Previously ignored climate benefits from afforestation in China

Afforestation connects isolated forests into larger contiguous forests, reducing forest fragmentation. This process restores previously fragmented edge areas by transforming edge forests into interior forests (termed transformed forests). However, the extra climate benefits of these transformed forests beyond afforestation itself remain unclear. Here, we estimate the carbon gain and the biophysical effects of the transformed forests by afforestation in China using multiple high-resolution remote sensing data. Planted forests area (89.6 M ha) accounts for 35.5% of the total forest area in China in 2015, transforming 51.8 M ha edge forests into interior forests. It increases aboveground biomass carbon (AGC) by 0.3~0.4 Pg C in the transformed forests, compared to the AGC increase of 2.1~2.3 Pg C in the planted forests. These transformed forests also induce a biophysical cooling effect of -0.020±0.015 °C. Combining the biogeochemical effects from increased AGC and the biophysical effects, the transformed forests provide an overall cooling effect of -0.026 °C, representing an extra 25.2% of the direct climate benefits of afforestation. Our study reveals the previously ignored extra climate benefits resulting from reduced forest fragmentation alongside afforestation, offering new perspectives on mitigating climate warming through afforestation.