How Old Are the Redwoods?
Redwood trees often grow more than 300 feet tall. Two species of trees commonly called redwood grow in North America: the coast redwood, the only member of the Sequoia sempervirens species; and the giant sequoia, the only species of the giant sequoia genus, according to San Francisco State University.
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History
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Redwoods belong among the oldest living things. According to the California Academy of Sciences, redwoods grew when dinosaurs roamed the earth. Fossils indicate the trees existed 60 million to 90 million years ago. Of the dozen species once found, only three remain. The coast redwood grows in California to the Oregon border, and the giant sequoia grows in the Sierra Nevadas. The third, the dawn redwood, grows in China.
Lifespan
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The number of rings indicates the age of a tree. According to the California Academy of Sciences, studying the rings---dendrochronology---allows researchers to learn more than just a tree's age, such as whether it lived through a fire and climate changes. Many giant sequoias live 2,000 to 3,000 years. Coast redwoods live 1,250 to 2,200 years.
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Survival
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Cooler and dryer climate changes resulted in the loss of areas where the trees--which need abundant rainfall and stable temperatures--can grow. Certain characteristics, such as the ability to grow among ashes after forest fires, help the redwood survive. According to the University of Wisconsin BioWeb, another characteristic includes resistance to disease. Organisms that aid the trees' growth include banana slugs and fungi, which help recycle nutrients.
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References
- San Francisco State University: Redwood Forest
- California Academy of Sciences: Redwood Forests Survivors Of An Ancient Time
- Oregon State University: Redwood Genus: Common Trees of the Pacific Northwest
- University of Wisconsin BioWeb: Interactions Of Coast Redwood With Other Species
- Oregon State University: Giant Sequoia (Sequoiadendron Giganteum)
Resources
- San Francisco State University Department of Geography: The Biogeography of Sequoia Sempervirens
- U.S. National Park Service: Redwood National and State Parks
- NASA: Redwood National Park Image of the Day
- Science Daily: Redwood Forest Ecosystem of Northern California Depends on Fog to Stay Hydrated During Rainless Summers
- Photo Credit three sequoias image by Kenneth Sponsler from Fotolia.com
