Relating the climate envelopes of urban tree species to their drought and thermal tolerance.Analysing the climate envelope of plant species has been suggested as a tool to predict the vulnerability of tree species in future urban climates.  However, there is little evidence that the climate envelope of a plant species directly relates to the drought and thermal tolerance of that species, at least not at the resolution required to identify or rank species vulnerability.  Here, we attempted to predict drought and thermal tolerance of commonly used urban tree species using climate variables derived exclusively from open-source global occurrence data.  We quantified three drought and thermal tolerance traits for 43 urban tree species in a common garden experiment: stomatal sensitivity to vapour pressure deficit, leaf water potential at the turgor loss point, and leaf thermal tolerance.  We found no strong relationships between drought and thermal tolerance traits and climatic variables.  But our results suggest that climate envelopes determined from species occurrence data alone may not predict drought or thermal tolerance at the resolution required to select tree species for future urban forests. 
THERM