Abstract: Exploring the formation and changes in tree microclimates can help improve the quality of urban green spaces. Temperature is an important indicator of microclimate, and tree temperature categories can be divided into ambient temperature and tree surface temperature (T_ts), from which the mean radiation temperature (T_mrt) and thermal comfort values are derived. In this study, the summer microclimate of Ficus altissima in southern subtropical China was determined, focusing on soil (T_s), air (T_a), globe (T_g), and Tts. Tmrt and four commonly used thermal comfort indicators, i.e., predicted mean vote (PMV), physiologically equivalent temperature (PET), standard effective temperature (SET*), and universal thermal climate index (UTCI), were also calculated. The results showed that: (1) T_mrt can be used to explain both the cooling effect and to predict thermal comfort in the shade; (2) the PET indicator is more advantageous for analyzing thermal comfort in the microclimate of Ficus altissima; (3) T_s is not a suitable important indicator for predicting ambient temperatures and thermal comfort; and (4) the site-specific sampling method of the crowns or trunks can be used to accurately explain changes in the whole-plant thermal environment and thermal comfort, respectively.

Key words: Ficus altissima, Mean radiation temperature (T_mrt), Southern subtropical China, Thermal comfort indicators, Tree temperature