Alongside what sibling comments said, I'll add that this can't really work large scale because of the road infrastructure. Even in European countries that are relatively forested, the road networks have an immense ecological impact. They segment the land into a fine mesh, which is very difficult or sometimes impossible for animals to traverse, which means that they have to live for generations isolated on a small plot of land, which entails inbreeding and many other subtler effects. You can't have a small ecologically healthy biosystem. It has to be of a certain size to be able to attain a healthy balance and that's virtually impossible in Europe, with some minor exceptions.
