Hydraulic architecture of deciduous and evergreen dry rainforest tree species from north-eastern Australia

Choat, Brendan, Ball, Marilyn C., Luly, Jon G., and Holtum, Joseph A.M. (2005) Hydraulic architecture of deciduous and evergreen dry rainforest tree species from north-eastern Australia. Trees, 19 (3). pp. 305-311.

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Hydraulic conductivity and xylem anatomy were examined in stems of two evergreen species, Alphitonia excelsa (Fenzal) Benth. and Austromyrtus bidwillii (Benth.) Burret., and two drought-deciduous species, Brachychiton australis (Schott and Endl.) A. Terracc. and Cochlospermum gillivraei Benth., from a seasonally dry rainforest in north Queensland, Australia. The deciduous species possessed hydraulic architecture typical of drought-sensitive plants, i.e. low wood density, wider xylem vessels, higher maximal rates of sapwood specific hydraulic conductivity (Ks) and high vulnerability to drought-induced embolism. In contrast, the evergreen species had lower rates of Kh and leaf specific conductivity (KL) but were less susceptible to embolism. The evergreen species experienced leaf water potentials <−4.0 MPa during the dry season, while the deciduous species shed their leaves before leaf water potentials declined below −2.0 MPa. Thus, the hydraulic architecture of the evergreens allows them to withstand the greater xylem pressure gradients required to maintain water transport to the canopy during the dry season. Our results are consistent with observations made in neotropical dry forests and demonstrate that drought-deciduous species with low wood density and high water storage capacity are likely to be more hydraulically efficient, but more vulnerable to embolism, than coexisting evergreens.

Item ID: 9037
Item Type: Article (Research - C1)
ISSN: 1432-2285
Keywords: drought-induced embolism; leaf phenology; water potential
Date Deposited: 15 Mar 2010 23:06
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050206 Environmental Monitoring @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 100%
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