Stomatal response to environmental variables in two tropical forest species during the dry season in Nigeria.
Measurements were made of stomatal conductance of Gmelina arborea and Tectona grandis over a 3-wk period in Jan. Stomatal conductance increased rapidly in the early morning and decreased after midday in both species but values in G. arborea were less than those in T. grandis. Leaf water potential was usually lower in Gmelina than in teak. Stomatal conductance in both species was mainly controlled by irradiance and air saturation deficit; a model relating stomatal conductance to these two variables accounted for >80% of variation. Transpiration rates calculated from conductances predicted by the model agreed closely with those calculated from measured conductances and environmental variables. Hydraulic resistances were similar for both species. From authors' summary.