Prediction of hydraulic conductivity loss from relative water loss: new insights into water storage of tree stems and branches

Abstract

More frequently occurring, drought waves call for a deeper understanding of tree hydraulics and fast and easily applicable methods to measure drought stress. The aim of this study was to establish empirical relationships between the percent loss of hydraulic conductivity (PLC) and the relative water loss (RWL) in woody stem axes with different P , i.e. the water potential (Ψ) that causes 50% conductivity loss. Branches and saplings of temperate conifer (Picea abies, Larix decidua) and angiosperm species (Acer campestre, Fagus sylvatica, Populus x canescens, Populus tremula, Sorbus torminalis) and trunk wood of mature P. abies trees were analyzed. P was calculated from hydraulic measurements following bench top dehydration or air injection. RWL and PLC were fitted by linear, quadratic or cubic equations. Species- or age-specific RWLs at P varied between 10 and 25% and P , the Ψ that causes 88% conductivity loss, between 18 and 44%. P was predicted from the relationship between Ψ and the RWL. The predictive quality for P across species was almost 1:1 (r = 0.99). The approach presented allows thus reliable and fast prediction of PLC from RWL. Branches and saplings with high hydraulic vulnerability tended to have lower RWLs at P and at P . The results are discussed with regard to the different water storage capacities in sapwood and survival strategies under drought stress. Potential applications are screening trees for drought sensitivity and a fast interpretation of diurnal, seasonal or drought induced changes in xylem water content upon their impact on conductivity loss.

Insights from in vivo micro‐CT analysis: testing the hydraulic vulnerability segmentation in Acer pseudoplatanus and Fagus sylvatica seedlings

“…In some cases, however, trunks were reported to be more vulnerable than branches (e.g. Johnson et al, 2016;Rosner et al, 2018), and other studies found similar vulnerabilities across organs (e.g. Choat et al, 2005;Hao et al, 2013).…”

Coupling between the terrestrial carbon and water cycles—a review

“…The phloem is the other transport tissue which brings carbohydrates downward in the plant from the leaf source to its sinks (Sala et al 2010, Nikinmaa et al 2013, Rathgeber et al 2016, Castagneri et al 2017, Ziaco et al 2018. Both xylem and phloem interact through changes in osmotic pressure and water potential, regulating the water and carbohydrate transports in the plant (Botha 2005, Cochard et al 2009, Holtta et al 2009, Rosner et al 2018, Sevanto et al 2018, as well as turgor. They therefore interact to modify Tr and GPP (Nikinmaa et al 2013, Konrad et al 2018).…”

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

“…Screening tools should be economical, require little labor, not be time-consuming, easy in application and -last but not least -applicable to conifers worldwide. Recently, Rosner et al (2019) presented an approach where hydraulic conductivity loss of angiosperm and conifer sapwood could be predicted from simple water loss measurements. The empirical predicting models in this preceding study were however species-specific.…”

“…The RWL method allows the comparison of the samples differing in total water volume and wood density (Domec and Gartner 2001). Rosner et al (2019) defined an additional capacitance parameter, the RWL at P 50 , i.e., the RWL that results from 50% conductivity loss. RWL at P 50 varies widely across angiosperm and conifer species and is negatively related to wood density, as found for other capacitance traits as well (Pratt et al 2007;Scholz et al 2007;McCulloh et al 2014;Trifilò et al 2015;Savi et al 2017;Pratt and Jacobsen 2017).…”