UC Riverside

When one studies drought tolerance, it is helpful to examine heat tolerance as well, because high heat accelerates drought. Across ecosystems woody plant mortality has been observed as warmer temperatures amplify the effects of arid conditions. Although plant heat and drought tolerance are frequently studied, the combination of these two stresses has received little attention, but is essential, because we cannot extrapolate responses to stress combinations simply by the addition of responses to the two single stresses given the nature of potential interactions, both in climate and physiological regulation (Cohen I, et al 2021). Our study revealed a significant negative correlation between the heat tolerance parameter, T50 and the drought tolerance parameter, πtlp using species data taken across all ecosystems. This correlation suggests that drought and heat tolerance may be co-selected in response to evolutionary stress. This result has implications for predicting which species are likely to survive global change type drought, where arid conditions are compounded with increasingly errant heat waves. Our study supports the trait co-selection hypothesis based on the significant correlations of drought and heat tolerant measurements across ecosystems with a broad range of climatic conditions.