This volume presents a body of research conducted over more than thirty years, including an intensive interdisciplinary five-year study begun in 1991. Chapters include studies of the relationships of biogeography and climate to the region's air pollution, the chemical and physiological mechanisms of ozone injury, as well as the impacts of nitrogen-containing pollutants and natural stresses on polluted forests.

During late 1985, the Research Management Committee (RMC) of the National Crop Loss Assessment Network (NCLAN) decided the most ap propriate way to bring the NCLAN program to a successful conclusion was to hold an international conference. It was envisaged as an opportunity to present an overview of results from the NCLAN program and as a chance to view the results in the context of ongoing research by members of the international community. * Although we wanted the Conference to have an assessment orientation, it was also intended for the Conference to focus on current state-of-knowledge. The Conference was designed to overview the needs of crop loss assessment, current approaches to assessment, progress in the development of predictive models, the use of the information for economic predictions, and the application of the data in policy decisions. Every effort was made to assure a broad representation of ideas. The Conference program was developed to evaluate major issues that address regional/national assessments of impacts of atmospheric pollutants on agricultural production. Sessions were structured to address specific issues by invited speakers, and by contributed papers and posters. First, background needs for doing loss assessment research including specific approaches and a rather detailed review of the NCLAN program were addressed (Session I). Session II addressed the needs for defining the exposure environment (e. g. extrapolating to regional concentrations and exposure characterization). Field approaches for determining crop loss were reviewed in Session III."

Since the 1950s, the pines native to the San Bernardino Mountains in Southern California have shown symptoms of decline that have proven to result from exposure to ozone, a major plant-damaging gas in photochemical oxidant air pollution. Because of their proximity to major urban areas, the San Bernardino Mountains have served as a natural laboratory for studying effects of oxidant and acidic air pollution on a mixed-conifer forest. This volume presents a body of research conducted over more than thirty years, including an intensive interdisciplinary five-year study begun in 1991. Chapters include studies of the relationships of biogeography and climate to the region's air pollution, the chemical and physiological mechanisms of ozone injury, as well as the impacts of nitrogen-containing pollutants and natural stresses on polluted forests. The synthesis of such long-term studies provides insights into the combined influences of pollutants on ecosystem function in forested regions with Mediterranean-type climates.