The brown cones are egg-shaped and only one-half inch in diameter. Their seeds average about , to a pound. The soft, reddish-brown bark, six to twelve inches thick, is one of the Coast redwood's most distinguishing characteristic and, together with the wood, names the species. On older trees the bark has a grayish tinge, and is deeply furrowed, giving the trees a fluted appearance.
Although the thick bark of older trees is relatively fire resistant, repeated fires can damage these trees considerably. The large hollows or "goose-pens" frequently found in the base of large trees give evidence of this fact. Fire also either seriously injures the young growth or kills it outright. However, redwood is exceptionally free from fungus diseases, and there are no insects which materially harm it.
Human demand for lumber is responsible for most of the destruction of first growth Coast Redwood forests. Their green leaves are small, scale-like, and arranged in spirals. Both male and females cones are carried on the same tree. Sequoias grow naturally along the western slope of the Sierra Nevada mountain range, between 5, and 7, feet 1, and 2, m above sea level and far inland. That elevation provides the trees with dry mountain air necessary for their cones to open and release seeds.
The snowpack from the Sierra Nevada provides sequoias with the thousands of gallons of water every day. Sequoias have shallow roots and require well-drained soil. Because of its brittle texture, the sequoia is not a valuable lumber species.
It was, nevertheless, logged extensively around the turn of the 20th century. Originally, sequoias could be found throughout the Northern Hemisphere. Today, they are found only in 77 scattered groves in Northern California. Droughts in California have scientists worried about sequoia health.
The drought of the s left many sequoias stressed from lack of water, according to Scientific American. Though sequoias usually die under their own weight, recently scientists have seen some die still standing, and others exhibiting symptoms of dehydration, including brown foliage at the top of the tree. One scientist told PBS in , "The trees are definitely as stressed as we've ever seen giant sequoia. Not all giant sequoia are suffering from the drought, however.
Deborah Zierten, education and interpretation manager with the Save the Redwoods League told LiveScience that a giant sequoia's response to drought is dependent on location. Fire suppression is another threat to giant sequoias. Fire helps release the seeds from their cones, recycle nutrients in the soil, reduce competition from other trees, remove undergrowth and expose bare soil in which new seedlings can take root and open holes in the forest canopy, which let in sunlight for young seedlings.
Researchers are working to understand how climate change is and will continue to affect giant sequoias. Lack of precipitation from snowmelt will probably be the biggest threat, said Zierten. Increased wildfires could also impact sequoias. These tallest of trees reach heights of more than feet m. The tallest tree in the world is named Hyperion, which reaches This tree is "only" feet tall, but it is over 25 feet in diameter six feet above the ground!
The largest tree in the North Grove is probably the Empire State Tree, which is 18 feet in diameter six feet above the ground. Most trees have their diameter measured at breast height, which is considered to be four and a half feet above the ground on the uphill side of the tree. Sierra redwoods however, are measured at six feet above the ground. This is because of the major increase in circumference at the lower end of the tree. This "butt swell" helps the redwood in a couple ways.
It adds stability to the tree, just as a wide stance adds stability to a football player. Also, it helps deflect falling vegetation away from the base of the tree.
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