|Scientific name of the genus|
|Scientific name of the species|
|( D.Don ) Endl.|
The coastal redwood ( Sequoia sempervirens ) is an evergreen conifer . He is the only kind of monotypic genus Sequoia in the subfamily of the Sequoias (Sequoioideae) in the family of the cypress family (Cupressaceae). The coastal redwood is the state tree of the US state of California . The tallest living trees in the world belong to this species.
The coastal redwood is also called the coastal sequoie . The term California redwood, which is often found in the English-speaking world, is ambiguous, as the closely related giant sequoia is also a "California redwood". The genus Sequoia was probably named by its first descriptor Stephan Ladislaus Endlicher in 1847 after Sequoyah (approx. 1770-1843), the inventor of the Cherokee alphabet .
Habit and growth
Coast redwoods can reach heights of over 110 m and a trunk diameter ( BHD ) of over 7 m. The tallest living specimen with a trunk length of 115.60 m is the " Hyperion " in Redwood National Park in northwestern California, making it the tallest known tree in the world. In adult specimens in the stand, the trunks are free of knots up to a height of around 30 m.
When young, the trees form narrow, pyramidal crowns with slender branches. Old trees have a compact, irregular, relatively small, but still slender crown; the branches are strong and horizontal.
Needles, twigs, buds
The coastal redwood has two leaf shapes .
The first form are 10 to 20 mm long, needle-shaped leaves that are spiraling on long shoots or two-lined on short shoots . These needles are dark green on the top and gray-green on the underside and have two stoma stripes. They are flat in cross section and resemble yew leaves . The needles are three to four years old, so they are evergreen. The stomata sit on both sides of the needles. In the cross-section three resin canals can be seen, one of which is located directly below the vascular bundle and two are located near the lower epidermis . The long needles occur mainly on shadow shoots.
The second form are scale leaves that are spiraling on long shoots . They are about 6 mm long, lie on the branch and are keeled on the underside. They occur mainly in the very sunny upper part of the crown.
Young twigs are slender and dark green and have a round cross-section. The buds are spherical and green. They consist of 10 to 12 egg-shaped bud scales that remain at the base of the branch even after they have sprouted.
Cones, flowers and seeds
The coastal sequoia is monoecious ( monoecious ), that is, female and male cones are on the same tree. Seed production begins when the trees are 10 to 15 years old. The cones appear in winter (December / January) and are at the terminal end of the short shoots. The elongated, 4 to 6 mm long male cones are also in the axils of needles. Bracts surround numerous stamens with three pollen sacs each. The pollen are 28 to 34 µm in size.
The female cones are elongated, erect and green when they bloom. They consist of 15 to 25 pointed cone scales that are arranged in a spiral. The seed scale is fused with the cover scale and usually has three to eight ovules that are in two rows. The cones, which are egg-shaped when ripe, are 1.8 to 2.5 cm long, 1.2 cm wide and drooping. They ripen at the end of the same growing season . When the cones ripen, the cones turn yellowish green, then brown. The ripe cones remain on the tree and scatter the seeds. Each cone contains 50 to 60 seeds . Up to five million seeds are formed per tree and year.
The seeds are 3.0 to 4.5 mm long, around 0.5 mm wide and have a 1 mm wide wing. The thousand grain weight is 3.8 to 4.4 g. The seeds are spread with the wind, but mostly only 60 to 120 m from the mother tree. Only around 20% of the seeds can germinate, the rest are deaf. This is interpreted as an adaptation to predators, which should be deterred by the laborious sorting out of the edible seeds from the empty seeds. X-ray studies showed that 1 to 32% of the seeds are healthy, 0 to 11% are fungal, and 58 to 97% are hollow or filled with tannin .
Wood and bark
The coastal redwood is one of the best types of timber. The reasons are the extraordinary dimensions, the durability, the knot cleanliness and the technical properties. The whitish sapwood is narrow and clearly stands out from the heartwood . This is light red to brownish-red (sometimes purple). The name "Redwood", which is often used in the timber trade, for the wood of the coastal redwood tree is derived from this. The wood darkens in the light.
The annual ring boundaries and the change from early to late wood are clearly visible . The wood does not contain any resin canals and consists of 90% tracheids . These are 2.9 to 9.3 mm long. The rays can only be seen with a magnifying glass.
The bark is up to 30 cm thick. It is gray-brown to brown and often deeply longitudinally fissured. It comes off the tree in long strips.
Characteristic of older trees nodes ( engl. Burls ), irregular, lumpy, woody stem excesses near the bottom surface. The origin of these nodes is not fully understood, the causes are suspected to be injuries as well as bacteria ( Agrobacterium tumefaciens ) and fungi . There is no evidence that the knots reduce the vitality of the tree. Even small knots contain hundreds of buds. These can be detached from the trunk and driven out.
See also → measles tuber
The coastal redwood is a shallow root with numerous strong roots that run close to the surface of the ground and cover a large area. There are mycorrhiza formed -Symbiosen, such. B. with Glomus mosseae .
