Poster

         Ecophysiology

Effects of stomatal size, spacing, and shape on water vapor diffusion through the leaf epidermis

Presenting Author
Paul Schulte
Description
Stomata play a key role in regulating the exchange of water vapor and CO2 between the leaf and the atmosphere.  Computational models were developed to solve Fick's Law and investigate the roles of the size, spacing, and shape of stomata on the rate of water loss through the stomatal pores.  Simple models of stomata as round were considered with various sizes and spacing of the pores.  Increasing the pore size from 5 to 25 μm led to a 16-fold increase in flux through a group of 5 pores.  Increasing the spacing between stomatal pores from 20 to 90 μm for a 7 x 7 array of pores led to a 27% increase in flux.  When water flux through the pores was calculated per unit pore area the wider 25 μm pores had 36% lower flux than the narrow pores.  These reductions in flux for wide and closely spaced pores are likely due to interactions between the flux fields of pores when in close proximity.  Models were also developed based on shapes of actual stomata from Populus trichocarpa leaves.  Flux through an actual pore was closely similar to a round pore of equal area.  However deviation from round to more elliptical pores of equal area led to an increased flux per pore area.