China’s answer to toxic smog: a city wrapped in 40,000 trees

For years, China’s usual fixes for its most polluted cities, tighter emission rules, factory shutdowns, upgraded public transport, have only chipped away at the smog. In Liuzhou, a city of about 1.5 million people in the mountainous Guangxi region of southern China, planners are now trying something far more radical: wrapping an entire neighbourhood in trees.

The project, called Liuzhou Forest City, has been designed by Italian architecture firm Stefano Boeri Architetti and commissioned by the Liuzhou Municipality Urban Planning Bureau. It covers about 175 hectares along the Liujiang river on the city’s northern edge, an area chosen partly because it already struggles with heavy smog from rapid industrial growth.

Once complete, the neighbourhood is expected to carry around 40,000 trees and close to a million plants across more than 100 species, spread over the rooftops, balconies and facades of offices, homes, hotels, schools and even a hospital. Rather than being added afterward, the greenery is built into each structure from the ground up.

The idea is based on Bosco Verticale, or ‘Vertical Forest’, a pair of Boeri-designed residential towers completed in Milan in 2014. The firm’s own figures say those two towers filter roughly 15 to 17.5 tons of soot from the air each year, a result Boeri has cited as proof the concept can scale.

For Liuzhou, the firm estimates the vegetation could absorb close to 10,000 tons of carbon dioxide and around 57 tons of fine particulate pollutants annually, while producing about 900 tons of oxygen. The design is also meant to reduce the urban heat island effect, cut traffic noise and support habitat for local wildlife, and the neighbourhood is planned to run on geothermal heating and cooling plus rooftop solar power, linked to the wider city by an electric-only rail line.

Stefano Boeri Architetti has already built smaller standalone vertical-forest towers in Nanjing and has proposed similar forest-city projects for other polluted Chinese cities, including Shijiazhuang. With China adding tens of millions of new city residents every year, the firm says projects like Liuzhou are meant to show dense urban living and genuine biodiversity can work together rather than against each other.