Into the woods (木)G30 for everyone
Marie CAPRON
Laboratory of Biomaterial Physics
Graduate School of Bioagricultural Sciences1

Contents
1. Use of wood
2. Wood anatomy
3. Growth of tree
4. Sap flow

2

木材の利用Use of wood•

Construction•Furniture

•Art

•

Lute-making
Uwajima Castle - 宇和島城
3

Use of wood•

Construction•Furniture

•

Art

•

Lute-making
Bonheur du jour - Charles Topino(1725-1789), assembly in oak andpoplar; marquetry of sycamore, roses
wood, buxus and ilex aquifolium. Muséedes Arts Décoratifs © AnticStore
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Use of wood•

Construction•Furniture

•

Art•

Lute-making
Mona Lisa, painted on Populus
5Use of wood•

Construction•Furniture

•

Art•

Lute-making

Few steps of violin making

Biwa (琵琶)6•What is under the bark?
Copyright University of Canterbury, 1996.
Artwork by Mark Harrington

Wood architecture7

Under the bark, we can observe two zones:

Heartwood (心材)
Sapwood (辺材)

BarkDuramen
8

Wood at the microscopicscale•

Different kinds of cells
composed wood•

What is the anatomy ofwood?

9Copyright University of Canterbury, 1996.
Artwork by Mark Harrington

Clair, (2001), PhD

Wood anatomy

Copyright University of Canterbury, 1996.
Artwork by Mark Harrington

Vessels used for sap flow
10y (µm)

Fibers used for supporting stress011510010x 103242.562810
1.5

12114

160.5

18
15200

Capron et al., (2015), PBM 8thx (µm)

Copyright University of Canterbury, 1996.
Artwork by Mark Harrington

Clair, (2001), PhD

Wood anatomy

Rays used as a reserve
12

Copyright University of Canterbury, 1996.
Artwork by Mark Harrington

Clair, (2001), PhD

Wood anatomy

S3 layer
Lumen

S2 layer
S1 layerPrimary wallMiddle lamella
13

Copyright University of Canterbury, 1996.
Artwork by Mark Harrington

Cell wall scaleCopyright University of Canterbury, 1996.
Artwork by Mark Harrington

Cell wall scale•Cell walls = microfibrils +matrix•

Microfibrils = cristallin
cellulose•Matrix = soft mixture of lignin
and hemicellulose
0100−62200−64300y (nm)

400−66500−68600700−70800−729001000−74014200

400

600x (nm)

800

1000

1200

Copyright University of Canterbury, 1996.
Artwork by Mark Harrington

Molecular scale•

50% cellulose•30% hemicellulose•20% lignin

15•How to observe wood at the
microscopic scale?
•Light microscope•

Scanning Electron Microscope (SEM)•Atomic Force Microscope (AFM)

16

Copyright University of Canterbury, 1996.
Artwork by Mark Harrington

Wood observations

Light microscopy

0,5 mm17•

See the chemicalcomposition between
different kind of cells(coloring)•

Observe large areas

Clair, (2001), PhD

Scanning ElectronMicroscope

18•

3D visualisation•

High magnification

Clair, (2001), PhD

Atomic Force Microscope•Topography•

High magnification•Local mechanicalproperties

x 103022.546y (µm)

Capron et al., (2015), PBM 8th10281.510121140.5

1618051015200x (µm)

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Wood - orthotropic material（異方性材料）
Soft wood

Hard wood

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Soft wood

針葉樹
Radial section

Cross section

90% of tracheid fiber — support + conduction

21

Tangential section

Hard wood

広葉樹
Radial section

Cross section

Fibers — mechanical support• Vessels — conduction• Radial parenchyme — reserve storage•

22

Tangential section

Growth of tree

Pith

樹木の成長
Bark
Sapwood
Living partof the woodHeartwood =tree’s skeleton
Hollow tree trunk
with living peripheryparts
23Cambium
barkphloem形成層

woodcambium
barkpithphloemcambiumbarkpithwood cell
24pithGrowth rings 年輪
Growth rings
1 year•Annual rings: Visible rings result from the change in growth
speed through the seasons of the year.

