The beauty of nature is sometimes found in the profound ‘intelligence’ it exudes. Perennials, which includes trees, must protect itself in order to get through the harsh, freezing temperatures of winter. If trees did not shed their leaves, their soft vegetation would certainly freeze during winter time, damaging and no doubt killing the tree.
In order to cope with the gruling winter temperatures, trees slowly close off the veins that carry water and nutrients to and from the leaves with a layer of new cells that form at the base of the leaf stem, protecting the limbs and body of the tree. Once the process of new cell creation is complete, water and nutrients no longer flow to and fro from the leaf - this enable the leaf to die and weaken at the stem, eventually falling gracefully to the ground.