9603659 Peterjohn Recent declines in stratospheric ozone may expose native plants to greater levels of ultraviolet-B radiation (UV-B). While numerous studies have investigated the potentially damaging effects of UV-B on agricultural plants, few studies have examined how UV-B affects native plants or important ecosystem processes. In this project, two field experiments will be conducted to determine whether UV-B changes the chemical composition of native plants in ways that alter the rate of nutrient release from decomposing plant tissue. Decomposition of deal plant tissue is the major source of plant nutrients in natural ecosystems, and changes in the rate of decomposition may significantly alter soil fertility. Six species of native plants will be grown under UV-B levels corresponding to a 0, 16, and 32% decrease in stratospheric ozone. The effect of removing normal levels of UV-B will also be examined. Data from this project will be used to test existing models of soil nutrient dynamics. These models will then be used to evaluate whether the effects of a major change in UV-B are likely to have an important impact on soil fertility.
