Tree texts

Softwood forrests planted for regualr logging cover large areas, often entire hill sides. Where they run allong roads they could be made to serve as massive natural bill boards. Basically you plant a background grid of one type of tree, say spruce. then to "type" your message replace indevidual trees in the matrix with a type of tree whith a distinctly different foliage colour, say pine. It'd be like a giant dot matrix printer. Obviously the adverts are long lived, changing the message means gurbbing out the entire hillside. So the messages would most likely be from big brands with well known long established logos they aren't going to change in six months. "Picture things like giant Ford or Coca-cola logos on hillsides. "The maintenence would be minimal, the trees will last years and being evergreen will be visible all year round. Best of all they'd be near on graffiti proof! The revenue from tree advertising could be quite large.