Project at a Glance

Title: Effects of acid rain on plants and soils in California

Principal Investigator / Author(s): McColl, John G.

Contractor: UC Berkeley

Contract Number: A8-136-31

Research Program Area: Ecosystem & Multimedia Effects

Topic Areas: Acid Deposition, Ecosystem Impacts


Effects of acid rain on some California plants and soils were studied. Plants growing in soil were treated with simulated rain of varying acidity. Direct foliar damage was not apparent, other than under extreme conditions which are not normally experienced in the field. Sugar beet was the most sensitive of the agronomic species tested. Germination of Douglas Fir seed was inhibited under severe acid conditions. Similarly, growth of two-year old conifer seedlings showed little deleterious effects. except under most severe treatments. Acid rain affected plant productivity (positively and negatively), and the effect for a given input acid was largely predicated by the soil in which the plants were growing. A simple, reliable laboratory method was developed for deteni1ining potential sensitivity of soils to leaching by acid rain. Silicic soils of low cation-exchange capacity. low base-saturation and shallow depths are most sensitive. Many granitic soils of the Sierra Nevada are sensitive because of their immaturity, geologic parent material. geographic location. and because possible remedial practices in these range and forest soils are impossible. Future research should focus on non-agronomic plants and soils on a long-term basis, on possible alteration of soil microbial processes, and on leaching of toxic elements from soils that may harm drainage waters.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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