Friday, September 17, 2010

Are Leaves "Turning" Already?

I've seen a ton of tweets & Facebook posts in the last couple of weeks from friends in the mid-Atlantic remarking that the leaves are "turning already."

What I'm seeing right now in my Falls Church, VA neighborhood isn't leaves turning -- they're dropping dead. There's a big difference between leaves gradually turning yellow, orange & brown while on the tree, then gently floating to the ground ... and leaves turning brown & immediately leaping to the sidewalk. My neighborhood features green trees with brown leaves lining the gutters. Not exactly prime leaf-peeping.

Why are they dropping so early? A scientist friend explains:
The leaves dropping is mostly because of the dry summer, but this summer's record heat also means the trees require even more water, making the same level of drought more severe than it would have been without the high heat. I'm hoping what we're seeing is the trees going into early dormancy, rather than signs of long-term damage.
Why do people assume any brown leaves after Labor Day are fall foliage? Part of it is an issue of transplantation. Many of us grew up in places up north where hints of fall foliage right now wouldn't be unusual. But here in the mid-Atlantic, it's way too early for true fall foliage -- we're still technically in summer.

Of course, this debate is a blip on the radar compared to what's facing New England. Why would tourists spend thousands to go leaf-peeping there if global warming makes it too hot for maple trees, the main source of New England's brilliant autumn colors?
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