Deferred Harvest on Smallholder Lands

This Module provides the requirements and procedures for the calculation of net carbon dioxide equivalent (CO₂e) removal from the atmosphere through improved forest management (IFM) practices implemented by small forest landowners — i.e, smallholders.

• For the purposes of this Module, smallholders are defined as those owning up to 2,000 hectares of harvestable forest land.

Small forest landowners represent a significant portion of the United States' forest ownership, controlling approximately 36% of total forestland¹. These landowners can substantially contribute to climate change mitigation through IFM practices. However, small landowners face disproportionate barriers to participating in carbon markets due to high transaction costs, complex verification requirements, and limited technical resources.

This Module addresses these systemic barriers by establishing a comprehensive approach to crediting specifically designed for small landowner participation in carbon markets with a design that incentivizes improved ecological and economic outcomes for small private landowners while leveraging technological innovations to reduce participation barriers. The Module focuses on deferred timber harvest strategies that allow forests to accumulate additional carbon beyond baseline management scenarios while maintaining the economic viability of forest ownership for participating landowners.

Carbon accumulation is quantified through a dynamic matching baseline approach that compares project forests to similar reference forests within the same region, accounting for variations in forest type, management history, and site conditions. This Module ensures accurate quantification of additional carbon benefits while reducing the technical burden on individual landowners through continuous change detection owned by Isometric and the Project Proponent. The Module employs advanced remote sensing technology, including LiDAR-enhanced forest inventories, to monitor carbon accumulation with high precision across multiple small properties while maintaining rigorous standards for measurement, reporting, and verification and reduced field-based verification costs.

To ensure ecological integrity and biodiversity conservation, this Module requires a high proportion of native species composition within project areas and prohibits enrollment of industrial plantation forests and monoculture systems. The Module includes provisions for invasive species management to enhance ecosystem function and resilience throughout the Crediting Period.

Further, this Module ensures the economic sustainability of project activities for participating landowners through guaranteed revenue sharing arrangements, with landowners receiving a large share of Credit revenue. Contract durations are established based on the biological rotation ages specific to forest types, with a conservative 50-year net-impact deduction to ensure meaningful carbon storage duration.

This Module accounts for the quantification of the gross amount of CO₂e removed via enhanced carbon storage in forest biomass, as well as all cradle-to-grave life-cycle Greenhouse Gas (GHG) emissions associated with the implementation process. This Module is developed to adhere to the requirements of ISO 14064-2: 2019 – Greenhouse Gasses – Part 2: Specification with guidance at the Project level for quantification, monitoring, and reporting of greenhouse gas emission reductions or removal enhancements.

The Module ensures:

• Consistent, accurate procedures are used to measure and monitor forest carbon accumulation through standardized methodologies appropriate for small landowner implementation;
• All net CO₂e removal claims are verified through robust field work and LiDAR-enhanced monitoring systems and third-party validation;
• Forest management practices maintain ecological integrity through native species requirements and biodiversity conservation measures;
• Removals are additional through the use of dynamic matching baselines that account for regional management practices and other guardrails set forth in the Isometric Standard;
• Dynamic baseline methodologies provide accurate quantification of additional carbon benefits through regional reference comparisons;
• Comprehensive risk management through buffer pools and optional insurance mechanisms protects against potential reversals while ensuring transparent Credit delivery;
• Economic viability for small landowners through guaranteed revenue sharing and appropriate contract terms; and
• Technology-enabled monitoring reduces transaction costs while maintaining high standards for carbon accounting and environmental integrity.

Throughout this Module, the use of "must" indicates a requirement, whereas "should" indicates a recommendation.

This Module relies on and is intended to be compliant with the following standards and protocols:

• The Isometric Standard
• Improved Forest Management v1.0, Isometric
• ISO 14064-2: 2019 - Greenhouse Gases - Part 2: Specification with guidance at the project level for quantification, monitoring, and reporting of greenhouse gas emission reductions or removal enhancements

Additional reference standards that inform the requirements and overall practices incorporated in this Module include:

• ISO 14064-3: 2019 - Greenhouse Gases - Part 3: Specification with Guidance for the verification and validation of greenhouse gas statements
• ISO 14040: 2006 - Environmental Management - Lifecycle Assessment - Principles & Framework
• ISO 14044: 2006 - Environmental Management - Lifecycle Assessment - Requirements & Guidelines

Additional principles that were considered in the development of this Module and aligned with, where feasible, include:

• The Core Carbon Principles of The Integrity Council for the Voluntary Carbon Market, v1.1, ICVCM, 2024
• Criteria for High-Quality Carbon Dioxide Removal, Carbon Direct & Microsoft, 2025

This Module was developed based on the current state of the art, publicly available science regarding IFM activities and long-term monitoring of forest carbon projects. This Module aims to be scientifically stringent and robust. We recognize that some requirements may exceed the status quo in the market and that there are numerous opportunities to improve the rigor of this Module as new approaches and techniques enter the Voluntary Carbon Market.

Additionally, this Module will be reviewed when there is an update to published scientific literature, government policies, or legal requirements which would affect net CO₂e removal quantification or the monitoring guidelines outlined in this Module, or at a minimum of every 2 years.

In addition to the requirements outlined in Section 4 of the Improved Forest Management Protocol, Projects are subject to the following applicability requirements, which must be demonstrated in the Project Design Document (PDD).

In order to maintain ecological integrity and ecosystem function, demonstrate additionality, and ensure trust and transparency, it is incumbent upon Projects to adhere to the requirements below, which must be demonstrated and reported in the Project Design Document.

Given the nature of this Module, it is anticipated that a Project, facilitated by the Project Proponent, may enroll many smallholder landowners within a Project.

To ensure accurate carbon sequestration claims and facilitate Validation and Verification, this Module requires that a Project be registered for a singular or grouped Site(s) — sets of land parcels subject to similar bioclimatic, regulatory, and geographic conditions.

• For the grouping of Sites under one Project, all Sites must be within the same RESOLVE Biome² and country.

Sites must consist of enrolled land parcels — discrete areas of land as defined by town, county, or regional tax maps — and/or all eligibile portions of enrolled mixed-use land parcels (Figure 1). Hereafter, the use of the term parcel shall mean both whole, single-use land parcels and all elibile portions of mixed-use land parcels, for simplicity.

• Contiguous parcels and/or parcels within 10 kilometers of each other that belong to the same parcel class (see Section 4.1.1.2) and are enrolled under the same contract should be grouped into a single Site. Parcels from seperate parcel classes, enrolled under different contracts, and/or discontinuous parcels more than 10 kilometers apart from one another must be enrolled as separate Sites (Figure 1).

Carbon quantification, as set out in Section 9, will be calculated at the Site level. Thus, each Site — and every constituent parcel — within a Project must independently meet all applicable eligibility criteria within this Module, which must be evidenced in the PDD.

The Project Proponent(s) and enrolled landowner(s) must adhere to the following additional requirements for parcel and Site enrollment:

• All Sites must be greater than 10 hectares.

• All parcels must have road or navigable waterway access.

  • Exceptions to this rule apply under extenuating circumstances — such as the presence of an easement or prior commercial harvest history — and can only be claimed after consultation with Isometric, and must be justified in the Project Design Document.

To ensure the credibility of the climate impact of project activities, non-additional areas of the Project must be excluded, as set out by various requirements in Section 4.1 of the Improved Forest Management Protocol and Section 4.1.2 of this Module.

It is vital to the integrity of the Project that no other areas within each parcel may be excluded from project activities. Smallholders participating in the Project must enroll all eligible areas of a parcel. This requirement prevents the selective enrollment of areas that are less desirable for harvest. Land can only be excluded for reasons stated within this Module or the Improved Forest Management Protocol, and these excluded areas must be documented and mapped within the PDD in accordance with and to fulfill the cumulative impact assessment requirements of the IFM Protocol (see Section 4.1.2) — with sufficient justification of the legal, financial, or operational restrictions on harvest.

For the purposes of this Module, parcel classes will be used for dynamic baselining and carbon quantification — i.e., distributed reference regions used as a point of comparison between behaviors observed in the enrolled Site(s) and those observed in areas with similar landowners (Figure 1).

The Project Proponent must generate between 10 and 50 parcel classes for the Project by clustering parcels in the ecoregion(s) of the country of the Site(s) into groupings with shared socio-economic, topographic, bioclimatic, historical, and structural attributes in relation to forest management.

• Project Proponents must provide all data and code used to generate parcel classes, with justification for the clustering algorithm(s).
  • Project Proponents should use k-means clustering to generate parcel classes.

• Unless the data is unavailable, Project Proponents must incorporate the attributes found in Table 1 into its clustering approach.

