Andean Soil Carbon — The Deep Pool, Still Uncredited

Posted by Ted Feldpausch

20 August 2026

Andean soil carbon: policy brief summary

Tropical forest carbon accounting concentrates on trees. In the Colombian Andes, that is the smaller half of the story. Across 36 plots spanning 176 to 3,139 m elevation, soil organic carbon rises six-fold with altitude — from 121 Mg C ha⁻¹ in the Low Andes to 772 Mg C ha⁻¹ in the High Andes, measured to 1 m depth. One hectare of high-Andean forest soil holds more carbon than six hectares of lowland forest soil.

A new policy brief distils this research for policymakers, carbon standard bodies, and project developers, and sets out what it means for conservation finance in the region.

Key findings

The elevation gradient: soil carbon climbs from 121 to 406 to 772 Mg C ha⁻¹ (0–100 cm) across low, medium, and high Andean forests. In montane forests, the soil — not the trees — is where most carbon lives.
A durable fraction: Andean soils hold on average 34 Mg C ha⁻¹ of pyrogenic carbon, roughly nine times the Amazon-wide average, reaching 83 Mg C ha⁻¹ in the High Andes. It makes up about 8% of total soil carbon, against 2%–5% typical of lowland tropical soils.
It survives land-use change: the pyrogenic share of soil carbon did not differ significantly across four disturbance classes, from selectively logged old-growth forest to active agro-silvopastoral land. This carbon, laid down by historical fires, endures the disturbances that deplete the rest of the soil pool — the durability that permanence claims require.
Baselines are predictable: clay content and annual precipitation, with pH, calcium, and satellite greenness (NDVI), explained 56% of the variability in pyrogenic carbon — meaning credible, locally calibrated soil-carbon baselines are achievable from one field campaign plus freely available satellite data.
The policy gap: under Verra’s Verified Carbon Standard and comparable programmes, soil carbon is an optional pool that projects routinely exclude. In Andean conservation and restoration projects, where aboveground biomass is modest and most carbon sits belowground, that omission leaves the majority of the climate benefit unmeasured, unpriced, and unprotected.

Recommendations

The brief makes three: include locally calibrated soil carbon baselines to 1 m depth, not just 0–30 cm, in Andean conservation and restoration projects; recognise the pyrogenic fraction as evidence of permanence by measuring carbon fractions rather than bulk totals alone; and prioritise high-elevation Andean forests in conservation finance and land-use planning, where each protected hectare locks away the most carbon.

Read the full policy brief below:

Colombian Andes soil carbon policy brief (PDF)Download

Companion brief

This brief pairs with Amazon Soil Carbon — The Missing Credit, which quantifies what fire and agricultural conversion cost the soil in lowland Amazonia. Together they cover both sides of the question: what disturbance takes from the soil, and what stays behind.

Reference:

Montes-Pulido, C. R., Bird, M. I., da Silva Carvalho, L. C., Serrano, J., Quesada, C. A., & Feldpausch, T. R. (2025). Climatic and edaphic drivers of soil organic carbon and pyrogenic carbon stocks across elevation and disturbance gradients in Colombian Andean forests. Global Change Biology, 31(7), e70135. https://doi.org/10.1111/gcb.70135

Research supported by the Natural Environment Research Council and Arts and Humanities Research Council under the Newton-Caldas Colombia Bio programme (NE/R017980/1) and NERC (NE/N011570/1), with support from the Universidad Nacional Abierta y a Distancia (UNAD).

Header image photo credit (Ted Feldpausch): forest and pasture across the Colombian Andes, where soil carbon stocks rise six-fold with elevation.