This is a phenomena I've not elsewhere in the forest, yeah, I regularly see where ponies have gnawed at trunks, usually Holly, extensively sometimes, and other species too. Though I've not seen mature semi ancient Beeches stripped in this fashion. Dotted around Mark Ash Wood I saw at least 8, and I'm sure there'd be more, majestic beech trees completely ringed, their outer bark removed, up to 2m or more up the trunk on some. It doesn't bode well for the trees survival, I'm sure. I wonder what it is that the ponies get from gnawing. Shame, they're some lovely trees.