• Prior to clustering, Project Proponents must standardize or normalize all variables used in clustering to ensure attributes with different units or scales contribute equally to the clustering, and report all these data transformation and pre-processing steps. Missing data should be handled through imputation, exclusion, or other justified methods.

• Project Proponents must justify their selection of the final number of parcel classes based on statistical metrics that assess cluster quality and ensure each parcel class contains a sufficient number of parcels for robust dynamic baseline development.

• Project Proponents should validate their parcel classes by reviewing attribute distributions within and between classes to confirm meaningful differentiation, mapping class spatial patterns to identify potential data quality issues, and confirming that parcel classes align with known regional forest management activities.

The Project Proponent must assign any parcel(s) enrolled prior to Validation to the respective parcel class(es) at Validation, and report these assignments.

• The Project Proponent must provide both a geospatial file of the parcel classes along with the data and algorithms used to generate these classes.

Upon enrollment of any additional Site(s), the Project Proponent must assign the constituent parcel(s) of each Site to the closest existing parcel class, and report these parcel class assignments to Isometric at the next Verification.

Table 1. Parcel Class Clustering Attributes

Project activities must demonstrate additionality by accounting for Site-specific constraints that limit harvesting feasibility under baseline conditions. If ecological and Site conditions would render harvesting unlikely under baseline conditions, these areas within the Project Boundary cannot be claimed as additional and must be excluded from the Project Boundary. Soil saturation, permanent water bodies, slope gradients, and proximity to dwellings and other structures create natural and regulatory limitations on smallholder harvesting activities that must be evaluated when determining eligible project areas.

Project Proponents must identify and exclude from Crediting (see Section 4.1.1.1) any areas within the Project Boundary where economic, physical or regulatory constraints make harvesting highly unlikely under baseline management scenarios based on the guidance and requirements below.

Historically, harvesting operations in waterlogged soils occurred primarily during periods of prolonged freezing temperatures, which provided ground stability for heavy timber equipment. Climate change has reduced the predictability and duration of these freezing periods, particularly in temperate and polar regions, making winter harvesting increasingly unreliable. Consequently, harvest avoidance in these soil types does not constitute additional management activity beyond what would occur under baseline conditions.

Project Proponents must identify and exclude from Crediting any areas within the Project Boundary with soils classified as "very poorly drained" or "inundated" according to the U.S. Soil Taxonomy classification system, or similarly classified soils in equivalent authoritative sources if a Project occurs outside of the United States of America.

• Exceptions to this rule can be made if the Project Proponent demonstrates all requirements in Section 4.1.2.1.1.

Project Proponents may include areas with soils classified as "very poorly drained" or "inundated" within the Project Boundary where evidence demonstrates that baseline harvesting operations remain economically viable despite soil drainage limitations.

Areas with waterlogged soils may be included when the Project Proponent demonstrates:

• Baseline harvesting activities in the region commonly occur during predictable seasonal windows when soil conditions permit equipment access, as evidenced by regional timber market data, harvesting permits, or forestry operation records covering a minimum of the prior 10 years;
• Specialized harvesting equipment or techniques (such as winter harvesting, low ground-pressure machinery, or helicopter logging) are established practice in the region for similar soil conditions, demonstrated through equipment rental availability, contractor specialization, or documented use in comparable forest stands; and
• The proposed IFM activities constitute a measurable departure from baseline management that would otherwise occur despite drainage constraints.

To include these areas, the Project must also demonstrate additionality of these waterlogged soils through financial analysis showing that baseline harvesting remains economically feasible despite drainage-related operational constraints, and that the carbon revenue represents a necessary incentive for the proposed management changes.

Project Proponents must identify and exclude from the Project any areas within the Project Boundary that fall within management buffers around permanent water bodies as defined by applicable governmental regulations or voluntary Best Management Practices, i.e., BMPs (see Appendix B of the Improved Forest Management Protocol).

• Project Proponents must provide documentation of applicable governmental regulations and BMPs governing management buffers around water bodies, along with mapping of permanent water bodies and associated buffer zones within the Project Boundary.

Project Proponents must provide evidence of common harvesting practices and equipment availability within the relevant wood basket to demonstrate whether steep-slope operations are feasible under baseline management scenarios.

• Project Proponents must include a spatially-explicit topographic analysis of slope gradients within the Project Boundary.

• Project Proponents must include a regional assessment of harvesting capabilities on steep terrain, collated from industry, government, or NGO reports and/or scientific literature.

• Project Proponents must document the selection of the relevant wood basket.
  • Project Proponents should ascertain the relevant wood basket by: (1) examining scientific literature; (2) evaluating governmental, regulatory, NGO, and industry databases; and/or (3) identifying the regional catchment of the timber product(s) of their harvests. In the absence of this information, Project Proponents should generate wood baskets as the Thiessen polygons of mills which intersect with the project boundary.

• Project Proponents must exclude from crediting calculations areas with sustained slopes exceeding 30% over 30 meters in regions where specialized steep-slope harvesting equipment is not commonly deployed⁴.
  • The U.S. Forest Service has found that harvest equipment encounters significant limitations on slopes of 25% to 35%, with severe constraints on slopes exceeding 35%⁵. Areas with sustained slopes above these thresholds represent natural barriers to conventional harvesting operations.

Research on non-industrial private forest owner preferences demonstrates that the majority of forest owners will not permit harvesting activities in the immediate vicinity of residential dwellings and other permanent structures⁶. Additionally, regulations or BMPs may prohibit harvesting within a certain proximity of built structures.

Project Proponents must exclude from crediting calculations any areas within 50 feet of permanent structures, or within larger buffers if required by applicable regulations or BMPs (see Appendix B of the Improved Forest Management Protocol).

• Project Proponents must document any applicable governmental or BMP buffer requirements which would prohibit harvesting around dwellings and structures.

• Project Proponents must include a spatially-explicit vector-based map of all permanent structures within and adjacent to the Project Boundary.

Project Proponents must demonstrate that each parcel contains sufficient merchantable stocking in a market where harvests would be economically viable in the baseline scenario. This merchantable stocking determination will establish which areas of each parcel contain timber that would be economically attractive for harvest under common practice, thereby demonstrating the additionality achieved through deferred harvest activities.

Project Proponents must exclude all areas from the Project which do not meet the requirements in Sections 4.1.2.5.1 and 4.1.2.5.2.

For each enrolled parcel, the Project Proponent must demonstrate economic viability through a parcel-specific financial analysis accounting for all revenues and costs associated with timber harvest operations under baseline management scenarios.

• Parcel-level financial analysis should include gross timber revenues calculated using: (a) stumpage values taken from regional market pricing and/or forest-type pricing from Isometric's implementation of the Global Timber Model (GTM); and (b) merchantable volumes by, if feasible, product class at the same timepoint as the generation and/or assignment of parcel classes (see Section 4.1.1.2).

• Project Proponents should include — to best approximation — cost enumeration taken from Isometric's implementation of the GTM (Section 8.2) or developed from estimates of: (a) logging and processing; (b) access infrastructure; (c) transportation from the parcel to a processing facility; (d) equipment mobilization; (e) post-harvest obligations; (f) administrative and regulatory costs; and (g) property carrying costs during harvest operations.

• Project Proponents must apply discount rates appropriate to landowner classification accordingly:
  • Smallholder - Commercial Orientation (5%)
  • Smallholder - Subsistence/Mixed Objectives (4.5%)
  • Community Forest (4%)
  • Indigenous Land(s) (3%) The selected rate will be assigned by Isometric upon parcel enrollment based on documented ownership characteristics, management objectives, and regional economic conditions — with higher rates indicative of greater commercial orientation.

• For each parcel, the Project Proponent must report the: (a) merchantable volumes, ideally by species and product class; (b) revenue calculations with price sources and dates and/or revenue estimates generated by Isometric's implementation of the GTM (Section 8.2); (c) complete cost enumeration with supporting data and/or cost estimates generated by Isometric's implementation of the GTM; (d) NPV or IRR worksheets showing discount rate application; and (e) sensitivity analysis demonstrating impacts of ±20% parameter variations on viability.

• A parcel shall be classified as economically viable for harvest in the baseline scenario if:

  • The Net Present Value (NPV) is greater than zero at the applicable discount rate, or
  • The Internal Rate of Return (IRR) is greater than or equal to the minimum acceptable rate for the ownership class and net stumpage value ≥ 0.

  Parcels which fail to meet one of these thresholds must be excluded from the Project.

• Economic viability must be re-evaluated at re-enrollment of the parcel(s). When triggered, the Project Proponent must update economic parameters, recalculate parcel viability, and adjust classifications as warranted. This re-evaluation is prospective, with changes affecting current and future baseline projections without retroactive adjustment to historical Credit issuance.

