akar.earthCarbon pool: Definition
What is a carbon pool? The five IPCC forest carbon pools, which ones carbon methodologies require, and which matter most for Indonesian projects.
A carbon pool is a part of an ecosystem that stores carbon and can gain or lose it over time. The IPCC recognises five forest carbon pools: above-ground biomass, below-ground biomass, dead wood, litter and soil organic carbon.
Why it matters
Carbon projects only earn credits for pools they measure, and they must account for losses from pools they affect. Choosing which pools to include shapes the monitoring budget, the credit volume and the risk of overstating benefits. Verifiers check that excluded pools are excluded conservatively.
The five pools
| Pool | What it includes | Typical treatment |
|---|---|---|
| Above-ground biomass | Stems, branches, leaves of live trees | Always included |
| Below-ground biomass | Live roots | Usually included |
| Dead wood | Standing and fallen dead trees | Often optional |
| Litter | Leaves and fine debris on the soil | Often optional |
| Soil organic carbon | Organic carbon in mineral or organic soil | Optional on mineral soil; central for peat and mangroves |
Some methodologies also track harvested wood products, which store carbon after timber leaves the forest.
How pools are chosen
A methodology lists mandatory and optional pools. Projects include optional pools when they expect meaningful gains, and may exclude them when the change is small or would reduce credits only slightly. In REDD+, excluding a pool that would lose carbon under the baseline is conservative. In ARR, excluding a pool that would decline after site preparation is not. Our guide to carbon pools goes deeper.
Indonesia angle
Pool choice changes dramatically by ecosystem in Indonesia. On mineral soils, biomass dominates. In peat swamp forests and mangroves, the soil pool can hold far more carbon than the trees, which is why peat and blue carbon projects measure soil depth and carbon density directly.
Common mistakes
- Excluding soil carbon on land where site preparation disturbs it.
- Counting root carbon in both below-ground biomass and soil.
- Including dead wood without a re-measurement plan.
Related terms
Explore carbon fraction and permanence, or start at the forest carbon hub.
Frequently asked questions
What are the five carbon pools?
Above-ground biomass, below-ground biomass, dead wood, litter and soil organic carbon. Some methodologies add harvested wood products as a sixth pool.
Do projects have to measure every carbon pool?
No. Methodologies usually make biomass mandatory and let projects exclude other pools if excluding them is conservative, meaning it does not increase credits.