How does the leaf heat sensitivity relate to the species' geographical distribution range in the Brazilian savanna?

Global warming poses a significant impact on plant species in the Cerrado, the largest savanna in the world. However, there is still a gap in understanding how species distribution patterns are associated with their thermal sensitivity. One approach to address this is quantifying species´ specific responses through leaf traits related to heat stress. Therefore, we determined the temperature that caused a 50% reduction (T₅₀) in the light-acclimated quantum efficiency of PSII (F_v′/F_m′) and the thermal safety margin (TSM) (T₅₀—maximum leaf temperature), together with Leaf Area (LA) and Leaf Mass Area (LMA) in 12 tree species from two climatic contrasting regions within the Cerrado. We compared the traits between widespread species (co-occurring in both sites) and species restricted to each region, and we explored the relationships between T₅₀ and TSM with LA and LMA. As a result, we found that T₅₀ and TSM values were similar across species, regardless of study region or species distribution range. Additionally, we observed that study species had lower TSM, which suggests that these species might be likely to approach high-temperature thresholds. Furthermore, the study species exhibited general relationships between LA and LMA with T₅₀, indicating that leaf traits mainly determine the thermal properties of Cerrado tree species.