PCS MA 002 Mangrove Methodology_v1.0

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Document identification

• Document code: PCS-MA-002

• Title: Mangrove Restoration and Conservation Methodology

• Scope: Mangrove ecosystem projects in intertidal/coastal zones, including hydrological restoration, assisted natural regeneration, mangrove reforestation/revegetation, and conservation/avoided degradation, subject to ecological feasibility and applicability conditions.

• Crediting outcome: Net greenhouse gas emission reductions and/or removals (tCO₂e), including biomass and soil organic carbon outcomes as applicable, net of project emissions, leakage, uncertainty deductions, and non-permanence risk requirements under PCS rules.

Version history and change log

Table DC-1. Revision history

Version	Date	Status	Summary of changes	Prepared by	Approved by
v1.0	TBD	Draft	Release for public consultation	PCS	TBD

Superseded versions

No superseded versions for v1.0.

Governance note on versioning and archiving

Only the latest approved version of this methodology shall be used for new project registrations. Superseded versions shall be archived and retained for traceability and audit purposes, including for projects registered under earlier versions where applicable, consistent with PCS governance rules.

Chapter 1 - Introduction And Scope

1.1 Purpose of the Methodology

1

Overview

The PCS Mangrove Restoration and Conservation Methodology provides a rigorous and standardized framework for quantifying greenhouse gas (GHG) emission reductions and removals resulting from activities that restore, enhance, or conserve mangrove ecosystems. Mangroves are globally recognized as some of the most carbon-dense ecosystems, storing large quantities of biomass above and below ground while accumulating substantial soil carbon over centuries. They also deliver significant ecological and social co-benefits, including coastal protection, fisheries productivity, biodiversity enhancement, and community resilience.

2

Integrity and scope

This methodology ensures that mangrove-based climate mitigation projects generate real, measurable, additional, and verifiable carbon benefits. It establishes rules for defining project boundaries, assessing baselines, estimating carbon stock changes, monitoring ecosystem conditions, and addressing leakage and non-permanence risks specific to mangrove landscapes.

3

Applicability

The methodology applies to a wide range of mangrove conditions, including degraded, fragmented, hydrologically altered, or deforested sites, as well as intact stands where conservation interventions prevent expected losses.

1.2 Applicability of the Methodology

This methodology applies to project activities located within intertidal and coastal zones where environmental conditions support the establishment, growth, or recovery of mangrove species. Eligible activities include:

• Restoration of degraded mangrove forests through hydrological rehabilitation, removal of physical barriers, sediment management, or assisted natural regeneration.

• Reforestation or revegetation of mangroves in areas where historical mangrove coverage has been lost due to anthropogenic or natural causes, provided restoration is ecologically feasible.

• Conservation or avoided degradation of intact or partially degraded mangrove ecosystems where credible evidence demonstrates a risk of continued decline or loss without the project.

• Hybrid restoration approaches, combining hydrological correction with planting, use of nursery seedlings, or community-managed planting programs, are permitted when ecologically justified.

The methodology is not applicable to inland forests, freshwater wetlands, peatland systems, seagrasses, saltmarshes, or terrestrial coastal vegetation. These ecosystems require separate methodological treatment due to differing carbon dynamics and ecological functions.

Table 1. Eligible Project Types and Descriptions

Project Type	Description
Hydrological mangrove restoration	Correcting tidal flow, opening blocked channels, rehabilitating hydrology
Assisted natural regeneration	Removing barriers to recovery, protecting seedlings, enrichment planting
Mangrove reforestation	Planting mangroves in areas historically converted or degraded
Mangrove conservation	Preventing anticipated losses from conversion, aquaculture, or harvesting
Integrated community restoration	Restoration combined with sustainable livelihood activities

1.3 Ecological Conditions for Project Eligibility

Mangrove carbon performance depends heavily on hydrology, sedimentation, salinity, nutrient availability, and tidal patterns. Therefore, project areas must demonstrate ecological feasibility supported by:

• hydrological assessments showing tidal exchange potential;

• soil and sediment characteristics suitable for mangrove growth;

• salinity ranges appropriate to the target species;

• absence of long-term physical barriers that cannot be removed.

Projects must demonstrate that selected species and restoration techniques match the ecological zone (fringe mangroves, estuarine mangroves, basin mangroves, river-dominated mangroves). Planting monocultures in unsuitable elevations or salinity gradients is not allowed unless supported by robust ecological justification.

1.4 Project Boundary and Geographic Context

The project boundary must encompass the full area where mangrove restoration or conservation activities take place, including intertidal zones, estuarine margins, and adjacent areas influenced by project hydrology. Mangrove landscapes often shift due to sedimentation and sea-level dynamics, and the boundary must reflect these natural processes without compromising accounting integrity.

The boundary must be delineated using high-resolution satellite imagery, tidal elevation models, geospatial mapping, and field verification. Inclusion of hydrologically connected areas is allowed when carbon dynamics are influenced by project interventions.

Table 2. Required Geographic Boundary Elements

Boundary Component	Requirement
Horizontal extent	Full mangrove stand or restoration zone
Vertical extent	Tidal elevation limits supporting mangroves
Hydrological influence area	Zones affected by tidal rehabilitation
Exclusion zones	Permanent water bodies, infrastructure, unfeasible areas

1.5 Greenhouse Gas Accounting Scope

Mangroves store carbon in multiple pools, many of which behave differently from upland forests. This methodology accounts for:

• above-ground biomass;

• below-ground biomass (extensive root systems);

• standing dead trees and woody debris;

• litter and non-woody biomass;

• soil organic carbon (deep sediments up to 1 meter or regional standard depth)—the most significant and long-lived pool;

• methane and nitrous oxide fluxes where material and affected by project activities.

Mangrove soils often contain centuries of accumulated organic matter; therefore, soil stability, erosion risk, hydrological changes, and accretion rates must be carefully assessed.

1.6 Additionality Requirements

Projects must demonstrate that restoration or conservation outcomes are not mandated by existing laws, would not occur through natural regeneration alone, and face barriers related to hydrology, community capacity, or financial resources.

Key determinants of additionality include:

• documented risk of conversion to aquaculture or urban expansion;

• evidence of persistent degradation without project action;

• lack of financial incentives for long-term mangrove stewardship;

• technical challenges in restoring tidal flows or sediment balance.

Additionality must be demonstrated at validation and revisited if land-use dynamics shift significantly during the project.

1.7 Safeguard and Social Inclusion Requirements

Mangrove ecosystems are closely linked to local livelihoods — fishing, shellfish collection, fuelwood gathering, and coastal protection. The methodology requires compliance with PCS Environmental and Social Safeguards (PCS-ESS-006), including:

• community consultation and participation;

• protection of customary and indigenous rights;

• monitoring of livelihood impacts;

• equitable benefit-sharing mechanisms;

• avoidance of displacement of fishing or farming activities.

Mangrove restoration must avoid introducing species that negatively affect fisheries or ecosystem function.

1.8 Relationship to PCS Standards and Tools

PCS-MA-002 must be applied alongside:

• PCS-PS-003 – Project Standard_v1.0

• PCS-ESS-005-Environmental & Social Safeguards Standard_v1.0

• PCS-SDG-006-Sustainability & SDG Integrity Standard_v1.0

• PCS-FMRS-015-Forest Monitoring & MRV_v1.0

• PCS-TA-005-Non-Permanence Risk Tool_v1.0

• Technical tools for SOC, burning emissions, and fertilizer emissions where applicable.

Mangrove projects must follow the same registration, validation, monitoring, and verification procedures as all PCS projects.

Chapter 2 - Project Boundary

2.1 Purpose of the Project Boundary

The project boundary defines the spatial, temporal, ecological, and accounting limits within which emission reductions and removals are quantified. Mangrove ecosystems occupy dynamic coastal landscapes characterized by tidal exchange, sediment deposition, erosion, and hydrological gradients. The boundary must therefore reflect both the ecological requirements of mangrove growth and the practical constraints of measurement and monitoring.

The project boundary establishes the carbon pools included, the greenhouse gas sources and sinks accounted for, and the temporal duration over which carbon changes are tracked. Its clarity ensures transparency, repeatability of assessment, and consistency across monitoring cycles.

2.2 Geographic Boundary

Because mangroves are tidally influenced and often occupy transitional zones between terrestrial and marine environments, the geographic boundary must encompass the full ecological footprint of the mangrove stand or restoration area. This includes:

• the area directly occupied by mangroves;

• adjacent zones where hydrological interventions will influence vegetation recovery;

• tidal channels, creeks, and sediment deposition areas that play a role in mangrove reestablishment;

• areas where degradation pressures may occur if unmanaged.

