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Estimating canopy gross primary production by combining phloem stable isotopes with canopy and mesophyll conductances
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  • Antoine Vernay,
  • Xianglin Tian,
  • Jinshu Chi,
  • Sune Linder,
  • Annikki Makela,
  • Ram Oren,
  • Matthias Peichl,
  • Zsofia Stangl,
  • Pantana Tor-Ngern,
  • John Marshall
Antoine Vernay
Swedish University of Agricultural Sciences - Umea Campus
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Xianglin Tian
University of Helsinki
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Jinshu Chi
Swedish University of Agricultural Sciences - Umea Campus
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Sune Linder
Southern Swedish Forest Research Centre,Swedish University of Agricultural Sciences (SLU), PO Box 49, SE-23053
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Annikki Makela
University of Helsinki
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Ram Oren
Duke University
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Matthias Peichl
Swedish University of Agricultural Sciences - Umea Campus
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Zsofia Stangl
Swedish University of Agricultural Sciences - Umea Campus
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Pantana Tor-Ngern
Chulalongkorn University
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John Marshall
Swedish University of Agricultural Sciences - Umea Campus
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Abstract

Gross primary production (GPP) is a key component of the forest carbon cycle. However, our knowledge of GPP at the stand scale remains uncertain because estimates derived from eddy covariance (EC) rely on semi-empirical modeling and the assumptions of the EC technique are sometimes not fully met. We propose using the sap flux/isotope method as an alternative way to estimate canopy GPP, termed GPPiso/SF, at the stand scale and at daily resolution. It is based on canopy conductance inferred from sap flux and intrinsic water-use efficiency estimated from the stable carbon isotope composition of phloem contents. The GPPiso/SF estimate was further corrected for seasonal variations in photosynthetic capacity and mesophyll conductance. We compared our estimate of GPPiso/SF to the GPP derived from PRELES, a model parameterised with EC data. The comparisons were performed in a highly instrumented, boreal Scots pine forest in northern Sweden, including a nitrogen fertilised and a reference plot. The resulting annual and daily GPPiso/SF estimates agreed well with PRELES, in the fertilised plot and the reference plot. We discuss the GPPiso/SF method as an alternative which can be widely applied without terrain restrictions, where the assumptions of EC are not met.

Peer review status:Published

29 May 2020Submitted to Plant, Cell & Environment
29 May 2020Submission Checks Completed
29 May 2020Assigned to Editor
02 Jun 2020Reviewer(s) Assigned
03 Jun 2020Review(s) Completed, Editorial Evaluation Pending
08 Jun 2020Editorial Decision: Revise Minor
21 Jun 20201st Revision Received
22 Jun 2020Submission Checks Completed
22 Jun 2020Assigned to Editor
23 Jun 2020Review(s) Completed, Editorial Evaluation Pending
23 Jun 2020Editorial Decision: Accept
24 Jul 2020Published in Plant, Cell & Environment. 10.1111/pce.13835