A China plantou 66 bilhões de árvores. Elas crescem rápido, mas não pelo motivo que parece

The Gobi desert grows and it eats good land. So in 1978, China starts a big plan. The country plants a wall of trees, 4,500 kilometres long. Today that wall has 66 billion trees.

Now scientists measure the leaves of these trees. The planted forests gain leaf area 66 per cent faster than natural forests. That sounds amazing. But the scientists look deeper, and the answer is calmer. The planted trees are younger, and young trees always grow fast. People also choose fast species, like eucalyptus.

So the team compares forests of the same age. And the difference falls to only 4,6 per cent. The trees still grow a little faster, and the wall still helps against the sand. But the big number is mostly about age. Good news is better when we read the whole story.