This partially burned giant sequoia snag speaks to the natural presence of fire in the forest ecosystem. While fire may kill young giant sequoias, it rarely harms healthy mature trees. The fire resistance of giant sequoias is attributed to its thick, fibrous, cinnamon-red bark. In addition to growing 1 to 2 feet thick, the bark contains tannic acid, a fire-resistant compound which has been used in fire extinguishers. These tannins protect the trees from insect and fungal attack as well, and are so strong that they often prevent the growth of lichens and mosses on the bark.