Many of the tallest trees in the forest are unique! People grow tall for a reason. North Americancoast redwoodsIt is the tallest tree in the world and one of the longest-lived trees. Whether they grow taller or live longer, they must withstand various environmental disturbances to achieve it.
△ This trunk is from a Coast Redwood
Among them, the most counter-intuitive is their adaptability to forest fires. Not only are they extremely fire-resistant, but they must also reproduce efficiently in fires - their seeds usually need to experience forest fires to germinate, and their seedlings also need forest fires to grow better.
Due to the strict control of forest fires in North America in recent decades, coastal redwoods have been hit hard and have even reached the brink of extinction, so much so that artificial forest fires are needed to help them reproduce.
Coast redwoods reach tree height limit
Trees becoming taller can bring many advantages in terms of survival and reproduction, the most obvious of which is the possession of sunlight resources. However, becoming taller will also cause many problems, such as they must overcome the influence of gravity and water transportation.
In 2004, an article published in Nature calculated that the theoretical height limit of any tree is 122 to 130 meters [1].
The tallest tree in the world is known to be a coast redwood, which is namedHyperion, discovered by scientists in 2006, its height reaches 115.85 meters.
However, the researchers found that many of the dead coast redwoods were over 122 meters tall.
So, coast redwoods are trees that can really grow to their ultimate plant height.
Their leaves are needle-like in shape, which may be related to the height they grow, because as the height increases, it becomes increasingly difficult for water to be transported to the crown, so their leaves are similar to those of trees growing in arid areas.
Coast redwoods grow in areas where rainfall is very abundant. More importantly, their distribution is highly related to fog (or air humidity). The richer the fog, the higher the density of coast redwoods. This is also because it is difficult for water to be transported to the canopy.
Coast redwoods have two types of leaves, one that is highly photosynthetic and one that absorbs moisture from the environment, so the thicker the fog, the more nourishing their leaves are.
Coast redwoods and fire
The long-lived trees in the forest must overcome the effects of fire, because forest fires are 100% likely to occur over time, usually from lightning.
Coast redwoods are also among the longest-lived trees in the world, the oldest known tree, is 3,200 years old.
Therefore, it is not surprising that coastal redwoods have evolved superior fire resistance.
The thickness of the bark at the bottom of their trunks can reach 35 centimeters, and they do not secrete various flammable resins like ordinary fir trees, all of which ensure that they will not damage the xylem in forest fires.
They are also very resilient and can recover quickly after a fire.
In addition, long-lived trees must also fight pests. The thickness of the bark of coast redwoods can also prevent beetles from eating (this may be because they have less need for resin). More importantly, they release large amounts ofTanninTo prevent termites and other insects from being parasitized.
However, the bark of coast redwoods becomes thinner as they get closer to the canopy, so the canopy will still be damaged by insects, but this is not fatal. The real killer is termites. Some termites will still eat coast redwoods from the bottom up, no matter how thick their bark is.
Regular forest fires can help remove termites from the trunks of Coast Redwood trees, which is equivalent to fire eliminating disease!
△ Coast redwood fruits and seeds
Coast redwood trees are very big, but their seeds are very small, only the size of oats. This is not the key. The key is that their seeds are sealed in green cones. The storage period can be as long as 20 years. Just one of them grows on the tree. These cones are waiting for an opportunity.
Yes, they're waiting for forest fires, too.
The green cones are moist, and coast redwoods have evolved to rely on fire to dry out the cones and create cracks before releasing their seeds.
Their seeds need to fall into soft soil to germinate easily, and after the fire, just such a soil environment is provided.
In addition, coastal redwood seedlings are slow-growing and require forest fires to destroy faster-growing shrubs and other trees before they can grow properly.
Generally speaking,Coast redwoods, from seeds to seedlings to full-grown trees, need the "nourishment" of forest fires to grow better at every stage.
△ The burn marks of coastal redwoods are reflected in the growth rings
Each of the larger coast redwoods has various marks of being burned by fire. These marks prove their extraordinary fire resistance and also indicate that they need fire to thrive.
In recent decades, many trees have benefited from efforts to control forest fires, making forests thicker, but coast redwoods have struggled and are at risk of extinction.
On the one hand, the coast redwoods have lost the "nourishment" of flames; on the other hand, the frequency of forest fires has dropped due to human control, but once a fire occurs, it is a very violent fire (because there are more combustibles), and the coast redwoods cannot benefit from such fires. On the contrary, they will also die due to violent fires.
Therefore, in recent years, some controlled man-made fires - known as "prescription burning” to burn off excess carbon sinks while helping coast redwoods thrive.
For other trees, forest fires are the most terrifying disaster, but coast redwoods have evolved to the point where it is difficult to reproduce without fire.
at last
In addition to fire, another killer of tall, long-lived trees in the forest is lightning!Because tall trees are more likely to be struck by lightning, lightning is the leading cause of death for the largest and oldest trees in many areas.
The coast redwoods we mentioned earlier are unable to withstand lightning, and they are often struck by lightning. Many tall coast redwoods die in lightning strikes, and some trees are broken by lightning strikes - but they recover with their strong regeneration capabilities.
Coast redwoods were originally distributed on the West Coast of the United States, where lightning frequency is not high. This is another reason why coast redwoods can grow so tall.
However, lightning becomes more frequent in the tropics, where the tallest trees in forests often die from lightning strikes.
There is a kind of tall tree that grows in the tropics - the Panama Peninsula. Not only do they rarely die from lightning strikes, they also cleverly use the power of lightning to kill competitors around them and those nasty parasitic vines, so that they can live better.
△ The scene when a Dipteryx oleifera tree was first struck by lightning in 2019 (left), and its scene 2 years later (right). Source: Evan Gora
The scientific name of this tree isDipteryx oleifera, there is currently no official Chinese translation, and some documents translate it as "oil cardamom tree".
Dipteryx oleifera can grow to 40-50 meters tall and is one of the tallest trees in the entire Panama Peninsula. They are also one of the longest-lived trees in the Panama Peninsula - they can live to be about 300 years old, so they are easily struck by lightning.
A study this year showed that Dipteryx oleifera is 68% more likely to be struck by lightning than other trees in the Panama Peninsula, with an average Dipteryx oleifera being struck five times in its lifetime.
However, when lightning strikes Dipteryx oleifera, they will quickly transfer the current to nearby trees, allowing the lightning to kill nearby competitors and parasitic vines, and then profit from it [3].
△ The tallest one is Dipteryx oleifera. Source: Evan Gora
The study noted that each time lightning struck Dipteryx oleifera, it killed nine other trees in its vicinity, as well as 80 percent of parasitic plants.
Additionally, individuals struck by lightning increased their seed production by an average of 14 times compared to individuals who were not struck by lightning.
However, it's unclear how Dipteryx oleifera deflects lightning without harming itself.
But anyway, lightning is also the most terrible killer of trees, but it is a definite fact that Dipteryx oleifera uses lightning to kill competitors.,They are just as unique and interesting as the Coast Redwoods!
refer to:
[1].https://doi.org/10.1038/nature02417
[2].https://www.savetheredwoods.org/interactive/giant-sequoia-and-fire/
[3].https://doi.org/10.1111/nph.70062