CO2 compensation point

Aci Curve

Aber et al. 1996

Ollinger et al.. 2002

Lambers et al. 1998

Chapin et al. 1987

CO2 CO2

O2

GPP

R leaf

R non-leaf

Net Ps

NPP

LiveBiomass

Litter ProductionSoilOrganicMatter

R decomposerR herbivory

Total Ecosystem Carbon

R autotroph

NPP = GPP – R autotroph = R herbivory + Litter Production + Change in Live Biomass

True Increment

NEP = GPP - R autotroph - R herbivory - R decomposer

R total

R heterotrophNPP

Melillo et al. 1993

63 Pg C/yr

Melillo et al. 1993

53.3 Pg C/yr

NPP = FPAR * PAR * E

Potter et al. 199348 Pg C/yr