Paris has vowed to plant 170,000 trees by 2026, and French volunteers are using a pioneering Japanese tree-planting method to create pocket forests in the French capital. Japanese botanist Akira Miyawaki claims densely planted indigenous species, grown in carefully prepared soil at four different heights, grow up to 10 times faster and capture more carbon than standard forests. The city's first mini-forest, planted in March 2018, is thriving. "Every time we go there we notice more and more insects and birds that weren't there before," says Boomforest volunteer Guillaume Dozier. Over the next three years, volunteers will return to the newly planted forest to weed and monitor progress. In a decade, Boomforest hopes it will look like a 100-year-old natural forest.