Modelling stomatal conductance in a northern deciduous forest, Chalk River, Ontario

1994 ◽  
Vol 24 (5) ◽  
pp. 904-910 ◽  
Author(s):  
J. Harry McCaughey ◽  
Antonio Iacobelli
Keyword(s):  
Stomatal Conductance ◽  
Least Squares ◽  
Environmental Variables ◽  
Deciduous Forest ◽  
Vapour Pressure Deficit ◽  
Multiple Linear Regression Model ◽  
Nonlinear Least Squares ◽  
Global Solar Radiation ◽  
White Birch ◽  
Conductance Data

Modelling results of stomatal conductance of trembling aspen (Populustremuloides Michx.) and white birch (Betulapapyrifera Marsh.) are reported. Stomatal conductance for the two species was related to global solar radiation, vapour pressure deficit, and air temperature using both linear and nonlinear least squares approaches. Both approaches provided an equally poor fit when relating the large scatter of stomatal conductance data to each of the environmental variables separately. However, an additive, multiple linear regression model and a multiplicative, nonlinear least squares model were able to explain between 50 and 62% of the variability in stomatal conductance when all three environmental variables were included in the models. The two models were able to track changes in stomatal conductance from one half-hour period to the next.

Stomatal conductance in a northern temperate deciduous forest: temporal and spatial patterns

1993 ◽  
Vol 23 (2) ◽  
pp. 245-252 ◽  
Author(s):  
Antonio Iacobelli ◽  
J. Harry McCaughey
Keyword(s):  
Stomatal Conductance ◽  
Deciduous Forest ◽  
Vapour Pressure Deficit ◽  
Diurnal Changes ◽  
White Birch ◽  
Temperate Deciduous Forest ◽  
Vertical Variation ◽  
Temperate Deciduous ◽  
Temporal And Spatial ◽  
Rain Events

Stomatal conductance measurements were obtained in the summer of 1989 in a deciduous forest near Chalk River, Ontario. Seasonal changes in stomatal conductance of trembling aspen (Populustremuloides Michx.) and white birch (Betulapapyrifera Marsh.) were related to changes in soil water content. Rehydration of water stores in trees following each of the two major rain events observed over the growing season likely influenced the magnitude of stomatal conductance. Diurnal changes in stomatal conductance were found to be related primarily to changes in solar radiation, vapour-pressure deficit, and air temperature. There was considerable vertical variation in stomatal conductance, such that the canopy could be divided into a total of five layers. There was also considerable variation in stomatal conductance trees.

The interpretation of the variations in leaf water potential and stomatal conductance found in canopies in the field

1976 ◽  
Vol 273 (927) ◽  
pp. 593-610 ◽  
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Vapour Pressure ◽  
Environmental Variables ◽  
Turgor Pressure ◽  
Radiant Energy ◽  
Vapour Pressure Deficit ◽  
Leaf Water ◽  
Scatter Diagram

Attempts to correlate values of stomatal conductance and leaf water potential with particular environmental variables in the field are generally of only limited success because they are simultaneously affected by a number of environmental variables. For example, correlations between leaf water potential and either flux of radiant energy or vapour pressure deficit show a diurnal hysteresis which leads to a scatter diagram if many values are plotted. However, a simple model may be adequate to relate leaf water potential to the flow of water through the plant. The stomatal conductance of illuminated leaves is a function of current levels of temperature, vapour pressure deficit, leaf water potential (really turgor pressure) and ambient CO 2 concentration. Consequently, when plotted against any one of these variables a scatter diagram results. Physiological knowledge of stomatal functioning is not adequate to provide a mechanistic model linking stomatal conductance to all these variables. None the less, the parameters describing the relationships with the variables can be conveniently estimated from field data by a technique of non-linear least squares, for predictive purposes and to describe variations in response from season to season and plant to plant.

Stomatal Responses to Environmental Variables in Shade and Sun Grown Coffee Plants in Mexico

1985 ◽  
Vol 21 (3) ◽  
pp. 249-258 ◽  
Author(s):  
Luis Fanjul ◽  
R. Arreola-Rodriguez ◽  
M. P. Mendez-Castrejon
Keyword(s):  
Stomatal Conductance ◽  
Air Temperature ◽  
Environmental Conditions ◽  
Vapour Pressure ◽  
Environmental Variables ◽  
Vapour Pressure Deficit ◽  
Net Photosynthesis ◽  
Stomatal Movement ◽  
Stomatal Responses ◽  
Coffee Plants

SUMMARYThe influence of air temperature (T), vapour pressure deficit (vpd), irradiance (Q) and leaf water potential (ψ) on diurnal stomatal movement of coffee plants was examined under field and controlled environmental conditions. Leaves of plants grown under shade had larger stomatal conductance (g) values than plants grown in open sun. Stomatal responses to vpd under constant temperature conditions were very strong, indicating that ambient humidity could play a major role in controlling stomatal aperture. Changes in g as vpd increased probably contributed to observed reductions in the rate of net photosynthesis (Pn), though the effect of vpd on Pn was smaller.

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