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Mastaj, M - Giant sequoia

Page history last edited by PBworks 12 years, 7 months ago

















            The Giant Sequoia

                    by Michael Mastaj




    My interest in the giant sequoia roots back to my childhood. I can still remember hearing rumors of trees in California that were as tall as buildings. I never took those “rumors” seriously, and thought of them as an exaggeration. However, my skepticism changed when I went to a museum that featured a life-size replica of the trunk of a giant sequoia tree. I was amazed at its size and have been fascinated by the tree ever since. The giant sequoia is known by many names. Among them are: mammoth-tree, Sierra redwood, Sequoiadendron giganteum, Sequoia washingtonia, and Sequoia wellingtonia, The Sequoia's exact genus and species are unknown and are debated. The tree's most common botanical name is the Sequoiadendron giganteum. Also, sequoia is the only word to contain all five volwels (Daly et al. 2000).









Illustration 2: Sequoia Tree (Sequoiadendrom giganteum)


According to the USDA's plants database, the giant sequoia is a perennial tree. Perennials are plants that live for a number of years before flowering (Fox... 189) The sequoia is most adapted to course soils and the tree prefers sandy, loamy soils that have a pH between 5 and 7. Its active growth periods are during the spring and summer. Sequoias regenerate by seeds in cones. The seed cones are 4-7 cm long and mature in 18-20 months, though they typically remain green and closed for up to 20 years. Young trees start to bear cones at the age of 12 years. At maturity, the tree can be over 200 feet in height and near 20 feet in diameter. The giant sequoia is classified as an evergreen tree. Trees are typically perennial, woody plants with a single stem (trunk), normally greater than 4 to 5 meters in height. While the giant sequoia is very tall - a large bigtree is 250 to 280 feet tall - it gets its name more for its giant diameter, which can be anywhere from 10 to 32 feet in a full-grown tree. The bark of the giant sequoia can be 10 to 24 inches thick on mature trees, ranging in color from orange-tan to cinnamon-red. The bark is soft and almost spongy, and is composed of fine fibers, pieces of which constantly break off causing "litter" to form at the base of the tree. Its awl-shaped, blue-green leaves are 1/8 to 1/4 inch long and overlap each other on the twigs. One of the things the giant sequoia is most noted for is its age. The giant sequoia can live as long as 4,000-5,000 years. There have been claims of trees 10,000 years old, but there is no evidence for that; The oldest documented giant sequoia is about 3,200 years old (Plants Database).










Illustration 3: Cone bearing seeds (Daly)




Sequoia trees begin to bloom in the spring. Their reproductive season stretches from the fall to the summer. The trees drop seeds in large cones, shown on the right. The cones are 5-8 cm long and 3 cm wide and have scales, which separate just far enough for the tiny seeds to exit The tree has anywhere from 96-304 seeds per cone. Seeds, once released from the cone, have many things they must overcome. Only about half of the seeds produced are viable, and of these, some are eaten as seeds, others fall where there is no hope of germinating, and some never make it out of the cone. Only about 35% of seeds actually germinate. Once the seed has begun to grow, it has a new set of problems it needs to overcome. Again they could be eaten, this time by deer or other larger animals, as opposed to squirrels and chipmunks; they are attacked by black wood ants or cutworms; they can die from lack of moisture or from the extreme winter cold; or they could perish from lack of adequate lighting (Daly et al. 2000).








Distribution (Plants Database).








The giant sequoia is native to temperate coniferous forests in the Sierra Nevada region of California. Here is what the world wildlife organizations has to say about the home of the giant sequoia: The Sierra Nevada ecoregion harbors one of the most diverse temperate conifer forests on Earth displaying an extraordinary range of habitat types and supporting many unusual species. Fifty percent of California's estimated 7,000 species of vascular plants occur in the Sierra Nevada, with 400 Sierra endemics and 200 rare species (World Wildlife Fund). The natural range of giant sequoia is restricted to about 75 groves scattered over a 420-km belt extending along the west slope of the Sierra Nevada in central California (Weatherspoon et al). The giant sequoia lives primarily at an elevation of 4,000-8,000 feet above sea level. It lives where it does for many reasons; the area has moderate temperatures (-12 to +100 degrees F) and moderate rainfall, with 18-60 inches per year (Daly et al. 2000).










Michael Mastaj

February 28, 2008

PBIO 209

Dr. Kim Brown

The Sierra Nevada Ecoregion


The Sequoiadendron giganteum is a unique and rare tree. Its size is unprecedented. Full grown giant sequoias, the tree's common name, can be over 250 feet tall and over 30 feet in diameter. These biological skyscrapers need a habitat that can suite their needs for growth. The sequoia is most adapted to course soils and the tree prefers sandy, loamy soils that have a pH between 5 and 7. The natural range of giant sequoia is restricted to about 75 groves scattered over a 420-km (260-mi) belt extending along the west slope of the Sierra Nevada in central California (Weatherspoon). The giant sequoia lives primarily at an elevation of 4,000-8,000 feet above sea level. It lives where it does for many reasons; the area has moderate temperatures (-12 to +100 degrees F) and moderate rainfall, with 18-60 inches per year (Daly 2000). The habitat of the giant sequoia is known as the Sierra Nevada forests.


The World Wildlife Fund has divided the Earth's surface into different ecozones. An ecozone is the largest scale of biogeographic division on the earth's surface based on the historic and evolutionary distribution patterns of plants and animals. Ecozones represent large areas of the earth's surface where plants and animals developed in relative isolation over long periods of time, and are separated from one another by geologic features, such as oceans, broad deserts, or high mountain ranges, that formed barriers to plant and animal migration. Ecozones are characterized by the evolutionary history of the plants and animals they contain (Ecozones...[updated 2008].


