As the world warms and the atmosphere becomes increasingly fertilized with carbon dioxide, trees are always growing faster. But they are dying young – overall, the world’s forests could lose their ability to store carbon. That is the main finding of our new study published in the journal Nature Communications.
In a world without humans, forests would be in equilibrium, emitting approximately carbon from the atmosphere in which they grow. However, humans have disturbed this balance by burning fossil fuels. As a result, the amount of atmospheric CO அதிகரி increases, which increases the temperature and composts plant growth. These changes have stimulated the growth of trees over the past decades, even so, “Old growth” forests They have not experienced recent human disturbances. This in turn allowed forests to take in more carbon than they emit, resulting in large net accumulations – often referred to as “carbon sinks”.
Earth scientists like us often wonder if forests can continue to be a pond. Excess CO₂ will benefit trees everywhere, and increasing temperatures will help them grow in cooler areas. So you can expect forests to continue to soak up our carbon emissions – that’s too much Earth system models Predict.
However, changes in the lifespan of the tree can throw a spanner in the works. When studying a few years ago Old growth Amazon forests, We noted an increase in tree mortality following early growth increases. We assume that this may be due to the fact that rapid growth reduces the life span of trees. If true, this means that predictions that the carbon sink will continue may be more optimistic because they do not take into account trade transactions between growth and longevity. Our new findings provide evidence for this hypothesis.
To study the relationship between tree growth and longevity, we used tree ring logs. The width of each ring tells how fast the tree grew, while counting the rings provides information about age and allows to estimate its maximum lifespan. We analyzed more than 210,000 unique tree ring records from more than 80 different species from around the world. This great endeavor was made possible by the decades-long work of dendrochronologists around the world, who made their data available to the public.
Rabbit and turtle
Our analysis shows that fast growing trees die at a young age. It has long been known that fast-growing species live shorter lives. For example, a balsa tree grows rapidly to 20 meters or more, but only lives for a few decades, while some pristilcon pine trees have been growing slowly and steadily for nearly 5,000 years.
We found this to be not only true when comparing different organisms, but also within trees of the same species. It was amazing that this trade occurs in almost all types of trees and ecosystems, from closed-canopy tropical forests to brave hardwoods in the Arctic. The slow-growing peach tree can be expected to last several decades longer than its fast-growing relatives. It’s like the story of the rabbit and the tortoise – only slow but steady trees that live long.
To study its effects we compared how much carbon is accumulated under two wood simulation models. One simulation involved this “fast-growing, dying” trade, while the other used a model that lived equally long regardless of tree growth rates. Initially we found that trees grow faster and die younger, but this has led to an increase in the amount of overall organism, but this has also led to an increase in tree mortality decades later.
Thus, eventually the forest loses its vitality and begins to return to its original state, but with fast-growing and short-lived trees. Our models indicate that rapid growth, without a real long-term increase in carbon storage, causes the death of trees. Some researchers have predicted this Long ago, Our results support their prediction.
Why do rock stars die at a young age?
An interesting question is why fast-growing trees, the “rock stars” of the forest, live such a short life. We do not yet have a definitive answer, but we have looked at some possible options. For example, other environmental variations that induce higher temperatures and faster growth will reduce the lifespan of trees. However, we find that reducing life expectancy is a result of rapid growth.
A simple hypothesis is that trees die when they reach a certain maximum possible size, and when a tree reaches this size it dies young. Other possible explanations are that fast-growing trees produce cheaper wood (in terms of energy cost) and invest less resources in fighting disease and pest attacks, or are more susceptible to drought. Whatever the reason, this algorithm must be developed into scientific models if we want to make realistic predictions about future carbon sinks, thus how much CO₂ is in the atmosphere.