•Boundary between « early wood » (rapid growth, lessdense) and « late wood » (denser)•More visible in temperate zones•

Dendrochronology: study of end grain patterns of growthrings, with a view to dating timber
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Primary and secondary growth
一次成長と二次成長
Primarygrowth• Plants growth — division ofmeristematic tissue• Primary growth — cell division at

the apical meristem at the tip of
the plant (making the shootlonger)

Secondarygrowthpith Secondarylayerlumen• Secondary growth — cell division

Primarylayer

new layer ofwood(stem)at the lateral meristem in acylinder encasing the shoot(increases the shoot’s girth)

new layer of cellwall(cell)26

Maturation
Bark• Setting up of secondary growth ended byligninification (chemical reaction to stiffen cell wall)• Lignin penetrates between polysaccharides(chemical components of the cell wall) andpolymerize• Mechanical consequences on the cells

Cambium

Coloringof lignin

due tomaturation?
Xylem27

Secondary growth
Clair, (2001), PhD

Isolated cellThe samecells attached
to older cells

maturation

compression
maturation

strenghtσσ

Stress profil

Consequence: Growth stress28

Reaction wood•

あて材

Trees are able to react to important stresses:•fierce unidirectional wind•tree-top loss of balance•partial lay baring•

Generation of stress strains on the top of the stem orcompression strains on the bottom of the stem•

Important changements in the wood cell structure•

Called reaction wood in opposite to normal wood29

Clair, (2001), PhD

Tension wood

GS3

S2S2S1S1LM + P

LM + PTension wood
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Normal wood

Clair, (2001), PhD

Compression wood

S3
S2

S2

S1

S1
LM + P

Normal wood
31

Compression woodHydrothermal recovery(HTR)•HTR is triggered by immersion in hot water at macroscopic
and microscopic scales.

•

Heating of wood used for rotary cutting or slicing•

Heating of wood induces a complex set of deformation
processes at the macroscopic, cellular and microscopicscale•

HTR induced a high tangential expansion, a little radialcontraction, a longitudinal contraction in normal andtension wood and a longitudinal expansion in compressionwood
32Effects of growth stress

Cracks - European Beech

Eucalyptus South Africa•

Cracks appears after the cutting•

Log destruction
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Scientific issues••

Reaction wood•

Understanding the mechanism of maturation stress generation in trees used tocontrol the orientation of its axes, to grow in height, maintain its branches at an
optimal angle or achieve adaptive reorientations•

Question of paramount importance in tree physiology•

Important technological outcomes regarding wood processing and biomimetic
inspiration in material design

HTR•

Understanding the variation of local cell wall properties resulting at different scales•

Contributing to the basic knowledge required for designing novel preconditioning
procedures aiming at increasing both processing yield and quality of woodproducts
34How do you think tree feeds?

Stroock et al (2014), Ann. Rev. Fluid Mech.

35•

Global view of transport
processes in a vascular plant.

•Photosynthetic reaction in theleaves•

Sap transport in xylem andphloem•

Water exchanges in roots

Stroock et al (2014), Ann. Rev. Fluid Mech.

Photosynthesis — 光合成•

Green plants are machines that run on sunlight, carbon dioxide,and water•

Photosynthetic reaction:•Plants generate all of the photosynthetic products in their leaves•

Photosynthetic products are exported to the rest of their tissues forgrowth and storage
36

Sap flow

Stroock et al (2014), Ann. Rev. Fluid Mech.

37•

Efficient convective transport overlong distances•

Leaves behave like a pump(capillary pressure)•Phloem : movement from theleaves to the roots — composedof sugars in water•

Xylem : movement from the roots
to the leaves — mostly composedof water•

Water enters in the roots due toosmotic pressureCavitation (キャビテーション)

Stroock et al (2014), Ann. Rev. Fluid Mech.

38•

Liquid are at negative
pressures in the xylem duringtranspiration•

The breakage of the liquid(cavitation columns in thexylem does occur•

Important consequences forplant function and viability —>death of tree•

Xylem fibers composed ofdeath cells connected bypits•

Pits = parts of the cellwalls composed of amembrane able to stop
gaz spreading and to allow
the exchange of liquid

Copyright University of Canterbury, 1996.
Artwork by Mark Harrington

How to prevent cavitation?

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Pit localisation
VesselPit (壁孔)

Bouchet et al. (2012)40

Pit architecture
Pit border

Pit membrane

Pit membrane (PM) allows liquid transfert and stops gaz
spreading due to its porosity.
• Pit border (PB) uses for mechanical structure.
•41

Capron (2014), PhD

Pit deformation
How pits behave during
gaz spreading?

Deformed pit membrane
due to increase of pressure

Silicon micro-molding
42

Capron (2014), PhD

Pit deformation
Modelling

Experimental data

Silicon micro-molding
43

Capron (2014), PhD

Scientific issues•Climatic changes and access to water will have aneffect on forestry ecosystems•

Find pertinent and operational selection criteria inorder to identify stronger genotypes able to resist toclimatic changes•

Understating the genetics of the embolism
resistance44Thank you for your attention
Any questions?

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