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Xylem hydraulic characteristics of subtropical trees from contrasting habitats grown under identical environmental conditions

Published online by Cambridge University Press:  01 January 2000

C. VANDER WILLIGEN
Affiliation:
School of Life and Environmental Sciences, George Campbell Building, University of Natal, Durban 4041, South Africa
H. W. SHERWIN
Affiliation:
School of Life and Environmental Sciences, George Campbell Building, University of Natal, Durban 4041, South Africa
N. W. PAMMENTER
Affiliation:
School of Life and Environmental Sciences, George Campbell Building, University of Natal, Durban 4041, South Africa
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Abstract

Five evergreen subtropical tree species growing under identical environmental conditions were investigated to establish which hydraulic properties are genotypically rigid and which show phenotypic plasticity. Maximum xylem-specific conductivity (ks) correlated well with the anatomical characteristics (conduit diameter and density) for the four angiosperms Tecomaria capensis, Trichilia dregeana, Cinnamomum camphora and Barringtonia racemosa; the anatomy of the gymnosperm Podocarpus latifolius was not assessed. Huber values (functional xylem cross-sectional area [ratio ] leaf area) varied inversely with ks among species. Maximum leaf-specific conductivity was similar in the five unrelated species. Vulnerability of xylem to cavitation differed between species, as did the relationship between transpiration and water potential. Models of these parameters and isolated midday readings confirm that these trees operate at similar maximum leaf-specific conductivity (kl) values. The data are consistent with the hypothesis that conductivity characteristics (kl, ks) are influenced by environment, whereas vulnerability to cavitation is genetically determined.

Type
Research Article
Copyright
© Trustees of the New Phytologist 2000

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