without the wolves, there is nothing stopping the deer population/elks from exploding, and when theres a ton of deer or elk theres an increase the trees, bushes being stripped for food since deers like to eat them. Also the drastic increase in parasites that would affect other animals the deers, have like ticks and tickborne diseases.

trees and bushes die from all thier leaves getting stripped constantly, unless its a super poisonous tree(which is more common in the tropics), and birds dont have nests, and insects wont able to pollinate certain plants,etc.