Stomatal conductance in a tropical xerophilous shrubland at a lava substratum

Abstract

Diurnal variation in leaf stomatal conductance (gs) of three xerophilous species (Buddleia cordata, Senecio praecox and Dodonaea viscosa) was measured over a 10-month period during the dry and wet seasons in a shrubland that is developing in a lava substratum in Mexico. Averaged stomatal conductances were 147 and 60.2 (B. cordata), 145 and 24.8 (D. viscosa) and 142.8 and 14.1 mmol m(-2) s(-1) (S. praecox) during the wet and dry season respectively. Leaf water potential (Psi) varied in a range of -0.6 to -1.2 (S. praecox), -0.6 to -1.8 (B. cordata) and -0.9 to -3.4 MPa (D. viscosa) during the same measurement periods. Stomata were more sensitive to changes in irradiance, air temperature and leaf-air vapour pressure difference in the rainy season than the dry season. Although stomatal responses to Psi were difficult to distinguish in any season (dry or rainy), data for the entire period of measurement showed a positive correlation, stomata tending to open as Psi increased, but there is strong evidence of isohydric behaviour in S. praecox and B. cordata. A multiplicative model relating gs to environmental variables and to Psi accounted for 79%-83% of the variation of gs in three sites (pooled data); however, the performance of the model was poorer (60%-76%) for individual species from other sites not included in the pooled data.

The Urban Tree as a Tool to Mitigate the Urban Heat Island in Mexico City: A Simple Phenomenological Model

“…Stomatal conductance was parameterized as a function of microclimate variables using the envelope function method (Fanjul and Barradas, 1985; Barradas et al, 2004) by: where g ( Q N ), g (VPD), and g ( T A ) are the envelope curve functions of normalized g S ( g SMAX = 1) that depend on Q N , VPD, and T A and are as follows: g ( Q N ) = ( a + Q N )/( b + Q N ), g (VPD) = c + d VPD, and g ( T A ) = e + f T A + g T A 2 , where a , b , c , d , e , f , and g are parameters of the model.…”

“…The release of water vapor corresponding to these heat loss values ranges from 0.28 to 12 L m −2 d −1 . Transpiration is mainly controlled by stomatal resistance and is dominated by environmental conditions (e.g., Jones, 1992; Meinzer et al, 1993), whereas stomatal resistance depends on the physiological behavior of the plant and is controlled by environmental conditions (e.g., Whitehead et al, 1981; Jones, 1992; Barradas et al, 2004). Therefore, transpiration rates are different among plant species, and individuals of the same species may present transpiration rate variations depending on the prevailing environmental conditions.…”

Stomatal responses of tree species from the cloud forest in central Veracruz, México

“…PAR), (2) the points below the selected function are the result of changes in the other variables (e.g. VPD and T A ), and (3) there are not synergistic interactions among variables (Fanjul and Barradas, 1985;Ramos-Vázquez and Barradas, 1998;Barradas et al, 2004). The relationship of g S in terms of air temperature (T A ) is given by the envelope values that fit a quadratic equation:…”

“…In order to compare ecophysiological responses among species measurements of physiological traits and climate variables must be taken as simultaneously as possible (Jones, 1992;Barradas et al, 2004;Barradas, 2014a, b, 2015), hence, measurements of physiological traits and climate variables were conducted under greenhouse conditions. Study Area.…”

“…Microenvironment factors such as photosynthetically active radiation, air humidity, air temperature, soil water availability, among other factors, affect stomatal movement and conductance (Jarvis, 1976;Fanjul and Barradas, 1985;Jones, 1992;Buckley, 2005;Buckley and Mott, 2013). Stomatal conductance (g S ) is an important physiological trait because stomatal function plays a key role in plant physiology (Jones, 1992;Meinzer et al, 1997;Barradas et al, 1994Barradas et al, , 2004Buckley, 2005;Esperón-Rodríguez and Barradas, 2014a). Also, stomatal behavior is considered a plant response to climate, as it controls transpiration (water status) and CO 2 assimilation, playing an important role in photosynthesis and plant productivity (Jones, 1992).…”