Contributions of Intraspecific Variation to Drought Tolerance in Trees

[Purpose of Review] The capacity of woody plants to cope with climate change depends on their adjustments to changing environmental conditions by phenotypic plasticity or by genotypic changes (i.e., local adaptation). To determine whether intraspecific trait variation (ITV) translates into resistance or tolerance to drought and eventually how it relates to performance when facing drought, we reviewed the recent literature on the intraspecific variation in woody plant functional traits along aridity gradients.
[Recent Findings] At the intraspecific level, functional traits vary along aridity gradients, but this variation depends on the considered trait and species. While ITV is ubiquitous and of relevant magnitude, its relationship with tree performance in the case of growth or survival is unclear and very idiosyncratic.
[Summary] ITV varies along aridity gradients and, for several traits, is of comparable magnitude as interspecific trait variation. However, the relationship between ITV and tree performance is not consistent among species. This makes the use of ITV challenging when quantifying its contribution to drought tolerance.