A small stand of ash where I walk my dog is covered in large white splotches on the bark. I am about to try the OPAL air quality survey and wondered if it was an early stage of a lichen?
No identification made yet.
No interactions present.
If you're about to try the OPAL air quality survey you'll have a better chance of identifying what you find if you begin with foliose or fruticose lichens.
Many crustose species (like the one in your photo) can be difficult to identify without chemical tests and some need microscopic examination of the spores as well .....
The Natural History Museum has an online Guide to Lichens on Twigs which is simple to use:
Only enter details you're sure of and then click 'Search' at the bottom of the page. That will give you a list of possibilities with links to photos.
Try and check possible IDs against several photos of that species as lichens can be very variable and a species can appear different depending on light, habitat etc.
If you look in the Fungi and Lichen forum on iSpot there is a post titled 'Lichen Identification resources' with links to websites with lichen photographs .
Lat/Lng: 52.4, -2.1
OS grid ref: SO9978