Trees become more powerful as they age

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It turns out that trees share a fundamental property with the universe itself. The the older they get, the more quickly they expand. A new study reveals that older trees grow more quickly than their younger counterparts. They are better carbon sinks, too. But why?

An international group of ecological and plant biologists conducted a massive study of 403 ancient trees around the world. They wanted to figure out how older trees contribute to the carbon cycle, where trees take in atmospheric carbon and release oxygen. What they discovered went against all the rules of ageing that we’ve learned in the animal world.

It turns out that older trees are the most powerful elements in the carbon-fixing machine that is the forest. Not only do older trees grow bigger more quickly than younger ones, but they also fix carbon at a much more prodigious rate.

Write the authors: Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree.

So one big, old tree can remove the same amount of carbon from the atmosphere in one year that a mid-sized tree has removed in its entire lifetime. Of course if that mid-sized tree makes it to old age, it too could start packing down the carbon as well. Via Trees become more powerful as they age.

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