Mapping must rely on a combination of satellite imagery, drone surveys, tidal elevation models, bathymetry (where relevant), and field transects.

Table 2.1. Required Elements of the Geographic Boundary

Boundary Component	Description
Core mangrove zone	Area currently or historically vegetated by mangroves
Transitional intertidal zone	Elevation range suitable for mangrove colonization
Hydrologically influenced area	Zones affected by tidal flow restoration
Sediment accretion/erosion areas	Areas where substrate conditions influence project outcomes
Exclusion zones	Permanent water bodies, deep channels, infrastructure

The boundary must remain stable across monitoring cycles unless ecological conditions shift significantly (e.g., sea-level rise, sedimentation changes, or natural expansion). Any revision must be justified and validated.

2.3 Vertical Boundary and Tidal Influence

Mangrove ecosystems function within specific tidal elevations, generally ranging from mean sea level to the highest astronomical tide. The vertical boundary must reflect:

• tidal elevation limits for the dominant species;

• local geomorphology (fringe, basin, riverine mangroves);

• sediment depth and stability;

• hydrological constraints such as embankments or blocked channels.

If restoration involves hydrological rehabilitation, the vertical boundary must extend to areas where tidal flow is expected to reestablish mangrove-suitable conditions.

2.4 Stratification of the Project Area

Stratification divides the project area into zones with similar ecological characteristics. Stratification is essential for improving the accuracy of carbon estimates, especially in mangroves where hydrology, species composition, and sediment properties vary across small spatial scales.

Example stratification variables include:

• hydrological regime (fringe, basin, estuarine, riverine);

• degradation status;

• species distribution (mono-dominant vs. mixed mangroves);

• sediment type (clay-rich, sandy, organic-rich);

• tidal elevation band;

• restoration intervention type (hydrological correction, planting, regeneration).

Table 2.2. Example Mangrove Stratification Framework

Stratum Type	Key Characteristics
Fringe mangroves	High tidal energy, rapid turnover, dominated by Rhizophora species
Basin mangroves	Low energy, high organic soils, deep sediment carbon
Riverine mangroves	High nutrient inflow, tall structures, high biomass
Degraded mangroves	Blocked hydrology, sparse vegetation, exposed soils
Newly restored zones	Areas undergoing natural recovery or planting

Stratification must be revisited during each monitoring cycle to reflect ecological maturation or shifting hydrology.

2.5 Carbon Pools Included in the Boundary

Mangroves accumulate carbon in both living biomass and sediments. The methodology includes carbon pools that change meaningfully due to project activities.

Table 2.3. Carbon Pools Included in PCS-MA-002

Carbon Pool	Included	Notes
Above-ground biomass	Yes	Rapidly increasing under restoration
Below-ground biomass	Yes	Extensive root systems characteristic of mangroves
Deadwood	Yes	Important in recovering stands and degraded forests
Litter	Optional	Included if material
Soil organic carbon (SOC)	Yes	Major long-term reservoir; typically measured to 1 meter
Sediment carbon accumulation	Yes	Included for restoration or conservation projects
Harvested wood products	No	Typically not applicable to mangroves

Mangrove sediments contain carbon accumulated over centuries. Changes in sediment deposition and erosion must therefore be assessed carefully.

2.6 Greenhouse Gas Sources and Sinks Included in the Boundary

Mangrove ecosystems may emit or sequester several greenhouse gases depending on hydrological conditions, disturbance intensity, and root activity.

Table 2.4. GHG Sources and Sinks for Mangrove Projects

Component	Included	Notes
CO₂ removals from biomass	Yes	Primary project benefit
CO₂ emissions from mangrove loss	Yes	For avoided degradation/conversion
SOC oxidation	Yes	Important in degraded or drained areas
Methane (CH₄) emissions	As applicable	Must be included when hydrology is altered
Nitrous oxide (N₂O)	As applicable	Relevant if fertilizers are used (rare)
Fossil fuel emissions	Yes	From restoration activities

Methane dynamics in mangroves can vary; inclusion depends on project-specific disturbance or hydrological changes.

2.7 Baseline Boundary

The baseline boundary encompasses all carbon pools and GHG sources that would change under business-as-usual conditions. For mangroves, this may include:

• continued degradation due to hydrological blockage;

• conversion to aquaculture ponds;

• erosion-driven vegetation loss;

• long-term absence of natural regeneration;

• sediment carbon oxidation.

Baseline boundaries must reflect expected changes in both biomass and sediment carbon.

2.8 Leakage Boundary

Mangrove restoration can shift community activities such as:

• fishing pressure;

• shellfish collection;

• fuelwood use;

• small-scale agriculture around reclaimed mangrove areas.

The leakage boundary must include any nearby areas where displaced activities may occur. Market leakage is generally limited in mangrove systems but must be assessed for fuelwood or charcoal markets.

Table 2.5. Potential Leakage Pathways

Leakage Pathway	Description
Fishing displacement	Increased fishing pressure in nearby estuaries
Fuelwood leakage	Extraction shifts to adjacent woodlands
Agricultural displacement	Cropland shifts inland from reclaimed mangrove areas
Aquaculture displacement	Expansion of ponds outside project area

2.9 Temporal Boundary

Due to slow carbon accumulation in sediments and sometimes rapid recovery in biomass, mangrove projects must define temporal boundaries carefully.

The temporal boundary includes:

• a crediting period up to 40 years;

• monitoring intervals (generally 5 years, more frequent for hydrological restoration);

• sediment carbon monitoring cycles (typically every 10 years).

Table 2.6. Temporal Boundary Requirements

Component	Requirement
Crediting period	Up to 40 years
Monitoring period	Maximum 5 years per cycle
Sediment carbon reassessment	Every 10 years or when disturbance occurs
Baseline renewal	Every 10 years

2.10 Conditions for Boundary Adjustments

Mangrove ecosystems undergo natural shifts due to sea-level rise, storms, erosion, and sedimentation. Boundary adjustments are allowed when ecological justification exists and when it does not cause double counting. Any change must be validated and transparently documented.

Boundary modifications may occur due to:

• natural colonization expanding mangrove extent;

• erosion removing parts of the initial project area;

• restored hydrology altering vegetation patterns;

• improved mapping resolution from drones or LiDAR.

2.11 Documentation Requirements

All project boundary information must be documented in the Project Design Document (PDD) and updated in each Monitoring Report. Required documentation includes:

• geospatial files (shapefiles, GIS layers);

• tidal and elevation data;

• hydrological assessments;

• stratification maps;

• sediment core sampling locations;

• justification for any boundary changes.

The boundary must be sufficiently detailed for an independent VVB to replicate mapping and confirm eligibility.

Chapter 3 - Baseline Methodology

3.1 Purpose of the Baseline

The baseline defines the greenhouse gas emissions and carbon stock changes that would occur in the project area if no intervention took place. In mangrove ecosystems, establishing a credible baseline requires an understanding of the ecological, hydrological, and socio-economic forces that shape current and future conditions. Mangroves may remain stable, degrade gradually due to hydrological disruption or sediment decline, or undergo rapid loss when exposed to strong conversion pressures. The baseline represents the most plausible of these trajectories based on measurable evidence and must form a reliable reference against which project performance can be assessed.

3.2 Establishing the Baseline Scenario

The baseline must reflect the actual ecological pathway the mangrove system is likely to follow in the absence of the project. This determination depends on the historical condition of the site, the degree of existing degradation, the presence or absence of hydrological barriers, the likelihood of conversion to other land uses, and the natural capacity for recovery. A stagnant hydrologically impaired site will follow a very different baseline pathway than an intact forest facing aquaculture expansion pressures. The baseline scenario must therefore be grounded in empirical observations of the project area and its surroundings, supported by remote sensing evidence, land-use records, hydrological studies, and ecological surveys.

3.3 Historical Land Use and Ecological Assessment

A detailed understanding of past land-use patterns is essential for determining the baseline. The analysis must reconstruct the condition of the mangrove ecosystem over a sufficiently long period, typically at least the previous decade, to reveal whether the area has experienced progressive decline, intermittent disturbance, sudden conversion, or periods of stability. Time series satellite imagery, historical maps, field verification, and community knowledge provide the foundation for this assessment. Hydrological alterations such as blocked creeks, constructed embankments, and abandoned aquaculture pond structures must be documented because they significantly influence mangrove growth, mortality patterns, sediment dynamics, and soil carbon stability.

