H2O/CO2 diffusion rates

Bill Williams bwilliam at oyster.smcm.edu
Wed Nov 11 09:10:19 EST 1992

In article <92311.111507MEK104 at psuvm.psu.edu> , MEK104 at psuvm.psu.edu
>I tend to agree in that I'm skeptical, but I think an important
factor that
>may not be included in some of the theoretical and experimental work
is the
>heat exchange that occurrs from leaf to atmosphere.  To take the
debate full
>circle, could the relative size of individual stomata have an effect
on heat
>exchange?  This could also be way out of whack since I'm not familiar
>with the literature.

Since the relevance of stomata to heat exchange is entirely through
transpiration, I don't see how this could be the case unless data for
transpiration were estimated from direct microscopic measurements of
stomatal aperture, distribution, pore length, and so on.  As far as I
know, no one has successfully modeled the biophysics of transpiration
at that level.  There is someone in Germany (name forgotten) who has
recently set up a gas-exchange apparatus with a transparent cuvette and
a long-distance microscope, so the dimensions of the pores and the
gross leaf conductance can be compared.  I haven't seen any results
yet, but they should be exciting.
William E. Williams, bwilliam at oyster.smcm.edu
Divison of Natural Sciences and Mathematics
St. Mary's College of Maryland
St. Mary's City, MD 20686

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