And nobody is too sure about why. From 538 Significant Digits:
20 percent
North American tree populations are moving westward. Scientists think that 20 percent of the observations in their study of the trend are explainable by changes in precipitation tied to climate change — but that other 80 percent of the reason trees are fleeing the coast? There are still a bunch of questions. [The Atlantic]
I know why. Ents, looking for their Entwives.