 Drought is a killer, and the reason being is, think of it this way. As a tree uptakes water, it's taking up water for a couple different reasons. One is to cool itself off. A tree can't go into an air-conditioned house, okay? A tree has to pull the water out of the soil and then move it through its xylem up through its petioles of its leaves, through the leaves themselves, where the leaves have what they call stomates.