Trees are living things, just like us. They are called organisms. You’ve seen that some trees lose all of their leaves in the fall and go dormant or in a resting stage in the winter. Only some trees do this weird behavior. We are going to find out why. Trees go dormant because the water in the trees’ trunks and leaves freeze in the cold weather. When water freezes, it expands or gets larger. This causes the trees’ trunk and leaves to burst! This severely harms the tree. Trees lose their leaves so that all of the water in the leaves can dry up and not be in or on the tree. The roots of the trees also stop sucking in water and nutrients, so that the tree can’t freeze! Without the water or nutrients, the tree has to “sleep” or shut down its functions to survive the cold weather. Remember, dormant trees are still alive. They are just not that active during the winter.