Cities present warmer environmental conditions than the surrounding areas due to the high concentration of CO2 in the atmosphere, an abundance of concrete surfaces, and changes in precipitation patterns. Identifying the vulnerabilities of urban tree species to high temperatures is an essential goal, especially in response to our changing climate. One major stressor in cities is the thermal pollution associated with urban heat islands (UHI). However, direct evidence supporting physiological adaptation to urban environments by trees is remarkably limited. That's why we want to go beyond and identify to what extent stress factors (i.e. temperature) alter the development of organisms, using cities as an experimental design to test the effects of climate change. For this study, we will compare the thermal tolerances of tropical and temperate tree species in urban environments and compare them with their synonymous counterparts in natural forest using the warming tolerance method.