I had a little chuckle when reading the title - it would seem in typing up the press release someone made a teeny mistake! It was not “3 rings” that they studied, rather TREE rings (and more than 3 of them)! LOL
I can’t believe the university didn’t catch this...
Three rings makes perfect sense.
Three Rings for the Elven-kings under the sky, Seven for the Dwarf-lords in their halls of stone, Nine for Mortal Men doomed to die, One for the Dark Lord ...
The Elves have charge of the woodlands, and so a study of their Rings to see which one was used at that time would tell us the culprit.