The species often forms stick rashes and root spawn and can thus naturally rejuvenate. The stick rashes arise from sleeping eyes and immediately form their own root system. Old sticks are often surrounded by a ring of stick rashes. Even from a fallen tree, several new trees can emerge from stick movements. New sprouts are also formed from the burls mentioned above .
Root rashes can also give rise to 'white redwoods', trees that have no chlorophyll and are completely supplied by the mother tree. They rarely get over 3 m high, but can reach 20 m.
The seeds germinate epigeously , the seedlings usually have two cotyledons and do not form any root hairs . The cotyledons are strong medium green and are wider and longer than the small, spiraling following leaves. The best germination substrate is mineral soil, as it is after forest fires . The seeds also germinate on trunks and under vegetation.
The youth growth is very rapid, annual seedlings can be 46 centimeters high, four to ten year old trees have an annual growth of 60 to 200 centimeters. The trees bloom for the first time when they are 10 to 15 years old; the highest production of seeds occurs only in trees over 200 years old. The greatest increase in height is reached at around 35 years. An adult specimen is around 90 meters high. The tallest known specimen and at the same time the tallest known living tree is, as mentioned above, the Hyperion with 115.5 meters. At the moment (2006) twelve specimens with a height of over 110 meters are known. The coastal redwood with the largest volume is the Del Norte Titan in Jedediah Smith Redwoods State Park, part of Redwood National Park, with a volume of 1,044.7 cubic meters at a height of 93.6 meters.
The species is self-fertile , but self-fertilizing offspring are weaker in their vigor.
An age of 600 years is not uncommon. The highest age was determined by annual ring counting to be around 2200 years.
The number of chromosomes is 2n = 66. Corresponding to the basic chromosome number of n = 11 in the cypress family, the coastal redwood is hexaploid . According to Yang et al. (2012), the results of genetic comparisons suggest that two different parent species, more precisely even different genera, could have been involved in the development. In this case the conifer would be called allopolyploid, with the chromosome constellation: AAAABB, whereby the letters symbolize the hereditary parts of the original species. The exact origin of the genus Sequoia has not yet been clarified, the assumed high phylogenetic age , and the lack of fossil evidence make the explanation unlikely. The mitochondrial genome is paternally inherited (via the father) (Neale et al. 1989), a peculiarity among conifers.
The coast redwood is native to the coastal areas of northern California and southern Oregon . The information about the remaining natural area varies between 6475 and around 8000 km². It consists of an approximately 750 km long and 8 to 56 km wide strip on the Pacific coast.
The northern border lies on the Chetco River in the extreme southwest of Oregon in the Klamath Mountains (42 ° 09 ′ north latitude), around 25 km north of the border with California. The southernmost occurrences are in Salmon Creek Canyon in the Santa Lucia Mountains , Monterey County (35 ° 41 ′ north latitude). Vertically, the type comes from sea level to 900 m above sea level. NN. In the southern part of the area, the species is restricted to western and northern slopes, near the southern area boundary it only grows at the bottom of the canyons. The most distant point of the area is in Napa County , 75 km inland.
Outside the natural area, the species is mainly cultivated as a park tree, for example in southern Europe , on the British Isles (where there are 50 m high specimens) or in Australia and New Zealand . In most areas of Central Europe , the coastal redwood is not reliably hardy ; especially young trees are sensitive to frost. The frost resistance for adult trees is given as −10 ° C for the leaves, −15 ° C for the buds and −20 ° C for the branches. There are forest crops in Great Britain , among others , and attempts to do so in Portugal and the Ukraine ( Crimea ). In Germany in 1952 cultivation attempts on the Lower Rhine in the Sequoia farm Kaldenkirchen by the dendrologist couple Illa and Ernst J. Martin were successful; the small redwood grove created there in 1953 with a tree height of 35 m (2011) is one of the few larger coastal redwood stocks north of the Alps, alongside a stock in the Burgholz state forest . These trees were found to be hardy in Germany and showed no leaf damage.
The habitat of the coastal sequoia are rainforests of temperate latitudes with a mild- humid climate. In the natural location, the mean annual temperature is between 10 and 16 ° C, the extremes are between −9 ° C and +38 ° C. Six to eight months are frost-free. The precipitation falls mainly in winter, but rarely as snow, the values are between 640 and 3100 mm, often around 2500 mm. The summers with little precipitation are compensated for by the typical summer mist, as they reduce solar radiation and thus evaporation and at the same time add water.
The trees grow on different soils . Near the coast they grow on alluvial alluvial soils , river terraces and delta landscapes with sometimes very thick sediments. In the mountains, they grow over marine sandstones , limestones and slates , often on loamy, light brown soils of medium acidity. High levels of magnesium and sodium have a limiting effect.
