Biogenic CO refers to carbon that is part of the natural carbon cycle.
This includes CO sequestration in the poplar biomass and CO2 produced from combustion of biomass.
Non-biogenic CO refers to CO emissions produced from fossil fuel combustion.
Biogenic CO is sometimes omitted when calculating the GWP as this CO is part of the carbon cycle, but is included in this study so that a full carbon mass balance can be presented.