Simulations and observations of patchy stomatal behavior in leaves of Quercus crispula, a cool-temperate deciduous broad-leaved tree species

Abstract

We investigated the occurrence of patchy stomatal behavior in leaves of saplings and a forest canopy tree of Quercus crispula Blume. Through a combination of leaf gas-exchange measurements and numerical simulation, we detected patterns of stomatal closure (either uniform or patchy bimodal) coupled with depression of net assimilation rate (A). There was a clear inhibition of A associated with stomatal closure in leaves of Q. crispula during the day, but the magnitude of inhibition varied among days and growing conditions. Comparisons of observed and simulated A values for both saplings and the canopy tree identified patterns of stomatal behavior that shifted flexibly between uniform and patchy frequency distributions depending on environmental conditions. Bimodal stomatal closure explained severe depression of A in saplings under conditions of relatively high leaf temperature and vapor pressure deficit. Model simulations of A depression through bimodal stomatal closure were corroborated by direct observations of stomatal aperture distribution using Suzuki's Micro-Printing method; these demonstrated that there was a real bimodal frequency distribution of stomatal apertures. Although there was a heterogeneous distribution of stomatal apertures both within and among patches, induction of heterogeneity in intercellular CO₂ concentration among patches, and hence severe depression of A, resulted only from bimodal stomatal closure among patches (rather than within patches).

An overview on isotopic divergences – causes for instability of tree-ring isotopes and climate correlations

“…As long as the yearly mean duration of the midday depression is short and varies little over time, cellulose is a trustable archive for isotope-based climate reconstruction. However, when the decline of the photosynthetic rate is severe (i.e., 60 %; Kets et al, 2010), a reduction of sugar production during this midday depression signifies that all daily conditions may not be imprinted in the isotopic composition of sugars and, consequently, of cellulose. If this phenomenon persists over several days during the growing season, cellulose becomes a biased, incomplete recorder of the diurnal environmental conditions.…”

Heterogeneity of Stomatal Pore Area Is Suppressed by Ambient Aerosol in the Homobaric Species, Vicia faba

“…Areas of coordinated stomatal behavior may range from a few mm to a few cm in extent ( Terashima, 1992 ; Mott and Buckley, 1998 , 2000 ; Mott and Peak, 2007 ) and are often bounded by veins, particularly in heterobaric leaves ( Siebke and Weis, 1995 ; Haefner et al, 1997 ; Weyers and Lawson, 1997 ; Mott and Buckley, 2000 ). Patterns of heterogeneity can be transient, with patches of coherent stomatal response migrating within and even between areoles of heterobaric leaves ( Kamakura et al, 2012 ), even though gas diffusion is restricted to areoles defined by vasculature with bundle sheath extensions ( Terashima, 1992 ; Mott and Buckley, 2000 ).…”

Linkages between diurnal patterns of root respiration and leaf photosynthesis in Quercus crispula and Fagus crenata seedlings

“…Therefore, diurnal patterns in photosynthetic CO 2 exchange under high temperature stress are not always consistently associated with environmental factors, such as PPFD and VPD, or with GPP based on eddy covariance measurements. Diurnal variation in weather patterns is known to cause midday depression of individual leaf physiological traits and to affect CO 2 assimilation (Kamakura et al 2012); however, the direct linkages between diurnal variation, environmental variations, and the physiological traits of roots are only beginning to be recognized.…”