Variability observed in C flux

(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, November, Sissi Lahti

Questions To 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 ? 1.  Chronosequence studies 2.  Analysis of a global NPP database

BIOMASS SOIL Dissolved Carbon ATMOSPHERE GPP Wood products life cycle harvest Fossile C RE Species choice Understorey control Vegetation management Pest management Carbon cycle in the forest – wood products chain. NPP NEE Fertilisation Drainage Soil work Landscape fragmentation Surface roughness Albedo GHG

Kowalski et al. Global Ch Biology Chronosequence studies

1.What have we learned from chronosequence studies ?  the age effect on forest carbon balance Disturbance  Forest = C Source Earlier recovery in fast growing forests Data Model

Mean annual T (deg C) Average C Flux (gC.m -2.y -1 ) GPP RE NEP (Magnani et al.) Chronosequence studies :  effect of temperature on rotation-averaged C fluxes

C Flux gC.m -2.an -1 Time since perturbance (years) Foliage Branch Stem Root Litter Humus layer Soil OM GPP NPP NEE Ra RECO A silhouette model 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)

GPP ( gC.m -2.y -1 ) Nb of Sites Fertilised / Irrigated Managed Unmanaged The NPP database

NPP (gC.m -2.y -1 ) Age (y) The NPP database

Management effects on NPP – age curve Max NPP Age at NPPmax Fertilised / irr. Managed Unmanaged

NPP Management increases the NPP share to the wood... The NPP database

Wood growth efficiency gC wood. m -2 leaf area. y -1 Fert. /ManagedUnmanaged Irrigated … and wood growth efficiency

Unmanaged forest have a low NPP/GPP ratio The NPP database

Management effects on NEE Production forest Ext. management unmanaged (Data fom Black et al. 2005, Hyvonen et al., New Phytol. In press)

GPP NPP NEE Ra 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 forest Managed tropical forests Role of species / age diversity