Table 1. Key Evidence Supporting Baseline Reconstruction

Evidence Source	Use in Baseline Development
Satellite imagery	Identifies long-term trends and disturbance history
Hydrological assessments	Determines feasibility and constraints of natural recovery
Soil and sediment studies	Reveals carbon-rich layers and erosion vulnerability
Land-use zoning or permits	Demonstrates development or conversion pressure
Local community information	Provides insight into resource use and past disturbances

3.4 Baseline Carbon Stocks

Baseline carbon stocks consist of the carbon contained in above-ground biomass, below-ground biomass, deadwood, litter where material, and soil organic carbon. Because mangrove soils often contain the majority of total ecosystem carbon, baseline SOC must be estimated with particular care. Soil cores must capture carbon concentration, bulk density, and depth distribution of sediments to at least one meter or a justified depth based on site-specific geomorphology.

Above-ground and below-ground biomass must be estimated using mangrove-appropriate allometric equations. Baseline SOC must not only quantify existing stocks but also characterize the stability of these stocks under current hydrological and ecological conditions. Degraded mangroves often exhibit suppressed growth and reduced organic matter input to soils, while intact systems with unrestricted tidal exchange may maintain stable or slightly increasing carbon stocks.

Table 2. Baseline Carbon Pools and Measurement Approach

Pool	Baseline Method
Above-ground biomass	Allometric equations applied to field measurements
Below-ground biomass	Root-to-shoot ratios or mangrove-specific models
Deadwood	Direct measurement and decay class analysis
Soil organic carbon	Soil cores, laboratory analysis, and depth profiles

3.5 Expected Carbon Stock Changes Under the Baseline

Once baseline carbon stocks have been quantified, the baseline must describe how these stocks are expected to change over the course of the project. The direction and rate of change depend on hydrology, land pressure, sediment availability, and ecological condition. Hydrologically impaired sites typically experience stagnant or declining biomass due to reduced oxygenation, hypersaline conditions, or altered inundation patterns. Soil carbon may gradually decline if soils dry or become aerated. In contrast, areas under imminent conversion to aquaculture or coastal development experience rapid biomass removal and long-term soil carbon emissions, often driven by excavation and sediment exposure.

Stable intact mangroves may show minimal change unless external pressures such as erosion, upstream damming, or land reclamation threaten their long-term viability. Permanently degraded flats that lack propagules or tidal exchange may remain in a low-carbon state indefinitely. The baseline must capture these realities and must not assume recovery or decline without ecological justification.

3.6 Hydrological Baseline

Mangroves depend on tidal exchange to maintain suitable salinity, oxygen levels, nutrient availability, and sediment deposition. The hydrological baseline must therefore reflect the current tidal regime and its influence on vegetation and soils. If tidal flow into the project area is restricted by embankments, abandoned aquaculture structures, roadways, or other physical barriers, the baseline must assume that these impairments persist. Under such conditions, mangroves typically suffer from reduced growth and elevated mortality. Soil carbon dynamics also shift as reduced inundation allows oxygen to penetrate deeper layers, leading to gradual oxidation of previously stable carbon pools. Elevation models, tide gauge data, and hydrological surveys must support the hydrological baseline.

3.7 Conversion Baseline

Where evidence indicates that mangrove lands are likely to be converted to aquaculture ponds, agricultural zones, or coastal development, the baseline must reflect this outcome. Conversion represents one of the most carbon-intensive transformation pathways in coastal ecosystems. Biomass carbon is removed almost immediately, while soil carbon is oxidized over time due to excavation, drainage, and increased exposure. The conversion baseline must reflect realistic conversion depth, sediment removal practices, and timeframes observed in the region. Baseline emissions must include both direct biomass losses and multi-year SOC losses associated with transformed land uses.

3.8 Soil Organic Carbon Baseline Dynamics

SOC behavior under the baseline depends on hydrological stability, sedimentation, erosion, and biological inputs. Intact mangroves tend to maintain SOC stocks with minor fluctuations. Degraded systems often exhibit reduced organic input and increased vulnerability to oxidation. In erosion-prone coastlines, sediment removal can expose carbon-rich layers, leading to significant SOC losses. In areas at risk of conversion, SOC emissions can be substantial and may continue over extended periods as sediments are excavated or desiccated. SOC trends must be derived from measured data, supported by field observations and sediment core profiles, and projected conservatively across the crediting period.

Table 3. SOC Trends Under Common Baseline Conditions

Baseline Condition	SOC Behavior
Intact hydrology	SOC remains stable
Blocked tidal flow	Gradual SOC decline
Conversion to ponds	Rapid and extensive SOC loss
Erosion-dominated coast	Progressive loss of carbon-rich sediments

3.9 Baseline Resource Use and Leakage Considerations

The baseline must document existing resource use patterns, such as fishing, fuelwood collection, pole harvesting, or small-scale agriculture. These activities define the no-project scenario and determine whether project interventions might cause displacement. For example, if communities already collect fuelwood from specific areas outside the project boundary, the baseline must acknowledge that these activities continue independently of the project. Leakage arises only when project actions alter these patterns. A clear narrative linking resource use under the baseline to potential leakage sources under the project scenario is necessary for transparent accounting.

3.10 Consistency Between Baseline and Additionality

The baseline must be fully consistent with the additionality demonstration. If natural regeneration is unlikely due to hydrological barriers, the baseline must reflect stagnant or declining biomass rather than spontaneous recovery. If conversion pressure is strong, the baseline must reflect probable land-use change unless prohibited by regulation or constrained by economic conditions. If the area is ecologically stable and has a natural tendency toward recovery, the baseline must not artificially suppress expected growth. The baseline and additionality assessment must present a coherent, evidence-based narrative describing why carbon benefits would not occur without the project.

3.11 Conservativeness and Uncertainty

Given the variability of mangrove landscapes, the baseline must adopt conservative assumptions whenever uncertainty cannot be resolved through data. Conservativeness applies to biomass change rates, SOC trajectories, hydrological dynamics, and conversion likelihood. Baseline projections must not overstate emissions or underestimate carbon remaining in the no-project scenario. Any data gaps or ambiguities must be addressed through conservative interpretation, ensuring that project credits remain credible and robust under verification.

3.12 Baseline Renewal

Because coastal environments evolve through sedimentation, erosion, sea-level changes, and human activities, the baseline must be renewed periodically to remain accurate. Renewal is required every ten years or following major ecological events such as severe storms, altered hydrological regimes, or land-use policy shifts. Renewal involves updating land-use analysis, hydrological assessments, soil profiles, and carbon stock estimates. The revised baseline must be validated to ensure continued alignment with PCS standards.

Chapter 4 - Project Scenario Calculations

4.1 Purpose of the Project Scenario

The project scenario represents the carbon stock evolution that results from the successful implementation of mangrove restoration or conservation activities. It reflects how restored hydrology, ecological rehabilitation, natural regeneration, enrichment planting, or conservation interventions alter biomass growth, soil carbon accumulation, and long-term ecosystem resilience. The project scenario must be scientifically credible, based on measurable ecological processes, and supported by data or literature relevant to the region.

The project scenario must demonstrate a clear and quantifiable departure from the baseline trajectory defined in Chapter 3. This departure may take the form of enhanced productivity, reduced mortality, increased below-ground biomass, restoration of soil carbon accretion processes, or avoided soil carbon loss that would otherwise occur under conversion or continued degradation.

4.2 Ecological Basis for Mangrove Carbon Recovery

Mangrove carbon dynamics depend strongly on hydrological restoration. When tidal exchange is reinstated, sediments begin to accumulate, salinity regimes normalize, seedlings establish naturally, and tree growth accelerates. These processes influence both above-ground and below-ground biomass, as well as long-term soil carbon burial.

Restoration of natural hydrology often triggers rapid ecological improvement compared to terrestrial systems. Seedlings of species such as Rhizophora, Bruguiera, Avicennia, and Sonneratia colonize suitable substrates within one to three years following hydrological rehabilitation. Biomass accumulation typically accelerates once canopy cover develops, progressing through stages of pioneer colonization, pole formation, and eventual mature stand structure. These stages form the basis of project scenario modeling and carbon accounting.

Where hydrology is restored correctly, soil carbon begins to stabilize. Re-connected sediments, reduced oxidation, and renewed organic deposition create conditions favorable for long-term SOC accumulation. The rate of SOC accretion depends on sediment supply, tidal amplitude, organic productivity, and disturbance frequency.

