The changing colour of leaves is an impressive annual spectacle, but it can make one wonder, why bother creating something so beautiful just before it withers away?
The sunscreen theory says that as leaves lose chlorophyll in autumn, trees begin to produce anthocyanin, turning the leaves red. The red helps them absorb sunlight that would otherwise damage leaves and trees. Sunlight becomes more damaging in the fall as leaves drop and sun exposure increases on surrounding trees. The trees turn red, in theory, to better absorb the light.
The other theory, referred to as the honest signal theory, says trees turn their leaves red to keep away aphids, which can cause substantial damage to trees. Stopping photosynthesis and producing anthocyanin can be costly to the tree, so only those with strong defences can afford to produce it. Aphids recognize that trees with red leaves have strong defences that could harm the bugs and thus avoid those trees.
Whatever reason is, looks beautiful and makes us feel warm and happy.
Enjoy and respect