ScienceDaily (Nov. 3, 2011) — A huge "migration" of trees has begun across much of the West due to global warming, insect attack, diseases and fire, and many tree species are projected to decline or die out in regions where they have been present for centuries, while others move in and replace them. In an enormous display of survival of the fittest, the forests of the future are taking a new shape.
http://www.sciencedaily.com/releases/2011/11/111103081431.htm