Scientists Used Drones to Count Trees in China — You Won’t Believe How Many There Are in Total
Ever since the great towering Himalayas burst from the Earth’s crust, they unwittingly became a barrier that initiated a desertification process in China that sits on its northern foot. As the warm winds lifting from the southern or windward side pushed the moisture-laden particles of the Indian Ocean upward, it triggered rains on the southern slope, creating a “rain shadow effect” on the northern side that reduced China into a mosaic of deserts. Inspired by this barrier, the country doubled its tree planting efforts. A recent study published in Science Bulletin reported that despite the shadowy clampdown imposed upon it by the Himalayas, it succeeded in becoming “the world’s largest managed forest area.”
Currently, nearly 27% of China’s landmass is blanketed by the arid, sun-baked sands of the desert, which is constantly swallowing up the remaining grassland areas, too. Take the Gobi Desert, for instance. As it expands, even the surrounding farmlands are turning into deserts. Since 2015, scientists from Peking University have been monitoring an area of 540 square miles to collect data by setting up drones in the forested plots of the region.
The objective of this study was to formulate effective forest management policies, to monitor and protect wildlife habitats, and prevent natural disasters in the country, also to calculate the amount of carbon locked in the trees. For this study, particularly, scientists gathered as much as 400 terabytes of data from the drones punctuated across more than 76,000 forest patches across the country. According to the data estimate, the country had 142.6 billion trees as of 2020, which is equivalent to around 100 trees per person.
This, according to the researchers, is the “most detailed tree density map of China.” It represents the first high-spatial resolution map of tree density across China, providing valuable insights for forest ecosystem management and policy development regarding natural forest protection and afforestation, researchers noted in the study. The tree census data was collected with the help of LIDAR, a laser-based mapping technique, short for “light detection and ranging.” Scientists utilized a LIDAR-based software called “LIDAR360,” which incorporates artificial intelligence, in addition to high-quality remote sensing, machine learning algorithms, forest management strategies, and various environmental factors.
In conversation with Live Science, lead researcher Qinghua Guo shared that, in 2019, China’s Ninth National Forest Resources Inventory counted a total of 1052 trees per hectare. In this study, the number is slightly lower, 689 trees per hectare to be precise. However, the number can’t be taken as an accurate or exact measure, given that the instruments and technologies they employed had their own limitations. LIDAR360, for example, cannot detect trees growing below thick canopies. Overlapping canopies often obstruct the accurate detection of mid-story and understory trees, leading to lower-than-actual tree counts, Guo explained.
And although a gigantic chunk of the country is still parched in blazing desert dunes, the propagating tree planting could dramatically transform this scenario in the upcoming years. Soon, there may be more trees in China than ever before. Take initiatives like “The Great Green Wall,” as outlined by the Royal Geographical Society. By planting trees in strips and patches in vast swathes across northern China, the country has already expanded its green carpet, which is slowing down the desertification. Plus, take the “Three-North Shelterbelt Forest Program,” which aims to plant 100 billion trees by 2050.
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