Beyond parcel-level economic analysis, Project Proponents must evaluate whether sufficient regional market capacity exists to absorb timber volumes from enrolled parcels under baseline harvest scenarios.

• For each parcel classified as economically viable, the Project Proponent must identify and/or confirm:
  • All processing sites (e.g., sawmills, pulp mills, biomass facilities, and specialty processors) within economic hauling distance; and
  • The road distance from the parcel to each facility, with maximum hauling distances established by regional standards.

• For each parcel classified as economically viable, the Project Proponent should identify and/or confirm:
  • The current annual processing capacity by product type within the identified scope, using mill surveys, published reports, or direct facility operator communication; and
  • That facilities accept the parcel's species composition and actively procure these species for timber products; or, for roundwood products,
  • The economic viability and costs associated with roundwood export, the anticipated market for roundwood export, and the historic export pricing and transportation costs of roundwood.

• The Project Proponent must assess whether aggregate baseline harvest volumes from all economically viable project parcels would exceed regional processing capacity by:

  • Summing the projected annual harvest volumes across all project parcels within the applicable region; and
  • Comparing aggregate volumes by product class to total facility capacity within economic hauling distance; or for roundwood,
  • Summing the projected annual harvest volumes across all enrolled parcels within the applicable region; and
  • Comparing aggregate roundwood volumes to average regional export levels.

  Project Proponents must account for existing non-Project timber supply as part of this analysis.

• Where appropriate, Project Proponents may consider temporal market dynamics to justify the additionality of the Project, such as:

  • Historical timber price trends for species over the previous 5-10 years to ascertain any significant fluctuations;
  • Processing facilities that have opened, closed, or changed capacity in the past five years and likelihood of similar changes during the Crediting Period; and
  • Whether competing timber supply sources may affect market capacity or pricing.

  Where significant market changes are documented or reasonably anticipated, the Project Proponent should adjust merchantability classifications or apply appropriate discount factors to baseline projections.

• When market capacity is excceded by the Project, Project Proponents must remove some parcel(s) until the aggregate baseline harvest volumes from all economically viable project parcels is less than the regional processing capacity.

• Market capacity determinations must be re-evaluated upon re-enrollment of the parcel(s). During re-evaluation, the Project Proponent must update market capacity assessments, recalculate regional absorption capacity, and adjust parcel merchantability classifications as warranted. This re-evaluation is prospective, with changes affecting current and future baseline projections without retroactive adjustment to historical Credit issuance.

Project Proponents must demonstrate that landowners — who have owned the land for more than 5 years — enrolling into the Project do not possess merchantable stocking significantly above the regional average of the parcel class. Such stocks of merchantable carbon would indicate a pre-existing intent to conserve or defer harvest in violation of the requirements set out in the IFM Protocol (see Section 7.7).

• For any landowner(s) who have owned their land less than five years, Project Proponents must provide legal documents to demonstrate the purchase date of the land in order to exclude the landowner(s) from the merchantable stocking requirements herein.
  • However, Project Proponents must still calculate all variables in Section 4.1.3.1 and generate the require curves for this land in order to calculate the appropriate contract length (see Section 5.1).

Project Proponents must first develop and report growth curves for each Site (Figures 2 & 3), which describe the average growth trajectory of the forest.

• Project Proponents should use peer-reviewed data and methods such as national or sub-national forest inventory plots, chronosequence sampling, and/or regionally-calibrated growth and yield models (e.g., FVS, ORGANON) to develop growth curves, fitting appropriate functions — such as a Chapman-Richards or logistic curve — to plot carbon stock or volume against stand age for each parcel class and Site.

• Project Proponents must provide the data and code used to generate the growth curve(s), along with justification for the selected approach (e.g. FVS, Chapman-Richards, etc.).

Using historical disturbance history (e.g., Hansen Global Forest Change Product) to find the average time, $\bar{RA}$, and standard deviation, $RA_{SD}$, between harvest events (e.g., average rotational age) within each parcel class, the Project Proponent must then determine and report the baseline average carbon stock, $\bar{RS}$, and standard deviation, $RS_{SD}$, of harvest within each Site (Figure 2).

Project Proponents must then calculate and report the dynamic extension period, $EP$, for each Site, which is $\frac{1}{6}$ of the relevant $\bar{RA}$.

The Project Proponent must then report the initial standing aboveground carbon stock, $M_{AGB}(t_0)$, of each Site eligible for enrollment through a field inventory or with LiDAR according to one of the following Capture & Conversion Modules:

Finally, the Project Proponent must plot $M_{AGB}(t_0)$ for each Site against its growth curve to determine the current stand age of the Site, $CSA$. Project Proponents must include these plots in the PDD.

If a Site’s carbon stocking exceeds one standard deviation, $RA_{SD}$, of that of the average harvest date, $\bar{RA}$, plus the dynamic extension period, $EP$ — to allow for growth into later size-classes — it shall be deemed ineligible under this Module and must be removed from the Project (Figure 3).

Figure 3. Average growth trajectory plot of a Site. (a) The average rotational time ($\bar{RA}$) and stocking level ($\bar{RS}$) at harvest within the parcel class and Site, respectively. One standard deviation above the average stocking level of the Site, $RS_{SD}$, intersects the growth curve at (b), which is also one standard deviation above the average rotational time ($\bar{RA}$) of the parcel class. (c) The carbon stock limit at which sites are not eligible for enrollment, determined by taking (b) one standard deviation above the mean $\bar{RA}$ plus $\frac{1}{6}$ of the $\bar{RA}$, or the $EP$, and finding its intersection on the growth curve. (d) and (e) represent the estimated initial carbon stock of potential Sites. (f) The current stand age, $CSA$, of an eligible Site, with an estimated stand age less than the carbon stock limit. (g) The current stand age, $CSA$, of an ineligible Site, with an estimated stand age greater than the carbon stock limit.

Under deferred harvest, the planting of new trees cannot be the primary method to achieve forest cover. Project Proponents must limit new planting only to fill in gaps in existing patches of degraded forests or to regenerate small areas — less than 1 hectare — of otherwise forested land.

• The Project Proponent must disclose this planting, as well as the justification for it, within the PDD for initial Validation and follow all biodiversity requirements as set forth in the IFM Protocol (see Section 6.4) of the Improved Forest Management Protocol.

• Any new planting after Validation must be reported to Isometric before the next verification event.

Enrolled landowners under this Module are afforded a three-cord-per-year ($\approx$ 10 cubic meters) per household harvesting allowance for subsistence activities (e.g., firewood) within their parcels, which does not need to be reported to Isometric.

• To ensure proper forest management, any additional subsistence harvests (i.e., not part of project activities) over the afforded limit must be reported to Isometric to ensure proper determination of any Reversal event and should be conducted under the supervision of either a third-party certified logger or government-certified forester.

The length of the Crediting Period of the Project shall be determined by the cumulative temporal maximum of the contract lengths of the enrolled landowner(s) and their site(s) or 40 years, whichever is longer.

• Projects whose initial cumulative temporal maximum of contract lengths is less than 40 years should continue to enroll Sites until the cumulative temporal maximum of contract lengths meets or exceeds 40 years.

The contract length for parcels enrolled in the Project is determined by the biological and economic trajectory of the forest stand, and set by an assessment of key forest characteristics measured using this Module’s approved remote sensing technologies, ideally LiDAR. These contracts must meet the requirements set forth in the IFM Protocol (see Section 5.1).

Project Proponents must assess three critical parameters — current forest size, estimated biological rotation age, and current stand age — to determine contract lengths for enrolled landowners, and provide due diligence that each contract was determined accordingly.

• For Projects which commenced activities prior to the publication of this Module, Project Proponents must provide justification for all existing contract lengths and demonstrate how these contracts ensure additionality in line with this Module.
  • All future contracts in these Projects must adhere to the guidance and requirements of this Module to determine contract length.

The initial contract length for each enrolled landowner, $Contract\ Length_{landowner}$, must be calculated using the following equation that takes these parameters into account:

$$Contract\ Length_{landowner} = (\bar{RA} + RA_{SD} + EP) - CSA$$

(Equation 1)

Where:

• $\bar{RA}$ is the mean rotation age of the Site as determined in Section 4.1.3.1
• $RA_{SD}$ is the standard deviation of the rotation age of the Site as determined in Section Section 4.1.3.1
• $EP$ is the extension period, which is set at $\frac{1}{6}$ of $\bar{RA}$
• $CSA$ is the current stand age of the Site, as determined in Section 4.1.3.1

The Crediting Period will commence either when the Project Proponent commences activities on a Site or on the date of the first enrolled landowner(s) contract signature within the Project, with project activities required to commence immediately. No Credits shall be issued for activities that occurred prior to the contract signature date.

