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