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Research article - Peer-reviewed, 2020

Estimating canopy gross primary production by combining phloem stable isotopes with canopy and mesophyll conductances

Vernay, Antoine; Tian, Xianglin; Chi, Jinshu; Linder, Sune; Makela, Annikki; Oren, Ram; Peichl, Matthias; Stangl, Zsofia R.; Tor-Ngern, Pantana; Marshall, John D.

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 modelling 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 GPP(iso/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 GPP(iso/SF)estimate was further corrected for seasonal variations in photosynthetic capacity and mesophyll conductance. We compared our estimate of GPP(iso/SF)to the GPP derived from PRELES, a model parameterized with EC data. The comparisons were performed in a highly instrumented, boreal Scots pine forest in northern Sweden, including a nitrogen fertilized and a reference plot. The resulting annual and daily GPP(iso/SF)estimates agreed well with PRELES, in the fertilized plot and the reference plot. We discuss the GPP(iso/SF)method as an alternative which can be widely applied without terrain restrictions, where the assumptions of EC are not met.

Keywords

boreal forest; intrinsic water-use efficiency; mesophyll conductance; nitrogen fertilization; phloem delta C-13; PRELES; sap flux; stand transpiration

Published in

Plant, Cell and Environment
2020, volume: 43, number: 9, pages: 2124-2142

Authors' information

Vernay, Antoine
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Tian, Xianglin
Univ Helsinki
Chi, Jinshu
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre
Makela, Annikki
Univ Helsinki
Oren, Ram
Univ Helsinki
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Stangl , Zsofia Réka (Stangl, Zsofia Réka)
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Tor-Ngern, Pantana
Chulalongkorn Univ
Marshall, John D (Marshall, John)
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management

UKÄ Subject classification

Ecology

Publication Identifiers

DOI: https://doi.org/10.1111/pce.13835

URI (permanent link to this page)

https://res.slu.se/id/publ/106977