Technical note: An experimental set-up to measure latent and sensible heat fluxes from (artificial) plant leaves
Leaf transpiration and energy exchange are coupled processes that operate at small scales yet exert a significant influence on the terrestrial hydrological cycle and climate. Surprisingly, experimental capabilities required to quantify the energy–transpiration coupling at the leaf scale are lack...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-07-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/21/3377/2017/hess-21-3377-2017.pdf |
| Summary: | Leaf transpiration and energy exchange are coupled processes that
operate at small scales yet exert a significant influence on the terrestrial
hydrological cycle and climate. Surprisingly, experimental capabilities
required to quantify the energy–transpiration coupling at the leaf scale are
lacking, challenging our ability to test basic questions of importance for
resolving large-scale processes. The present study describes an experimental
set-up for the simultaneous observation of transpiration
rates and all leaf energy balance components under controlled conditions,
using an insulated closed loop miniature wind
tunnel and artificial leaves with pre-defined and constant diffusive
conductance for water vapour. A range of tests documents the above
capabilities of the experimental set-up and points to potential improvements.
The tests reveal a conceptual flaw in the assumption that leaf temperature
can be characterized by a single value, suggesting that even
for thin, planar leaves, a temperature gradient between the irradiated and
shaded or transpiring and non-transpiring leaf side can lead to bias when
using observed leaf temperatures and fluxes to deduce effective conductances
to sensible heat or water vapour transfer. However, comparison of
experimental results with an explicit leaf energy balance model revealed only
minor effects on simulated leaf energy exchange rates by the neglect of
cross-sectional leaf temperature gradients, lending experimental support to
our current understanding of leaf gas and energy exchange processes. |
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| ISSN: | 1027-5606 1607-7938 |