Sunday, 21 April 2013

Redwoods - and why are they fireproof?

The Redwood trees are some of the tallest trees on the earth, they can reach over 350ft in height. The name Redwood coming from the red colour of the bark. The bark itself is very thick, can be up to 1 foot, and contains tannins which make it form a protective layer against fire, insects, fungus's and diseases which could cause any harm to the tree. They can live for 2000 years although many of them only live between 500 and 700 years. 

The roots

You would expect a tree that's so tall to have very deep roots, however this is not the case for the Redwood tree. It has very shallow roots which are only between 6 and 12 feet deep and have a small span of 50 to 80 feet with a diameter of 1 inch. 

Why is the Redwood tree fireproof?

Redwood trees have very thick bark which has a lot of water inside it. They also do not have any pitch inside the trunks which is a very flammable substance found in many other trees. Another factor that helps to make the redwood trees fireproof is the fact that they do not have any of the resins that other trees like pine and the sap that the tree contains is made up of a majority of water also adding to the fireproofing ability. However over time as the tree has to survive more fires, the fire will eventually find its way into the tree through cracks in the bark and it will then begin to hollow out parts of the tree leaving the rest of the tree to remain in tact. 

The redwoods themselves can actually benefit from the fires as it helps to remove some of the other non fireproof plants and trees from around them giving them access to more light and nutrients etc. 

How does the tree get water from the ground to the top?

With the trees being so tall one question that could be asked is how does the tree manage to actually get the water to the top. Scientists have discovered that in order for the water to reach the top, the molecules have an interaction with the walls of the capillaries inside the tree. The bond that is then created forces the water to be dragged up the capillaries, also at the same time evaporation from the leaves will create a vacuum effect which also pulls the water up. The tree will stop growing when its suction can no longer pull the water up to the top of the tree. 

New trees

The redwood trees spread their seeds by producing cones with seeds in, each of the seeds will be tiny - only about 3 mm and when they fall out of the cone they will only usually travel between 60 and 120m away from the parent tree. If it lands on moist, warm soils it will begin to germinate within a month and if the conditions are suitable it will start to root itself. Then after it has started to grow its first leaves it can then begin to produce its own food and they usually grow about 5-7cm in their first year. 

They also have the ability to reproduce by stump sprouting, this can be very advantageous especially compared to those which can only reproduce by seeds. Stump sprouting allows the tree to grow new sprouts from burls around the base of the tree when the tree has been badly damaged by cutting or fires. Burls being developed from buds that do not turn into shoots. The buds will continue to grow as wart like patches on the side of the tree until they are needed, when the tree is damaged and they will then use the parent trees roots as their own. 

Other facts

  • After repeated fires the bark is eventually damaged and then the middle rots out and settlers used to use the hollowed out redwood trees as pens for animals. 
  • The bark is often used as a soil conditioner especially for plants that need a lot of space around their roots such as orchids. 
  • Used to be used as an insulator due to its nature of not pests not being able to live in it and the fact it doesn't absorb water. 



Biography

About Coast Redwoods available at: http://www.parks.ca.gov/?page_id=22257 (accessed 18/04/13)
First Image available at: http://www.coolcrack.com/2012/06/redwood-ancient-giants-14-pics.html (accessed 18/04/13)
Redwood Trees available at: http://www.shannontech.com/ParkVision/Redwood/Redwood2.html (accessed 18/04/13)
Second image available at: http://www.visualphotos.com/photo/1x7038921/redwood_cones_sequoia_sempervirens_3L1024.jpg (accessed 18/04/13)
The Redwood Forest available at: http://sunnyfortuna.com/explore/redwoods_facts.htm (accessed 18/04/13)
Third Image available at Thick Redwood Bark http://sunnyfortuna.com/explore/redwoods_facts_02.htm (accessed 18/04/13) 

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