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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