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|Redwood National Park|
The redwood trees of the northern and north central California coast are the tallest trees on earth. A relative of the sequoias found in Kings Canyon, Sequoia, and Yosemite National Parks, these trees are not as wide as sequoias at the base, as large, or as long-lived, but they are considerably taller. These skyscrapers may reach over 350 feet in height, a scale that is difficult to comprehend until it is seen first hand. It is also quite difficult to convey the height of the redwood trees in photographs. The specimen below is found in the Lady Bird Johnson Grove in the southern portion of the park.
The root system of the redwood tree is surprisingly shallow, especially given the great height the mature tree attains. There is no tap root and the other roots may reach no deeper than 6-12 feet. The major roots are about 1 inch in diameter. and they typically spread 50 to 80 feet. One way in which the trees are able to remain upright for millennia is by growing close together with other redwood trees, intermingling root systems. In the picture below a number of redwoods crowd together in a typical grove.
Although called "redwoods" the name of the tree derives more from the appearance of the "heartwood" than the color of bark, although some trees present an auburn color (compared with the more cinnamon appearance of sequoias).
However, like sequoias, the bark, which may be up to 1 foot thick, contains tannin which provides protection against fire, insects, fungus, and diseases which might damage the tree. For example, there is no insect which can kill a redwood. The bark also gives the tree its distinctive "fluted" appearance.
The statistics which describe the redwood are truly amazing. These giants can live 2000 years, may weigh upwards of 500 tons, and reach over 350 feet in height. A feeling for this experience can be gained in the picture below, showing a view of a tree more than 250 feet in height. As they grow upwards the redwoods usually lose their lower limbs, producing a canopy over the forest.
The scientific name of the redwood is sequoia sempervirens. Although, as stated above, the trees may live 2000 years (compared to 3000 for the sequoia), a more typical life span for the giants is 500-700 years.
The range of the redwood tree is restricted to areas of infrequent frost, moderate summer temperatures, and a combination of high levels of precipitation in winter combined with fog in the summer, and removed from salt spray along the coastline. Therefore, the habitat of the redwood goes only inland as far as the lower levels of the coast range of mountains. The redwood tree does not like freezing, and there is very little snow in the park at the altitudes where the redwood thrives. It does occur on occasion, however,
The wood of the redwood tree is amazingly resistant to fire and rot, but when a tree falls it is evident that it is somewhat brittle, and when loggers cut the tree they would try to cushion the fall of the tree to avoid having it shattering.
One of the keys to the survival of the redwood is its regenerative abilities. One of the regenerative capabilities of the redwood involves the burl. A burl is made up of dormant redwood stems, and is covered in bark. A burl grows when a redwood is cut, damaged, or injured, or diseased. A burl is a lumpy outgrowth from the tree's trunk, often at its base as is seen below. Saplings may sprout from these burls. The trees which result from growth originating in a burl are genetically identical to the original tree.
The damaged redwood tree provides many advantages to the rest of the forest as well. Fallen redwood logs serve as nurseries for the growth of new trees. Standing trees, snags, may serve as perches for raptors. The cavities in redwood trunks provide locations for woodpeckers and owls, as well as food for insects.
The redwood likes the mild, moist climate of coastal northwest California. The trees enjoy lots of water from the rain and fog which is prevalent in the area. The area receives an average of 70 inches of precipitation each year, 90% of it during the period between October and April. The coast may receive 122 inches of rain per year. A large redwood tree--a 200 foot redwood with a trunk 5 feet in diameter--holds 34000 pounds of water and transpires up to 200-500 gallons of water each day.
The oldest trees are not necessarily the tallest, as among grown trees there is no correlation between age and height. Interestingly, the needles at the top of the redwood are different than those on lower branches.
The Role of Fire Fire plays an important role in the life of a redwood tree. In general, the redwood tree is very resistant to fire for several reasons. The trunk is very thick, there is a lot of water contained in the wood itself, and pitch, which is very flammable, is not contained in the tree. The bark lacks the resin found in pine, fir, and spruce trees, and the sap is largely water which adds to the fire resistance. The redwood tree is particularly resistant to fires which remain primarily along the ground.
Despite its resistance, however, repeated fires may reach the heartwood through cracks in the bark. The tree may be "hollowed out"as the damaged heartwood decays, while the outside, growing layers remain intact.
What is surprising to many visitors, however, is the degree to which an enormous redwood tree can survive fire damage which hollows out and weakens the wood at the base of the tree. Fungi can invade the damaged wood and cause it to rot, eventually forming a cavernous hollow area. A "chimney tree" is a redwood whose entire interior was burned out by fire. Trees with hollows this large, which may be the result of 50-100 fires, are often also called "goosepen" trees as they made convenient places to keep domestic animals such as geese. The may also serve as shelter or residences for black bears and colonies of bats.
Fire can be advantageous to redwood trees in that it removes less fire resistant trees and vegetation which compete for sunlight and nutrients in the forest. The life of the redwood, however, is not as dependent on fire as is that of the sequoia.
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