Answer:
Winter temperatures cause the production of auxin to slow down and this breaks the abscission layer, causing the leaves to detach from the trees. Losing leaves helps the tree to retain water during in the winter and means that it needs less energy to stay alive.
Explanation:
In botany and horticulture, deciduous plants, including trees, shrubs and herbaceous perennials, are those that lose all of their leaves for part of the year. This process is called abscission. In some cases leaf loss coincides with winter—namely in temperate or polar climates.