I see plenty of birds in these Finnish planted forests, and definitely lots of bugs too, though you can't see them most of the time. Squirrels, moose, foxes, bears, wolves, deer, all live in them. Blueberries, lingonberries and wide variety of mushroom too. Of course you don't see any of them from aerial pictures or Google Street view. You see the big trees.

Obviously a naturally formed forests would have even more biodiversity, but these Finnish industrial forests are by no means dead. Some areas are more lush than others, depending on the ground and whether there's lakes or rivers nearby. If the ground is good, other types of trees tend to spread naturally, in addition to whatever was planted.