Influences of light and humidity on carbonyl sulfide-based estimates of photosynthesis

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Kooijmans , L M J , Sun , W , Aalto , J , Erkkilä , K-M , Maseyk , K , Seibt , U , Vesala , T , Mammarella , I & Chen , H 2019 , ' Influences of light and humidity on carbonyl sulfide-based estimates of photosynthesis ' , Proceedings of the National Academy of Sciences of the United States of America , vol. 116 , no. 7 , pp. 2470-2475 . https://doi.org/10.1073/pnas.1807600116

Title: Influences of light and humidity on carbonyl sulfide-based estimates of photosynthesis
Author: Kooijmans, Linda M. J.; Sun, Wu; Aalto, Juho; Erkkilä, Kukka-Maaria; Maseyk, Kadmiel; Seibt, Ulrike; Vesala, Timo; Mammarella, Ivan; Chen, Huilin
Contributor: University of Helsinki, INAR Physics
University of Helsinki, Department of Physics
University of Helsinki, Institute for Atmospheric and Earth System Research (INAR)
University of Helsinki, INAR Physics
Date: 2019-02-12
Language: eng
Number of pages: 6
Belongs to series: Proceedings of the National Academy of Sciences of the United States of America
ISSN: 0027-8424
URI: http://hdl.handle.net/10138/305664
Abstract: Understanding climate controls on gross primary productivity (GPP) is crucial for accurate projections of the future land carbon cycle. Major uncertainties exist due to the challenge in separating GPP and respiration from observations of the carbon dioxide (CO2) flux. Carbonyl sulfide (COS) has a dominant vegetative sink, and plant COS uptake is used to infer GPP through the leaf relative uptake (LRU) ratio of COS to CO2 fluxes. However, little is known about variations of LRU under changing environmental conditions and in different phenological stages. We present COS and CO2 fluxes and LRU of Scots pine branches measured in a boreal forest in Finland during the spring recovery and summer. We find that the diurnal dynamics of COS uptake is mainly controlled by stomatal conductance, but the leaf internal conductance could significantly limit the COS uptake during the daytime and early in the season. LRU varies with light due to the differential light responses of COS and CO2 uptake, and with vapor pressure deficit (VPD) in the peak growing season, indicating a humidity-induced stomatal control. Our COS-based GPP estimates show that it is essential to incorporate the variability of LRU with environmental variables for accurate estimation of GPP on ecosystem, regional, and global scales.
Subject: carbonyl sulfide
photosynthesis
stomatal conductance
carbon cycle
STOMATAL CONDUCTANCE
EXCHANGE
COS
FLUXES
MODEL
VEGETATION
ANHYDRASE
CONSUMPTION
ATMOSPHERE
FOREST
1172 Environmental sciences
4112 Forestry
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