Ecology of SO2 resistance: II. Photosynthetic changes of shrubs in relation to SO2 absorption and stomatal behavior.

In an effort to predict SO2 sensitivity of plants from their morphological and physiological features, the effects of SO2 on photosynthesis were partitioned between stomatal and nonstomatal components for a drought deciduous shrub, Diplacus aurantiacus, and an evergreen shrub, Heteromeles arbutifolia. As predicted, the drought deciduous shrub had the higher gas conductance, and hence SO2 absorptance. However, nonstomatal components also play a role in determining SO2 sensitivity. Apparently a plant with a high intrinsic photosynthetic capacity will be more sensitive to SO2 than one with a lower capacity.