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- Title
Mesophyll conductance measured at the whole-tree canopy level does not respond to elevated temperature.
- Authors
Gimeno, Teresa E.; Campany, Courtney E.; Barton, Craig M. V.; Marshall, John D.
- Abstract
Mesophyll conductance (gmes) plays a central role in the regulation of plant-atmosphericexchange of carbon and water from the leaf up to the whole canopy. Nonetheless,most commonly available techniques for measuring gmes are still costly and/ortime-consuming and thus are usually limited to the leaf level. Hence, we lack a holisticunderstanding of how gmes scales to the canopy level. Here, for the first time, we presentmeasurements of whole-tree canopy gmes, calculated from concurrent measurements ofwhole-tree discrimination against 13C (Δ13C) and whole-tree gas-exchange measuredover the course of one day. We measured gmes, photosynthesis (A), transpiration(E) and phloem carbon isotopic composition (δ13Cphloem) once a month overone growing season (October-April) in large, field-grown Eucalyptus tereticornistrees. Six trees were exposed to ambient and six to warmed air-temperature (3 ˚ Cabove ambient). Our results showed that at the canopy level, gmes strongly limitsA and that this limitation is greater in spring and autumn than in the peak of thegrowing season. Warming did not increase gmes at the canopy level, in agreement withleaf-level measurements on the same trees. Lack of a significant effect of warming onboth leaf- and canopy-level gmes contrasts with most leaf-level observations fromprevious studies. Finally, we suggest that δ13Cphloem serves as a good proxy ofcanopy-integrated gmes and, once calibrated, for whole-tree water-use efficiency.
- Subjects
HIGH temperature physics; EUCALYPTUS; CARBON isotopes; GROWING season; PHLOEM; AUTUMN
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article