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Incorporating non-stomatal limitation improves the performance of leaf and canopy models at high vapour pressure deficit
- Source :
- Addi. Archivo Digital para la Docencia y la Investigación, instname, Addi: Archivo Digital para la Docencia y la Investigación, Universidad del País Vasco
- Publication Year :
- 2019
- Publisher :
- Oxford University Press (OUP), 2019.
-
Abstract
- Vapour pressure deficit (D) is projected to increase in the future as temperature rises. In response to increased D, stomatal conductance (gs) and photosynthesis (A) are reduced, which may result in significant reductions in terrestrial carbon, water and energy fluxes. It is thus important for gas exchange models to capture the observed responses of gs and A with increasing D. We tested a series of coupled A-gs models against leaf gas exchange measurements from the Cumberland Plain Woodland (Australia), where D regularly exceeds 2 kPa and can reach 8 kPa in summer. Two commonly used A-gs models were not able to capture the observed decrease in A and gs with increasing D at the leaf scale. To explain this decrease in A and gs, two alternative hypotheses were tested: hydraulic limitation (i.e., plants reduce gs and/or A due to insufficient water supply) and non-stomatal limitation (i.e., downregulation of photosynthetic capacity). We found that the model that incorporated a non-stomatal limitation captured the observations with high fidelity and required the fewest number of parameters. Whilst the model incorporating hydraulic limitation captured the observed A and gs, it did so via a physical mechanism that is incorrect. We then incorporated a non-stomatal limitation into the stand model, MAESPA, to examine its impact on canopy transpiration and gross primary production. Accounting for a non-stomatal limitation reduced the predicted transpiration by ~19%, improving the correspondence with sap flow measurements, and gross primary production by ~14%. Given the projected global increases in D associated with future warming, these findings suggest that models may need to incorporate non-stomatal limitation to accurately simulate A and gs in the future with high D. Further data on non-stomatal limitation at high D should be a priority, in order to determine the generality of our results and develop a widely applicable model. © The Author(s) 2019. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. J.Y. was supported by a PhD scholarship from Hawkesbury Institute for the Environment, Western Sydney University. M.G.D.K. acknowledges funding from the Australian Research Council (ARC) Centre of Excellence for Climate Extremes (CE170100023), the ARC Discovery Grant (DP190101823) and support from the NSW Research Attraction and Acceleration Program. EucFACE was built as an initiative of the Australian Government as part of the Nation-building Economic Stimulus Package and is supported by the Australian Commonwealth in collaboration with Western Sydney University. It is also part of a Terrestrial Ecosystem Research Network Super-site facility.
- Subjects :
- 0106 biological sciences
0301 basic medicine
Canopy
summer
Stomatal conductance
warming
Vapor Pressure
Physiology
Vapour Pressure Deficit
Flow (psychology)
Plant Biology & Botany
Plant Science
Atmospheric sciences
Photosynthesis
01 natural sciences
0602 Ecology, 0607 Plant Biology, 0705 Forestry Sciences
03 medical and health sciences
sap flow
alternative hypothesis
Transpiration
canopy
water supply
Australia
Primary production
Water
Plant Transpiration
flow measurement
Photosynthetic capacity
leaf gas exchange
writing
Plant Leaves
030104 developmental biology
sweating
stomatal conductance
Plant Stomata
Environmental science
down regulation
010606 plant biology & botany
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Addi. Archivo Digital para la Docencia y la Investigación, instname, Addi: Archivo Digital para la Docencia y la Investigación, Universidad del País Vasco
- Accession number :
- edsair.doi.dedup.....e373c9f44ae44967262a62c58e60f8ef