4.3 Above-Ground Biomass Calculations

Above-ground biomass must be estimated using mangrove-specific allometric equations that reflect the species composition and ecological conditions of the project site. These equations relate measurable tree parameters, typically diameter at breast height and height, to biomass. The project scenario must calculate above-ground biomass for each monitoring event and each stratum of the project area.

Biomass accumulation in restored mangroves often follows a non-linear pattern, with slow initial growth followed by rapid increase once structural development begins. In conservation projects, biomass may remain stable or increase modestly depending on age structure and disturbance history. Allometric models must reflect appropriate species or mixed-species groups and must be applied consistently throughout the project duration.

Table 1. Example Structure for Project AGB Calculations

Stratum	Mean DBH (cm)	Height (m)	Allometric Equation Applied	AGB (t/ha)

4.4 Below-Ground Biomass Calculations

Below-ground biomass forms a substantial share of mangrove carbon stocks due to extensive root networks and pneumatophores. The project scenario must estimate below-ground biomass using root-to-shoot ratios or equations specifically developed for mangrove species. Ratios must be selected based on ecological zone, sediment type, and species composition. Restored mangroves often exhibit strong below-ground biomass development once hydrological conditions become suitable, reflecting increased root density and soil stabilization.

4.5 Deadwood and Litter Carbon Calculations

Deadwood carbon must be estimated where material to the project’s GHG accounting. Restoration activities may initially increase deadwood stocks as degraded stands transition through mortality and regeneration cycles. Over time, deadwood levels stabilize as stand structure matures. Litter carbon is typically a minor pool but may be included where measurement is feasible and variability is limited.

4.6 Soil Organic Carbon Accretion

The most distinctive aspect of mangrove carbon accounting is the behavior of soil organic carbon. Healthy mangroves bury carbon through continuous sediment deposition, root production, and organic matter incorporation. In restored areas, SOC accumulation may resume once hydrology is re-established, sediment supply improves, and vegetation begins contributing organic inputs. SOC change must be estimated using measured soil cores collected at intervals consistent with PCS requirements or through sediment accretion monitoring where applicable.

SOC accumulation rates vary by region but generally fall within ranges documented in peer-reviewed literature. The project scenario must adopt conservative values where empirical measurements are limited. If the baseline involved ongoing SOC loss, project SOC change may include both avoided loss and new accumulation. The methodology requires clear separation of these components to ensure transparent quantification.

Table 2. Conceptual Representation of SOC Change Under the Project Scenario

Layer Depth	Baseline SOC Change	Project SOC Change	Net SOC Change
0–30 cm	Declining	Stable or increasing	Positive
30–100 cm	Declining under degradation	Stable after restoration	Positive
Below 100 cm	No change assumed unless justified	No change	Neutral

4.7 Project Emissions from Restoration Activities

Certain restoration activities may generate emissions. These include the operation of machinery during hydrological rehabilitation, soil disturbance during the removal of embankments, and transportation associated with seedling planting. These emissions must be recorded and quantified according to PCS emission factor guidance. Emissions must be deducted from project carbon benefits.

4.8 Avoided Emissions Under the Project Scenario

Mangrove conversion often results in substantial emissions from biomass removal and soil oxidation. Conservation projects must quantify the avoided emissions resulting from preventing such conversion. The project scenario must therefore demonstrate how conservation activities secure carbon stocks that would otherwise be lost. Avoided emissions must only be credited when conversion risk is well-established and validated through historical land-use analysis and contextual evidence.

4.9 Aggregation of Carbon Benefits

Total project carbon benefits are calculated by combining biomass changes, SOC changes, avoided emissions, and any deductions for project emissions. For each monitoring period, carbon benefits must be aggregated across all strata. The aggregation must be transparent, reproducible, and fully aligned with PCS reporting formats.

Table 3. Example Structure for Project Carbon Benefit Aggregation

Component	Value (tC or tCO₂e)
AGB change
BGB change
Deadwood change
SOC change
Avoided emissions
Project emissions
Net project benefit

4.10 Conservativeness in Project Calculations

Project scenario calculations must be conservative to avoid overestimation of carbon benefits. When data gaps exist or ecological conditions introduce uncertainty, the methodology requires applying conservative biomass growth rates, SOC accumulation rates, and hydrological response assumptions. Any model or parameter choice must be scientifically justified and favorable to environmental integrity. The objective is not to maximize credit issuance but to ensure that all credited removals and avoided emissions reflect genuine, verifiable climate benefits.

4.11 Consistency With Monitoring Requirements

All calculations described in this chapter must be supported by field measurements, soil analyses, hydrological observations, or remote sensing data collected according to PCS monitoring standards. The project scenario must remain internally consistent across monitoring periods. Whenever monitoring reveals deviations from expected ecological responses, the project scenario must be updated accordingly while preserving conservative treatment of uncertainty.

Chapter 5 - Leakage

5.1 Purpose of Leakage Assessment

Leakage refers to greenhouse gas emissions that occur outside the project boundary as an unintended consequence of project activities. In mangrove landscapes, such emissions may arise when restoration or conservation interventions restrict land uses, alter patterns of resource extraction, or displace activities that rely on coastal ecosystems. The purpose of the leakage assessment is to quantify these effects in a transparent and conservative manner, ensuring that credited emission reductions or removals represent genuine net climate benefits.

5.2 Understanding Leakage in Mangrove Ecosystems

Mangrove ecosystems are often intertwined with local livelihoods, including fishing, crab and shellfish harvesting, fuelwood collection, honey gathering, small-scale grazing, salt production, and the use of coastal areas for aquaculture or agriculture. When project activities modify access, convert degraded sites to protected zones, or prohibit practices that previously occurred within the project area, these activities may shift elsewhere. The nature and scale of this displacement depends on socio-economic conditions, community reliance on mangrove resources, availability of alternatives, and the degree to which project implementation changes local land-use patterns.

Leakage may occur gradually as ecological restoration progresses or immediately following interventions such as hydrological rehabilitation or conservation zoning. Not all changes constitute leakage; only those attributable to the project and resulting in additional emissions outside the boundary must be counted. A clear narrative linking local behavior to observed or likely displacement is required to ensure that leakage calculations remain grounded in evidence rather than speculation.

5.3 Identifying Activities That May Cause Leakage

Leakage assessment begins with a structured understanding of how communities and stakeholders use the mangrove landscape under baseline conditions. Resource extraction, seasonal land-use activities, informal aquaculture practices, settlement expansion pressures, and wood harvesting patterns must be evaluated. The assessment must distinguish between activities that would continue unchanged without the project and those that shift because of project interventions. Only the latter contribute to leakage.

This analysis must be supported by field surveys, interviews, spatial mapping of resource-use patterns, and historical evidence of how such activities evolve over time. The project must demonstrate that any observed displacement is project-induced rather than part of long-term baseline trends.

5.4 Leakage From Fuelwood and Timber Collection

In many regions, mangrove wood serves as an important source of fuel, construction material, or poles for fishing gear. If restoration or conservation restricts access to these resources, communities may increase harvesting in nearby forests or coastal woodlands outside the project boundary. The resulting reduction in biomass and associated emissions must be quantified. The baseline must first establish whether wood collection occurred within the project area. If it did not, then the restoration project does not create displacement and no leakage arises from this activity.

Where displacement occurs, emissions must be estimated based on the volume of wood extracted, the carbon stock characteristics of the affected forests, and the change in harvesting intensity relative to baseline practices. This calculation requires evidence-supported estimates of wood demand, local harvesting patterns, and biomass characteristics of non-project forests.

5.5 Leakage From Agricultural or Grazing Displacement

Mangrove shorelines and adjacent mudflats may serve as seasonal grazing grounds or agricultural plots during low tides or dry seasons. If restoration activities exclude livestock or restrict land conversion practices, these activities may shift inland or to adjacent wetlands. When this occurs, the project must assess whether such displacement leads to measurable emissions outside the boundary. The mere relocation of grazing without carbon consequences does not constitute leakage. Only when the displaced activity results in decreased biomass, increased soil disturbance, or additional land clearing in non-project areas does leakage occur.

To quantify these effects, the project must determine the area affected, the biomass or soil carbon impacted, and the expected magnitude of carbon stock losses resulting from displaced land use.

