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

In: IAWA Journal
Authors:
Nadia S. Santini 1 Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Sydney, NSW 2007, Australia
2 Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia

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James Cleverly 1 Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Sydney, NSW 2007, Australia

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Rolf Faux 1 Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Sydney, NSW 2007, Australia

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Katie McBean 3 Centre of Expertise Microstructural Analysis, University of Technology Sydney, PO Box 123, Sydney, NSW 2007, Australia

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Rachael Nolan 1 Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Sydney, NSW 2007, Australia

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Derek Eamus 1 Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Sydney, NSW 2007, Australia

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Online Publication Date:
20 Feb 2018
Free access

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.).

Title:
Root xylem characteristics and hydraulic strategies of species co-occurring in semi-arid Australia
Article Type:
Research Article
DOI:
https://doi.org/10.1163/22941932-20170188
Language:
English
Pages:
43–62
Keywords:
Groundwater; deciduous; evergreen; phreatophytes
In:
IAWA Journal
In:
Volume 39: Issue 1
Publisher:
Brill
E-ISSN:
2294-1932
Print ISSN:
0928-1541
Subjects:
Botany, Biology

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