The conifer-curve: fast prediction of hydraulic conductivity loss and vulnerability to cavitation

Sabine Rosner,Daniel M Johnson,Klara Voggeneder,Jean-Christophe Domec

doi:10.1007/s13595-019-0868-1

Abstract

Key messageThe relationship between relative water loss (RWL) and hydraulic conductivity loss (PLC) in sapwood is robust across conifer species. We provide an empirical model (conifer-curve) for predicting PLC from simple RWL measurements. The approach is regarded as a new relevant phenotyping tool for drought sensitivity and offers reliable and fast prediction of diurnal, seasonal, or drought-induced changes in PLC. ContextFor conifer species drought is one of the main climate risks related to loss of hydraulic capacity in sapwood inducing dieback or mortality. More frequently occurring drought waves call for fast and easily applicable methods to predict drought sensitivity. AimsWe aimed at developing a fast and reliable method for determination of the percent loss of hydraulic conductivity (PLC) and eventually the drought sensitivity trait P50, i.e., the water potential that causes 50% conductivity loss. MethodsWe measured the loss of water transport capacity, defined as the relative water loss (RWL) together with PLC in trunk wood, branches, and saplings of eight different conifer species. Air injection was used to induce specific water potentials. ResultsThe relationship between RWL and PLC was robust across species, organs, and age classes. The equation established allows fast prediction of PLC from simple gravimetrical measurements and thus post hoc calculation of P50 (r2 = 0.94). ConclusionThe approach is regarded as a relevant new phenotyping tool. Future potential applications are screening conifers for drought sensitivity and a fast interpretation of diurnal, seasonal, or drought-induced changes in xylem water content upon their impact on conductivity loss.

Highlights

Conifers are among the most endangered plant groups regarding forest dieback related to drought (Solberg 2004; Hentschel et al 2014; Allen et al 2015; Mencuccini and Binks 2015; McDowell and Allan 2015; Rosner et al 2018; Klein et al 2019)
A. nordmanniana had the lowest P50 (− 8.1 MPa) and P. menziesii grown in Austria had the highest P50 (− 5.0 MPa)
P50 was highest in the wood of the main trunk, ranging from -4.9 MPa in P. menziesii to − 2.2 MPa in P. abies

Summary

Introduction

Conifers are among the most endangered plant groups regarding forest dieback related to drought (Solberg 2004; Hentschel et al 2014; Allen et al 2015; Mencuccini and Binks 2015; McDowell and Allan 2015; Rosner et al 2018; Klein et al 2019). Facing global change (IPCC 2013), we urgently need fast and reliable screening tools for predicting drought sensitivity of conifer species and provenances thereof (David-Schwartz et al 2016, Voltas et al 2018). Screening tools should be economical, require little labor, not be time-consuming, easy in application and - last but not least - applicable to conifers worldwide. Rosner et al (2019) presented an approach where hydraulic conductivity loss of angiosperm and conifer sapwood could be predicted from simple water loss measurements.

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Conclusion