Waaaaaait... okay, so you want something.. like... dead dead. That used to be alive but now nothing can grow, right? Like some kind of unnatural burning maybe?


Going by your story description, I'd focus on the *trees* first... then scorch them.. then try to turn it into a brush/texture... like...

trees 1.png

trees 2.png

trees 3.png


Only, y'know... better than my 30 second scribbles


Edit: and using your land color as the base for the dirt/trees in your brush, of course