CDM AR-ACM0003 Large-Scale Afforestation and Reforestation

Updated 2026-11-02 · 3 min read · By the akar.earth specialist team

AR-ACM0003 explained: the CDM large-scale afforestation and reforestation methodology, its tools, its status under Verra, and what replaced it for ARR projects.

AR-ACM0003 is the Clean Development Mechanism (CDM) consolidated methodology for large-scale afforestation and reforestation on land other than wetlands. For more than a decade it was the standard choice for tree-planting projects under both the CDM and Verra’s VCS. Verra has since replaced it with VM0047 for new ARR projects.

Many registered Asian ARR projects, including in Indonesia, still run on AR-ACM0003. Understanding it helps when you review their credits, renew their crediting periods or compare them with VM0047.

What AR-ACM0003 covers

The methodology applies to planting or assisted regeneration of trees on land that is not forest at the start of the project, and is not a wetland. It is modular in practice. The methodology text sets applicability and structure. The detailed calculations come from CDM A/R tools:

Small projects run by low-income communities could use the simplified AR-AMS0007 instead.

How AR-ACM0003 works step by step

1. Check land eligibility. Show the land was not forest at the project start and, under CDM rules, has not been forest for a defined historical period. Read the 10-year rule for how this works under current Verra rules.
2. Check applicability. The land must not be wetland. There are conditions on organic soils, soil disturbance and grazing. Read the applicability section of the version your project uses.
3. Identify the baseline and test additionality. The combined tool lists plausible land-use alternatives, then applies investment or barrier analysis and common practice analysis.
4. Stratify and design sampling. Stratify by species, planting year and site. Calculate the number of plots needed for the target precision.
5. Estimate baseline carbon. Pre-existing trees and shrubs that would remain or grow in the baseline are counted.
6. Estimate project carbon. Measure plots and apply allometric equations or biomass expansion factors through AR-Tool14. Add dead wood, litter and soil if selected.
7. Deduct leakage. Estimate emissions from displaced cropping or grazing.
8. Calculate net removals and, under VCS, apply the non-permanence buffer.

Under the CDM itself, A/R credits were temporary (tCERs or lCERs) because of reversal risk. Under VCS, projects using CDM A/R methodologies received standard VCUs, with permanence handled through the Verra buffer pool.

Status and transition

Verra moved ARR to VM0047. According to Verra, projects using AR-ACM0003 or AR-AMS0007 that were listed as under validation had to complete validation no later than 30 June 2025. VM0047 v1.1 has been effective for all projects since 14 May 2025.

Registered projects generally keep using their registered methodology for the current crediting period. At crediting period renewal, the project must update to the methodology and rules in force at that time. Check the VCS Standard version in force. Verra issued VCS Standard v5.0 on 16 December 2025, and v4.7 remains active until 1 July 2027.

The main differences in VM0047 are a dynamic performance benchmark for additionality in the area-based approach and the use of remote sensing to measure baseline vegetation change. See VM0047 vs AR-ACM0003.

Indonesia application

AR-ACM0003 suited large plantings on degraded agricultural land, grassland (alang-alang) and scrub. In Indonesia that included community reforestation and some timber-based ARR. At renewal, these projects face VM0047’s performance benchmark, which can reduce credited volumes if surrounding land is regreening anyway.

Plot data collected under AR-Tool14 can usually be reused under VM0047, provided plot design and measurement protocols are documented.

Preparing a crediting period renewal

At renewal, a project usually has to reassess its baseline and update to current rules. Start a year ahead. Collect historical imagery for the control and project areas, review whether plot data meets VM0047 requirements, and update the non-permanence risk assessment. Model credits under VM0047 early so that offtake partners are not surprised by lower volumes.

Pitfalls verifiers flag

• Weak evidence that land was non-forest in the required historical period.
• Additionality based on generic barriers without project-specific evidence.
• Allometric equations used outside their validated range.
• Too few plots, triggering uncertainty discounts.
• Ignoring displaced agriculture.

See the ARR hub, the standards hub or our ARR carbon estimator.