lastname: Loustau
authors.forename: J
authors.initials: J
authors.lastname: Gudmundsson
authors.forename: H
authors.initials: H
authors.lastname: Thorgeirsson
authors.forename: A
authors.initials: A
authors.lastname: Ibrom
authors.forename: K
authors.initials: K
authors.lastname: Morgenstern
authors.forename: R
authors.initials: R
authors.lastname: Clement
mesh_terms: D001272:Atmosphere; D002244:Carbon / Q000378:metabolism*; D017753:Ecosystem; D005060:Europe; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis; D012987:Soil; D014197:Trees
chemical_list: D012987:Soil; D002244:Carbon; D010100:Oxygen