Modelling Stomatal Behaviour and and Photosynthesis of Eucalyptus grandis

Abstract

Stomatal conductances, CO2 assimilation, transpiration and intercellular CO2 mol fractions of Eucalyptus grandis leaves were measured in the field using a portable, controlled environment cuvette. Test leaves were subjected to a range of temperatures, humidities, photon irradiances and external CO2 mol fractions. An empiral function, gsw = g0 + g1 Ahs/(cs-I'), was able to account for steady- state stomatal conductances g*sw, over a wide range of environmental conditions and leaf photosynthetic capacities. In this equation, termed the stomatal constraint function, A is CO2 assimilation rate, hs and cs are relative humidity and CO2 mol fraction at the leaf surface respectively, I' is the CO2 compensation point, g0 is conductance at A = 0 and gl is an empirical coefficient. Equations describing the supply of CO2 through stomata and demand for CO2 in photosynthesis were solved simultaneously with the constraint function to give a combined model of stomatal conductance, CO2 assimilation and intercellular CO2 mol fraction in terms of external environmental factors and several parameters describing C3 photosynthesis. The model provided a good description of experimental observations.

Response of central Siberian Scots pine to soil water deficit and long‐term trends in atmospheric CO2concentration

“…If an appreciable internal resistance is assumed, then the Rubisco kinetic constants must be modified accordingly [von Caemmerer et al, 1994]. Especially as the study here is concerned with long-term trends and short-term fluctuations in D 13 C rather than the absolute values (the latter being confounded in any case by the large but uncertain difference between the d 13 C of cellulose versus that of bulk leaf carbon discussed in section 3.2), then especially as the absolute magnitude of the internal resistance in pine leaves is uncertain, the usual simple simplification of C i = C C allows the substitution of either (A17) or (A18) into (A13)), giving for the V max case Leuning [1990].…”

Modeling permafrost thaw and ecosystem carbon cycle under annual and seasonal warming at an Arctic tundra site in Alaska

“…where Γ is the CO 2 compensation point in the absence of day respiration in ppmv and is a function of leaf temperature [Leuning, 1990], C i is intercellular CO 2 concentration in ppmv, V c is carboxylation rate and depends on maximum carboxylation rate (v cmax ), maximum rate of potential electron transport (j max ), Michaelis-Menton constant for CO 2 carboxylation (K c ) or for O 2 oxygenation (K o ), C i , absorbed photosynthetically active radiation (Q), and canopy leaf area index (L). Parameters v cmax , j max , K c , and K o all vary with leaf temperature [Leuning, 1990].…”

“…Γ is the CO 2 concentration point of photosynthesis in mol m À1 and is a function of canopy temperature (T c ) [Leuning, 1990]; a 1 and D 0 are two model parameters (a = 4 for C4 plant and = 9 for C3 plants, D 0 = 1500 Pa); f wsoil is the influence of soil water limitation on stomatal conductance and is calculated as…”

“…In the surface flux submodel, canopy photosynthesis and transpiration is coupled through stomatal conductance that is modeled using the following model [Ball et al, 1987;Leuning, 1990]:…”

A coupled model of stomatal conductance and photosynthesis for winter wheat

“…The apparent simplicity of BWB model has led to its adoption by modellers working at the scale of individual leaves (e.g. Leuning 1990, Tenhunen et al 1990, Collatz et al 1991, Kim and Lieth 2003, Yu et al 2004, Messinger et al 2006, at the scale of canopies (Hatton et al 1992), at the landscape scale (McMurtrie et al 1992), and in some global climate models (Sellers et al 1992). However, BWB model and its subsequently revised model can not predict the irradiance (I)-response curve of g s of plant when relative humidity (h s ) and CO 2 concentration at leaf surface (C s ) are held constant.…”