California’s native ecosystems are increasingly subject to nitrogen deposition resulting from air pollution, particularly in the greater Los Angeles area. In addition to global-warming greenhouse gases, emissions from industry, agriculture and transportation contain significant amounts of nitrogen, which eventually settles onto the earth’s surface, fertilizing native ecosystems which are adapted to low nutrient soils. This phenomenon is referred to as nitrogen deposition and can have strong negative ecological impacts on native plant communities.

To date, we have observed decreasing native plant diversity and increased levels of nonnative plant invasion with increased nitrogen deposition across the Santa Monica Mountains. Current efforts are focused on understanding how elevated levels of nitrogen deposition will influence native shrublands during prolonged drought and following disturbances, such as wildfire. A key goal of this work is to use the results to increase our ability to predict future impacts on wildlands under future global change.