The oaks turn a variation of yellow, orange or bronze. Leaves stay on oaks the longest and it is often their dry leaves that you hear rustling in the breeze. The final step in the abscission process occurs when a tree sheds its leaves. Gradually, the bond between leaves and a tree weakens. The tiny veins that carried sap to the leaves all summer long are sealed off.
Leaves then fall to the ground encouraged by wind or by the sheer weight of gravity.
Now the dominant color is brown as the chemical reaction of decomposition starts. Although the dry, brown, decaying leaves may not be beautiful, they are extremely valuable. Most of us spend hours raking leaves, and putting them into plastic garbage bags, only to have these bags buried in a local landfill, taking up ever-decreasing and valuable space. As the leaves decompose, they release nutrients back into the soil. If you have a mulching mower, leaves can be cut into smaller, faster-decomposing pieces.