Friday, 8 June 2007

The largest type of trees on Earth

The largest type of trees on Earth is the Giant Sequoia Redwood tree ( Sequoiadendron giganteum ). Another name the tree has been referred to is the 'Stafford Giant.' The oldest of this type of tree found is around 5000 years old. This massive evergreen tree is as heavy as 10 whales. Pardon me if I'm wrong, but this was what I heard on the documentary, Planet Earth. They grow to an average height of 50-85 m (150-280 ft) and 5-7 m (16-23 ft) in diameter. Record trees have been reported to be 93.6 m (307 ft) in height and 8.85 m (29 ft) in diameter. Sequoia bark is fibrous, furrowed, and may be 60 cm (2 ft) thick at the base of the columnar trunk. It provides significant fire protection for the trees. The leaves are evergreen, awl-shaped, 3-6 mm long, and arranged spirally on the shoots. 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; each cone has 30-50 spirally arranged scales, with several seeds on each scale giving an average of 230 seeds per cone. The seed is dark brown, 4-5 mm long and 1 mm broad, with a 1 mm wide yellow-brown wing along each side. Some seeds are shed when the cone scales shrink during hot weather in late summer, but most seeds are liberated when the cone dries out from fire heat and/or insect damage. Wood from mature Giant Sequoias is highly resistant to decay, but is fibrous and brittle, making it generally unsuitable for construction. From the 1880s through the 1920s logging took place in many groves in spite of marginal commercial returns. Due to their weight and brittleness trees would often shatter when they hit the ground, wasting much of the wood. Loggers attempted to cushion the impact by digging trenches and filling them with branches. Still, it is estimated that as little as 50 percent of the timber made it from groves to the mill. The wood was used mainly for shingles and fence posts, or even for matchsticks. But nowadays, the main uses are tourism and horticulture.

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