Tree Census, with Drones and Lasers

A new study published in the journal Science Bulletin estimates that there are 142.6 billion trees in China, which means about 100 trees for every inhabitant. However, the researchers warn that the real number may be underestimated due to technological limitations used to count them.

• LIDAR technology - mapping method

To obtain this estimate, Chinese researchers used LIDAR (light detection and ranging) technology. It works similarly to sonar, but with laser waves, allowing for mapping of tree density. Since 2015, scientists have collected LIDAR data over an area of 1,400 km² using drones.

Although LIDAR is a state-of-the-art technology, it also has limitations. It cannot detect trees growing under the canopy of other trees, which can lead to an underestimate of the total number. The study results are lower than China's official data, which shows 1,052 trees per hectare compared to the 689 trees per hectare estimated by the new study.

Accurately estimating the number of trees in China is essential for: Monitoring the health of forest ecosystems; Calculating the amount of carbon dioxide absorbed from the atmosphere; Establishing effective environmental policies.

• "Great Green Wall" - China's reforestation project

China is carrying out one of the most ambitious reforestation programs in the world, known as the "Great Green Wall". This project, launched in 1978, aims to stop the advance of the Gobi and Taklamakan deserts by planting a vast artificial forest. Currently, this "green wall" includes more than 66 million trees, and by 2050 their number could exceed 100 million.

Although current technology provides a rough estimate of the number of trees in China, improvements in measurement methods will allow for a more precise assessment in the future. With massive reforestation programs underway, the number of trees in China is expected to increase significantly, helping to combat climate change.