I had never seen this before. I didn't know what was happening. I remember asking if these Americans painted their trees this way. The color magic happens as a matter of survival, during a process botanists call abscission. When the shorter days and cooler temperatures signal winter's approach, trees, like animals, prepare for the coming rigors by building a wall of protection.
Animals store fat, seek shelter, and retreat into various states of slowed animation.
The great hardwoods of the deciduous forest follow that pattern by closing all openings, all spots vulnerable to freezing cold. It begins at the stem of the leaves. Sensing the threatening chill, the tree closes off the stem by forming a layer of cork, a small yet strong wall that blocks the flow of water from the roots. That one miraculous step stirs the palette that eventually paints fall's colors. Reds, yellows, oranges, and a staggering combination of the three turn a quiet withdrawal into a wild celebration.