Projects seeking to extend the initial Crediting period must demonstrate continued additionality in line with all requirements set forth in this Module, the Improved Forest Management Protocol, and the Isometric Standard.

The first Reporting Period shall end at a date set by the Project Proponent and approved by Isometric at Validation. This first Reporting Period must occur within 5 years of the initiation of the Crediting Period.

As Projects enroll any additional landowner(s), the Site(s) from the newly enrolled contract(s), $i$, must take a deduction of Credits based on the time between the date of enrollment and the end of the Reporting Period according to the following Equation 2:

$$ARPF_i= \frac{Days\space to\space end\space of\space Reporting\space Period}{Total\space Days\space of\space Reporting\space Period}$$

(Equation 2)

Where $ARPF_i$ is the Adjusted Reporting Period Factor discount rate applied in Equation 7 to the calculation of CO₂e stored for the parcel(s) under each individual contract, $i$, weighted to ensure only growth since contract initiation is included in the Credit issuance for the Reporting Period (see Section 9.1).

In addition to the requirements set forth in the IFM Protocol (Section 6.4) of the Improved Forest Management Protocol, Projects must not resemble industrial commercial or monoculture plantations.

• In cases where a species naturally grows in monoculture within the project region or there is scientific evidence for a single dominant species during natural succession, Project Proponents may proceed with monoculture silviculture of this species in consultation with Isometric as outlined in the IFM Protocol (Section 6.4) of the Improved Forest Management Protocol.

While a forest management plan is not required for landowner enrollment into the Project, Project Proponents should work with enrolled landowner(s) to develop parcel- and site-specific plans. Project Proponents should facilitate expert forester consultation with enrolled landowners as part of enrollment into the Project, and disclose any such past or planned activity in the Project Design Document.

Certain forest management activities must be disclosed by the Project Proponent, such as Stand Improvement Activities and Harvesting Plans. These activities are subject to the requirements set forth by Isometric in this Module, the IFM Protocol (Section 6.5), and the Isometric Standard.

By providing advanced notice of intended forest management activities, enrolled landowners can assist the Project Proponent in managing the expected issuance of Credits, enabling greater flexibility in forest management activities and harvesting. Enrolled landowners who intend to harvest or actively manage their forest should disclose these plans to the Project Proponent with enough advance notice to ensure compliance with this Module, the Improved Forest Management Protocol, and the Isometric Standard.

Enrolled landowners may engage in Isometric-approved stand-improving activities in consultation with the Project Proponent. These activities must follow specific restrictions set initially by the Project Proponent and approved in consultation with Isometric to ensure that the volume of harvested wood does not exceed the volume of issued Credits.

The Project Proponent must disclose all planned stand-improvement activities in the Project Design Document prior to Validation and at each subsequent Verification, and must inform Isometric of any changes to these plans immediately and report these changes prior to the next Verification.

• Stand-improving activities in the first five years of Site enrollment may reduce initial standing carbon stock value by no more than 15% within the enrolled Site.

• Stand-improving activities after the first five years of Site enrollment may reduce the most recently verified standing carbon stock value by no more than 15% within the enrolled Site.

• Only stand-improvement activities defined by the USDA NRCS guidance are permitted.

• All stand-improvement activities must comply with applicable environmental and social safeguards set out in the IFM Protocol (see Section 6).

Credits will not be issued until the forest biomass within the Site recovers above the Site’s most recent pre-stand-improving-activity carbon stock baseline.

Project emissions associated with stand improvement activities must be reported according to the requirements in the IFM Protocol (see Section 8).

To ensure that the Project’s carbon stock does not dip below a reasonable threshold of the levels at which Credits were previously issued — which would trigger a Reversal — Project Proponents should work closely with enrolled landowners to plan all non-intervention (i.e., deferred harvest) harvest activities.

Project Proponents must work with enrolled landowners and certified foresters to determine any such anticipated non-intervention harvesting schedule and pre-emptively plan reporting to ensure Credit issuance occurs when enough carbon has been sequestered to prevent the triggering of an avoidable reversal. This non-intervention harvesting is additionally subject to the following requirements:

• Selection harvesting within the first five years must not reduce the Project's carbon stock more than 15% below the standing carbon stock value from the last Verification.

• Selection harvesting after the first five years must not reduce the Project’s carbon stock more than 15% below the standing carbon stock value from the last Verification.

• Project Proponents should provide guidance on minimum stocking and volume requirements to enrolled landowners.

• Approved activities include fire fuel load management, pre-commercial thinning, and invasive species control — including pest and disease management.
  • Additional activities are permitted subject to consultation with and approval by Isometric.

• All stand-improvement activities must comply with applicable environmental and social safeguards set out in the IFM Protocol (see Section 6).

To ensure this compliance, the Project Proponent must describe all non-intervention harvesting plans and timelines for the enrolled site(s) prior to Validation and at each subsequent Verification. It is anticipated that these will be informed by the forest management plan of each enrolled landowner.

Credits will not be issued until the forest biomass within each Site recovers above the Site’s most recent pre-non-intervention-harvesting carbon stock baseline.

Project emissions associated with harvesting activities must be reported according to the requirements in the IFM Protocol (see Section 8).

Project Proponents must disclose all pre-existing forest management or traditional stewardship plans for any enrolled Site(s).

• Plans which expire during the Crediting Period but after Validation fulfill this requirement.

• For Indigenous landowners practicing traditional forest stewardship: Where principles of traditional land use are not documented in a formal plan, demonstration may include oral histories, cultural practices documentation, or traditional ecological knowledge (TEK) assessments that evidence ongoing forest engagement and resource use patterns informed by traditional practices.

These plans must specify likely or planned harvest(s), or traditional forest stewardship activity, during the Crediting Period.

In addition to any Indigenous Peoples stakeholder engagement and Free, Prior, and Informed Consent (FPIC) process that may be required for the Project as proscribed in the IFM Protocol (see Section 6.6), Project Proponents must follow the same stakeholder engagement plan and principles of FPIC described in the IFM Protocol (see Section 6.6.1) for all enrolled landowners.

It is vital that enrolled landowners understand the contracts they are entering into as part of the Project. As part of this stakeholder engagement and FPIC process, Project Proponents must make publicly available and disclose to enrolled landowner(s), and ensure that these landowner(s) understand the following, during the process:

• Financials, including: revenue sharing arrangement and requirements incumbent upon the landowner to recieve benefits, the anticipated value of the Credits, and the anticipated earnings of the Project.

• Carbon Markets, including: the volatility of the carbon market and understand that the sale of Credits is not guaranteed.

• Project Baselines, including: the concept of dynamic baselines, and the unpredictability of forest growth and loss overtime — Credits may be less than anticipated under ex-ante projections.

• Monitoring, including: that their land is being monitored via satellite imagery, airborne manned flights, and/or unmanned aerial systems (UAS) on as frequent a basis as is required by the Improved Forest Management Protocol and this Module, and that this satellite, manned flight, or UAS derived data — as well as geospatial information related to their parcel and site(s) — will be shared with the public through the Isometric Registry.
  • Geospatial information and other data that must be publicly shared by enrolled landowners includes remote-sensing maps and imagery that document the Project’s forest carbon stocks, structure, and ecological benefits.

Given the inherent economic nature of forest management activities, the impacts of the Project extend beyond enrolled landowner(s) to local economies. Giving these stakeholders early notice of planned changes in timber harvest enables market adaptation and prevents job losses in any local timber-based economy.

Project Proponents must provide enrolled landowners an estimate of the likely change in the volume of their future harvest and, if applicable, any quality changes in their forests during the Project that should also be disclosed to loggers and local resource management agencies to inform broader resource and timber planning.

• Project Proponents should also provide similar information to any and all requesting entities/individuals — e.g., municipal authorities, research groups, or reporters.

The Project Proponent or enrolled landowners must notify local authorities and loggers, mills, or other parties with whom the enrolled landowner(s) has existing formal or informal offtake agreements of the contracted change in harvest volume and/or schedule of timber upon enrollment into the Project.

In addition to the requirements set forth in the IFM Protocol (Section 6.6.2), the Project Proponent must disburse to enrolled landowners a minimum of 40% of the revenues generated from Credits issued to the Project. Eligible forms of revenue sharing include:

• Direct payments
• Silviculture materials (e.g., seedlings, fertilizer)
• Equipment and/or infrastructure
• Forester consultation(s) and/or training(s)

If any of revenue sharing is contingent upon the landowner meeting particular requirements (e.g., adherence to a harvesting plan), these requirements must be clearly communicated to the landowners and disclosed to Isometric.

