Since 1978, China has planted 66 billion trees to hold back two deserts, and the planted forest is now gaining leaf cover faster than the country's natural woodland

China has planted an estimated 66 billion trees since 1978 as part of the Three-North Shelterbelt Program, the afforestation effort more commonly known as the Great Green Wall, built to slow the advance of the Gobi and Taklamakan deserts across the country’s north. A study published this year adds a specific and somewhat counterintuitive finding to that record: measured by satellite, the planted sections of that forest are increasing their leaf cover faster than China’s naturally occurring forests.

This is one study, not a settled account of how planted and natural forests compare everywhere. The research, led by landscape ecologist Yuhang Luo of Peking University in Shenzhen and published in Geophysical Research Letters in 2026, measured a single metric, leaf area index, a proxy for canopy density derived from satellite imagery, across a set of planted and natural forest sites in China. It is not a comprehensive audit of the country’s forestry, and its authors are explicit that the advantage it documents is time-limited.

What the satellite data actually measured

Luo and colleagues set out to understand why global climate and carbon models tend to treat forests as a single category, without distinguishing planted stands from naturally regenerated ones or accounting for how a forest’s age affects its response to rising atmospheric carbon dioxide. Luo told Live Science that most global climate models lump all forests together, without accounting for whether a stand was planted or grew naturally, or how its age shapes its response to rising CO2 — a gap he says the study was designed to help close.

The headline number from the study is that planted forests increased their leaf area index 66 per cent faster than natural forests. Most of that gap, though, came down to age: planted stands in China are, on average, much younger than natural ones, and young trees put on leaf area faster than old ones simply by virtue of being earlier in their growth curve. When Luo’s team controlled for age and growing conditions, comparing planted and natural forests at similar life stages, the advantage narrowed to 4.6 per cent, still faster, but a considerably smaller margin than the topline figure suggests. The gap was more pronounced in mixed and evergreen forest types.

Why planted forests grow the way they do

The explanation the study offers is partly about species and partly about management. Much of the Great Green Wall’s planted acreage favours fast-growing species such as eucalyptus and poplar, chosen for rapid establishment rather than long-term ecological complexity, and these plantations are often actively managed, with competing vegetation cleared and, in places, fertiliser applied. Reduced competition for light, water and nutrients appears to amplify the growth-promoting effect of rising atmospheric CO2, a phenomenon sometimes called CO2 fertilisation, more in planted stands than in natural ones, where a denser and more varied understorey competes for the same resources.

That advantage is not permanent. According to the study, the growth-rate gap between planted and natural forests peaks when planted trees are around 30 to 40 years old and then declines noticeably afterward. Natural forests grow more slowly across their lifespan but keep growing on a longer trajectory. “For long-term carbon storage and resilience, natural forests remain irreplaceable,” Luo said

What the finding does not settle

Leaf area is a proxy, not a complete measure of a forest’s ecological or carbon value, and independent researchers have flagged that limitation directly. Kevin Dsouza, who worked on reforestation modelling during his postdoctoral research at the University of Waterloo and was not involved in Luo’s study, told Live Science the result “makes intuitive sense” given how quickly young trees spread leaf canopy, but questioned whether leaf area is the right yardstick for tracking carbon sequestration. “It’s not a bad proxy, but it doesn’t give you the full picture,” he said. “The canopy is just the top of the tree and the carbon is stored in all sorts of different places like wood, bark, roots and soil.” It’s not a bad proxy, but it doesn’t give you the full picture,” he said — leaf canopy is only the visible top of the tree, while carbon is stored across wood, bark, roots, and soil as well. Dsouza also pointed to a separate study of Chinese forests that found natural forests actually accumulate more carbon above ground than planted ones in their early years, a result that sits in some tension with a straightforward reading of the leaf area findings and is a reminder that different measurements of forest growth do not always point the same way.

The record behind the 66 billion figure

The scale of the underlying planting programme is well documented independently of this study. Begun in 1978 with a target of raising forest cover across northern China from around 5 per cent to 15 per cent, the Three-North Shelterbelt Program is intended to run until roughly 2050 and eventually cover a belt stretching close to 4,800 kilometres. China’s government reported in November 2024 that it had completed a 3,000-kilometre green belt around the Taklamakan Desert, 46 years into the project, and that national forest coverage had grown from 10 per cent of the country’s territory in 1949 to 25 per cent in 2024. The country’s desert coverage, meanwhile, has edged down only slightly, from 27.2 per cent to 26.8 per cent over the past decade, a reminder that reforestation and desertification are moving in the right direction together, slowly, rather than one having decisively defeated the other.

The programme’s history includes real setbacks alongside its scale. In 2000, a single disease outbreak destroyed roughly one billion poplar trees in Ningxia, erasing about two decades of planting effort in one province. A 2023 study of the programme’s first 40 years found that only about one in five of the forest and shrubland plots that survived their initial establishment had become a proper forest stand within ten years, and only about one in ten remained alive after 40. Ecologists including John MacKinnon, former head of the EU-China Biodiversity Programme, have criticised the reliance on fast-growing monoculture plantations, noting they support far less biodiversity than natural forest and are more vulnerable to disease outbreaks of exactly the kind that hit Ningxia’s poplars. Separately, Hong Jiang, a geography professor at the University of Wisconsin, has raised concerns that dense tree planting in arid regions can draw down groundwater that the surrounding landscape can ill afford to lose, a concern echoed in research on the Loess Plateau showing afforested land losing more soil moisture than adjacent farmland.

What to make of the comparison

None of this cancels out the finding that planted stands are currently building canopy faster than natural ones, on the metric this study used, in the sites it sampled. But it is worth being precise about the scope of that claim. It describes a general pattern detected via satellite-derived leaf area index across a sample of forest plots, not a plot-by-plot verdict on every planted stand against every wild one, and it says nothing directly about which forest type stores more carbon overall, since leaf canopy and total carbon storage, distributed through wood, roots and soil, are related but distinct measures.

The planted forest China has built since 1978 is, on this evidence, growing quickly through its middle years. Whether it matches the long-term ecological function of the natural woodland it was built to supplement is a question this study was not designed to answer.