5.6 Leakage From Aquaculture or Coastal Development

Mangroves are frequently cleared to make way for aquaculture ponds, salt pans, fish drying areas, or small-scale infrastructure. A conservation project may prevent such conversion within the boundary, potentially shifting development pressure to other coastal areas. Leakage arises only if the project demonstrably redirects such development to nearby forests or wetlands, causing additional emissions that would not occur in the baseline.

In evaluating these risks, the project must consider land availability, economic demand, government licensing practices, and historical settlement patterns. If development pressure is diffuse and not specifically directed toward alternative sites, leakage may be low or non-existent. If evidence indicates a direct shift in conversion location due to project implementation, the corresponding emissions must be included.

5.7 Quantifying Leakage Emissions

Leakage emissions must be quantified using transparent, replicable calculations supported by data. The project must present a narrative describing how displacement occurred, the location of affected areas, the magnitude of activity causing emissions, and the carbon pools impacted. This narrative must be supported by maps, field observations, community surveys, remote sensing analysis, or other empirical evidence.

Leakage emissions typically arise from changes in biomass stocks, soil disturbance, or conversion of land uses outside the project boundary. The calculations must follow PCS-approved tools or, when no such tools exist, well-accepted scientific approaches. All assumptions must be conservative. Where uncertainty exists, the project must adopt values that avoid overestimating net climate benefits.

Table 4. Structure for Reporting Leakage Emissions

Leakage Source	Description of Displacement	Affected Area	Emission Source	Emissions (tCO₂e)

5.8 Avoiding Overestimation of Leakage

Leakage calculations must be based solely on project-induced changes. Activities that shift because of external market forces, long-term socio-economic trends, natural resource depletion outside the boundary, or government policies unrelated to the project must not be attributed to the project. This requirement ensures that leakage adjustments remain fair and proportionate. If the project cannot demonstrate a credible causal link between project interventions and activity displacement, no leakage may be applied for that source.

5.9 Leakage Prevention Measures

While leakage must be quantified, projects are encouraged to reduce its occurrence. This may be achieved through community agreements, livelihood diversification programs, participatory resource management, or improved coastal governance. When these measures demonstrably reduce or eliminate displacement, leakage estimates may be adjusted accordingly. Evidence must show that such strategies were implemented effectively and that leakage risk was materially decreased.

5.10 Conservative Treatment of Residual Leakage

Residual leakage that cannot be mitigated must be accounted for conservatively. This includes situations where evidence suggests a range of possible displacement outcomes. The project must adopt the lower-bound interpretation of avoided emissions and the upper-bound interpretation of leakage emissions. This approach ensures the integrity of credited carbon benefits and maintains consistency with PCS principles.

5.11 Integration of Leakage Into Net GHG Benefits

Leakage emissions must be deducted from the total GHG benefits calculated in Chapter 4. The Monitoring Report must clearly present a combined summary showing project removals, avoided emissions, project emissions, and leakage in a single transparent table. The final net GHG benefit is the value eligible for crediting and subsequent issuance of Planetary Carbon Units.

Chapter 6 - Net GHG Emission Reductions And Removals

6.1 Purpose of Net GHG Accounting

Net GHG accounting determines the actual climate benefit generated by the project after considering all relevant carbon pools, avoided emissions, leakage, and project-related emissions. Mangrove ecosystems require a comprehensive accounting approach because their carbon dynamics involve both rapid biomass changes and long-term soil carbon processes. The calculation of net benefits must be transparent, conservative, and consistent with PCS principles to ensure that credited emission reductions or removals accurately reflect real atmospheric mitigation.

6.2 Integrating Biomass Changes

The net impact of the project on above-ground and below-ground biomass is measured by comparing biomass stocks under the project scenario with those projected in the baseline. In restoration projects, improved hydrology and successful regeneration generally lead to increases in biomass that exceed any natural recovery expected in the absence of intervention. In conservation projects, protection from harvesting, conversion, or degradation ensures that biomass remains intact, thereby avoiding emissions that would have occurred under the baseline scenario.

Biomass changes must be calculated at the stratum level and based on field measurements and allometric equations appropriate to mangrove species. The resulting values must reflect both gains in live biomass and reductions in expected losses.

6.3 Changes in Soil Organic Carbon

Soil organic carbon is a major contributor to net GHG benefits in mangrove systems. Restored hydrology promotes sediment deposition, organic matter burial, reduced oxidation, and renewed SOC accumulation. Where the baseline predicts a decline in soil carbon due to drying, erosion, excavation, or other degrading influences, the project scenario reflects the avoided loss of SOC. Where restoration also enables new SOC accumulation, this additional storage must also be included in net benefits.

SOC dynamics must be derived from soil core measurements, sediment accretion studies, or validated models and must remain consistent with the soil carbon methods defined in Chapter 4. In all cases, the accounting must be conservative and based on measurable or scientifically supported values.

6.4 Avoided Emissions From Prevented Conversion

In areas where mangroves face credible conversion pressure, such as aquaculture expansion or coastal development, the baseline may include substantial emissions from biomass removal and sediment oxidation. Conservation activities that prevent such conversion generate avoided emissions. These avoided emissions often account for a large share of net benefits in conservation projects.

The estimation of avoided emissions must be rooted in documented conversion risk and supported by evidence such as historical land-use changes, government zoning, economic trends, and proximity to converted or vulnerable areas. Avoided emissions must not be credited unless the baseline clearly demonstrates the likelihood of conversion.

6.5 Project Emissions

Restoration activities may generate emissions through the use of machinery, transport of materials, or soil disturbance during hydrological rehabilitation. These emissions must be quantified and deducted from the project’s gross GHG benefit. Project emissions tend to be relatively small compared to the benefits generated by mangrove restoration but must be accounted for with the same level of rigor applied to other components.

6.6 Leakage Adjustments

Leakage emissions quantified under Chapter 5 must be deducted in full from the project’s gross climate benefit. Leakage may arise from displaced fuelwood extraction, grazing, aquaculture, or settlement expansion outside the project boundary. Only emissions directly attributable to project activities may be deducted. Leakage adjustments ensure that net benefits reflect the true change in emissions at the landscape scale.

6.7 Consolidation of All Components

The net GHG emission reduction or removal is calculated by consolidating project removals, avoided emissions, project emissions, and leakage deductions into a single accounting framework. This consolidation must occur at each monitoring event and must be presented clearly in tabular form.

Table 1. Structure for Net GHG Benefit Calculation

Component	Value (tC or tCO₂e)	Notes
Increase in above-ground biomass
Increase in below-ground biomass
Change in deadwood and litter
Soil organic carbon change
Avoided emissions from prevented conversion
Subtotal: Gross project benefit
Minus: Project emissions
Minus: Leakage emissions
Net GHG reductions or removals	Final value

This table must be completed for each monitoring period and included in the Monitoring Report.

6.8 Treatment of Uncertainty

Mangrove ecosystems exhibit natural variability in biomass, soil carbon, hydrology, and sedimentation. Uncertainty must therefore be assessed and reported for all carbon pools. Projects must apply conservative adjustments when uncertainty exceeds PCS thresholds. Sampling intensity, measurement accuracy, and modelling assumptions must be described transparently so that verification bodies can assess the credibility of estimates.

Uncertainty may apply to biomass equations, SOC accumulation rates, conversion risk projections, and the extent of leakage. Where uncertainty is high and cannot be reduced, the project must adopt the lower bound of estimated benefits, thereby protecting environmental integrity.

6.9 Final Expression of Net GHG Benefits

The final net GHG benefit represents the number of tonnes of CO₂ equivalent removed from or avoided being emitted to the atmosphere as a result of project implementation. This value becomes the basis for credit issuance following the application of buffer deductions under the PCS Non-Permanence Risk system.

Net benefits must be expressed both cumulatively and for each monitoring interval. The Monitoring Report must also include clear documentation explaining any variations in net benefits relative to previous monitoring periods, particularly where ecological conditions, hydrology, sediment dynamics, or community interactions have changed.

Chapter 7 - Monitoring Requirements

7.1 Purpose of Monitoring

Monitoring ensures that carbon stock changes, ecological responses, hydrological improvements, and social or environmental safeguards are measured consistently and accurately over the lifetime of the project. Mangrove ecosystems are dynamic, and their carbon performance depends on conditions that may evolve over time, including sedimentation rates, tidal patterns, vegetation recruitment, and land-use pressures. The goal of monitoring is to track these changes with sufficient precision to support transparent verification of greenhouse gas benefits and safeguard compliance.

