Figure 5.

Stomatal resistance of cottonwood, willow and saltcedar plants under stressed and unstressed conditions. Clusters of plants (6 per species) were grown outdoors in Tucson, Arizona. Sap flow sensors measured plant transpiration over an eight day period in summer, and micrometeorological data were used to model the diurnal course stomatal resistance for each species based on potential ET. Plants were then subjected to drought or salt stress (3 per treatment) for the final 3 days of the measurement period. Stomatal resistance was calculated based on sap flow measurements at three time points in the mid-day period, and plotted against unstressed stomatal resistance calculated from meteorological data. Plants are combined across replicates and stress treatments in the plot. From data in [36].