I read a story, a long time ago, about a land where most animals joined the dinosaur and the dodo bird on a long list of used-to-bes.  Unlike these, though, the animals of this story weren't a casualty of natural disasters or imported pigs, they had been wiped out by the expanding human civilization.  So too had fallen most of the forests, the old places of the world.  What men learned, though, was that people are far less happy when surrounded by glass and iron and smog than they are water and mountains and clean air.  And so they tried to reverse the destruction they had caused.  They forged forests of metal, painted them green, but it didn't matter.  But they couldn't reverse it, couldn't rebuild it.  I don't remember the author, or even the title of the story, but it stuck with me.
...