Reforestation policies around 2000 in southern China led to forest densification and expansion in the 2010s

Forest expansion has been observed in China over the past decades, but the typically applied coarse resolution satellite data does not reveal spatial details about China's forest transition. By using three decades of satellite observations at a 30-m spatial resolution, we reveal here the complex spatiotemporal patterns of individual forest stands forming the forest return history of southern China. We calculate forest age, forest densification rates, and annual forest fragmentation and show that the observed forest area surge around 2010 is a result of trees planted after 2000 that formed dense forests about a decade later. We document that old forests in the 1980s were mostly fragmented into scattered patches located on mountain tops, but forests rapidly expanded downhill by 729,540 km(2) and alleviated the clear-cut and logging pressure from old forests. Our study provides a detailed documentation of forest densification and expansion for a country that had been largely deforested three decades ago. The increase in forest area observed around 2010 in southern China is the result of trees planted after 2000 that formed dense forests about a decade later, according to an analysis of high-resolution Landsat satellite data during 1986-2020.

Automated summary

Using high-resolution satellite data from 1986 to 2020, our analysis reveals the complex spatiotemporal patterns of southern China's forest transition. We find that the surge in forest area around 2010 is due to the growth of trees planted after 2000, which formed dense forests about a decade later. Our study documents the densification and expansion of forests in a country that had been largely deforested three decades ago.