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Root xylem characteristics and hydraulic strategies of species co-occurring in semi-arid Australia

Root xylem characteristics and hydraulic strategies of species co-occurring in semi-arid Australia Xylem traits such as xylem vessel size can influence the efficiency and safety of water transport and thus plant growth and survival. Root xylem traits are much less frequently examined than those of branches despite such studies being critical to our understanding of plant hydraulics. In this study, we investigated primary lateral and sinker roots of six co-occurring species of semi-arid Australia. Two species are restricted to a floodplain, two were sampled only from the adjacent sand plain, and two species co-occur in both habitats. We assessed root wood density, xylem traits (i.e., vessel diameter, fibre and vessel wall thickness), outer pit aperture diameter and calculated theoretical hydraulic conductivity and vessel implosion resistance. We hypothesized that (1) roots have larger xylem vessel diameters and lower wood density than branches of the same species and that (2) there is an inverse correlation between theoretical sapwood hydraulic conductivity and vessel implosion resistance for roots. Variation in root wood density was explained by variations in xylem vessel lumen area across the different species (r2 = 0.73, p = 0.03), as hypothesized. We rejected our second hypothesis, finding instead that the relationship between theoretical hydraulic conductivity and vessel implosion resistance was not maintained in roots of all of our studied species, in contrast to our previous study of branches from the same species. Xylem traits were found to depend upon habitat and eco-hydrological niche, with the groupings including (i) arid-adapted shrubs and trees with shallow lateral roots (Acacia aneura and Psydrax latifolia), (ii) trees restricted to the floodplain habitat, both evergreen (Eucalyptus camaldulensis) and deciduous (Erythrina vespertilio) and (iii) evergreen trees co-occurring in both floodplain and adjacent sand plain habitats (Corymbia opaca and Hakea sp.). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png IAWA Journal Brill

Root xylem characteristics and hydraulic strategies of species co-occurring in semi-arid Australia

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Publisher
Brill
Copyright
Copyright © Koninklijke Brill NV, Leiden, The Netherlands
ISSN
0928-1541
eISSN
2294-1932
DOI
10.1163/22941932-20170188
Publisher site
See Article on Publisher Site

Abstract

Xylem traits such as xylem vessel size can influence the efficiency and safety of water transport and thus plant growth and survival. Root xylem traits are much less frequently examined than those of branches despite such studies being critical to our understanding of plant hydraulics. In this study, we investigated primary lateral and sinker roots of six co-occurring species of semi-arid Australia. Two species are restricted to a floodplain, two were sampled only from the adjacent sand plain, and two species co-occur in both habitats. We assessed root wood density, xylem traits (i.e., vessel diameter, fibre and vessel wall thickness), outer pit aperture diameter and calculated theoretical hydraulic conductivity and vessel implosion resistance. We hypothesized that (1) roots have larger xylem vessel diameters and lower wood density than branches of the same species and that (2) there is an inverse correlation between theoretical sapwood hydraulic conductivity and vessel implosion resistance for roots. Variation in root wood density was explained by variations in xylem vessel lumen area across the different species (r2 = 0.73, p = 0.03), as hypothesized. We rejected our second hypothesis, finding instead that the relationship between theoretical hydraulic conductivity and vessel implosion resistance was not maintained in roots of all of our studied species, in contrast to our previous study of branches from the same species. Xylem traits were found to depend upon habitat and eco-hydrological niche, with the groupings including (i) arid-adapted shrubs and trees with shallow lateral roots (Acacia aneura and Psydrax latifolia), (ii) trees restricted to the floodplain habitat, both evergreen (Eucalyptus camaldulensis) and deciduous (Erythrina vespertilio) and (iii) evergreen trees co-occurring in both floodplain and adjacent sand plain habitats (Corymbia opaca and Hakea sp.).

Journal

IAWA Journal – Brill

Published: Feb 20, 2018

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