Fracture mechanics of tree root breakage

Thesis submitted for the degree of

Master of Science in Forestry

Submitted by

Mauro Lanfranchi - ID 51337724

In August 2014

Supervisors

Prof. Paul Hallett

Dr. Andrew Cameron

College of Life Science and Medicine

ScotlandUnited Kingdom

FRACTURE MECHANICS OF TREE ROOT BREAKAGE

AND FURTHER IMPLICATIONS FOR TREE BLOWDOWN

FRACTURE MECHANICS OF TREE ROOT BREAKAGE AND FURTHER IMPLICATIONS FOR TREE BLOWDOWN

Study area

FRACTURE MECHANICS OF TREE ROOT BREAKAGE AND FURTHER IMPLICATIONS FOR TREE BLOWDOWN Mauro Lanfranchi MSc Forestry Wednesday 3 May 2023

5

13

134

1415

10

2

128

6

9

117

Sampling – Direction of fall – Prevailing wind


Root plate

MetOffice; Windfinder

N

NE

E

SE

S

SW

W

NW

0

10

20Direction of fall

Degree Range

From to

N 337.5 22

NW 292.5 337

W 247.5 292

SW 202.5 247

S 157.5 202

SE 112.5 157

E 67.5 112

NE 22.5 67


100

200

300

400

500

600

700

800

Compression Bending

Tensile

Median +/- SE

Lab tests: YM

[MPa]

BENDING TEST COMPRESSION TEST TENSILE TEST

Load Proot

supportl/2

Load Py

yroot

root

Yoshihara and Tsunematsu, 2006

F clamps

Fx

Root Ø: 0.2 - 3.2 mm

Root Ø: 3.4 - 48.5 mmRoot Ø: 2.22 - 26 mm


Field and Raw data[N]

Root Ø [mm]

Tosi (2007); Achim and Nicoll, (2009); Phillips et al. (2008).

[m]

1 2 3

20

40

60 R² = 0.816

0.3 0.35 0.40 0.45 0.50 0.55

1

2

3

4

5

Root

pla

te


Mean +/- SE

Tensile test: Fracture toughness (Ƭ)

Ş = stress intensity factor: constant set at 1.442

ʂ = maximum stress: Fmax / Ɖ [Pa]

L = crack length (Ø * 0.79)

N NE E SE S SW W NW N NE E SE S SW W NW

500

1,000

1,000

500

Ƭ = Ş * ʂ *

Johnson et al. (2010)

Significant difference from windward roots

east * p < 0.001

west * P = 0.048

north-west * P = 0.021

North-east P = 0.940

[KPa

m½

]

[KPa

m½

]

* = significant (p < 0.05)

Mean +/- SE

E NW – W N - NE E NW / W N / NE

500

700

1000

1000

600

800

[KPa

m½

]

[KPa

m½

]

Significant difference from N/NE roots

E * p < 0.001

W / NW * P = 0.001

Tensile test: Fracture toughness


* = significant (p < 0.05)

Thank You

References

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• • Websites:

• BaseCamp: http://www8.garmin.com/support/download_details.jsp?id=4435

• Edina.com: http://digimap.edina.ac.uk/digimap/home• MetOffice: http://www.metoffice.gov.uk/• Windfinder.com:

http://www.windfinder.com/windstatistics/aberdeen


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Fracture mechanics of tree root breakage

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