Project Proponents must also provide details of the systems which will be used for the disbursement of revenue and how the disbursement will be tracked (e.g., digital payment records, other documentation in absence of formal financial systems).

• These systems must include a mechanism for landowners to report any grievances or disputes related to revenue sharing, and for the tracking of the response and resolution of these issues.

• Any non-monetary, in-kind compensation must involve a transfer of ownership to the enrolled landowner(s).

Revenue sharing percentages should also be made public, including percent revenue or Credits divided among each party (e.g., Project Proponent, enrolled landowner(s), insurance provider(s), and other documented parties listed in the PDD).

Project Proponents must provide an anticipated timeline of revenue sharing disbursement over the duration of each contract.

• At every Verification, Project Proponents must provide evidence demonstrating progress against this plan, including proof of revenue disbursement, and report any grievances raised by landowners, and the subsequent responses and resolution by the Project Proponents.
  • Projects which fail to report or provide sufficient evidence may be required to undergo an audit by an independent certified financial auditor.
  • If at any Verification the cumulative revenue disbursement has fallen >20% below the original projected level for that timepoint, the Project Proponent must submit an updated revenue disbursement plan and timeline to demonstrate how the Project will meet the revenue sharing requirement of this Module.
    • This new plan will be used for benchmarking at any future Verification(s).

In order to ensure additionality, the Project Proponent must demonstrate a pre-existing intent to harvest trees within the Project Boundary and prove a demonstrable history of commercial harvesting and/or traditional forest stewardship within the parcel(s) of any enrolled landowner(s). These requirements must be robustly evidenced by data of the following types.

• A written attestation that enrolled landowner(s) intended to harvest, would accept harvest offers, and/or conduct traditional stewardship activities during the Crediting Period.
  • If applicable, this attestation must include reference to the pre-exisiting forest management plans disclosed in Section 6.2.3.

• Historical satellite imagery that clearly shows evidence of commercial harvesting and/or indicators of traditional forest stewardship activities during the Project Proponent’s and/or landowner’s tenure.
  • Landowners who have owned any parcel(s) for less than 5 years do not need to meet this requirement, but must meet all other requirements within this section.
  • For traditional forest stewardship, indicators include, but are not limited to, patterns of selection harvesting for cultural or subsistence purposes, traditional fire management practices, or other sustainable use consistent with established Indigenous land management practices.

• This evidence should prioritize high-resolution historical imagery with clear sourcing information and acquisition dates. Preferred sources include: the USDA's NAIP, the USGS's NHAP programs, and/or private data providers (e.g., Planet).
  • In cases where high-resolution imagery is unavailable, Sentinel-2 or Landsat imagery may be used as an alternative, which must be accompanied by spectral analysis showing patterns consistent with harvest activities and a detailed explanation for why high-resolution imagery could not be obtained.

The carbon pools within the scope of this Module are aboveground and belowground woody biomass, as these are the main carbon pools affected by the intervention of deferred harvest. Soil carbon is excluded $CO_2e_{Stored, RP}$ as the literature suggests minimal change under low-intensity deferred harvests⁷. For the remainder of the Module, the use of AGB and BGB refers to only the living aboveground and belowground woody biomass, respectively, unless otherwise noted.

This Module requires Projects to account for leakage through the Global Timber Model (GTM), which captures both direct landowner behavioral responses (activity-shifting) and broader market-mediated effects (market leakage) within a unified economic modeling approach. This integration reflects the reality that in improved forest management, activity-shifting behaviors are often driven by the same market signals and economic incentives that drive broader market leakage in response to timber supply restrictions. In this Module, leakage is calculated for distinct species groups for each regional wood basket, which vary by geographic location and forest composition.

Recent scientific literature has highlighted significant challenges in accurately quantifying leakage from forest carbon projects. Studies by Badgley et al. (2021)⁸, Haya et al. (2023)⁹, and others have found systematic over-crediting in forest carbon offset programs, largely due to inadequate accounting for leakage impacts¹⁰. This research indicates that traditional approaches to leakage assessment for forest carbon offset programs often underestimate both the magnitude and geographic scope of displacement effects.

The complexity of global timber markets means that reduced harvest in one location can trigger responses across multiple regions and through various economic pathways. Market-mediated leakage can occur through price signals that incentivize increased harvesting in distant locations, while activity-shifting often occurs through landowner responses that extend to other land owned by the Project Proponent or enrolled landowners, but not included in the Project.

This methodology adopts a conservative modeling approach with a minimum 10% leakage deduction, using the Global Timber Model (GTM) to prevent well-documented overcrediting that has resulted from other improved forest management methodologies.

Any enrolled landowner(s) who own or manage forested land outside of the enrolled parcel(s) of the Project must provide an attestation that they will not alter forest management on this land outside of the enrolled parcel(s) as a result of project activities.

Additionally, for all non-primary residence non-enrolled land parcel(s) greater than 10 hectares, the attestation document must also include, in order of preference:

• A forest management plan dated at least 2 years prior to enrollment outlining historical and future expected harvests on all land(s) outside of the enrolled parcels; or
• Historical records of harvests including timing and volumes that cover the ownership tenure of the enrolled landowner(s); or
• A credible, third-party approved regional landscape management plan (LMP); or
• Satellite records of harvest timing that cover the ownership tenure of the enrolled landowner(s); and
• An outline of anticipated factors (e.g., land inheritance, market fluctuations, pest management, etc.) that may affect the landowner(s) decisions around future deviation from the harvesting schedule outlined in the forest management plan.

The enrolled landowner(s) should provide documentation of their annual harvest volume(s) for all non-enrolled lands for every year that the landowner(s) remain enrolled in the Project to the Project Proponent, who shall report all available annual harvest volume(s) to Isometric prior to each Verification.

Isometric reserves the right to audit future harvests on non-enrolled land(s), inclduing via earth observation remote sensing systems, and compare these harvests against the submitted attestation.

The Global Timber Model (GTM) was conceptualized by Sohngen et al. (1999)¹¹, and it seeks to re-balance supply and demand in response to market shocks over decadal time periods for forest-type regions.

The GTM has been adopted for carbon projects through an update led by the University of Maine, in collaboration with The Nature Conservancy and the Global Forest Lab at The Ohio State University, as discussed in Daigneault et al. (2025)¹². This updated GTM estimates how forest carbon projects in aggregate change trade balances regionally and globally, as a result of both direct and indirect leakage.

Isometric will quantify the leakage deduction for each Reporting Period for Projects based on global runs of leakage rates (Equation 3) for the forest-type using the Global Timber Model (GTM), annualized and weighted by the Project’s basal area. As changes to timber harvest through project activities directly and indirectly impact the balance of supply and demand for decades, and the GTM initiates this predicted response within the same decadal time period as the start of the Crediting Period, the leakage deduction schedule for the percent deduction of a Reporting Period, $L_{project, RP}$ will be set at project initiation, and updated as needed by Isometric with the inclusion of any new site(s).

Further information on how Isometric implements the GTM and determines leakage is set forth in Appendix D, which contains additional information on the technical requirements of model implementation and the data sources used for modeling.

The average leakage rate, LR, for each forest type-region (see Appendix D3) in 10-year time periods is calculated as:

$$LR_{f,r,t} = \rho_t \left[ \frac{(PCS_{project,f,r,t} - PCS_{counterfactual,f,r,t}) - (GCS_{project,f,r,t} - GCS_{counterfactual,f,r,t})}{(PCS_{project,f,r,t} - PCS_{counterfactual,f,r,t})} \right]$$

(Equation 3)

Where:

• $LR_{f,r,t}$ is the average leakage rate per given decade in a forest type-region
• $PCS$ indicates the carbon stock within the Project Boundaries, in tonnes of $C$
• $GCS$ indicates global forest carbon stock, in tonnes of $C$
• $f$ is the forest type
• $r$ is the region
• $t$ is the time period (in decades)
• $\rho$ is the discount rate, conservatively set at 5%

The Project’s leakage for each Reporting Period, $CO_2e_{leakage, RP}$ is then calculated using the following equations:

$$L_{project,t} = \frac{\sum B_{f,r,t} \times LR_{f,r,t}}{B_{project,t}}$$

(Equation 4)

Where:

• $L_{project,t}$ is the project leakage for a given decade
• $LR_{f,r,t}$ is the average leakage rate per given decade in a forest type-region
• $B_{f,r,t}$ is the basal area in each forest type-region in the project area
• $B_{project,t}$ is the basal area in the project area
• $f$ is the forest type
• $r$ is the region
• $t$ is the time period (in decades)