7.2 Monitoring Framework

The monitoring framework must remain consistent with the baseline and project scenario described in earlier chapters. It must provide a comprehensive and repeatable structure for collecting field data, conducting soil surveys, evaluating hydrological conditions, and analyzing remote sensing information. Monitoring must follow a schedule that reflects ecological processes. Above-ground biomass typically responds within shorter periods, whereas soil carbon may exhibit slower and more gradual changes. The monitoring framework must also align with the PCS Monitoring Standard and the requirements for validation and verification.

7.3 Monitoring of Above-Ground Biomass

Above-ground biomass must be monitored through permanent sample plots established during project implementation. Field measurements must include diameter at breast height, tree height where relevant to the selected allometric models, species or genus identification, and tree survivorship. Plot design, measurement procedures, and allometric models must remain consistent across monitoring cycles to ensure comparability. If unavoidable modifications are made due to ecological changes or practical constraints, these changes must be documented and justified.

Biomass estimates must be updated during each monitoring period and aggregated at the stratum level. Remote sensing may be used to support or validate field data but cannot replace field measurements entirely unless approved under PCS methodological guidance.

7.4 Monitoring of Below-Ground Biomass

Below-ground biomass must be estimated indirectly using the same root-to-shoot ratio or mangrove-specific allometric relationships applied in the project scenario. Because roots are not directly measured, below-ground biomass monitoring relies on above-ground measurements combined with consistent application of selected models. Any changes in species composition, tree density, or stand age structure must be reflected in the recalculated estimates.

7.5 Monitoring of Deadwood and Litter

Deadwood and litter may be monitored when these pools make a material contribution to carbon dynamics. Where deadwood has been included in the project scenario, the project must assess standing and fallen deadwood at intervals consistent with biomass monitoring. Litter may be sampled where it exhibits significant variation or where site-specific studies demonstrate that it contributes meaningfully to carbon changes.

7.6 Monitoring of Soil Organic Carbon (SOC)

Monitoring soil organic carbon is central to mangrove project integrity because a substantial share of climate benefits results from SOC stabilization and accumulation. SOC must be monitored using soil cores collected from representative locations within each stratum. Sampling depth must be consistent with that used in the baseline, typically to one meter unless a scientifically justified alternative is applied.

Laboratory analysis must determine carbon concentration and bulk density. These values must be used to calculate SOC stocks for each sampled depth interval. Sampling frequency should be aligned with expected SOC dynamics. In many mangrove systems, a monitoring interval of ten years may be appropriate, although shorter intervals may be required in zones undergoing rapid sedimentation or hydrological transformation.

Table 1. Summary of SOC Monitoring Requirements

Parameter	Requirement
Sampling depth	Consistent with baseline, typically 1 meter
Sampling frequency	Every 10 years or as justified
Laboratory analysis	Dry combustion or equivalent
Bulk density	Required for each depth interval

7.7 Monitoring of Hydrological Conditions

Mangrove performance depends fundamentally on hydrology. Projects that involve hydrological restoration must therefore monitor the extent to which tidal flow, inundation patterns, salinity, water depth, and channel connectivity have been improved. Monitoring may include the use of tide gauges, water-level loggers, salinity measurements, or direct field observations of tidal amplitude and frequency.

Any deviation from expected hydrological outcomes must be documented and assessed for its influence on biomass recovery and SOC dynamics. If hydrological improvements do not materialize as expected, restoration strategies may need to be adapted, and the implications for carbon accounting must be evaluated.

7.8 Monitoring of Vegetation Regeneration and Species Composition

Vegetation monitoring must document natural regeneration, seedling establishment, survival rates, canopy development, and changes in species composition. Mangrove species differ in growth rates, root structures, salinity tolerance, and carbon storage potential. Monitoring changes in species composition is therefore important for understanding carbon outcomes and ensuring ecological appropriateness.

Vegetation monitoring must also document any replanting or enrichment planting activities and their success. Dead or damaged seedlings must be accounted for, and replanting strategies must be adjusted as necessary.

7.9 Monitoring of Erosion, Sedimentation, and Shoreline Change

Mangrove ecosystems experience constant geomorphological change, including shoreline retreat or advance, erosion of exposed sediment, and deposition of new material. These changes must be monitored using remote sensing, elevation surveys, sediment pins, or similar methods. Significant geomorphological changes may affect SOC dynamics, root stability, seedling establishment, and stand persistence. Monitoring must therefore capture whether erosion or sedimentation influences carbon accounting or project boundaries over time.

7.10 Monitoring of Socio-Economic and Safeguard Indicators

Mangrove restoration and conservation may influence community livelihoods and resource access. Monitoring must therefore include indicators related to social safeguards, such as community engagement, inclusion of marginalized groups, resolution of grievances, and equitable distribution of project benefits. Any changes in local resource use must also be documented to determine whether the project contributes to or mitigates leakage risks.

7.11 Monitoring of Project Emissions

Any emissions associated with restoration activities, such as those generated by machinery, transportation, or the removal of physical barriers, must be monitored and quantified. Records must include fuel consumption, equipment usage, and any other relevant operational activity. Monitoring results must be used to calculate project emissions as required in Chapter 6.

7.12 Remote Sensing and GIS Integration

Remote sensing plays a critical role in mangrove monitoring due to the difficulty of accessing certain zones and the value of observing spatial patterns at scale. Satellite imagery, drone surveys, and other geospatial tools may be used to validate field measurements, monitor regeneration, detect disturbances, and assess hydrological changes. All remote sensing products must be processed transparently, with clear documentation of classification methods, accuracy assessments, and imagery sources.

7.13 Data Recording, QA/QC, and Archiving

All monitoring data must be recorded in standardized formats, subjected to quality assurance and quality control procedures, and stored in secure databases. Field measurements must be checked for consistency, laboratory analyses must include internal and external controls, and remote sensing data must undergo accuracy validation. Data archiving must allow reproducibility of all calculations and must be maintained throughout the project duration and any required retention period thereafter.

7.14 Monitoring Frequency

Monitoring frequency must reflect the ecological processes involved. Biomass should typically be monitored every five years, while SOC may be monitored at ten-year intervals unless local conditions justify shorter cycles. Hydrological monitoring may require more frequent measurement during early restoration to confirm the success of interventions. The Monitoring Report must clearly indicate the schedule used and justify any deviations.

Table 2. Recommended Monitoring Intervals

Parameter	Monitoring Interval
Above-ground biomass	5 years
Soil organic carbon	10 years
Hydrological measurements	1–3 years initially, then as needed
Vegetation regeneration	1–2 years in early phases

7.15 Integration of Monitoring Results Into Carbon Accounting

Monitoring results form the foundation of verified carbon accounting. Each parameter must be linked clearly to the calculations in Chapter 6, ensuring that the Monitoring Report presents a coherent and transparent chain of evidence. When monitoring reveals outcomes that diverge from initial expectations, the project must explain the cause, document ecological or hydrological factors, and adjust calculations where necessary while maintaining conservativeness.

Chapter 8 - Uncertainty And Conservativeness

8.1 Purpose of Addressing Uncertainty

Uncertainty is inherent in the measurement and estimation of carbon stocks, carbon stock changes, and emissions in mangrove ecosystems. These uncertainties arise from natural variability, sampling limitations, measurement error, ecological dynamics, hydrological fluctuations, and model assumptions. The purpose of this chapter is to ensure that uncertainty is identified, quantified where possible, and addressed through conservative adjustments so that credited emission reductions or removals remain robust and credible. PCS requires that methodologies and projects apply conservative assumptions whenever uncertainty cannot be fully resolved, thereby protecting environmental integrity.

8.2 Sources of Uncertainty in Mangrove Carbon Accounting

Uncertainty in mangrove projects may originate from several components of carbon accounting. Field measurements of biomass are influenced by tree size variability, species composition, and measurement consistency, while allometric equations introduce additional model uncertainty depending on their applicability to local species. Below-ground biomass estimates depend on root-to-shoot ratios or species-specific models that may vary across ecological zones. Soil organic carbon estimation introduces deeper complexity because SOC depends on sediment type, hydrological processes, and historical disturbances, all of which may change over time.

Remote sensing interpretations, hydrological assessments, and baseline projections also contribute to uncertainty. Variations in tidal patterns, sedimentation rates, shoreline change, and land-use dynamics introduce additional layers of complexity that require careful interpretation. Uncertainty is therefore a multidimensional consideration that must be managed holistically.

