Question

When a tree sheds its leaves, they turn red first. Is there an advantage to the increased energy of blue/green wavelengths in photosynthesis as the tree is preparing for "hibernation" during winter. Or can a tree not use green/blue for photosynthesis. (was going to ask this in biology but there is little activity there)

Answer 1

Today, at least, it seems like biology has just one less person than physics.

I think of lot of this depends on the complex mechanisms of the tree, what it does with the light, what the pigments do, and things like that. For that reason, I think biology is a good place to try!

That said, I want to offer some of what I know, though it might be irrelevant, and my biology knowledge is weak.

Electromagnetic waves are fluctuating electric and magnetic fields. Their speeds depend on the material through which they travel. (It's approximately \(3\times 10^8\) in a vacuum, and air. ) The frequency of the fluctuations corresponds to the waves energy. Greater energy with greater frequency.
If you look through the electromagnetic spectrum of frequencies, we group off sections based on what the energy can do, I guess.
So it seems many "green" wavelengths and some others are NOT absorbed by the green leaves. You can find charts about what certain pigments absorb and reflect.

You mentioned green and blue. Blue has more energy. Red has the least.

As for an advantage, I'm not sure! Maybe the leaves have a more energy demanding process for which it takes in more energy. But why wouldn't it accept more energy normally? Maybe the increased energy is harmful? I don't know.