Southern California Lichen Diversity from the Islands to the Desert

California has over 1600 reported lichen species and yet most of the state is unexplored for lichens. An overview of the southern California lichen biota from the islands to the desert is presented, based on current floristic research. The Pacific Plate Lichen Bioregion will be discussed. The threats to lichen diversity in California, especially increased fire frequencies and rapid climate change, are expected to continue the extirpation of rare species and lichens on bark and wood.