8.3 Quantifying Uncertainty in Biomass Estimates

Uncertainty in biomass measurements must be quantified using statistical methods applied to field plot data. Variance and standard error calculations at the plot and stratum level form the basis of biomass uncertainty. Allometric equations contribute further uncertainty due to their coefficients, species coverage, and regional calibration. When multiple allometric models are available, the project must select those that most closely match local ecological conditions, thereby reducing model-induced variability. If uncertainty remains high despite careful equation selection, conservative adjustments must be applied to avoid overstating biomass gains.

8.4 Uncertainty in Soil Organic Carbon

Soil organic carbon is often the largest carbon pool in mangrove ecosystems, and its estimation involves greater uncertainty than biomass due to spatial heterogeneity, depth variability, and the influence of hydrological processes. SOC sampling must adhere to consistent depth, laboratory precision, and standardized bulk density procedures to minimize uncertainty. Even with rigorous measurement protocols, some degree of uncertainty is unavoidable because SOC profiles may vary significantly across small distances, particularly in disturbed or rapidly accreting environments.

Where uncertainty cannot be fully resolved through increased sampling, compositing strategies, or repeated measurements, the methodology requires a conservative interpretation of SOC trends. This may involve applying lower-bound accumulation rates or limiting crediting to the portion of SOC change that is supported by strong empirical confidence.

8.5 Uncertainty in Hydrological Restored Conditions

Hydrological restoration contributes significantly to carbon benefits but introduces uncertainty regarding its success and long-term stability. Variations in tidal exchange, sediment supply, channel formation, and salinity response may affect biomass recovery rates and SOC accretion. These uncertainties must be reflected in the project scenario, especially where hydrological rehabilitation occurs in complex or highly altered landscapes.

Field measurements of water depth, inundation frequency, and salinity must be used to verify whether restoration outcomes match expected ecological responses. If monitoring reveals deviations from expected conditions, biomass and SOC projections must be adjusted conservatively.

8.6 Uncertainty in Baseline Projections

Baseline projections introduce their own uncertainties because future degradation, conversion, or regeneration pathways may not unfold exactly as predicted. These uncertainties are particularly significant when baseline scenarios involve potential conversion to aquaculture or infrastructure. Historical trend analysis, land-use planning data, and spatial modeling help reduce this uncertainty, but predictive limitations remain.

To ensure conservativeness, baseline projections must be grounded in documented evidence, and, where multiple plausible baseline pathways exist, the scenario that yields the lowest carbon losses must be selected. This prevents over-crediting of avoided emissions while still recognizing real risks of degradation or conversion.

8.7 Treatment of Uncertainty in Leakage Estimates

Leakage assessments must consider uncertainty in the extent and impact of displaced activities. Community surveys, land-use mapping, and behavioral assessments may indicate ranges of possible displacement outcomes. In such cases, the methodology requires adopting estimates that do not underestimate potential leakage emissions. When evidence supports a range rather than a single value, the higher end of leakage emissions must be applied, ensuring conservative deductions from project benefits.

8.8 Combining Uncertainties and Applying Conservativeness

Uncertainties from multiple carbon pools and processes must ultimately be combined to determine whether overall project uncertainty falls within PCS thresholds. Combined uncertainty may influence the interpretation of biomass change, SOC change, avoided emissions, and leakage. If combined uncertainty exceeds acceptable limits, adjustments must be applied to reduce the risk of overestimating net GHG benefits.

Conservativeness may involve lowering estimated biomass growth rates, applying reduced SOC accumulation rates, limiting projections for restored hydrology, or increasing deductions for leakage. These adjustments must be clearly documented and justified in the Monitoring Report and must be transparent to validators and verifiers.

Table 2. Examples of Conservative Adjustments for High-Uncertainty Conditions

Area of Uncertainty	Conservative Adjustment Applied
High variance in biomass plots	Use lower bound of biomass increase
Limited SOC sampling resolution	Apply reduced accretion rate
Uncertain hydrological response	Adjust recovery trajectory downward
Uncertain leakage magnitude	Apply upper-bound emission estimate

8.9 Transparency and Documentation

All uncertainty-related decisions must be fully documented. This includes descriptions of data limitations, measurement challenges, model uncertainties, sampling constraints, and any deviations from expected ecological responses. The Monitoring Report must describe how the project addressed each source of uncertainty and must demonstrate that conservative choices were applied consistently throughout the carbon accounting process.

Transparency in uncertainty treatment ensures that VVBs can independently assess the credibility of project outcomes and that stakeholders can rely on the integrity of certified removals or avoided emissions.

8.10 Final Role of Uncertainty and Conservativeness in Crediting

Uncertainty and conservativeness form the backbone of credible carbon accounting in mangrove ecosystems. By ensuring that project benefits are never overstated, PCS upholds environmental integrity and prevents over-crediting. The final credited emissions reductions or removals must reflect not only measured ecological improvements but also the degree of confidence in those measurements. Conservativeness safeguards against natural variability, measurement noise, and ecological unpredictability, allowing the methodology to support large-scale restoration and conservation while maintaining scientific rigor.

Chapter 9 - Safeguards, Co-Benefits, And Non-Permanence Risk

9.1 Purpose of Safeguards and Co-Benefits

Mangrove ecosystems provide a wide array of ecological and social functions beyond carbon storage. Their restoration or protection can enhance fisheries, stabilize coastlines, support biodiversity, and strengthen local livelihoods. However, project activities may also alter access to resources, shift local economic patterns, or inadvertently create environmental risks if not properly managed. The purpose of safeguards is to ensure that mangrove restoration and conservation actions do not harm people or ecosystems and that any risks are mitigated through responsible project design. At the same time, the methodology recognizes the importance of documenting and tracking co-benefits, which add value to the project and contribute to broader sustainable development outcomes.

PCS requires adherence to its Environmental and Social Safeguards Standard, ensuring transparency, inclusiveness, and protection of rights and ecosystems throughout the project life cycle.

9.2 Environmental Safeguards

Mangrove ecosystems support complex ecological networks, and restoration actions must be designed in a manner that reinforces natural processes rather than disrupts them. Environmental safeguards require careful assessment of hydrological restoration methods, species selection, sediment characteristics, and expected ecological responses. Hydrological interventions must be designed so that water flow, salinity levels, sedimentation patterns, and habitat conditions improve rather than create unintended ecological stress.

The project must avoid introducing non-native species, altering natural tidal channels excessively, or creating conditions that destabilize soils and accelerate erosion. Restoration techniques must be ecologically appropriate and aligned with local biodiversity values. Any risks of harm to wetlands, fisheries, or adjacent habitats must be identified and mitigated.

9.3 Social Safeguards and Community Well-Being

Mangrove systems are closely tied to the livelihoods of coastal communities, who depend on them for fisheries, timber, honey, fodder, and protection from storms. Safeguards therefore require that communities be meaningfully consulted throughout project development and implementation. Engagement must be inclusive of women, youth, and marginalized groups and must reflect cultural and customary practices associated with land and water use.

Projects must avoid restrictively altering access to essential resources without providing alternative options or benefit-sharing arrangements. Restoration activities must not displace communities or limit their livelihood opportunities without clear mitigation measures. Community roles in monitoring, seed collection, planting, nursery development, and ecological stewardship should be emphasized to reinforce shared ownership and improve project sustainability.

9.4 Free, Prior, and Informed Consent (FPIC)

Where Indigenous Peoples or traditional communities hold customary rights or cultural ties to mangrove areas, the project must obtain Free, Prior, and Informed Consent. FPIC must be an ongoing process rather than a singular event. Communities must have the opportunity to understand project implications, negotiate their involvement, and withdraw support if conditions materially change. Documentation of FPIC procedures must be maintained and reviewed at each monitoring cycle to ensure continued alignment with safeguard requirements.

9.5 Co-Benefits and Sustainable Development Contributions

Mangrove projects often produce significant co-benefits. Restored ecosystems support fisheries by improving nursery habitats, offer natural protection against storms and coastal erosion, improve water quality, and contribute to greater biodiversity. Social co-benefits may arise from livelihood diversification, community employment, ecotourism opportunities, and improved coastal resilience.

The project must describe and monitor these co-benefits using measurable indicators. Co-benefits may include increased fish catch stability, reduced storm damage, improved shoreline stability, or greater vegetation richness. In social terms, projects may report improved income, skill development, or strengthened community governance structures.

Table 1. Examples of Co-Benefit Indicators

Co-Benefit Category	Indicator
Biodiversity	Species richness, habitat structure, juvenile fish abundance
Coastal protection	Shoreline stability, reduction in erosion hotspots
Livelihoods	Employment generated, income diversification, participation rates
Ecosystem health	Seedling survival, canopy density, hydrological restoration success

Projects are not required to quantify every co-benefit but must ensure that those claimed are supported by evidence and consistent with PCS SDG guidance.

