zez fpi 15feb13

Veneering of Plantation Grown Subtropical

Species from Thinning Experiments

Anton Zbonak

Queensland Department of Agriculture, Fisheries and Forestry

Brisbane, Australia

SWST Convention, Zvolen 23-27 June 2014

© State of Queensland, 2013

Drivers for plantation hardwood R&D

• Native hardwood forest logging from Crown lands phased out by 2023

• Plantation to provide substitute resource, around 20-year rotation

• Queensland government are expecting the private sector to establish

and manage the plantations

• Limited hardwood plantations established until 2000


Opportunities for small diameter trees

Sawn timber

• Log size and quality make efficient processing difficult

• Low recovery (8-18%)

Power distribution poles

• Limited by available log size and quality

• More suited to final harvest

Veneer based composite products

• High recovery of product

• Opportunities to use thinnings & final harvest

• Veneer: quick and easy to dry

• Existing products and opportunities for new products


Current plantation estate in Queensland

• The subtropical eucalypt estate totals about 116,000 ha with over 54,000

ha of spotted gum (CCV) and Eucalyptus dunnii


• Two species – Corymbia citriodora subsp. variegata (CCV) and Eucalyptus dunnii

• Two regions:

• Ellangowan in northern New South Wales - wetter more productive site

• Kingaroy in Queensland - drier site

Site Species

Mean annual

rainfall

(mm)

Age

thinnedHarvest age

Ellangowan CCV 1096 7y 9m 10.5

Ellangowan E. dunnii 1096 7y 9m 10.5

Kingaroy CCV 783 6y 9m 10.5

Kingaroy E. dunnii 783 6y 9m 10.5

• Three thinning treatments:

• 300 spha

(5 trees/tmt 2 heights)

• 500 spha (not sampled)

• 900 spha - unthinned

(5 trees/tmt 2 heights)

Material - Thinning trials


Material and Methods

E. dunnii CCV

low % of heartwoodAcoustic velocity measurement

Forest inspectors


Billet end splitting

0

2

4

6

8

10

12

Lo

g e

nd

sp

lit

are

a i

nd

ex

Thin Unthin Mean

Ellangowan Kingaroy Ellangowan Kingaroy

CCV CCVE. dun E. dun CCV CCVE. dun E. dun

After 24 hrs After steam

• No splitting issues for CCV

• E. dunnii is splitting prone species – adverse effect on veneer quality

wet site dry site wet site dry site

24 hr after felling 96 hr after felling After steaming


Billet dynamic stiffness

10000

15000

20000

25000

Bu

tt b

ille

t M

OE

(M

Pa)

Thin Unthin Mean

Ellangowan

CCV CCVE. dun E. dun

Kingaroy

10000

15000

20000

25000

To

p b

ille

t M

OE

(M

Pa)

Thin Unthin Mean

Ellangowan


Kingaroy

• No clear effect of thinning treatments

• E. dunnii significantly lower billets stiffness

• Evident site effect on stiffness, lower for drier site

• Top logs o average 10% and 20% stiffer than butt log (CCV and E.

dunnii)

butt log top log

wet site dry sitewet site dry site


Peeling using spindleless lathe

Maximizing product recovery from small logs

45 mm core


Overall gross recoveries

• Ranging from 35 to 80% - double or triple recoveries from sawing

similar diameter logs

• No clear effect of thinning treatments on recoveries

• Kingaroy (dry site) lower in recoveries – effect of smaller trees

• Splitting did not affect veneer recovery

30

40

50

60

70

80

90

Ven

eer

gro

ss r

eco

very

(%

)

Thin Unthin Mean

Ellangowan


Kingaroy

30

40

50

60

70

80

90

Ven

eer

gro

ss r

eco

very

(%

)

Thin Unthin Mean

Ellangowan


Kingaroy

butt log top log



Grade recovery

• Veneer sheets graded according to AS/NZ 2239: 2008


Veneer grade distribution

• Consistently better grade for butt logs

• Evident effect of site – CCV better grades from wet site

• Indication that thinned plots produced veneers of higher grades

• The majority of D-grade quality is not unexpected given the known presence

of knots and other defects that are present in plantation hardwood trees of

the size and age processed

0%

20%

40%

60%

80%

100%

Thin Unthin Thin Unthin Thin Unthin Thin Unthin

CCV E.dun CCV E.dun

Ellangowan Kingaroy

Dis

trib

uti

on

rela

ted

to

bille

t vo

lum

e

Grade D

Grade C

Grade B

Grade A

0%

20%

40%

60%

80%

100%

Thin Unthin Thin Unthin Thin Unthin Thin Unthin

CCV E.dun CCV E.dun

Ellangowan Kingaroy

Dis

trib

uti

on

rela

ted

to

bille

t vo

lum

e

Grade D

Grade C

Grade B

Grade A

butt log top log



Acoustic veneer stiffness assessment

1.55 m

veneer sheet

• Veneer assessment samples obtained subsequently after each 1.55 m veneer sheet

• Samples assessed for acoustic stiffness and density

Veneer assessment sample


Acoustic veneer stiffness with cambial age

5000

8000

11000

14000

17000

20000

23000

4 5 6 7 8 9 4 5 6 7 8 9

Kingaroy Lismore

Cambial age (yrs)

Ve

ne

er

MO

E (

MP

a)

CCV - Thinned CCV - Unthinned E.dunnii - Thinned E.dunnii - Unthinned

• CCV is stiffer than E. dunnii; dunnii regarded as pulp species displays high

stiffness despite its low density

• Evident effect of site for both species, no clear effect of thinning

• MoE values above average stiffness of radiata pine

Ellangowan

Drier site Wet site

Average MoE

of mature radiata pine


E. dunnii drier E. dunnii wetter

Effect of dry period on MOE drop

5000

9000

13000

17000

21000

25000

2 4 6 8 10

Cambial age

Ven

eer

MO

E (

MP

a)

Tree 1

Tree 2

Tree 3

Tree 5

5000

9000

13000

17000

21000

25000

2 4 6 8 10

Cambial age

Ven

eer

MO

E (

MP

a)

Tree 1

Tree 2

Tree 3

Tree 4

Tree 5


Predicting veneer stiffness using standing tree acoustics

7000

11000

15000

19000

23000

3.0 3.5 4.0 4.5 5.0

Fakopp AV (km.s-1

)

Ve

ne

er

av

era

ge

MO

E (

MP

a)

CCV

E. dunnii

R2=0.85

Standing tree acoustics can provide reliable estimate

of the quality of the veneer stiffness


Concluding remarks

• Veneering is suitable option for processing of small diameter plantation

resource, maximizing the recovery

• Thinning treatment not affecting veneer stiffness, there are site

differences – less stiff on drier, less productive site

• Both species achieving high values of veneer stiffness – resource suited

to structural veneer products rather than appearance products

• Veneers have attributes suited to engineered wood products (plywood,

LVL,…) and opportunities for novelty products

• Gluability of veneer sheets needs to be explored further


AcknowledgementAcknowledgements

• Collaboration effort of DAFF Forestry Science teams and Southern Cross University

• Sites accessed through Forest Enterprises Australia Ltd

[email protected]

http://www.daff.qld.gov.au/29.htm

mailto:[email protected]

http://www.daff.qld.gov.au/29.htm

zez fpi 15feb13

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