Coordination between water-transport efficiency and photosynthetic capacity in canopy tree species at different growth irradiances
Paula I. Campanello (1), M. Genoveva Gatti (1) and Guillermo Goldstein (1, 2, 3)
1. Laboratorio de Ecología Funcional, Departamento de Ecología, Genética y Evolución, Facultad de Ciencias, Exactas y Naturales,
Universidad de Buenos Aires Ciudad Universitaria, Pabellón II, 4 piso, Ciudad de Buenos Aires (C1428EHA), Argentina / 2. Present address: Department of Biology, University of Miami, P.O. Box 249118, Coral Gables, FL 33124, USA / Corresponding author () / Received November 16, 2006; accepted March 30, 2007; published online October 15, 2007
Summary
Plasticity in hydraulic architecture of five dominant Atlantic forest species differing in light requirements and growth rates
was evaluated in saplings grown at different irradiances to determine if hydraulic architecture changes in coordination with
photosynthetic capacity. Saplings were grown in shade-houses at 10, 30, 45 and 65% of full solar irradiance for 4 months.
In four of the five species, maximum relative growth rates were observed at intermediate irradiances (30 and 40% of full sun).
Slow-growing species had lower maximum electron transport rates (ETRmax) than fast-growing species. A positive correlation between ETRmax and maximum leaf hydraulic conductivity (KL) was found across species, suggesting that species-specific stem hydraulic capacity and photosynthetic capacity were linked.
Species with relatively high growth rates, such as Cedrela fissilis Vell., Patagonula americana L. and Cordia trichotoma (Vell.) Arrab. Ex Stend, exhibited increased KL and specific hydraulic conductivity (KS) with increased growth irradiance. In contrast, KS and KL did not vary with irradiance in the slower-growing and more shade-tolerant species Balfourodendron riedelianum (Engl.) Engl. and Lonchocarpus leucanthus Burkart, despite a relatively large irradiance-induced variation in ETRmax. A correlation between KS and ETRmax was observed in fast-growing species in different light regimes, suggesting that they are capable of plastic changes in hydraulic
architecture and increased water-transport efficiency in response to changes in light availability resulting from the creation
of canopy gaps, which makes them more competitive in gaps and open habitats.
