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Giant Sequoia

Sequoiadendron giganteum

The largest living things on earth (excluding colonial organisms such as corals), giant sequoias can be up to 311 feet high and over 100 feet around at the base. The world's largest tree in volume of wood is the General Sherman Tree in Sequoia National Park, which is 272.4 feet tall and has a base that is 101.6 feet circumference; it has been estimated that the General Sherman would yield over 600,000 board feet (1,400 cubic meters) of lumber.

left: the General Sherman tree
right: bases of two other giant sequoia trees

the General Sherman tree bases of two giant sequoia trees

Like its close cousin the giant redwood, the giant sequoia has reddish-brown bark that, while quite soft, can be up to two feet thick. The wood is very brittle.

Mature trees are usually devoid of branches for the first half of their height. The trunk tapers markedly, and the top branches form a rounded crown, with individual branches sweeping downward with upturned ends. The green scale-like needles are 1/4 to 1/2 inch long. They cover the branches completely and lie almost parallel to the twig, except for the tip, which is sharp and stands out. Each tree bears both male and female cones. Each woody, oval-shaped cone is about 2-3 inches long; Female cones bear about 230 seeds, each of which is only about 1/4 inch long. Seeds are dispersed by the wind, birds, and other animals.

giant sequoia cones and seeds
giant sequoia cones and seeds

The thin seeds require deep, moist soils with no overlying vegetation into which they can bury easily in order to germinate. The ideal location is also prone to frequent low intensity fires that help rid the area of competitors while also providing the nutrients required for germination and growth.The heat generated by these fires also helps to dry out the cones and open them, allowing the seeds to disperse.

It takes around 20 years for a giant sequoia to reach maturity. This slow growth, combined with immunity to most diseases and insects, allows giant sequoias to live for well over a thousand years. The General Sherman Tree is believed to be about 2,500 years old, and the oldest confirmed giant sequoia was about 3,500 years old when it was felled for its timber. The thick bark of the giant sequoia makes it resistant to fire, but its great height does make it prone to lightning damage.

The resistant nature of the wood made it a favorable timber and, beginning in the mid-1800's, it was used to make a wide variety of items from fence posts to patio furniture. Roughly 34 percent of the original range of the giant sequoia was lost to timber extraction. Ironically, a further threat to sequoia groves came from fire prevention strategies imposed by forest managers; this strategy prevented sequoias from regenerating successfully, whist allowing competitor species to proliferate. Once common across most of the Northern Hemisphere, the giant sequoia is now restricted to about 75 distinct groves on the western slopes of the Sierra Nevada mountains of California, with the greatest concentrations in Yosemite, Sequoia, and Kings Canyon National Parks.

Scientific Classification

Division Pinophyta
Class Pinopsida
Order Pinales
Family Taxodiaceae
Genus and Species Sequoiadendron giganteum

PRINT SOURCE
World Book Encyclopedia Chicago: World Book-Childcraft International, 1979

WEB SOURCE
Arkive http://www.arkive.org/giant-sequoia/sequoiadendron-giganteum/

SEE ALSO
Yosemite National Park

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The Robinson Library >> Science >> Botany >> Conifers (Cedars, Pines, Etc.)

This page was last updated on 02/01/2017.