Unanticipated cooling gains from afforestation in Southwestern China

Abstract Amid accelerating forest degradation and climate warming, afforestation is increasingly regarded as a strategic intervention to reconfigure land–atmosphere energy exchange. However, most existing studies have predominantly emphasized direct biophysical effects, namely surface cooling resulting from forest replacement of non-forest cover, while largely overlooking the indirect regulation caused by environmental feedbacks during forest expansion. To address this gap, a dual-pathway analytical framework was proposed to diagnose afforestation-induced changes in land surface temperature ( LST ). Within this framework, a ‘zero-impact line’ was defined to represent the LST response solely from forest cover conversion, and the indirect effect amplification index ( τ ) was introduced to quantify the magnitude and direction of indirectly driven LST variation. Results indicated that each 1% increase in forest cover reduced LST by 0.029 °C–0.036 °C through direct effects ( DE ). In the early stages of forestation, τ reached 187%, 227%, and 242% in Yunnan, Guizhou, and Guangxi, respectively, revealing that indirect feedbacks can equal or exceed DE , thereby amplifying the overall cooling outcome in the subtropical evergreen broadleaf forests of Southwest China.