The title may sound like a ‘well DUH’ kind of question – everybody knows the leaves are changing colors because it’s autumn and winter is close behind.
Bolt Mountain, WV - Emerson Stover Overlook
Generally speaking, because winter is coming is the right answer. But why does it happen? And why does it happen to some trees and not others (evergreen)?
The answer is actually pretty simple and pretty cool when you think about it.
The leaves are changing because of a defense mechanism triggered by the tree to prepare for winter. As it gets colder the changing leaves are caused by the tree pulling sap back into the main trunk to protect the tree from freezing… essentially, and slowly, starving the leaves.
This doesn’t happen on evergreen trees because the sap is so thick freezing is not an issue.
Trees with thin sap are basically protecting the branches from freezing and splitting open. We all know how frozen water can damage a water line, it’s the same principle. When water freezes it expands. This would be devastating to a tree.
I’m sure there is a scientific name for the process, I don’t know it and really don’t care. I’m happy with knowing the why of it.
I do hope you get out and enjoy the beauty of Mother Nature and watch as she prepares for the coming winter. She can sure put on quite a show!
Photos best viewed in high definition!!
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When one tugs at a single thing in nature; he finds it attached to the rest of the world.
