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Research article - Peer-reviewed, 2024

Partitioning gross primary production of a boreal forest among species and strata: A multi-method approach

Vernay, Antoine; Hasselquist, Niles; Leppa, Kersti; Klosterhalfen, Anne; Lopez, Jose Gutierrez; Stangl, Zsofia R.; Chi, Jinshu; Kozii, Nathaliia; Marshall, John

Abstract

We compared three methods of estimating gross primary production (GPP) of a boreal forest dominated by spruce and pine with the goals of 1) converging on the best estimate and 2) disaggregating the GPP among the two canopy species and the understory stratum. The three methods were: 1) eddy covariance (EC), 2) a soilvegetation-atmosphere transfer model, APES, driven by meteorological data, and 3) an ecophysiological approach (Iso/SF) based on sap flux and phloem δ13C, where sap flux is used to estimate stomatal conductance and δ13C is used to estimate intrinsic water-use efficiency (WUEi). The EC and APES methods agreed rather well, which was expected because APES was developed to predict eddy covariance data. The Iso/SF method, which is based on independent data, yielded lower estimates. This was partly because it excluded understory vegetation from the GPP estimate. We also found that the measured sap flux/transpiration estimates for spruce in Iso/SF were much lower than those from APES. In contrast, the absolute values for Scots pines were very similar between the two methods, especially in the summer. In both species, the seasonal dynamics match well among all methods. This multi-method approach allowed us to detect possible problems in the spruce sap-flux measurements, but successfully upscaled pine data from ecophysiological traits to stand and ecosystem functioning.

Keywords

APES; Boreal forest; Eddy -covariance; Gross primary production; Phloem delta 13 C; Species partitioning

Published in

Agricultural and Forest Meteorology
2024, Volume: 345, article number: 109857