The base of the leafstalk, or petiole, connects the leaf blade to the branch. Tubes in the petiole transport sap in and out of the leaf blade. A layer of cells, called the abscission layer, develops and gradually severs the tissues supporting the leaf. At the same time, nature heals the break, so that after the leaf is finally blown off by the wind or it falls from its own weight, a leaf scar marks the place where it grew on the branch. Above this scar, next spring's leaves are tightly wrapped in buds waiting to unfurl.
Decomposition releases the leaves' nutrients and adds organic material to the soil.
Trees and other plants will take up the nutrients. The brilliance of fall colors depends on the weather. Watch the temperature before and during the time leaf chlorophyll is dwindling. These conditions will create the most spectacular color displays. During warm days the leaf produces lots of sugars.