TY - JOUR
T1 - Influences of light and humidity on carbonyl sulfide-based estimates of photosynthesis
AU - Kooijmans, Linda M.J.
AU - Sun, Wu
AU - Aalto, Juho
AU - Erkkilä, Kukka Maaria
AU - Maseyk, Kadmiel
AU - Seibt, Ulrike
AU - Vesala, Timo
AU - Mammarella, Ivan
AU - Chen, Huilin
PY - 2019/2/12
Y1 - 2019/2/12
N2 -
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 (CO
2
) 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 CO
2
fluxes. However, little is known about variations of LRU under changing environmental conditions and in different phenological stages. We present COS and CO
2
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 CO
2
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.
AB -
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 (CO
2
) 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 CO
2
fluxes. However, little is known about variations of LRU under changing environmental conditions and in different phenological stages. We present COS and CO
2
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 CO
2
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.
KW - Carbon cycle
KW - Carbonyl sulfide
KW - Photosynthesis
KW - Stomatal conductance
U2 - 10.1073/pnas.1807600116
DO - 10.1073/pnas.1807600116
M3 - Article
C2 - 30683727
AN - SCOPUS:85061373273
SN - 0027-8424
VL - 116
SP - 2470
EP - 2475
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 7
ER -
