The giant sequoia (Sequoiadendron giganteum) is the world's most massive tree, and arguably the largest living organism on Earth. It is neither the tallest extant species of tree (that distinction belongs to the coast redwood), nor is it the widest (that distinction belongs to the baobab tree or Montezuma cypresses), nor is it the longest-lived (that distinction belongs to the Great Basin bristlecone pine). However, with a height of or more, a circumference of or more, an estimated bole volume of up to , and a documented lifespan of 3266 years, the giant sequoia is among the tallest, widest, and longest-lived of all organisms on Earth. Giant sequoias grow in well-defined groves in California mixed evergreen forests, along with other old-growth species such as California incense-cedar (Calocedrus decurrens). Because most of the neighboring trees are also quite large, it can be difficult to appreciate the size of an individual giant sequoia. The largest giant sequoias are as tall as a 26-story building, and the width of their bases can exceed that of a city street. They grow at such a rate as to produce roughly of wood each year, approximately equal to the volume of a 50-foot-tall tree one foot in diameter. This makes them among the fastest growing organisms on Earth, in terms of annual increase in mass. Distribution Giant sequoias occur naturally in only one place on Earth—the western slope of the Sierra Nevada mountain range in California, on moist, unglaciated ridges and valleys at an altitude of above mean sea level. There are 65–75 groves of giant sequoias in the Sierra Nevada, depending upon the criteria used to define a grove. The northernmost of these groves is Placer County Grove in the Tahoe National Forest, Placer County, California, while the southernmost grove is Deer Creek Grove in the Giant Sequoia National Monument, Tulare County, California. The combined total area of all groves of giant sequoias is approximately . Fire limits growth Giant sequoias are in many ways adapted to forest fires. Their bark is unusually fire resistant, and their cones will normally open immediately after a fire. However, fire is also the most serious damaging agent of giant sequoias. Seedlings and saplings are highly susceptible to death or serious injury by fire. Larger giant sequoias are more resistant to fire damage, due to their thick protective layer of nonresinous bark and elevated crowns. However, repeated fires over