Growth dynamics of root and shoot hydraulic conductance in seedlings of five neotropical tree species: scaling to show possible adaptation to differing light regimes |
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Authors: | Melvin T Tyree Virginia Velez J W Dalling |
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Institution: | (1) USDA Forest Service, Aiken Forestry Sciences Laboratory, P.O. Box 968, South Burlington, VT 05402, USA E-mail: mtyree@zoo.uvm.edu, US;(2) Smithsonian Tropical Research Institute, P.O. Box 2072, Balboa, Republic of Panama, PA |
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Abstract: | The dynamics of growth (shoot and root dry weights, surface areas, hydraulic conductances, and root length) were measured
in seedlings of five neotropical tree species aged 4–16 months. The species studied included two light-demanding pioneers
(Miconia argentea and Apeiba membranacea) and three shade-tolerant young- or old-forest species (Pouteria reticulata, Gustavia superba, and Trichilia tuberculata). Growth analysis revealed that shoot and root dry weights and hydraulic conductances and leaf area all increased exponentially
with time. Alternative methods of scaling measured parameters to reveal differences that might explain adaptations to microsites
are discussed. Scaling root conductance to root surface area or root length revealed a few species differences but nothing
that correlated with adaptation to light regimes. Scaling of root surface area or root length to root dry weight revealed
that pioneers produced significantly more root area and length per gram dry weight investment than shade-tolerant species.
Scaling of root and shoot hydraulic conductances to leaf area and scaling of root conductance to root dry weight and shoot
conductance to shoot dry weight also revealed that pioneers were significantly more conductive to water than shade-tolerant
species. The advantages of scaling hydraulic parameters to leaf surface area are discussed in terms of the Ohm's law analogue
of water flow in plants.
Received: 24 March 1997 / Accepted: 17 November 1997 |
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Keywords: | Hydraulic conductance Root Shoot Growth dynamics Neotropical tree seedlings |
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