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| Titel |
Stomata size and spatial pattern effects on leaf gas exchange - a quantitative assessment of plant evolutionary choices |
| VerfasserIn |
Dani Or, Shmuel Assouline, Milad Aminzadeh, Erfan Haghighi, Stan Schymanski, Peter Lehmann |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250099058
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| Publikation (Nr.) |
 EGU/EGU2014-14801.pdf |
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| Zusammenfassung |
| Land plants developed a dynamically gas-permeable layer at their leaf surfaces to allow CO2
uptake for photosynthesis while controlling water vapor loss through numerous adjustable
openings (stomata) in the impervious leaf epidermis. Details of stomata structure, density and
function may vary greatly among different plant families and respond to local environmental
conditions, yet they share basic traits in dynamically controlling gaseous exchange rates by
varying stomata apertures. We implement a pore scale gas diffusion model to quantitatively
interpret the functionality of different combinations of stomata size and pattern on
leaf gas exchange and thermal management based on data from fossil records and
contemporary data sets. Considering all available data we draw several general
conclusions concerning stomata design considerations: (1) the sizes and densities of
stomata in the available fossil record leaves were designed to evaporate at rates in the
range 0.75-¤e/e0 -¤0.99 (relative to free water evaporation); (2) examination of
evaporation curves show that for a given stomata size, the density (jointly defining the
leaf evaporating area when fully open) was chosen to enable a high sensitivity in
reducing evaporation rate with incremental stomatal closure, nevertheless, results
show the design includes safety margins to account for different wind conditions
(boundary layer thickness); (3) scaled for mean vapor flux, the size of stomata plays
a minor role in the uniformity of leaf thermal field for a given stomata density.
These principles enable rationale assessment of plant response to raising CO2,
and provide a physical framework for considering the consequences of different
stomata patterns (patchy) on leaf gas exchange (and thermal regime). In contrast
with present quantitative description of traits and functionality of these dynamic
covers in terms of gaseous diffusion resistance (or conductance), where stomata size,
density and spatial pattern are lumped into a single effective resistance parameter,
the present approach enables derivation of nuanced insights and offers predictive
capabilities that link changes in stomata structure and geometrical attributes to
quantifying environmental influences and feedbacks on leaf structure and function. |
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