Assessing the effects of water availability on selected wood properties of E. grandis

in South Africa

Sasha Naidoo, Anton Zbonak, Norman Pammenter and Fethi Ahmed

Forestry and Forest Products Research Centre

CSIR, Durban

IUFRO Taipei October 29 – November 2 (2007)

Background

• Previously:

Plantation yield quantified in terms of

stem volume

• Currently:

Focus on wood quality as determinants

of plantation productivity

Background

Environmental factors

• Significant effects on wood properties of eucalypts

• Subtle interactions among environmental factors

• Soil type, depth and nutrient status influence water

retention and water availability

Eucalyptus grandis –

• grown across a range of sites

• dependant on water availability

General aim

• To assess the response of wood properties of Eucalyptus grandis to varying levels of water availability

• To improve understanding of factors that affect wood properties

Outline of presentation

• Review experimental approach used

• Illustrate some results and outcomes

• Summarize the next phase in this study

MACRO ZONES MAT Cool Temperate< 16oC Warm Temperate 16.1- 19oC Sub-Tropical > 19.1oC

Cool Temperate

MEAN ANNUAL PRECIPITATION (MAP)

15.1-16oC DRY MOIST WET

14.1-15oC DRY MOIST WET

< 14oC DRY MOIST WET

Sub-tropical

Warm Temperate

LOW, MEDIUM and HIGH soil water storage (SWS) values form 3rd level of classification

ICFR site classification system

Sub-tropicalWarm temperateCool temperate

HOWEVER:

E. grandis is not grown in

all the macro zones:

INCOMPLETE DESIGN

• 3 compartments per cell

• 5 trees per compartment

• Ages: ~ 6-12 years

• No coppiced material

Experimental design

  MAP

SWS

  DRY MOISTWET

LOW 3  2  3 

MED. 3  3 

HIGH   2  3 

  MAP

SWS

  DRY MOIST WET

LOW  3 1  2 

MED.      

HIGH3   3  3

WARM TEMPERATE (16.1-19oC)SUB-TROPICAL (> 19.1oC)

Sample preparation for measuring wood properties

pith

N

breast height(1.3 m)

Twin-blade sawPith-to-bark strip (x 2)

Image analysis –

vessel and fibre

characteristics

Density and NIRS

(predicted cellulose

and lignin)

WOOD PROPERTIES MEASURED

x 2 cores per tree

Vessel and fibre measurements

20-25 µm thick section

Fibres measured every alternate 0.5 mm

• Vessel diameter

• Vessel frequency

• Vessel percentage

• Fibre diameter

• Fibre lumen diameter

• Cell wall thickness

Vessels measured every 0.5 mm

Gamma-ray densitometry and near-infrared spectroscopy

Density measured every 0.5 mm

Gamma ray densitometer

XDS NIR Spectrometer• NIR spectra obtained

every 5 mm

• NIRS – prediction of cellulose and lignin contents

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 20 40 60 80 100 120

STRIP LENGTH (mm)

DE

NS

ITY

DE

NS

ITY

(g.

cm-3)

BARK PITH

BARK PITH

Constructing radial maps

10 20 30 40 50 60 70 80 90 100

0.61 0.54 0.54 0.46 0.42 0.41 0.43 0.45 0.44 0.44

     

% Total strip length

Density (g.cm-3)Key

0.40-0.49 0.50-0.59 0.60-0.69     Key

Density (g.cm-3)

DRY MOIST WET

LOW

HIGH

Mean density (MD) (g.cm-3) 0.40-0.49 0.50-0.59 0.60-0.69

Key      

Density in the sub-tropical region

SWS

MAP

MD = 0.57 a MD = 0.47 bMD = 0.46 b

MD = 0.55 a MD = 0.54 a

n=15

n=15

n=14

n=14

n=5

n=15

MD = 0.58 a

Proportion of lower density wood increases with increasing MAP

DRY MOIST WET

LOW

MED.

HIGH

SWSMAP

MD = 0.52 a MD = 0.49 aMD = 0.51 a

MD = 0.53 a MD = 0.50 a

MD = 0.53 a MD = 0.51 a

n=14

n=15

n=15

n=15

n=8

n=10 n=14

Mean density (MD) (g.cm-3) 0.40-0.49 0.50-0.59 0.60-0.69

Key      

Density in the warm temperate region

SUB-TROPICAL WARM TEMPERATE

• Increase in fibre diameter with increase in MAP• Similar pattern of response to MAP in both regions

LOW SWS HIGH SWS

DRY MOIST WET DRY MOIST WET

Mea

n f

ibre

dia

met

er (

µm

)

LOW SWS HIGH SWSMED. SWS

DRY MOIST WET MOIST WET MOIST WET

Fibre diameter

Mea

n f

ibre

dia

met

er (

µm

)

bc

a

ab

c

bc

abc

bc

a

ab

c

abc

c

abc

32H

33M

333L

WMD

SWS

MAP

32H

33M

323L

WMD

SWS

MAP

333H

M

323L

WMD

SWS

MAP

333H

M

313L

WMD

SWS

MAP

SUB-TROPICAL WARM TEMPERATE

LOW SWS HIGH SWS

DRY MOIST WET DRY MOIST WET

NIR

-pre

dic

ted

cel

lulo

se (

%) LOW SWS HIGH SWSMED. SWS

DRY MOIST WET MOIST WET MOIST WET

NIR-predicted cellulose

• Significantly higher NIR-predicted cellulose values with higher MAP

b

aa

b

aa

a

b

bc

bcd cdd d

32H

33M

333L

WMD

SWS

MAP

32H

33M

323L

WMD

SWS

MAP

333H

M

323L

WMD

SWS

MAP

333H

M

313L

WMD

SWS

MAP

NIR

-pre

dic

ted

cel

lulo

se (

%)

SUB-TROPICAL WARM TEMPERATE

LOW SWS HIGH SWS

DRY MOIST WET DRY MOIST WET

NIR

-pre

dic

ted

lig

nin

(%

)

LOW SWS HIGH SWSMED. SWS

DRY MOIST WET MOIST WET MOIST WET

NIR-predicted lignin

a

b

b

a

b

ab

a

b

aa

a

aa

32H

33M

333L

WMD

SWS

MAP

32H

33M

323L

WMD

SWS

MAP

• Significantly lower NIR-predicted lignin values with higher MAP

333H

M

323L

WMD

SWS

MAP

333H

M

313L

WMD

SWS

MAP

NIR

-pre

dic

ted

lig

nin

(%

)

Summary of results

• At low MAP - higher density, smaller vessel and fibre diameters, lower

predicted cellulose and higher predicted lignin

• As MAP increases - Lower density, larger vessel and fibre diameters, higher

predicted cellulose and lower predicted lignin

Sub-tropical region

• Response of wood properties followed similar trends with an increase in

MAP

• Differences in wood properties measured usually only significant at low SWS

Warm temperate region

Future work planned for study

• Use bark to pith profiles and climate to identify growth

rings climate

• Separate portions of bark to pith profiles into age

classes• compare wood characteristics among similar age

classes

• Model wood properties with climatic variables

Significance of study

• Assess existing sites

• Improved use of existing material

• Evaluate future sites for planting

Acknowledgements

• Eucalyptus Co-operative –

• Center for Scientific and Industrial Research

(CSIR), Mondi and Sappi

• Institute for Commercial Forest Research (ICFR) –

Site Classification System

THANK YOU

http://ffp.csir.co.za

983179111@ukzn.ac.za