>>banana+(OP)
At last a somewhat sane headline from BBC. By their usual practice in recent times it would be patterned something like: 'The unknown mystery animal that shaped the Lake District'.
>>public+K7
And yet here I was, going to the comments first (as is tradition), wondering whether Herdwicks is an individual sheep with the power to terraform, or a breed of some mild historical significance.
>>rwnspa+J9
Well, I guess 'terraforming' is an overstatement, but hill farming in general and the sheep specifically have had a profound effect on the landscape. This link is to a polemic, but it also contains plenty of references. https://www.monbiot.com/2013/05/30/sheepwrecked/
>>bloat+Vb
I've heard of goats used for "terraforming". Several U.S. states have used them to remove invasive plant species (by eating them, because goat).