Afforestation, reforestation and revegetation (ARR) projects generate carbon credits by sequestering atmospheric carbon dioxide into growing trees and soil. Unlike avoidance projects, forestry credits represent actual carbon removal, which makes them increasingly attractive to buyers seeking high-integrity credits. The calculation framework is more complex than energy-based projects because sequestration rates change over time as forests grow, and buffer and leakage deductions can significantly reduce net credit yield.
The four key components
Above-ground biomass sequestration
The primary driver of credit volume. Calculated from species growth rates, stocking density, and biomass expansion factors (BEFs) that convert stem volume into total above-ground dry mass. The allometric equations and growth models used must be approved by the relevant methodology. Verra VM0047 uses IPCC Tier 2 methods with country-specific coefficients.
Below-ground biomass and soil carbon
Root biomass is typically estimated as a fraction of above-ground biomass using root-to-shoot ratios. Soil organic carbon changes are optionally included but require baseline sampling and add monitoring complexity. Many projects conservatively exclude soil carbon from the credit claim to simplify verification.
Buffer pool deduction
A mandatory percentage of gross credits is deposited into a buffer pool held by the registry as insurance against reversal events (fire, disease, illegal logging). Buffer percentages typically range from 10 to 30 percent depending on a project risk assessment. Credits withheld in the buffer are not available for sale but are retired if the project suffers a reversal.
Leakage deduction
If the project displaces activities (such as agriculture or grazing) that simply relocate outside the project boundary, the resulting emissions are deducted from the gross credit claim. Market leakage is estimated using activity-specific factors approved by the methodology.
Try the calculator
Use the full tool in The Carbon Workbench to model a full crediting period, compare species scenarios and export a PDF summary.
Open full Forestry CalculatorTypical credit yield ranges
| Forest type and climate | Annual sequestration (tCO2e/ha) | Notes |
|---|---|---|
| Tropical plantation (fast-growing species) | 12-25 | Eucalyptus, Acacia; high growth rates |
| Tropical mixed native species | 6-14 | Lower growth; higher biodiversity value |
| Temperate broadleaf (UK, Europe) | 4-9 | Oak, beech, ash; 80-100 year crediting periods |
| Temperate conifer plantation | 6-12 | Sitka spruce, Douglas fir; faster than broadleaf |
| Savanna / dryland restoration | 2-5 | Lower productivity; high co-benefit value |
Methodology and registry fit
Verra VM0047 (Afforestation, Reforestation and Revegetation) is the current standard for most commercial ARR projects globally. Gold Standard's Land Use and Forests methodology is an option for projects prioritising SDG co-benefit claims. Plan Vivo suits smaller community-based projects where social outcomes are the primary driver. See the registry comparison guide for a fuller assessment.