The number of trees on the screen at once should break the game.
If you look close, however, you'll see that any tree (or bigger bush) that's farther than a couple of meters away is just a 2d cardboard construction that only fills out to a full tree/bush when players get close. Not very noticeable in screenshots, but ingame they fade in.
The same is going to be true for any building or landmark I'm going to add at some point. E.g. the bridge in one of the screenshots. Only the bare minimum that is necessary to make the scene look like a rich and full landscape is going to be visible form afar. Details will only fade (or pop) in at close distances.