Why do giant redwood trees grow so big? It is a combination of things. It could be the amount of soil they have access to, it could be the climate in California, it could be their resilience, and it could be because they live so long.
Giant Redwood trees are famous for their size. They are the tallest trees on Earth and grow to about 0 to 85 meters on average. The tallest known redwood is called Hyperion and it is in California’s Redwood National Park. It is 115.92 meters tall. They are also very broad, which is necessary to support their enormous height. The average breadth of the tree trunk is about 6 to 8 meters. There have probably been even taller trees over the years but they have either fallen down or been felled by humans. Between 1900 and 1950, about 95% of all the redwoods in California were cut down for lumber. It turned out that their wood is brittle and not good for timber, so they were turned into matches. What an incredible shame. Giant Redwood trees are classed as endangered because there are only 80,000 of them left. The increasing number of forest fires and droughts is harming them.
So, why do they grow so much taller than other trees? One possible reason is because of the amount of soil they have access to. Trees They need the soil to spread out their roots to anchor and support themselves, but they also need soil for its water, nitrogen, and minerals. Trees grow by adding a new layer of cells on the outer side of their trunk each year, which is why they have rings, and they need nitrogen and minerals to be able to do this. Many giant redwoods live in areas that flood regularly. These flood waters carry in silt, which settles as very fertile soil. The soil around the redwoods gets deeper every flooding season and the minerals are replenished. More soil and minerals mean they can just keep growing.
The climate is another reason why they grow so tall. California has a fairly warm climate, with relatively mild winters. It also has snow higher up on the mountains, which provides the redwoods with a constant supply of water to their roots. However, the fog that California is famous for might be one of the reasons why redwoods reach such heights. Redwoods take a lot of their water out of the air through their leaves. The thick fog comes in off the coast and is trapped among the upper branches of the trees. One square meter of fog can hold almost 40 liters of water and redwoods get almost half of their water in this way. Redwoods might have evolved to grow so tall to take advantage of this climate, but having water in the air is the reason why they can grow so tall. Trees have to pump water from their roots all the way up to the leaves. The taller a tree is, the harder it becomes to get the water all the way to the top. Redwoods don’t have to worry about that, because they have a supply of water that comes in at the top. This is one of the reasons why climate change is such a worry. California is suffering more droughts and redwoods need a constant supply of water. When the weather is hot trees close the pores in their leaves to prevent water loss, a trick cactuses use, but this stops them from photosynthesizing.
Another reason they grow so tall could be their resilience. Many trees are killed or succumb to diseases before they can reach any great heights. Redwoods can survive forest fires because they have a chemical called Tannic acid in their bark, which is a flame retardant. However, thanks to climate change, forest fires are becoming more common and more severe, and there is a limit to what the redwood can survive. They can also survive diseases because they have the ability to isolate any part of them that becomes infected with a disease, stopping the disease spreading through the tree. A third trick they have is polyphenols in their bark, which insects and fungi don’t like. This resilience lets them survive many of the common things that kill trees, and gives them more freedom to grow.
This resilience gives them a longevity that other trees would be jealous of. Many redwoods live for a few thousand years and the oldest known redwood is 3,200 years old. Trees generally grow every year, so being able to live longer gives trees more chance to grow. If they have access to growing material and are safe from the usual things that harm trees, there is nothing to stop them from just growing throughout their lives. And this is what I learned today.
Photo by Mike Krejci: https://www.pexels.com/photo/trees-beside-road-2645414/
Sources
https://possibleworlds.edc.org/sites/possibleworlds.edc.org/files/RedwoodStoryFINAL_81913.pdf
https://en.wikipedia.org/wiki/Sequoiadendron_giganteum
https://www.cnn.com/travel/article/hyperion-tree-redwood-national-park/index.html
http://famousredwoods.com/hyperion/
https://www.treehugger.com/hardwood-trees-and-how-they-grow-1343506
https://northernwoodlands.org/articles/article/tall-tree-grow
[…] can use this biomass to grow for much longer than trees in the tropical rainforests could. The giant redwood is a good example of this. And this is what I learned […]