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Abstract

While the significance of leaf transpiration (f(e)) on carbon and water cycling is rarely disputed, conflicting evidence has been reported on how increasing mean wind speed (U) impacts f(e) from leaves. Here, conditions promoting enhancement or suppression of f(e) with increasing U for a wide range of environmental conditions are explored numerically using leaf-level gas exchange theories that combine a stomatal conductance model based on optimal water use strategies (maximizing the 'net' carbon gain at a given f(e)), energy balance considerations, and biochemical demand for CO2. The analysis showed monotonic increases in f(e) with increasing U at low light levels. However, a decline in modeled f(e) with increasing U were predicted at high light levels but only in certain instances. The dominant mechanism explaining this decline in modeled f(e) with increasing U is a shift from evaporative cooling to surface heating at high light levels. New and published sap flow measurements for potted Pachira macrocarpo and Messerschmidia argemea plants conducted in a wind tunnel across a wide range of U (2 - 8 m s(-1)) and two different soil moisture conditions were also employed to assess how f(e) varies with increasing U. The radiative forcing imposed in the wind tunnel was only restricted to the lower end of expected field conditions. At this low light regime, the findings from the wind tunnel experiments were consistent with the predicted trends. (C) 2015 Elsevier Ltd. All rights reserved.

Keywords

Energy balance; Laminar boundary layer; Leaf-level gas exchange; Optimality hypothesis; Wind effects

Published in

Advances in Water Resources
2015, volume: 86, number: Part A, pages: 240-255
Publisher: ELSEVIER SCI LTD

SLU Authors

UKÄ Subject classification

Forest Science

Publication identifier

  • DOI: https://doi.org/10.1016/j.advwatres.2015.10.009

Permanent link to this page (URI)

https://res.slu.se/id/publ/69412