looking for “paradoxical” species for a sustainable · 2014. 8. 23. · • bagassa...
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Looking for “paradoxical” species for a sustainable forest management in French Guiana.
Julie BOSSU PhD student – CNRSUMR EcoFoG - Ecologie des Forêts de Guyane , French Guiana
Bruno CLAIR, CNRS, Kourou - SupervisorJacques BEAUCHENE, CIRAD, KourouMériem Fournier, Agroparistech, Nancy
Julie BOSSU- PhD Student, CNRS
EcoFog, French Guiana
• Ecological context • Economical and social context• Wood quality and products adapted to French Guiana
• Concept of « paradoxical » species• Sampling and tree description• Selection of the wood traits and measures
• Variability of the specific gravity• Comparison between species• Parameters influencing shrinkage
Looking for “paradoxical” species for a sustainable forest management in French Guiana.
ConclusionOutlooks
Forest cover : 8 Millions ha
83.534 km2
8.515.767 km2
1500 species identifiedWith 500 exploitable
Source: Ruth S. DeFries et al., 2006
70 exploited
With 3 species represent 70% of the production
Well preserved region High biodiversity Small and specific production System acceptable for a small demand
Ecological context
Favorable Adapted region to try new sustainable models Monitored area
Conserved park
Current system of production need to be adapted!
Objectives : 1. Provide the next generation2. Avoid massive importation
Economic and social context
Requires rapid adaptations
High birth rates Population x 3 within 50 years!
Very young populationOne in two people is under 25 years
Plantations
2 - What kind of data set to represent wood quality?
Physical and mechanicaldatabase
(207 species)
Growth monitoring database
(352 species)
What is an adapted wood product for Tropical Regions?
?
Promising species??
Crossing analysis
1 – What are we searching for?
Fast-growing species Adapted to plantations Quality wood for timber Local species
Cordia alliodoraBORAGINACEAE
20cm
Bagassa guianensisMORACEAE
20cm
Tree description and sampling
0
10
20
30
40
50
60
1 2 3 4 5 6 7 8 9
• 9 trees / species • Different stages of development
Measures
Basic Specific Gravity (SG) : • Integrator of wood properties in the “wood
economics spectrum” (Chave et al., 2009).
Good “proxy” of the others wood propertiesGood indicator of the tree development.
Shrinkage:• Representative of wood heterogeneity.
Useful wood trait to isolate the different types of wood observed in the trunk.
Inversed principle of Archimede:
Deformations measure Sassus (1998)
Saturated
25%
10%
7%
Oven-dried
Main results:
• Singular specific gravity profile in tree
• Density gradient in tree enables rapid growth
• Shrinkage – Main results
• Parameters influencing wood shrinkage
• Fiber-saturation point
Julie BOSSU- PhD Student, CNRS
EcoFog, French Guiana
Singular density profile in tree
1.30m
Exceptionnal gradient from the pith to the bark!
Different values but similar profiles
Representative of the construction of the tree through ontongeny
Density gradient in tree enables rapidgrowth
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
-20 -10 0 10 20
• Juvenile zone - low specific gravity• Increase of the density with cambial age
Heliophilous Pionners Grow fast Low density
Long lived Climax Grow slow High density
Paradoxical species, able to mix differentgrowth strategies along tree life!
Hypothesis:Wood density is related to tree construction costs (Larjavaara, 2010).
Why?
Shrinkage - Main results
0.4 0.6 0.8 1.0 1.2
05
10
15
20
25
Density 12%
Tota
l volu
mic
shrinkage (
%)
C. alliodoraB. guianensis
Both species differ from the global tendency
Very low volumic shrinkage for sucha mean density
dL
dT
dRdT = 4.9%dR = 3.6%dL = 0.22%
dV = 8.74%
dT = 5.7%dR = 3.1%dL = 0.18%
dV = 9.02%
Paradoxical species represent a real advantage for industrial
wood products
Tradeoff between density and woodquality?
0.05 0.10 0.15 0.20
01
02
03
04
0
Total volumic shrinkage (%)
Density
Cordia alliodora
Bagassa guianensis
Difference between the two species: homogeneity!
Samples from BG showed the largestshrinkage dispersion.
CA stands out!Its wood is more homogeneous
Parameters influencing wood shrinkage
What parameter clusters Bagassaguianensis samples into two goups?
Influenced by the type of wood !
Individual effect !
Cordia alliodoraBagassa guianensis
Influence of wood type on shrinkage
0.3 0.4 0.5 0.6 0.7 0.8
0.0
60.0
80.1
00.1
20.1
4
Specific Gravity
Tota
l S
hrinkage (
%)
Sapwood
Heartwood
0.00 0.02 0.04 0.06 0.08 0.10
0.0
00.0
50.1
00.1
50.2
0
Tangential shrinkage(%)
Mois
ture
conte
nt(
%) Sapwood
Heartwood
Unsual relations betwween wood densityand shrinkage
Heartwood/Sapwood: Two differentshrinkage behaviors
Why?Secondary metabolites!
Benefits for Heartwood:
Lower anisotropy over the radial profile.Lower probability of drying defects.
0.00 0.05 0.10 0.15 0.20
0.0
00.0
20.0
40.0
60.0
80.1
0
Moisture content(%)
Tangential shrinkage
Sapwood
Heartwood
21%16.4%
What about Fiber-saturation point (FSP)?
Also a significant difference between heartwood and sapwood
FSP = minimum of humidity acceptable for wood storage without deformities.
In that sense the heartwood is more convenient.
Sapwood stabilize faster than heartwood
Limit to this analysis :Moisture content / Relative humidity
Species ASpecies B
dV(A)%
dV(B)%For the same FSP and the same conditions:
dV(A)% > dV(B)%
Shrinkage: criterions to select a species over another?
FSP is not sufficient to predict properly the potential deformations.
The slope of the mean drying profile used to determine the FSP is also relevant!
Thinking about FSP
Conclusion
• Paradoxical species combine medium density and low shrinkagePromising species for quality wood products
• High changes in density during ontogeny enables high growth ratesWell adapted for plantations
• Example of an optimized tradeoff between strength and cost of construction.
• Bagassa guinanensis : effect of the heartwood extractives on shrinkage
• Model for the physical properties in the tree? Requires wood type classification!
In French Guiana:Bagassa guianensis and Cordia alliodora represent local species of interest
Julie BOSSU- PhD Student, CNRS
EcoFog, French Guiana
Julie BOSSU- PhD Student, CNRS
EcoFog, French Guiana
Outlooks
• Future results
Mechanical properties Durability …
• Description of the tree development
Photosynthetic performances Plant architecture / Wood properties
• Tests in plantation and agroforestry
• Other paradoxical species?
