Sequoias
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Giant sequoia |
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| Sequoioideae | ||||||||||||
| ( Luerss. ) Quinn | ||||||||||||
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The sequoia trees (Sequoioideae) are a subfamily of the plant family of the cypress family (Cupressaceae). This subfamily currently comprises only three monotypical genera , that is, they each consist of one living species . However, numerous other fossil species have survived.
Systematics
In the subfamily sequoids ( Sequoioideae ) there are currently three monotypic genera, each with a living species:
- Genus Sequoiadendron
- Giant sequoia ( Sequoiadendron giganteum )
- Genus Sequoia
- Sequoia affinis †
- Sequoia chinensis †
- Sequoia dakotensis †
- Sequoia jeholensis †
- Sequoia langsdorfii †
- Sequoia magnifica †
- Coast redwood ( Sequoia sempervirens )
- Genus Metasequoia
- Metasequoia disticha †
- Metasequoia foxii †
- Primeval sequoia ( Metasequoia glyptostroboides )
- Metasequoia milleri †
- Metasequoia occidentalis †
Ecology and description of the species
The giant sequoia trees Sequoiadendron giganteum of the genus Sequoiadendron are pyrophytes ; their thick, fibrous bark protects them from forest fires , which can often occur in the arid forests of the Sierra Nevada in the western United States .
Most old trees such as B. those in Sequoia - & - Kings Canyon National Park show clear burn scars, which, however, heal again if the tree is not too badly damaged. The cones of the giant sequoia trees only open after a forest fire. After many of the other competing plants are burned, the seeds can germinate undisturbed in the nutrient-rich ash layer. The giant sequoia trees can get very old and grow enormously in width. The sequoia is a deep root or tap root. Therefore it is not dangerous for buildings.
The currently largest giant sequoia by the volume of its trunk, the General Sherman Tree in Sequoia National Park , is almost 84 meters high and has a diameter of about 8.25 meters at chest height and around 9.95 meters at the bottom, which is a basic circumference of over 31 meters. The General Grant Tree is said to have the widest trunk , with an oval base and a maximum diameter of almost 13 meters. The oldest of these trees are said to be over 3000 years old. The trunk volume of the largest living trees alone is almost 1500 m³, making them the largest plants on earth; their weight is said to be over 2400 tons. (For comparison: an Airbus A380 , the largest civil passenger aircraft, has a takeoff weight of almost 600 t; a blue whale weighs around 140 t; a small car around 1 t.)
Since the middle of the 19th century, these trees have also been planted as (rare) park trees in Central Europe , mostly in spacious English landscaped gardens .
The coastal sequoia of the genus Sequoia forms a much slimmer trunk than the giant sequoia and does not get as old either. He specializes in the rainy to foggy Pacific coastline from Northern California via Oregon to Washington / State in the north. Many specimens of the coastal sequoia are over 100 m high.
The English name "Californian Redwood" for the coastal redwood tree is very unfortunate and the source of a myriad of widespread errors about sequoias, because this name fits both the giant sequoia and the coast redwood: both grow in California and both have reddish wood.
In contrast to the coastal redwoods (genus Sequoia ), giant sequoias (genus Sequoiadendron ) of certain origins and the primeval redwoods of the genus Metasequoia are generally considered to be frost-tolerant under Central European conditions. The latter two species have therefore been part of the regular tree nursery range for years.
threat
So far, the subfamily has been considered extremely resilient, as before the drought period 2012-2016, according to records dating back 100 years, it was neither threatened by normal forest fires nor by insects. Since then, however, a small proportion is of the trees in Sequoia National Park by only 3-4 mm long bark beetle (Phloeosinus punctatus) destroyed been what the climate change is returned. Therefore now contingency plans put in place, which were originally intended only for the 2050s.
See also
- Redwood National Park
- Yosemite National Park
- Muir Woods National Monument
- List of the thickest sequoia trees in Germany
Web links
- Cypress family ( Cupressaceae ) with the subfamily sequoia trees ( Sequoioideae ) at conifers.org (English)
- Comparison of the three species of sequoia in a sequoia school at mammutbaumschule.de
- Mammutbaum community and register for Germany and Europe (Mammutbaum project) at mbreg.de
- Information about sequoias: (biodiversity, distribution, location requirements , special features) at geo.tu-freiberg.de
- Sequoia trees and their technical characteristics: (distribution, location requirements , special features) at holzrecognition.at
- (AP): In the realm of giant trees - The Muir Woods National Monument. (No longer available online.) In: net-tribune.de. May 10, 2008, archived from the original on February 17, 2009 .
- Project Mammutbaum e. V. at projekt-mammutbaum.de
Individual evidence
- ^ Robert van Pelt: Forest Giants of the Pacific Coast. Global Forest Society, Vancouver 2001, ISBN 0-9684143-1-1 , p. 4 f.
- ↑ The Largest Giant Sequoias by Trunk Volume, created by the Sequoia & Kings Canyon National Park Service (as of 2012) ( nps.gov PDF; 118 kB; English; list of the 30 largest giant sequoia trees).
- ↑ Patrick Greenfield, Mette Lampcov: Beetles and fire kill dozens of 'indestructible' giant sequoia trees. In: The Guardian . January 18, 2020, accessed on April 27, 2020 .