The species tolerates flooding and sedimentation. In the case of high mud deposits, new roots are formed in the lower trunk area, which root through the new, meter-high soil. This allows the trees to adapt to the new soil level. As a result, they are superior to competing tree species and form pure stands at such locations.
The best locations are river plains and flat slopes below 300 m above sea level. NN. Here solid wood masses of 10,000 to 14,000 cubic meters per hectare are formed.
The species is often associated with other conifers such as Douglas fir , coastal fir , West American hemlock and Sitka spruce . In higher, drier areas it grows together with Acer macrophyllum , Arbutus menziesii and Umbellularia californica .
These forests are important habitats for the endangered species Marmelalk and spotted owl . Other occurring species of mule deer ( Odocoileus hemionus columbianus ) and the Pileated Woodpecker ( Dryocopus pileatus ) and Wapiti - subspecies Cervus canadensis roosevelti , German Roosevelt Elk, which works closely with the Red Deer is related.
Biotic influences and fire
The coastal redwood tree is generally less susceptible to disease. As a seedling, however, it is quite susceptible to gray mold rot ( Botrytis cinerea ). The stem rot pathogens Poria sequoiae Bonar (in the south of the area) and Poria albipellucida Baxt. (in the north of the area) infested old trunks near the ground. They penetrate the heartwood through burns or broken branches and cause brown rot or white rot and thereby increase the risk of trunk breaks and reduce the forestry value of the wood. Seiridium juniperi causes cancer on branches.
Fire is of great importance among the abiotic influences. Young stands are particularly sensitive because of their thin bark, but regenerate through root brood. Due to their thick bark and the very high branches, adult specimens are quite insensitive to fire. Before human intervention, there were fires in coastal redwood forests every 20 to 50 years, which also reduced the competition between sequoias and other trees. Even if a number of stands grow near the seashore, the trees are not windproof and also not salt-resistant.
|Technical wood data|
|Bulk density (r 12-15 )||0.40-0.45-0.50 g / cm 3|
|Compressive strength||2650-4200 N / cm 2|
|Flexural strength||4400-6850 N / cm 2|
|Tensile strength , parallel to the fiber||7550 N / cm 2|
|modulus of elasticity||540-930 kN / cm 2|
|Source: Schütt and Lang, 2004|
"Redwood" is one of the most valuable and durable timber on the world market. Although the tree population is rapidly declining, the species continues to be used. The wood is used for furniture, paneling, windows, doors and floors. Due to its good splittability and durability, it was also used for roof shingles. Since it does not contain resin and is odorless, containers for storing food were also made from the wood.
The heartwood is largely resistant to burrs , insects , rot and wood-destroying fungi; it is also flame retardant. It is easy to work with and dries well with little loss of volume (around seven percent). The tendency to tear and warp is low. Because of its resistance to fungal and termite infestation, “redwood” is also exported to tropical countries.
The buds of the knots are a popular souvenir in the redwood parks. The knots themselves are made into table tops and veneers, the wood being called Vavona burl . The bark is used as an insulating material and also as a garden mulch.
Hazard and protection
At the time of its discovery for the European world in 1769, the area of the coastal redwood forests covered 6500 to 8000 square kilometers, depending on the source. Numerous Indian tribes lived in the range of the species , such as the Sinyone , Kashaya Pomo , the southwestern Pomo, the Wappo (Ashochimi), Yurok and the Tolowa . The now extinct Sinyons saw the sequoia trees as the holy guardians of the forest. Redwood groves guarded the spirits of the ancestors, whose tombs were among the trees. The Indians used the wood to build houses and boats, other parts were used as medicines.
Commercial use began around 1850. Large areas of redwood were felled as early as the 1860s, the wood was mainly used for houses, but also for railway sleepers, ship planks and in mining. By the 1960s, around 90 percent of the stock was cleared, and use continued after that.
First efforts to protect the forests began in 1879 following the establishment of the first national park ( Yellowstone ). In 1918 the Save the Redwoods League was founded, which bought forests with donations, which in the following years, together with the state of California, were used to establish the state parks Jedediah Smith , Del Norte Coast and Prairie Creek . The most important state and national parks are: Redwood National Park , founded in 1968 with around 50 percent of the total remaining stock (with the integrated state parks Jedediah Smith Redwoods , Prairie Creek Redwoods and Del Norte Coast Redwoods ), Muir Woods National Monument , Humboldt Redwoods State Park and Big Basin Redwoods State Park.
After 15 years of conservation efforts and 738 days of tree occupation by activist Julia Hill , the US government offered a $ 480 million offsetting deal in 1999 for the largest commercial redwood near Eureka , purchasing the area from two Logging companies and placed it under protection on March 1, 1999 as Headwaters Forest Reserve .
Almost 10 percent of the original area of the species is now under protection. Only around three percent of today's area is still primeval forest. Due to the small area of primeval forest, reforestation areas are increasingly placed under protection in order to secure the existence of the species. The forests that are not under protection are still used commercially.
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