A novel approach for fast prediction of hydraulic vulnerability in conifers

Global warming calls for fast and easily applicable methods to measure hydraulic vulnerability in conifers since they are one of the most sensitive plant groups regarding drought stress. Classical methods to determine P₅₀, i.e. the water potential resulting in 50% conductivity loss, are labor intensive and prone to errors. In this study, the empirical relationship between percent loss of hydraulic conductivity and relative water loss in sapwood of six conifer species was used to establish a novel proxy for P₅₀. Our new proxy P_25W, defined as 25% of relative water loss induced by air injection, is easy and fast to measure and correlates strongly with P₅₀ (r = 0.95) as well as with functional wood traits such as the tracheid wall/lumen ratio (r = -0.87). The method is regarded as a strong new phenotyping tool for screening trees for drought sensitivity.