Coastal sage scrub vegetation in southern California has been converting rapidly to exotic annual grassland over the past 30 to 40 years. This vanishing vegetation type includes plant and insect species of concern under the Endangered Species Act and provides habitat for endangered wildlife, such as the California gnatcatcher, and game animals, such as the California quail and mule deer. Ecological responses to atmospheric nitrogen deposition include increases in exotic invasive annual grasses, loss of native shrub and forb cover, reduced diversity of native annual forbs and arbuscular mycorrhizal fungi, and elevated nitrogen mineralization. The conversion of coastal sage scrub to grassland is likely caused by a combination of elevated nitrogen depositionthat promotes increased grass biomass and frequent fire, which in turn prevents re-establishment of native shrubs and forbs. As native forbs and shrubs disappear, so does the habitat for sensitive species native to this area. The increase in fire frequency affects a number of ecosystem services because the fire itself directly impacts residential property owners, while the landscape changes induced by fire affect the vegetation and wildlife communities that are valued by many beneficiaries, including tourism-dependent businesses, recreational birders, and people who value undisturbed habitats of the Mediterranean California Ecoregion.