And, $B_{project,t}$ must equal $B_{f,r,t}$

As the GTM outputs leakage estimates on decadal timesteps, Isometric will then annualize the project leakage, applying a linear interpolation between decadal estimates to derive the leakage deduction for each year within a decade:

$$L_{project, RP} = L_{project, 0} + \frac{t}{10}\left( L_{10}-L_0 \right)$$

(Equation 5)

Where:

• $L_{project, RP}$ is the project leakage rate for a given Reporting Period, RP
• $L_{project, 0}$ is the project leakage rate for the first year within a decadal time-step
• $L_0$ is the project leakage rate for the first year within a decadal time-step
• $L_{10}$ is the project leakage rate for the last year within a decadal time-step
• $t$ is the year into the decadal time step for the Reporting Period, $RP$

The final leakage deduction for each Reporting Period, $CO_2e_{leakage, RP}$ can then be calculated as a percentage of the sequestered carbon in a Reporting Period, $CO_2e_{Stored, RP}$ (see Section 9.1).

$$CO_2e_{leakage, RP} = L_{project, RP} \times CO_2e_{Stored, RP}$$

(Equation 6)

If the leakage rate, $L_{project, RP}$, is <10%, the minimum annual leakage deduction of 10% will be applied by Isometric. When positive leakage is predicted by a negative leakage rate ($L_{project, RP} < 0$%), it will be subject to the minimum annual leakage deduction of 10%. Positive leakage indicates a model which predicts that restricting supply in the region could increase timber prices, and incentivize more considered forest management or land to be converted to forest.

Given the distributed nature of improved forest management projects under this Module, the Project Proponent may have project sites with variable contract lengths for the intervention of deferred harvest and forest management practices, often with multiple enrolled landowners. As described in Section 10.1, this creates challenges for the permanence claim and issuance of Credits with verifiable additionality.

Projects crediting under this Module must apply the permanence factor, $PF$, calculated in Section 10.1.1 to the stored carbon for each Reporting Period, $RP$, to derive the proper value of $CO_2e_{Stored, RP}$ for Credit issuance under the Improved Forest Management Protocol following Equation 7.

$$CO_2e_{stored,RP} = \sum_{i=1}^{n} ARPF_i \times PF_i \times \left( CO_2 e_{AGB,RP,i} + CO_2 e_{BGB,RP,i} \right)$$

(Equation 7)

Where:

• $CO_2 e_{stored,RP}$ is the total $CO_2$ removed from the atmosphere and stored as organic carbon in living trees for the $RP$, in tonnes of $CO_2e$.
• $CO_2 e_{AGB,RP,i}$ is the total carbon stored in living aboveground woody biomass (AGB) over the $RP$, in tonnes $CO_2e$, for the parcel(s) under each individual contract, $i$.
• $CO_2 e_{BGB,RP,i}$ is the total carbon stored in living belowground woody biomass (BGB) over the $RP$, in tonnes of $CO_2e$, for the parcel(s) under each individual contract, $i$.
• $ARPF_i$ is the discount rate applied to the calculation of $CO_2e$ stored for the parcel(s) under each individual contract, $i$ (see Section 5.2).
• $PF_i$ is the discount rate applied to the calculation of $CO_2e$ stored for the parcel(s) under each individual contract, $i$ (see Section 10.1.1).
• $n$ is the number of individual contracts $i$.

To derive $CO_2e_{AGB, RP, i}$ and $CO_2e_{BGB, RP, i}$, Project Proponents must calculate $CO_2e_{AGB, RP}$ and $CO_2e_{BGB, RP}$ for the parcel(s) under each individual contract, $i$, according to the guidance and requirements found in Sections 9.3.2 and 9.3.4 of the IFM Protocol, respectively.

Isometric encourages Project Proponents to quantify the total above-ground biomass, $M_{AGB}$, in the project area at time point, $t$, through one of the Capture & Conversion Modules listed in the IFM Protocol (see Section 9.3.3).

• If either LiDAR or Earth Observation methods are selected, benchmarking these methods with field plots must occur, at minimum, every ten years following the procedures within the corresponding Module. This benchmarking may use field data from national or sub-national forest inventory plots, as long as it can be demonstrated that these plots are representative of the project area in species composition and range of biomass density, and the data are otherwise adherent to the requirements for the benchmarking procedure.

Alternatively, subject to meeting all the requirements set forth in Section 9.2.1, Projects may elect to quantify $M_{AGB}(t)$ through an alternative growth-disturbance model. Projects electing to use a growth-disturbance model must obtain approval from Isometric at Validation based on a comprehensive evaluation of the methodology in accordance with the requirements in Sections 9.2.1.1 and 9.5.

The total aboveground woody biomass, $M_{AGB}$, at the current timepoint, $t$, can be derived via modeling of the change in biomass due to growth and disturbance (loss) since the most recent direct measurement of biomass within the project area (Figure 4). The model must be developed using national or sub-national forest inventory (NFI), or other publicly-available inventory (e.g., research, industry) plot data from the region, which may be derived from field plot measurements, LiDAR measurements, or some combination thereof. Hereafter these will be collectively referred to as NFI data for simplicity, but eligible datasets are broader as noted.

To apply the model across the project area, the project area should be subdivided in a manner than corresponds to the NFI dataset which is being used for model development. For example, if rasterized NFI data are being used, the project area should be divided into pixels of equivalent or greater (up to 100%) size. If NFI field plots are being used, sampled field plots of equivalent size should be used within the project area as the basis for assessment.

Under this approach, the Project’s total aboveground woody biomass, $M_{AGB}$, at the current time point, $t$, can be calculated as:

$$M_{AGB,i}(t) = M_{AGB,i}(t_m) + \int_{t_m}^t G_i \, dt + \int_{t_m}^t D_i \, dt$$

(Equation 8)

Where:

• $M_{AGB,i}(t)$ is the total aboveground woody biomass at timepoint $t$ in project area sub-unit $i$ (e.g., pixel or plot), removed from the atmosphere and stored as organic carbon in living trees, in tonnes of C.
• $M_{AGB,i}(t_m)$ is the carbon stock of sub-unit $i$ at year $t_m$, where $t_m$ is the time of the most recent assessment of pixel-level carbon using field surveys or LiDAR (see Section 9.2.1.4).
• $t$ is the current year.
• $G_i$ is the rate of carbon accumulation in sub-unit $i$, derived from the modeling approach, in tonnes C yr$^{-1}$.
• $D_i$ is the rate of carbon loss associated with disturbance in sub $i$, derived from the modeling approach, in tonnes C yr$^{-1}$.

To determine the project-level aboveground biomass, the mean across the project area sub-units should be used:

$$M_{AGB}(t) = \frac{\sum_{i=1}^{n} M_{AGB,i}(t)}{n}$$

(Equation 9)

Where:

• $M_{AGB}(t)$ is the project-level mean total aboveground woody biomass at timepoint $t$ in tonnes of C.
• $n$ is the total number of project area sub-units (e.g., pixels or plots) over which the model was applied.

To apply the growth-disturbance model described in Equation 8, Projects must meet all of the applicability requirements in Sections 9.2.1.2 and 9.2.1.3 for the respective model components.

Project Proponents demonstrate that the growth-disturbance model development and performance meets the following requirements:

• Model performance must be assessed using out-of-sample data not involved in model training (e.g., using the model to predict biomass in NFI plots withheld from model development, and comparing modeled biomass to actual measured biomass in these plots).
• The validation dataset must cover a range of biomass values that encompasses those within the project area, be from the same ecoregion, be at least 30% the size of the project area dataset, and include a disturbance magnitude/frequency which is relevant for the project area.
• Based on assessment against the validation dataset, the model must achieve a minimum $R^2$ of 0.6.
• The characterized model uncertainty impacts on overall Removal estimates must be propagated in accordance with the Isometric Standard (see Section 2.5.7).

Growth in the project area can be assessed through the development of models which estimate growth based on observed growth measured in NFI data for similar areas.

Project Proponents must meet all of the following requirements for the development and application of such growth model(s):

• The model(s) must be developed using NFI plots with repeat measurements spanning at most 10 years;
• Sub-area i must be matched to the three most similar NFI plots using k-nearest neighbors and compared to the average growth rate of these matched plots; and,
• Current sub-area growth in i must be matched to a historical NFI or publicly-available inventory plot, with plot re-measurements occurring over a period of time equal to or greater than the number of imputation years.

If using NFI data with spatially disjoint sub-plots, Project Proponents should aggregate these sub-plots according to the guidance and design of the NFI dataset.

Absolute change is then imputed on an annual basis for each sub-area plot matches, and those annualized growth estimates are added to the latest direct measurement-derived estimate of the pixel (Equation 8).

