Combining optics and acoustics to characterise cavitation in trees

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https://hal.archives-ouvertes.fr/hal-01191363

Submitted on 3 Jun 2020

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Combining optics and acoustics to characterise

cavitation in trees

Alexandre Ponomarenko, Olivier Vincent, Eric Badel, Hervé Cochard,

Philippe Marmottant

To cite this version:

Alexandre Ponomarenko, Olivier Vincent, Eric Badel, Hervé Cochard, Philippe Marmottant. Com-bining optics and acoustics to characterise cavitation in trees. Plant Biomechanics Conference, Aug 2012, Clermont-Ferrand, France. 1 p., 2012, 7th Plant Biomechanics International Conference. �hal-01191363�

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A link between hydric stress and acoustic events

t

0 1h 2h 3h 0 50 100 150 200 250 300

Combining optics and acoustics to characterise cavitation in trees

Voids in hydrogel

Experimental set up

Cohesion-Tension theory

Dixon & Joly (1895)

hydrogel

microphone

camera

Wheeler & Stroock (2008)

Vincent (2012)

Tyree & Dixon (1983)

Origin

of the

acoustic events?

Modeling a tree with hydrogel microfabrication Experiment with a photodiode t=-20 s t=20 s t=0 s t=40 s t=60 s t=100 s t=80 s t=120 s

Influence of the void geometry on frequency

The hydrogel dries in ambiant air. Water tension in the hydrogel increases from 0 MPa up to 20 MPa and cavitation events appear. We monitor the drying using simultaneously (i) a microphone in the ultrasound range and (ii) a camera.

Alexandre Ponomarenko

1

_{, Olivier Vincent}

1

_{, Eric Badel}

2

_{, Hervé Cochard}

2

_{and Philippe Marmottant}

1

1_{Laboratoire Interdisciplinaire de Physique}

Université Grenoble 1 - CNRS (UMR 5588), France

2_{INRA UMR 547 PIAF, F-63100 Clermont-Ferrand,}

t=-20 s

t=60 s

Potential mechanisms for the acoustic events

- evaporation from the leaves establishes a liquid column from the roots to the leaves - the water column is under strong tension (several MPa)

picture: Badel (2011)

Sap in a metastable state

Wood in hydrogel

0 s 2 s 4 s 6 s 8 s 50 µm 500 µm optics 0 1h 2h 0 50 100 150 200 250 300 350 400 450 500 optics acoustics optics acoustics 0 2 4 6 8 10 0 10 20 30 40

Cavitation events during hydrogel drying

Comparing acoustic and optic signals

The images on the right are obtained by substracting two images with 1s time interval. It enables to see tiny movements. Here, as a bubble grows, the neighbouring wood fibers are deformed.

0 s

2 s

4 s

6 s

- Cavitation events in the xylem - Embolism in the circulation

100 µm 100 µm 100 µm 3. bubbles 3.a nucleation 3.b growth 100 µm 1. wood cracks 100 µm 10 µm 0 100 200 300 400 0 1 2 3 4 5 Contact: aponoma@liphy.ujf-grenoble.fr 4. pits movements 50 µm 5 µm

pictures: Tyree & Zimmermann (2001)

2. xylem collapse

10 µm 10 µm