In 1972, a multi-disciplinary team of ecologists assembled to monitor and analyze some of the ecological consequences of photochemical oxidant air pollutants in California Mixed Conifer Forest ecosystems of the San Bernardino Mountains east of Los Angeles. The purposes included gathering documentary evidence on the impact on these forests, designing a computerized data management system to process the data, and constructing computer simulation models to project possible future consequences. Seven meteorological and air quality monitoring stations have been maintained, nineteen mountain study plots have been examined for air pollution injury to vegetation, and a variety of additional plots have been identified for studying soil conditions, tree growth and death, tree diseases, bark beetle interactions, needle litter build-up beneath trees, decay of dead wood in the forest, microarthropods in the litter, and microbial breakdown of pine needles. Additional work examines conifer tree seed production in relation to small mammal populations and oxidant levels, as well as long-term changes occurring in the kinds of trees present.