Seems to be a common misconception that lichens are generally harmful to vascular plants, e.g. implied by the their abundance on dead and dying trees, although more likely these lichens are just taking advantage of increasing available light. However, it would appear salal and other evergreen plants around here are harmed when their leaves are completely covered by Fellhanera bouteillei. That may be debatable; see these interesting pages (also see p. 85 Robert Lücking Foliicolous Lichenized Fungi. 2008):
https://www.anbg.gov.au/lichen/ecology-plants.html
https://www.anbg.gov.au/lichen/ecology-foliicolous.html
Particularly interesting to me - “In another study undertaken in Costa Rica two researchers carefully removed liverworts and lichens from randomly selected leaves of grapefruit (Citrus paradisi) and an understorey cyclanth (Cyclanthus bipartitus). They found that the denuded leaves suffered 2 to 3 times more damage by leafcutter ants (“one of the most destructive herbivores in neotropical rainforests”) than was the case with the covered leaves. Presumably the chemicals produced by the liverworts or lichens are harmful either directly to the ants or to the ants’ fungus gardens.”
addition from Field Museum Flickr site https://www.flickr.com/photos/fieldmuseum/14151177100/:
Posting some photos in the gallery. F. bouteillei is quite abundant in some places around here, particularly up around Deception Pass, e.g. one may come across it 6 or 8 times comes along a quarter mile of trail, (although the relative number of plants affected and the number of leaves severely affected is very small).
see:
https://northwest-lichenologists.wildapricot.org/page-1816539/64264638#photo
https://northwest-lichenologists.wildapricot.org/page-1816539/64264729#photo