We know that trees start to shed their leaves during autumn season. This seasonal shedding of leaves is governed by combination of shortening hours of daylight and cooling temperatures. A sudden imbalance in daylight, darkness and cold are some of indicators that tell the trees to shed their leaves. Broad leaved trees create a wall of special cells where the leaf stem joins the twig. Sealed off from the tree’s circulatory system, the leaf slowly dies.
Without food and water, leaves get weak and drop from the tree. When the leaf drops, another layer of specialized cells seals the minute wound protecting against moisture loss. It also helps to prevent the formation of fungi.
In regions with strong wet and dry seasons, trees drop their leaves at the beginning of dry season. The reduction in soil moisture is what triggers the shedding of the leaves and the trees leaf out again when it starts to rain.