Variability observed in C flux. (Pine plantation, SW Fance) (Rimu Forest SW NZ) A foresters paradise...
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Transcript of Variability observed in C flux. (Pine plantation, SW Fance) (Rimu Forest SW NZ) A foresters paradise...
Variability observed in C flux
-500
0
500
1000
1500
2000
0 100 200 300 400Age(years)
NE
P (
gC
.m-2
.an
-1)Tropical
Mediterranean
Temperate
boreal
0
2500
5000
GP
P (
gC
.m-2
.an
-1)
(Pine plantation, SW Fance) (Rimu Forest SW NZ)
A foresters paradise Environmentalist paradise
Management effects on the annual carbon balance of forests: analysis of global databases.
Denis Loustau, Sebastiaan Luyssaert, Ivan Janssens, John Grace, Maurizio Mencuccini, Lisa Wingate, André Granier, Ilaria Inglima, Fredrik Lagergren, Anders Lindroth, Giorgio Matteucci, Eero Nikinmaa, Jianwu Tang.
The GHG Cycle in the Northern Hemisphere, 14-18 November, Sissi Lahti
QuestionsTo what extent do management effects contribute to the
global variability of NEE, NPP and their components ?
Is the age effect on carbon balance of forests changed by management ?
Is carbon allocation among biomass compartments modified by management ?
11 Chronosequence studies
11 Analysis of a global NPP database
BIOMASS
SOIL
Dissolved Carbon
ATMOSPHERE
GPP
Wood products life cycle
harvest
Fossile C
RE
Species choiceUnderstorey controlVegetation managementPest management
Carbon cycle in the forest – wood products chain.
NPP
NEE
FertilisationDrainageSoil work
Landscape fragmentationSurface roughnessAlbedoGHG
-8
-6
-4
-2
0
2
4
6
01/05/00 01/07/00 31/08/00 31/10/00 31/12/00 02/03/01 02/05/01 02/07/01 01/09/01
Date
Fc
(m
ol
m-2 s
-1)
Le site après coupe rase (Bilos) est une source de ~ 200 gC .m-2.an-1
Le site de 30 ans (Bray) est un puits de ~540 gC .m-2.an-1 (Berbigier et al., 2001)
Kowalski et al. Global Ch Biology 2004
1. Chronosequence studies
1. What have we learned from chronosequence studies ?
the age effect on forest carbon balance
Disturbance Forest = C SourceEarlier recovery in fast growing forests
Data Model
0
1000
2000
3000
-10 0 10 20 30Mean annual T (deg C)
Average C Flux (gC.m-2.y-1)
GPPRENEP
(Magnani et al.)
Chronosequence studies :
effect of temperature on rotation-averaged C fluxes
Humus and soil
Trees
Stock (gC.m-2)
-2500
0
2500
0 25 50 75
Time (yrs)
Flux(gC.m-2.y-1)
''
C F
lux
gC
.m-2.a
n-1
Time since perturbance (years)
FoliageBranch
Stem
Root
LitterHumus layer
Soil OM
GPPNPP
NEERa
RECO
A silhouettemodel of forest carbon balance.
1. What have we learned from chronosequence studies ?
Disturbance
Juvenile
Mature
Post mature
2. The NPP database. Management classes
• Managed (M): reference to planting, thinning, harvest.
• Unmanaged (UM): no record of management for the last 50 yrs
• Fertilised irrigated (FI): experimental set up with fertilisation or irrigation
• Recently disturbed: burnt or clearcut during the previous 25 yrs (not used)
0
2
4
6
8
10
12
14
16
18
GPP (gC.m-2.y-1)
Nb of Sites
0 2000 4000
Fertilised / IrrigatedManagedUnmanaged
The NPP database
0
1000
2000
0 200 400 600
F IMUM
NPP(gC.m-2.y-1)
Age (y)
The NPP database
The NPP database
Management effects on NPP – age curve
Max NPP Age at NPPmax Fertilised / irr.
Managed
Unmanaged
1800 17
1800 50
1350 85
0
400
800
1200
1600
Fertilised Managed Unmanaged
gC.m
-2.y
-1
FoliageWoodBelow ground
NPP
Management increases the NPP share to the wood...
The NPP database
0
100
200
300
Wood growth efficiencygC wood . m-2 leaf area . y-1
Fert. / Managed UnmanagedIrrigated
… and wood growth efficiency
Unmanaged forest have a low NPP/GPP ratio
0
0.25
0.5
0.75
1
0 100 200 300Age (yr)
NPP / GPPFI
M
UM
The NPP database
Management effects on NEE
Production forestExt. managementunmanaged
(Data fom Black et al. 2005, Hyvonen et al., New Phytol. In press)
Humus and soil
Trees
Stock (gC.m-2)
-2500
0
2500
0 25 50 75
Time (yrs)
Flux(gC.m-2.y-1)
''
Humus and soil
Trees
-3000
0
3000
0 25 50
''
GPPNPP
NEERa
RECO
C Flux (gC.m-2.yr-1)
C Stock (gC.m-2)
Synthesis:
Management keeps forest stands younger
Conclusions from database analysis
Age and management effects cannot be easily separated
Management affects mainly NPP (20-30% global variance explained)
NPP allocation to wood is increased, (foresters do well !)
Management keeps forest stands younger :
- shortens life cycle
- amplifies NEP and NPP magnitude
Future plan
Refine management classes
Complete the sites coverage:Pristine temperate forestManaged tropical forests
Role of species / age diversity