On the shifting edge of the Tengger Desert, thin rows of poplars stand like a fragile barricade against advancing sand. For decades, China has pursued one of the most ambitious environmental engineering projects in history a vast afforestation drive widely known as the Green Great Wall, designed to halt the spread of the Gobi Desert and other northern deserts.
From satellite imagery, the results appear striking. Expanding green belts cut across once-barren land. Officials report that tens of millions of hectares of forest and shrubland have been added since the late 1970s. In cities once battered by frequent dust storms, residents say the “black wind days” have become less common.
But beyond the headlines and aerial photographs, scientists are raising a more complicated question: is more green always better?
When Trees Solve One Problem and Create Another
China’s anti-desertification push has relied heavily on fast-growing species such as poplar and pine, planted in dense, uniform rows. In the early years, these plantations often stabilize dunes and reduce wind erosion. Yet ecologists studying arid regions warn that such monocultures can quietly undermine fragile ecosystems.
Many of the chosen species consume significant amounts of groundwater. In semi-arid provinces such as Ningxia and Gansu, researchers have documented falling water tables and drying springs in areas dominated by dense plantations. As groundwater declines, native shrubs and grasses already adapted to survive on minimal moisture can disappear under the shade of thirstier imports.
In some parts of Inner Mongolia, large poplar belts planted decades ago began dying off almost simultaneously once underground water supplies could no longer sustain them. What remained was degraded soil and fewer native plants than before.
The paradox is stark: a campaign intended to prevent desertification can, under certain conditions, intensify ecological stress.
Desert Is Not the Enemy
Environmental scientists emphasize that deserts are not empty wastelands awaiting correction. Natural desert-steppe systems consist of hardy grasses, deep-rooted shrubs and scattered trees that evolved to endure temperature extremes and scarce rainfall. These mosaics may look sparse compared to dense forests, but they are often far more resilient.
The problem, experts argue, lies in equating “green coverage” with “ecosystem health.” A plantation may boost tree-count statistics and look impressive from space, yet function like a fragile system vulnerable to drought, pests or policy neglect.
Increasingly, researchers advocate a more measured approach: stabilizing dunes first with straw grids, restoring native grasses and shrubs, and introducing trees sparingly and strategically. The focus shifts from planting the most seedlings to ensuring long-term survival rates and sustainable water use.
China’s Green Great Wall remains one of the world’s largest environmental restoration efforts. It has undeniably reduced sandstorms in some regions and provided windbreaks for farmland. Yet its mixed outcomes offer broader lessons for other countries pursuing large-scale tree-planting pledges.
The central takeaway is caution. Tree-planting campaigns must account for local water budgets, species suitability and long-term ecosystem balance. Dense monocultures may deliver rapid visual gains, but ecological stability in drylands often depends on diversity and restraint.
As climate pressures intensify globally, the instinct to “plant more trees” has become a near-universal reflex. China’s experience suggests that in thirsty landscapes, the better question may be not how many trees to plant but which ones, where, and whether some places are healthiest when left mostly as they are.
In the battle between sand and saplings, the outcome depends less on numbers and more on understanding the land itself.