It's about time! Leaf minimum conductance determines time to reach critical thresholds for leaf dehydration in a seasonal tropical forest

Abstract

O_LILeaf minimum conductance (gmin) is important in determining plant responses to drought. However, we do not understand how gmin is related to drought tolerance across species, and how important it is in determining the time to reach critical dehydration levels. C_LIO_LIIn 18 coexisting species from a seasonal tropical forest we quantified gmin to test relationships with early, moderate and severe dehydration thresholds associated with tolerance to turgor loss, breakdown of structural integrity, and disruption of cellular function, respectively. We quantified other functional and hydraulic traits to determine the major axes of trait variation in these species. C_LIO_LIVariation in gmin was the primary determinant of the time to reach critical levels of dehydration, and was unrelated to thresholds for early and severe dehydration. Surprisingly, gmin was negatively related to maximum stomatal conductance, but unrelated to other functional and hydraulic traits. C_LIO_LIThese results highlight the importance of avoiding dehydration via minimizing gmin, and suggest that avoidance, tolerance to early, and severe dehydration represent independent strategies for coping with drought. This would allow coexisting species to balance opportunities for carbon gain with costs of physiological breakdown when faced with varying intensities and durations of drought. C_LI