Sierra Nevada is found in the Neartic ecozone. The Nearctic ecozone covers most of North America, including Greenland and the highlands of Mexico (Nearctic...[updated 2006]. Ecozones are divided into different ecoregions. The World Wildlife Fund has defined 14 major ecoregions.

Ecoregions are divisions of the earth's surface based on life form, or the adaptation of plants and animals to climatic, soil, and other conditions. They are characterized by similar climax vegetation, regardless of the evolutionary lineage of the specific plants and animals (Ecozones).

The Sierra Nevada forests are classified as a temperate coniferous forest. Temperate coniferous forests are found mainly in the northern hemisphere. They are common in the coastal areas of regions that have mild winters and heavy rainfall, or inland in drier climates. Many species of trees inhabit these forests including pine, cedar, fir, and redwood. The under story also contains a wide variety of herbaceous and shrub species. Little light penetrates the thick canopy of trees to reach the forest floor. Because of the lack of light, there are few flowering plants.

Temperate coniferous forests sustain the highest levels of biomass in any terrestrial ecosystem. Structurally, these forests are rather simple, consisting of 2 layers: an overstory and understory. However, some forests may support a layer of shrubs. The forests support an herbaceous groundlayer that may be dominated by grasses and mosses that lend themselves to ecologically important wildfires. Eventually the trees shed their leaves and grow new ones. The needles fall to the forest floor and form a thick springy mat. Thread-like fungi help to break down or decompose the fallen needles. These fungi provide nutrients from the decomposed needles back to the roots of the trees (Coniferous...[updated 2006].


The Sierra Nevada ecoregion is a very diverse forest in Central California. It is home to many different species of plants and animals and features a majority of California's wildlife. According to the WWF: Fifty percent of California s estimated 7,000 species of vascular plants occur in the Sierra Nevada, with 400 Sierra endemics and 200 rare species. The southern region has the highest concentration of species and rare and endemic species, but pockets of rare plants occur throughout the range... Approximately 400 terrestrial vertebrate species occur in the Sierra Nevada , although around 100 of these are largely distributed elsewhere. Around 60 percent of California’s vertebrate species are found here. Thirteen vertebrate species are endemic to the range, this includes some of the highest levels of mammal endemism in the United States and Canada (Sierra...[updated 2007].


Unfortunately, most of the region has been altered by humans. As a result the region as a whole is now in danger. A century of intensive logging, mining, railroad building, development, fire suppression, and grazing by sheep and cattle have left only around 25 percent "intact" natural habitat in the Sierra Nevada. Much of this intact habitat occurs at higher elevations, often in non-forested alpine or in less productive forests and woodlands. More than 60 percent of the ponderosa pine or mixed conifer forests have been altered with many remaining forests degraded through logging and fire suppression (Sierra).


Loggers usually don't target sequoias because of their size. The trees' large size makes them unpractical to cut down and transport. However fire suppression has been detrimental to the sequoias. Sequoias and many other tree, shrub, and herbaceous plant species tolerate frequent fires and some require fire for their regeneration. Sequoias benefit from fire’s reduction of fungal pathogens and carpenter ants, which can weaken structural integrity in larger trees. Fires also clear the under story of trees and brush that compete with seedlings, and can open seed cones through heat. Fires in the past were often frequent and of low intensity because fuel loads were generally low (Sierra).

Efforts are being made to slow deforestation in Sierra Nevada. National parks have been established in the region to protect intact areas of forest. The National Parks share a high degree of protection. Recent changes in fire management policies within National Parks are helping to restore natural disturbance regimes (Sierra). In addition to the protection provided by national parks, other efforts are being made to restore Sierra Nevada's forests. This includes the cessation of logging on mature forest blocks, restoring linkage zones to maintain seasonal migration of wildlife, the removal of domestic livestock, and revising fire suppression policies.






The Biogeography of the Giant Sequoia. [Internet]. San Fransisco, CA: Daly J; c2000 [cited 2008 Feb 17]. Available from http://bss.sfsu.edu/holzman/courses/Fall00Projects/Sequoia.html


Coniferous Forests. [Internet]. : World Wildlife Fund.; c2006 [cited 2008 Feb 29]. Available from http://www.panda.org/news_facts/education/middle_school/habitats/coniferous_forests/index.cfm


Ecozone. [Internet]. : Wikipedia.; c2008 [cited 2008 Feb 29]. Available from http://en.wikipedia.org/wiki/Ecozone


Giant Sequoia. [Internet]. : Weatherspoon PC; c1998 [cited 2008 Feb 17]. Available from http://www.na.fs.fed.us/spfo/pubs/silvics_manual/Volume_1/sequoiadendron/giganteum.html


Gurevitch J, Scheiner S, Fox G. 2006. The Ecology of Plants. Sunderland, MA: Sinauer Publishing Inc. 574 p.


Nearctic. [Internet]. : Bigpedia.; c2006 [cited 2008 Feb 29]. Available from http://www.bigpedia.com/encyclopedia/Nearctic


Sequoiadendron giganteum (Lindl.) J. Buchholz. [Internet]. : USDA National Plant Data Center. [cited 2008 Feb 17]. Available from http://www.plants.usda.gov/java/profile?symbol=SEGI2


Sierra Nevada Forests. [Internet]. : World Wildlife Fund.; c2007 [cited 2008 Feb 29]. Available from http://worldwildlife.org/wildworld/profiles/terrestrial/na/na0527_full.html

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