Disturbance models may be used to estimate forest carbon loss stocks since the last field survey or LiDAR acquisition. Disturbance models both detect the occurrence of a loss within the project area, and estimate the carbon stock changes associated with the loss. The loss model is developed based on relevant observations of post-disturbance biomass change from NFI data or other publicly available datasets.

Project Proponents must meet all of the following requirements for model development and performance to use any disturbance model(s):

• The model(s) must directly forecast absolute or relative decreases in carbon stock following a disturbance;
• The model(s) must be parameterized with NFI data or repeat LiDAR acquisitions which capture a sufficiently large sample of disturbance events;
• The model(s) must have a minimum recall of 0.85 for detecting disturbances with the harvested class; and
• The model(s) must be able to detect partial harvests equivalent to ≤ 30% removal of carbon stocks.

Project Proponents are encouraged to leverage commercial high-resolution imagery, spaceborne multi-spectral imagery (e.g., Sentinel-2), and/or synthetic-aperture radar SAR (e.g., ALOS or NISAR) in the development of their disturbance model(s).

In the event of a disturbance, the corresponding carbon stock must then be subtracted from the sub-unit biomass, and sub-unit plot matches must be remapped for subsequent years (Equation 8).

At the initial enrollment of a parcel, and at a minimum frequency of every 10 years thereafter throughout the Crediting Period, the Project Proponent will collect field-based or LiDAR-derived estimates of carbon stock on the parcel to establish $M_{AGB,i} (t_m)$. Further, if the modelled losses over the entire project area are greater than 60% of the modeled growth over the entire project area for a given Reporting Period, direct measurements must be made for that Reporting Period. Project Proponents must quantify this carbon stock through one of the following two approved Capture & Conversion Modules:

The following section outlines the workflow that Isometric will take for the calculation of $CO_2e_{Counterfactual, RP}$ via a dynamic baseline approach; the Project Proponent is not responsible for carrying out the steps in this section. Project Proponents may suggest areas that could constitute suitable control pixels or features for matching based on their expert knowledge of their unique system. However, the ultimate determination of control pixels will be done by Isometric following the procedure and criteria below.

At Validation, the control plot zone must meet the following eligibility criteria:

• Located in the same country and ecoregion as the project area;
• Does not lie within protected areas, or within other carbon projects;
• Be subject to the same relevant regulations, government incentives, and programs as the project area; and
• Biomass, e.g., carbon stock values, and productivity values must be within 10% of those of the project plots.

If possible, other features should also be matched between the control plot zone and project area, such as:

• Within State/Province boundaries
• Species
• Productivity
• Stocking (i.e., tree size)
• Bioclimatic variables (e.g., temperature and precipitation)
• Topography
• Accessibility
• Wealth/Land value
• Millsheds

Initially, the zone for eligible control plots should be limited to the same state or province, or a 100 km band around the project area — whichever is smaller. However, if suitable matches (see Section 9.3.3) are not found in this zone, additional step-outs in 10 km increments may occur to find appropriate control plots, assuming they meet the criteria above. The final area determined for suitable control plots is hereafter referred to as the Donor Zone.

Once the boundaries of the Donor Zone are determined, Isometric will generate high-resolution (≤30 m) pixel maps representing forest carbon stocks or a suitable proxy for forest carbon stocks. These layers must cover the entire project area and Donor Zone at the same resolution for at least five historical time points relative to the start of the Project. Each historical time point must be separated by at least 1 year.

Isometric will select a suitable proxy that meets the following criteria:

• The proxy must be correlated with AGB throughout the Crediting Period.
• If the proxy saturates in the project area or Donor Zone during the Crediting Period and becomes insensitive to further carbon gain (e.g., as is the case for many simple optical indices), it will be excluded¹². Proxies such as canopy height from models which use datasets from multiple types of earth observation (particularly 2D satellite imagery, LiDAR and SAR) are preferred¹³.
• The proxy map product should exclude cloud occlusion, saturation, and other contamination. This may lead to seasonal composite images.
• The proxy should be insensitive to seasonal variability, which may be addressed through taking an annual average to remove the seasonal cycle.
• The proxy should be stable, so that in the absence of carbon change, the proxy value stays the same.

Project and control plot pixels will be matched by Isometric at Validation, and these matches will be retained and tracked over the Crediting Period. In this procedure a representative random sample of project pixels are matched to control plot pixels based on a mix of current and historical time series of environmental, socioeconomic, management, and forest structure data — including the selected forest carbon proxy, $C_{proxy}$, of each pixel — using k-nearest neighbors without replacement, or an alternative justified algorithm. Isometric shall use, at minimum and where possible, the datasets in Table 2 for matching.

Project and control plot pixels will be matched within the same parcel classes (see Section 4.1.1.2). To reduce spatial autocorrelation, a maximum of 15 control plot pixels are permitted within individual non-project parcels. Additionally, a minimum of one project pixel will be selected for each hectare of project area.

This matching will use, at a minimum, five historical time points capturing at least the five years prior to project initiation. Each selected project pixel must be matched to a minimum of 5 different control pixels, and the mean of each dataset over the group of control pixels is used — with the mean forest carbon proxy over the group of control pixels derived from the map product created using the procedure described in Section 9.3.2.

Table 2. Dynamic baseline pixel matching Criteria and clustering.

All dynamic remotely sensed variables must be captured within 18 months of each Verification.

For individual project pixels, the change in carbon stock over the Reporting Period is calculated both for the project pixel and for the collection of corresponding control pixels (taking the mean across the group) using the values from the carbon proxy map:

$$\Delta C_{proxy}=C_{proxy}(t_2)- C_{proxy}(t_1)$$

(Equation 10)

Where:

• $t_1$ and $t_2$ are the start and end of the Reporting Period, respectively.
• $\Delta C_{proxy}$ is the change in carbon proxy value over the Reporting Period.

The estimated carbon removal of the counterfactual scenario is found by scaling the quantified carbon removal in the project area by the ratio of the mean differences of the proxy change between the project and control pixels:

$$CO_2e_{Counterfactual,RP} = CO_2e_{Stored,RP} \times \frac{\mu_{\Delta C_{proxy,project}} - \mu_{\Delta C_{proxy,difference}}}{\mu_{\Delta C_{proxy,project}}}$$

(Equation 11)

Where:

• $CO_2e_{Counterfactual, RP}$ is the total counterfactual CO₂ removed from the atmosphere and stored as organic carbon in living trees in the absence of Project activities for the Reporting Period, in tonnes of CO₂e.
• $CO_2e_{Stored, RP}$ is the CO₂e stored for the Reporting Period, as calculated in Section 9.1.
• $\mu \Delta C_{proxy,project}$ is the mean change in carbon proxy over the Reporting Period for all sampled project pixels.
• $\mu \Delta C_{proxy,difference}$ is the mean difference in proxy change between each sampled project pixel and its matched control pixels. (e.g., $\Delta C_{proxy project,i} - \Delta C_{proxy, control,i}$)
  • $\Delta C_{proxy, control, i}$ is the average change in forest carbon proxy over the Reporting Period, $RP$, in the group of control pixels matched to project pixel $i$.
  • $\Delta C_{proxy, project, i}$ is the change in forest carbon proxy over the Reporting Period, $RP$, in project pixel $i$.
  • $i$ denotes each project pixel.

To meet the additionality condition, the change in proxy value in the project area, $\Delta C_{proxy, project}$, must be statistically greater (p < 0.05, inclusive of uncertainty) than the mean change in proxy value for the matched control pixels, $\Delta C_{proxy, control}$. If the mean proxy change in the control pixels is negative such that the resulting product of Equation 11 is negative, the counterfactual carbon storage, $CO_2e_{Counterfactual,RP}$, will be assumed to be 0 in order to ensure the accounting of carbon storage is limited to removals above the harvest counterfactual.

The counterfactual carbon storage is then used to calculate a performance benchmark for the project area, $PB_{RP}$:

$$PB_{RP}= \frac{CO_2e_{Removed, RP}}{CO_2e_{Counterfactual, RP}}$$

(Equation 12)

If the additionality requirement is met, the performance benchmark will be greater than 1, with larger magnitudes indicating a greater difference between storage in the Project and control areas.

At each Verification, the control pixels are reviewed to determine continued eligibility around similar regulatory regimes within control plots as outlined in Section 9.3.1. In the event that control pixel matches are no longer suitable, replacements will be selected for the impacted project pixels. For example, a change in regulations around IFM projects which leads to variance in the legality of such projects between control and project pixels would lead to rematching of control and project pixels.

