Leaf Watching in the US

Some trees are very sensitive to drought and, of course, the water is lost from the leaves there's tiny pores in the leaves. But those are the same pores that they take up carbon dioxide from the atmosphere to do photosynthesis that's how they grow. So it's kind of a penalty if you want to take up co two and grow, you have to lose some water. The way for a tree to stop losing so much water is to drop its leaves,. particularly the older ones that are less efficient. Like a dramatic mature leaf drop. When the leaf falls off in the tree is sealed up, and it can stay dormant until next spring and then it makes new leaves.