Biophysical effects of afforestation on local land surface temperature in china: A comprehensive analysis incorporating forest age and afforestation intensity

Afforestation changes the surface biogeochemical and biophysical processes and thus affects land surface temperature (LST). The historic studies on the LST effect of afforestation ignored the variation of energy exchange caused by the difference in forest structure such as LAI, vegetation fraction, and canopy height that is directly related to forest age. In this study, we constructed a model of the Land Surface Temperature Effect from Afforestation (LSTEA) considering forest age and afforestation intensity for different climate zones in China and then analyzed the biophysical effects on LST from historical and future afforestation in China. Results showed that (1) the LSTEA model revealed significant spatial and seasonal variability, with minimal warming effects in winter and pronounced cooling effects in other seasons. (2) from 1990 to 2020, the total national afforestation area reached 71.44 × 104 km2, of which 78.2 % originated from cropland and 12 % from grassland. The current afforestation has induced a grid-/national cooling effect of −0.35 ℃/-0.29 ℃ in summer and −0.26 ℃/-0.21 ℃ in winter by 2021. (3) The projected afforestation initiatives are projected to induce progressively intensifying cooling effects during 2030–2100. By 2100, it will bring a summer grid-/national cooling effect of −1.29 ℃/-0.51 ℃, −0.90 ℃/-0.35 ℃ and −0.75 ℃/-0.28 ℃ under the SSP-RCP2.6, SSP2-RCP4.5 and SSP5-RCP8.5 scenario respectively. The projected years of 2060 in SSP1-RCP2.6, 2070 in SSP-RCP4.5, and SSP-RCP8.5 will be the time that the maximum of LST effects in the near decades. Our study highlights the important role of afforestation as a mitigation strategy for climate change.