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.

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