Isometric will account for uncertainty in the dynamic baseline to obtain a conservative estimate of $CO_2e_{Counterfactual, RP}$ in Equation 11. This will include an evaluation of at least the following sources of uncertainty:

• Uncertainty in the forest carbon proxy maps, due to the uncertainty in data and models used to generate the proxy map;
• Uncertainty in how well the forest carbon proxy represents relative changes in carbon stock between the control and project pixels;
• Variation in the ensemble of control pixel values matched to each project pixel, representing the uncertainty across the ensemble of baseline scenarios therein; and
• Uncertainty in the control pixels matched and if they adequately represent the likely Counterfactual scenario.

$CO_2e_{Emissions, RP}$ is the total GHG emissions associated with a given Reporting Period, RP.

Equations and emissions calculation requirements for $CO_2e_{Emissions, RP}$ are set out in the relevant Protocol and are not repeated in this Module.

As part of $CO_2e_{Emissions, RP}$, $CO_2e_{Leakage, RP}$ must be quantified for the Reporting Period. $CO_2e_{Leakage, RP}$ is quantified following the approach described in Section 8.2.

Any models used under this Protocol which contribute to the quantification of net CDR must be well-validated and skillful for the purpose that they were used for. Proof of model validation can be achieved through either:

• A track record of use in science, industry, or government applications, which is demonstrated through multiple peer-reviewed papers, or proof of usage in a number of previous applications. Furthermore, the model must be relevant to the project area and tree species (e.g., covers similar ecoregions); or
• Newly developed models without a track record of usage must be validated against reputable data sources, which include quality-controlled in situ measurements and public datasets adhering to FAIR (Findable, Accessible, Interoperable and Reusable) principles¹⁴). Sufficient model validation data must be provided with the PDD.

Any models developed or used for the purpose of AGB quantification using the methodology described in Section 9.2.1 must also be evaluated and approved by Isometric at Validation in line with the requirements set forth in Section 9.2.1.1.

Harvest deferral activities require customized contract commitments to achieve additionality. Contract durations must be calibrated to avoid the issuance of Credits for Projects where similar forest growth would have occurred under baseline conditions. Often, short-term harvest deferrals result in the crediting of young forest growth that would have occurred within the existing forest management practice.

• For example, take the case where a 10-year-old forest operating on a 40-year rotation cycle enters a 30-year deferral contract, no additional carbon storage occurs beyond baseline projections, as the trees were already expected to grow for this duration under existing management practices.

Conversely, contract periods that significantly exceed the original harvest timeline may fail to demonstrate financial additionality. Extended commitments may only attract landowners who have already incorporated conservation objectives independent of carbon market incentives into their financial and forest management plans^{15, 16, 17, 18}.

• For example, take the case where a 30-year-old forest on a 40-year rotation enters a 30-year deferral contract, this suggests the Project Proponent may have pursued conservation activities regardless of carbon credit revenue — as the new extended harvest would require either additional outside revenue beyond carbon finance or belies pre-meditated agenda of conservation.

This Module’s additionality framework therefore requires customized contract durations that defer planned harvest activities and incentivize enhanced forest management practices in line with the additionality requirements set forth in the Isometric Standard and Improved Forest Management Protocol.

Within aggregated smallholder sites, individual parcels must demonstrate varying deferral periods aligned with their specific baseline management scenarios. This variability in contract lengths, ranging from 20 to 50 years within a single Project, presents challenges for the application of a uniform durability claim and for Credit standardization for IFM through deferred harvest.

To ensure consistent durability across all Credits issued under this Module, a conservative discount factor will be applied to normalize permanence to a standardized 50-year time horizon. Credits issued from contracts with durations shorter than 50 years will receive proportional deductions through this approach to meet an equivalent 50-year durability claim.

• For example, a 25-year contract will receive a permanence factor, PF, of 0.5, meaning 50% of calculated removals will be Credited. This approach establishes uniform 50-year durability across all parcels within the Project while maintaining minimum contract length requirements to ensure additionality.

The permanence factor, PF, is calculated as the contract length divided by 50 years.

$$PF_i = \frac{contract\ length_i}{50}$$

(Equation 13)

Where:

• $PF$ is the discount rate applied to the calculation of CO₂e stored in the IFM Protocol Section 9.3.1 for the parcel(s) under each individual contract, $i$.
• $contract\ length_i$ is the length of each individual contract, $i$, in years.

The permanence factor approach assumes a linear relationship for normalizing different contract lengths representing removals of different lengths. This linear relationship is grounded in the proportional relationship between cumulative emissions and temperature increase which has been well-demonstrated in climate literature and which is distinct from equivalency approaches used elsewhere in the voluntary carbon market to align short-term removals with long-term impacts of emissions¹⁹.

This durability framework ensures that all Credits achieve equivalent permanence regardless of individual contract variations, while maintaining scientific rigor and conservative assessment consistent with the Isometric Standard and Improved Forest Management Protocol requirements for additionality and long-term carbon removal and storage. While shorter contract lengths will not result in 50 years of carbon storage, this approach ensures the crediting will reflect the proportional, putative physical climate impact that is derived from storage time and amount.

The Risk Assessment is used to assess the overall delivery and storage risk associated with improved forest management through deferred harvest and may inform the Buffer Pool contribution during Credit delivery (see IFM Protocol Section 10.4 of the Improved Forest Management Protocol). The assessment must first be filled in by the Project Proponent and must be validated by a VVB. During project Validation, discrepancies between the Project Proponent’s self reported score and VVB may result in monitoring or risk mitigation activities, or project ineligibility. Eligible projects must have an initial risk score ≤ 16 and initial risk category scores at or below the following thresholds:

• Project Proponent Capacity Risk ≤ 7
• Financial Viability Risk ≤ 7
• Social Governance Risk ≤ 9
• Disturbance Risk ≤ 14

All risk categories shall have a minimum score of 0, regardless of the outcome of the Risk Assessment.

If Project Proponents choose to forgo a flat 20% Buffer Pool contribution, this Risk Assessment will inform Buffer Pool contributions for the Project according to the process outlined in Appendix C for each Reporting Period and in accordance with the requirements in the IFM Protocol (see Section 10.4.1).

• After each new Risk Assessment evaluation, Isometric will update the required percentage of newly issued Credits that must be contributed to the Buffer Pool by the Project. Isometric encourages Project Proponents to continuously monitor, mitigate, and reduce risks.

Table A1. Risk Assessment for Improved Forest Management projects applying deferred harvest on smallholder land, with the score to be filled out for each question.

The following section outlines how Isometric calculates the indicator scores for climate-related extreme weather disturbance risks to carbon permanence within a project’s region (Figure B1). Project Proponents should use Table B1 to lookup the Isometric-calculated values for their project's region and include those scores in their Risk Assessment (see Appendix A).

Extreme weather risks are assessed via two indicators: a temperature indicator (extreme heat and/or cold) and a hydrologic indicator (flooding and/or drought). Each indicator includes both historical data (1961-2015) and projected future extreme events. Historical data indicate the likelihood of extreme events based on past climate patterns, e.g., projects in regions with extended dry periods are expected to experience increased water stress as part of their typical climate. Climate model projections describe how changing climate conditions, relative to historical patterns, might present an increased risk of disturbances. Areas where there is a larger shift towards extreme conditions under future climate relative to their historical baseline have a greater disturbance risk (e.g., drier conditions relative to historical averages increases risk for drought-driven mortality).

To calculate the scores in Table B1, Isometric uses values from the Intergovernmental Panel on Climate Change AR6 report²¹. The temperature indicator, IndicatorTemperature, is calculated using data describing the annual number of frost days (FD, minimum temperature below 0°C) and annual number of days with a maximum temperature above 40°C (TX40) to capture extreme cold and extreme heat risks, respectively. The hydrologic indicator, IndicatorHydrological, is calculated using data describing the maximum 5-day precipitation (RX5Day) and annual maximum number of consecutive dry days (CDD) to capture risks of flooding and drought, respectively. All values come from the CMIP6 climate models. Future projections use the SSP2-4.5 medium term (2041-2060) scenario and are assessed as the change in value relative to a historical baseline (1961-1990).

For each indicator subcomponent, the region’s terrestrial median value is compared with the global terrestrial distribution of the same variable (Table B2). To convert the regional value into a subscore, regional values below the global 75th percentile are considered Low Risk, regional values equal to or greater than the global 75th percentile but below the 90th percentile are Medium Risk, and any regional values equal to or greater than the global 90th percentile are High Risk. Low Risks are given a subscore of 0, Medium Risks are 0.25, and High Risks are 0.5. The overall score for each of the indicators is calculated by summing the corresponding subscores, as described below:

Projected change in the number of frost days is not included as a subcomponent since it is projected that they will decline under future climate across the globe, representing a low risk of future extreme cold events.

Table B1. Regional Lookup Table of Disturbance Risk