The Giant Sequoia Trees in California USA

How do these forest giants grow so tall and how does the water travel up so high? These questions are still waiting for a definite answer, but the boffins have most of the answers. I will try and relate to you some of the answers without getting too technical.

When the seed geminates it forms a water column, this remains for the life of the tree, if cut off, it will die. The root system for such a tall tree is very shallow. The trees grow very close together and their roots intertwine with each other and give each other support. Water is passed up first from root pressure, but this is not enough. Just under the bark there are cells, Tracheids and the Xylem, these are the living part of the tree and they transport the water upwards, but they need help against gravity. At the top of the tree are the leaves, they cause transpiration and because of this it sucks the water upwards like drinking a glass of water through a straw. Sometimes air bubbles form in the water passages cutting off the supply of water, this is an embolism similar to a blood clot, the tree is very clever and it is able to bypass the embolism and use a different route to maintain the water supply. All this is happening just beneath the bark and each year it forms a new system just outside the previous years, thus forming the annual rings. Apart from holding water the inside of the tree is dead.

The Sequoias grow in 7000 foot mountains, at that height they are prone to lightning strikes and most of them loose their topmost branches, this is why they are not as tall but are more massive than the Coast Redwoods which are of the same species but have different growing conditions .

The mature trees grow up to 275 feet and 30ft in diameter weighing up to 2100 tons; a third of this is water. Their bark can be up to 3 feet thick, is virtually fire proof, that is why they can survive in forest fires, in fact they need these fires to keep the shrubs and undergrowth clear so their seeds can open and geminate.

Up to 500 gallons of water is required per day for just one tree to survive, so they mostly grow in ravines with a constant water supply. I have only touched on the complex way these trees can get water so high and the scientists are still struggling with the complete answer.

Next time. The Coastal Redwoods.

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