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Developing Dynamic Baselines for ACR's Afforestation and Reforestation Projects 

Published: January 29, 2025 by Victoria Lockhart , Director of Reforestation

In 2023, The Climate Trust launched our reforestation program with a goal of planting trees on 25,000 acres across the United States. Planting is being accompanied by the establishment of rigorous carbon offset projects to support ongoing sustainable forest management and to demonstrate successful models of carbon finance. 

To achieve this ambitious goal, we are assessing a variety of leading afforestation and reforestation (A/R) project methodologies against different landowner group financial assistance needs, forest types, and timber markets to identify pathways to scale while also meeting the evolving needs of offset buyers. 

One methodology we have identified as particularly promising for US forests is ACR’s methodology for Afforestation and Reforestation of Degraded Land (A/R). As the offset market community embraces the concept of dynamic baselines, we are exploring how ACR’s A/R methodology achieves lasting additionality through the application of Regeneration Monitoring Areas (RMAs). Although the terminology is different, RMAs represent dynamic baselining within the ACR framework and benefit from precise tree measurements.

How RMAs Work

RMAs are established at the beginning of a project and measured directly to assess levels of natural regeneration that are present without the implementation of planting, direct seeding, or other project activities. RMAs are allocated on land outside of the project that are representative of the conditions within the project—including slope and aspect, distance from seed sources, and soil types. Third-party project verifiers evaluate the procedures for establishing and measuring RMAs. 

At each verification for credit issuance, the RMAs are re-measured and the baseline assumptions for natural regeneration are assessed to confirm the baseline accurately represents the conditions on-site and remains valid over the full project life. Baseline assumptions are updated if the natural regeneration rates within the RMAs significantly deviate from the original assumptions (10% or more) and if the natural regeneration is different from the original assumptions by more than 10 trees per hectare. If this occurs, and the baseline is adjusted, then future credit issuances are also adjusted to ensure they match baseline dynamics and provide rigorous additionality through time. 

Why Dynamic Baselines Matter for US Forests

A dynamic baseline supported by directly measured RMAs provides measurement precision that is important for US A/R projects. Many US forests feature relatively slower growth compared to tropical forest systems where the majority of A/R project development efforts have focused to date. Tree growth is particularly slow in the dry west where A/R projects are becoming an important source of financing for forest restoration post-wildfire. The length of time between planting and the realization of financially meaningful credit issuances is much longer for projects in dry forests in the western US than those developed in faster growing tropical forests or wetter temperate forests in the US east and southeast. Additionally in post-wildfire landscapes, natural regeneration can be highly varied through time and across landscapes, especially in areas impacted by wide-scale, variable severity burns. 

In these landscapes, dynamic baselines supported by direct field measurements increase the level of rigor in A/R offset projects when remotely sensed data is unavailable or is not at a fine enough resolution to identify small naturally regenerating trees.  The risk of overly conservative estimates of changes in baseline natural regeneration arising from remotely sensed data may cause outsized negative impacts to the carbon revenue received by landowners.  

Looking Ahead

We look forward to applying these principles to our upcoming projects with diverse landowners and forest types. Together, we’re setting a new standard for rigor and innovation in A/R projects, helping scale reforestation efforts across the United States.