Zombie trees” sound straight out of science fiction, but don’t worry: Your trees aren’t going to bite you. They’re just thirsty. Although seven years of drought in California finally relented this March, high heat and lack of water have caused a severe decline in the health of some trees, with many now essentially suspended between life and death, Sacramento-area arborist Matt Morgan said. “The whole zombie tree issue came about after years of drought stress,” Morgan, assistant district manager with The Davey Tree Expert Co., said. “They structurally declined and the health decreased to a point where the trees are just there right now.”