Post-processing

Following the simulation of the data by the GCBM, this section discusses the next steps and how to make sense of the data that the GCBM simulation presented.

Comparing the outputs

After the GCBM runs the simulation, a compilation process generates spatial output and non-spatial data. The resulting data from the GCBM simulation should be used to conclude the trends the pilot study area will follow in the coming years. We can conclude with the GCBM data if the land unit is a net C sink or a net C source.

This section will discuss whether the land unit is a carbon sink or carbon source and the difference between ecosystem flux indicator GCBM outputs.

Is this land unit a carbon sink or a carbon source?

Terrestrial carbon dynamics are characterized by long periods of small carbon uptake rates, interrupted by short periods of rapid and large carbon releases during disturbances or harvest.

Disturbances, most notably wildfire and oil and gas explorations that cause large direct emissions to the environment, are usually accompanied by declining Net Primary Production(NPP) and Net Ecosystem Productivity (NEP). Declining NPP and NEP meant that not only do these forests decline due to these disturbances, but it becomes difficult for these forests to recover or regrow after a large disturbance.

As a direct result of the declining NPP, a forest landscape can gradually change from a carbon sink with a positive Net Biome Production(NBP) to a carbon source associated with a negative NBP.

Net Biome Production can be achieved by subtracting the losses resulting from disturbance from the NEP.

What is the long-term trend for this ecosystem?

The results from simulating the carbon dynamics of forest landscapes have shown that while deforestation regimes tend to have a more homogenous behavior over time, afforestation events have a much larger contribution in the results-based payment period than in the reference level period.

The deforestation activity was modeled in the GCBM, and calculations of the CO2 emissions from losses of live biomass (both above and belowground biomass) and DOM were extracted. As seen in the figure below, the emissions from biomass are far larger than those from the transfer of DOM to CO2 (atmosphere).

What is the difference between NEP and NBP?

Net Primary Production(NPP) can be defined as the sum of all stock exchanged in the aboveground, belowground biomass, and net litter turnover. This ecosystem flux indicator output illustrates a forest stand’s ability to recover from a disturbance. Reductions in NPP are usually caused by disturbances with larger net emissions that retain the lands in an unvegetated state over time.

Net Biome Production(NBP), can be defined as the subtraction of losses resulting from disturbances from NEP. The NBP flux indicator indicates whether a land unit is a carbon sink or a carbon source, with carbon sinks associated with positive NBP and a carbon source associated with negative NBP.