Abstract: Selection of thermotolerant urban tree species is vital for coping with global frequent occurrence of heatwave events and the aggravation of urban heat island effect in the future. In this study, we examined leaf photosynthetic thermotolerance (the corresponding temperature at 50% loss of PSII potential quantum efficiency, T₅₀) and its relationship with leaf morpho-anatomical structure (leaf morphology, leaf surface traits and cross-sectional anatomical traits) across 16 urban greening tree species. The results showed that T₅₀ in these tree species ranged from 46.1 ℃ in Salix babylonica to 50.6 ℃ in Platanus acerifolia, and averaged 48.6 ℃, almost the same as T₅₀ in tropical trees. The T₅₀ was positively correlated with leaf area, and was not correlated with other morpho-anatomical traits. Leaf area and specific leaf mass could predict T₅₀ based on multilinear regression. These results are helpful for the selection of future urban greening trees in northern China.

Key words: photosynthetic thermotolerance, PSII potential quantum efficiency, deciduous tree, leaf morphological trait, leaf anatomical structure.