India, Sept. 30 -- Since 1978, China has planted about 66 billion trees and hopes to add another 34 billion by mid-century. Now, a study by Yuhang Luo and colleagues in Geophysical Research Letters in 2026 has checked how those forests compare with natural ones. It turned out that planted forests gained leaf area 66% faster. It sounds like a big win, but the full story is more interesting than the number.

The trees are part of a huge reforestation effort, including the Great Green Wall to slow the spread of the Gobi and Taklamakan deserts. Planted forests are forests people create intentionally. Natural forests grow by themselves. Scientists know these forests absorb carbon dioxide from the air, but they have not fully understood how the...