Effects of field exposures to SO2 on Douglas fir, Agropyron spicatum and Lolium perenne.

Abstract

Grasses spicatum Pursh, (S23) and 2-year old Douglas fir ( (Mirb.) Franco) were exposed to low SO concentrations under field conditions for approximately eleven weeks. SO was released continuously via manifold delivery systems, and provided treatment mean concentrations of 0.007 (ambient air), 0.042, 0.106 and 0.198 ppm. The concentrations in each treatment were approximately log-normally distributed, with standard geometric deviations ranging from 2.58 to 3.24. In both grass species, 0.198 ppm SO caused substantial reduction of total growth. In this was largely the result of impaired root growth, whereas both shoot and root growth of were reduced. 0.106 ppm SO had no significant effect on growth, but reduced root growth of . Growth of Douglas fir was reduced in each of the tree highest concentrations, with root growth being markedly diminished, particularly on trees which showed chlorotic and necrotic injury. However, in these trees the shoot and total leaf weights tended to increase at the highest SO concentrations, suggesting that in these plants injury to leaves stimulated further shoot growth at the expense of root development. Agropyron Lolium perenne L.Pseudotsuga menziesii222L. perenne,A. spicatum2 A. spicatumL. perenne2