Intraspecific drought tolerance of Betula pendula genotypes: an evaluation using leaf turgor loss in a botanical collection

Simon Hannus,Andrew Hirons,Timothy Baxter,Hugh A Mcallister,Björn Wiström,Henrik Sjöman

doi:10.1007/s00468-020-02059-7

Abstract

Key messageThe results showed a significant relationship between the potential evapotranspiration of the provenance collection site and the leaf turgor loss point and significant positive differences in drought tolerance between provenances and subspecies of B. pendula.The ecosystem services provided by urban trees make substantial contributions to the quality of urban living and securing resilience towards the challenges posed by a changing climate. Water deficits are a major abiotic stress for trees in urban environments and, in many regions, this stress is likely to be amplified under future climate scenarios. Although wide variation in drought tolerance exists at the species level, many species also show substantial intraspecific variation in drought tolerance. The aim of this study is to evaluate how drought tolerance, inferred from the water potential at leaf turgor loss point (ΨP0), varies in Betula pendula from different geographical origins and determine if the observed drought tolerance can be related to the local climate and seasonal water balance from the provenance of origin, despite the trees now being established in similar soil and climatic conditions within a single botanical collection. Six subsp. betula, five subsp. mandshurica and two subsp. szechuanica were evaluated, giving a total of 12 different provenances. The results showed a significant relationship between the potential evapotranspiration of the provenance collection site and the leaf turgor loss point and significant positive differences in drought tolerance between provenances and subspecies of B. pendula. By directing efforts towards identifying more drought-tolerant genotypes, it will be possible to diversify the palette of trees that could confidently be integrated by urban tree planners and landscape architects into the urban landscape. The results of this study on different ecotypes of B. pendula clearly show that it is possible to find more drought-tolerant plant material.

Highlights

Societal benefits from trees are positively related to the size and health of the tree (Hirons and Sjöman 2019)
The overall aim of this study is to evaluate how drought tolerance, inferred from the water potential at leaf turgor loss point (ΨP0), varies in Betula pendula from different geographical origins and determine if the observed drought tolerance can be related to the local climate and seasonal water balance from the provenance of origin, despite the trees being established in similar soil and climatic conditions within a single botanical collection
There was a significant effect on ΨP0 for inclusion of the different sites (L = 38.22, df = 1, p < 0.0001) and ΨP0 varied from – 2.07 to – 2.94 MPa across the examined B. pendula

Summary

Introduction

Societal benefits from trees are positively related to the size and health of the tree (Hirons and Sjöman 2019). Large healthy trees are more effective at intercepting rainfall and mitigating flood risk (Berland et al 2017). Those seeking to maximize the value of the urban forest, need to preserve space for large, mature trees, and diligently specify species that are capable of performing well on those sites. Water deficits are a major abiotic stress for trees in urban environments (Sieghardt et al 2005; Hirons and Thomas 2018) and, in many regions, this stress is likely to be amplified under future climate scenarios (Allen et al 2010; Ruosteenoja et al 2018).

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