In my time in carbon, I’ve come across more than my fair share of Three Letter Acronyms (TLAs) and obscure technical terms. Over the next few posts, I’ll be sharing some of my favourite TLAs and the ABCs of Carbon.
First up: Above Ground Biomass (AGB) and the M-Layer.
The M spatial layer represents the maximum above ground biomass for locations across continental Australia.
Embedded within the Full Carbon Accounting Model (FullCAM), the M-Layer and is one of the key spatial inputs for vegetation methods under the ACCU Scheme that use the FullCAM to model changes in vegetation carbon stocks over time.
The M spatial layer has undergone one major update which was integrated into FullCAM 2020.
Below is a comparison of the original M-Layer and new M-Layer datasets and how the predicted maximum above ground biomass data measured in tonnes of Dry Matter per hectare (t DM/ha) has evolved. The orange shades represent areas with lower maximum biomass potential, while blue shades represent areas of higher above ground biomass potential, corresponding to regions where environmental conditions support greater woody biomass accumulation, which can influence the suitability and productivity of vegetation projects such as environmental plantings.
Next up in the ABCs of Carbon is B for Baseline.
The Baseline period for modelled vegetation projects refers to the historical period used to establish the baseline or reference scenario of a project, where evidence is collected on the counterfactual – what would have happened without the project activities being undertaken?
The baseline period helps ensure projects represent additional and conservative abatement outcomes.
For Human-Induced Regeneration projects the Carbon Estimation Areas must exclude areas with historical forest cover that meets the forest definition during the baseline period. For HIR projects the baseline is 10-year period ending when the project was declared eligible. The HIR guidelines give examples of baseline evidence such as date-stamped georeferenced, remotely sensed imagery for each year of the baseline period, or the National Inventory Forest Extent Data for the relevant year.
For Reforestation by Environmental or Mallee Plantings the baseline is a 5-year period. In addition, ACCU Scheme eligibility requirements under the CFI Act specify the land must not have been subject to clearing of native vegetation for 7 years prior to the project being declared eligible.
One of the most misunderstood terms in carbon is a Carbon Estimation Area.
A Carbon Estimation Area or CEA is the part of a land-based carbon project where eligible project activities are undertaken, and carbon abatement is estimated under the relevant ACCU Scheme method.
Exactly what that CEA looks like visually and in satellite and remote sensed imagery differs greatly depending on the method applied and the stage of a project.
For a regeneration project under the HIR method, at the beginnings of the project, the CEA represents an area of forest potential that is expected to regenerate to forest cover.
For a reforestation by environmental or mallee plantings project, the CEA at the beginnings of a project represents the area planted.
Where complexity is introduced is the areas excluded from a CEA and the stratification process. In both the HIR and EP examples, exclusion areas, pre-existing forest cover during the baseline period is stratified and excluded from the CEA to ensure it remains conservative. Although the HIR and EP activities differ, the objective is similar – for the CEA to achieve forest cover and sequester carbon.
Why does understanding CEA matter?
The CEA is one of the most important spatial components of a land-based carbon project. It defines the area over which carbon abatement is estimated and reported and is central to understanding how a project is expected to deliver carbon abatement outcomes.
Improvements to ACCU Scheme transparency in recent years have made these spatial boundaries publicly available on the ACCU register, providing greater visibility into where carbon project activities are applied within a project area.
