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Anatomical adjustments of the tree hydraulic pathway decrease canopy conductance under long-term elevated CO$_2$

Gattmann, Marielle 1; McAdam, Scott A. M.; Birami, Benjamin 1; Link, Roman; Nadal-Sala, Daniel 2; Schuldt, Bernhard; Yakir, Dan; Ruehr, Nadine K. ORCID iD icon 2,3
1 Institut für Meteorologie und Klimaforschung (IMK), Karlsruher Institut für Technologie (KIT)
2 Institut für Meteorologie und Klimaforschung – Atmosphärische Umweltforschung (IMK-IFU), Karlsruher Institut für Technologie (KIT)
3 Institut für Geographie und Geoökologie (IFGG), Karlsruher Institut für Technologie (KIT)

Abstract:

The cause of reduced leaf-level transpiration under elevated CO$_2$ remains largely elusive. Here, we assessed stomatal, hydraulic, and morphological adjustments in a long-term experiment on Aleppo pine (Pinus halepensis) seedlings germinated and grown for 22–40 months under elevated (eCO$_2$; c. 860 ppm) or ambient (aCO$_2$; c. 410 ppm) CO$_2$. We assessed if eCO$_2$-triggered reductions in canopy conductance (g$_c$) alter the response to soil or atmospheric drought and are reversible or lasting due to anatomical adjustments by exposing eCO$_2$ seedlings to decreasing [CO$_2$]. To quantify underlying mechanisms, we analyzed leaf abscisic acid (ABA) level, stomatal and leaf morphology, xylem structure, hydraulic efficiency, and hydraulic safety. Effects of eCO$_2$ manifested in a strong reduction in leaf-level g$_c$ (−55%) not caused by ABA and not reversible under low CO$_2$ (c. 200 ppm). Stomatal development and size were unchanged, while stomatal density increased (+18%). An increased vein-to-epidermis distance (+65%) suggested a larger leaf resistance to water flow. This was supported by anatomical adjustments of branch xylem having smaller conduits (−8%) and lower conduit lumen fraction (−11%), which resulted in a lower specific conductivity (−19%) and leaf-specific conductivity (−34%). ... mehr


Verlagsausgabe §
DOI: 10.5445/IR/1000152634
Veröffentlicht am 14.11.2022
Originalveröffentlichung
DOI: 10.1093/plphys/kiac482
Scopus
Zitationen: 1
Dimensions
Zitationen: 2
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung – Atmosphärische Umweltforschung (IMK-IFU)
Institut für Geographie und Geoökologie (IFGG)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2022
Sprache Englisch
Identifikator ISSN: 0032-0889, 1532-2548
KITopen-ID: 1000152634
HGF-Programm 12.11.24 (POF IV, LK 01) Adaptation of natural landscapes to climate change
Erschienen in Plant Physiology
Verlag American Society of Plant Biologists
Band 191
Heft 1
Seiten 252-264
Vorab online veröffentlicht am 17.10.2022
Nachgewiesen in Web of Science
Dimensions
Scopus
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