Stem and leaf hydraulic properties are finely coordinated in three tropical rain forest tree species |
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Authors: | Markus Nolf Danielle Creek Remko Duursma Joseph Holtum Stefan Mayr Brendan Choat |
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Affiliation: | 1. Institute of Botany, University of Innsbruck, Innsbruck, Austria;2. Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales, Australia;3. School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia |
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Abstract: | Coordination of stem and leaf hydraulic traits allows terrestrial plants to maintain safe water status under limited water supply. Tropical rain forests, one of the world's most productive biomes, are vulnerable to drought and potentially threatened by increased aridity due to global climate change. However, the relationship of stem and leaf traits within the plant hydraulic continuum remains understudied, particularly in tropical species. We studied within‐plant hydraulic coordination between stems and leaves in three tropical lowland rain forest tree species by analyses of hydraulic vulnerability [hydraulic methods and ultrasonic emission (UE) analysis], pressure‐volume relations and in situ pre‐dawn and midday water potentials (Ψ). We found finely coordinated stem and leaf hydraulic features, with a strategy of sacrificing leaves in favour of stems. Fifty percent of hydraulic conductivity (P50) was lost at ?2.1 to ?3.1 MPa in stems and at ?1.7 to ?2.2 MPa in leaves. UE analysis corresponded to hydraulic measurements. Safety margins (leaf P50 – stem P50) were very narrow at ?0.4 to ?1.4 MPa. Pressure‐volume analysis and in situ Ψ indicated safe water status in stems but risk of hydraulic failure in leaves. Our study shows that stem and leaf hydraulics were finely tuned to avoid embolism formation in the xylem. |
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Keywords: | hydraulic coordination hydraulic vulnerability plant– water relations safety margin ultrasonic emissions |
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