9.6 Identifying Non-Permanence Risks

Mangrove ecosystems face risks that may lead to partial or complete reversal of carbon benefits. These risks include natural disturbances such as storms, cyclones, flooding, erosion, pest outbreaks, and disease. Anthropogenic risks arise from illegal harvesting, aquaculture encroachment, pollution, upstream hydrological impacts, or governance failures. Management risks may result from inadequate maintenance of restored hydrology, poor planting success, or insufficient community participation.

The project must assess these risks comprehensively using the PCS Non-Permanence Risk Tool, considering the likelihood and severity of events that could compromise ecosystem stability and carbon storage.

9.7 Mitigation of Non-Permanence Risks

Risk mitigation involves designing project activities that reduce the likelihood of carbon reversals. In restoration projects, this may include reinforcing hydrological structures, strengthening tidal connectivity, selecting resilient species mixtures, improving sediment stabilization, and conducting continuous ecological monitoring. Community engagement also plays a critical role in reducing illegal harvesting and improving stewardship.

In conservation projects, mitigation may include regular surveillance of vulnerable areas, reinforcement of governance systems, and community-based monitoring networks. The project must demonstrate that risk mitigation measures are proportional to identified risks and are implemented effectively.

9.8 Buffer Contributions

Non-permanence risks are addressed through mandatory contributions to the PCS Buffer Pool. The contribution percentage is determined by the risk assessment and reflects the overall vulnerability of the project to potential carbon reversals. Projects with higher exposure to storms, erosion, or social risk must contribute a greater proportion of carbon benefits to the buffer. These buffer units are not owned by the project and serve as insurance for the entire PCS system.

Table 2. Illustrative Risk Factors and Influence on Buffer Levels

Risk Factor	Typical Influence on Buffer Contribution
High storm frequency	Increases buffer requirement
Unresolved land tenure issues	Increases buffer requirement
Strong community stewardship	Reduces buffer requirement
Stable hydrological regime	Reduces buffer requirement

The buffer calculation must be performed at each monitoring period because risks may change as the ecosystem evolves and as governance or community participation strengthens or declines.

9.9 Monitoring Safeguards and Risk Factors

Safeguards and non-permanence risks must be monitored throughout the project. This includes tracking changes in community well-being, resource access, shoreline stability, ecological regeneration, and hydrological conditions. If safeguard issues or new risks arise, corrective measures must be implemented promptly. The Monitoring Report must describe any safeguard incidents, their resolution, and any adjustments made to risk assessments.

9.10 Reporting Responsibilities

The Monitoring Report must include a comprehensive assessment of safeguard performance, co-benefit outcomes, and risk mitigation measures. It must present measurable indicators, describe community engagement processes, and document evidence supporting co-benefit claims. The report must also include an updated risk assessment and corresponding buffer contribution calculation. All supporting documentation, including community agreements, ecological surveys, hydrological data, and risk assessments, must be retained for verification.

9.11 Integration With Credit Issuance

Safeguards and non-permanence risk considerations influence the number of credits issued. The final quantity of Planetary Carbon Units is determined by deducting the calculated buffer contribution from the net GHG benefits described in Chapter 6. Projects that demonstrate strong ecological stability, community stewardship, and effective management practices may reduce their buffer requirement over time, while those facing greater or increasing risks may see higher deductions. This integration ensures that credit issuance reflects both climate benefits and long-term durability.

Chapter 10 - Reporting Requirements

10.1 Purpose of Reporting

Reporting ensures that all information relevant to project performance, monitoring, carbon accounting, safeguards, and risk management is presented clearly and consistently for validation and verification. Transparent reporting is essential because mangrove ecosystems are complex, and their responses to restoration, hydrological improvements, and protection activities must be documented with evidence rather than assumptions. The reporting requirements in this chapter provide a structured framework for presenting field data, analytical outputs, hydrological assessments, and social and environmental information needed to confirm the credibility of claimed emission reductions or removals.

10.2 Structure of the Monitoring Report

The Monitoring Report must present all information in a coherent narrative format supported by tables, figures, and geospatial materials. It must begin with a description of project activities during the monitoring period and a summary of observed ecological responses. The report must detail the status of vegetation, biomass changes, soil organic carbon assessments, hydrological findings, shoreline dynamics, and any relevant socio-economic observations. All monitoring procedures must be described with sufficient clarity to allow replication by independent reviewers.

The report must then present the measured carbon stock changes, followed by a clear explanation of how these values were converted into greenhouse gas benefits. The presentation must show the connection between raw data, processed results, and final accounting tables. Any deviations from expected outcomes must be explained, including ecological anomalies, hydrological setbacks, or unforeseen disturbances.

10.3 Reporting on Plot Measurements and Biomass Data

All field measurements collected during the monitoring period must be documented. The report must describe the geographic distribution of plots, the methods used for measuring diameter, height, species identification, and the procedures used to maintain plot consistency. It must present summary tables showing mean values, variance, and distributions of biomass within strata.

Table 1. Example Biomass Reporting Table

Stratum	Number of Plots	Mean AGB (t/ha)	Standard Error	Biomass Change Since Last Period

The methodology requires that all information used to apply allometric equations, including species composition and measurement thresholds, be included within the report or its annexes.

10.4 Reporting on Soil Organic Carbon

SOC reporting must include the locations and depths of all soil cores, laboratory procedures, carbon concentration results, bulk density measurements, and calculated SOC stocks. The Monitoring Report must disclose how sampling locations were selected and must provide enough information to allow verification.

SOC results must be presented in a manner that clearly distinguishes between changes attributable to avoided loss under the baseline and new accumulation resulting from restoration. Any uncertainty in SOC measurement must be addressed transparently, including any conservative adjustments applied.

Table 2. Example SOC Reporting Table

Depth Interval	Bulk Density (g/cm³)	Carbon (%)	SOC (tC/ha) at Start	SOC (tC/ha) at End	Net Change

10.5 Reporting on Hydrological and Geomorphological Conditions

Where hydrological restoration is part of the project, the Monitoring Report must document tidal patterns, water levels, salinity variations, and the condition of tidal channels. The report must describe whether expected hydrological improvements occurred and how these changes influenced vegetation growth and soil carbon processes.

Geomorphological observations, including shoreline retreat or advance, sediment accumulation, or erosion, must also be documented. Remote sensing imagery must be included to illustrate major spatial changes.

If hydrological outcomes differ from expectations, the project must explain the cause and describe how this affected carbon accounting and ecological performance.

10.6 Reporting on Safeguards and Social Outcomes

The Monitoring Report must include a section describing community engagement activities, benefit-sharing mechanisms, and safeguard-related findings. It must document how communities were consulted, how access to resources was managed, and whether any grievances arose and were resolved. The report must also describe participation levels, employment opportunities created by the project, and any observed improvements in local livelihoods.

If the project affects Indigenous Peoples or traditional communities, the report must document how FPIC was maintained and confirm that conditions relevant to consent remain valid.

10.7 Reporting on Project Emissions

Any emissions associated with project activities, including hydrological restoration, material transport, equipment use, or construction, must be reported with supporting data. Fuel consumption, activity logs, and emission factor calculations must be clearly presented.

10.8 Reporting on Leakage

Leakage assessment must be reported as a narrative supported by empirical evidence. The project must describe any observed displacement of resource extraction or land-use activities, identify the locations affected, and explain how emissions were quantified. The Monitoring Report must include a table summarizing leakage emissions and demonstrate how these were deducted from the project’s GHG benefits.

Table 3. Example Leakage Reporting Table

Leakage Source	Description	Affected Area	Emissions (tCO₂e)

10.9 Reporting on Uncertainty and Conservativeness

The report must describe how uncertainty was evaluated in biomass measurements, SOC analyses, hydrological assessments, and leakage quantification. It must provide the combined uncertainty of the project and explain any conservative adjustments applied to ensure that results remain within PCS thresholds. These explanations must be clear and supported by evidence or methodological justification.

10.10 Consolidated Presentation of Net GHG Benefits

The Monitoring Report must provide a consolidated summary of all greenhouse gas components including biomass changes, SOC changes, avoided emissions, project emissions, and leakage. This summary must show the logical progression from measured values to net climate benefits. The following table format is required:

Table 4. Net GHG Benefit Summary

Component	Value (tCO₂e)
Biomass Carbon Change
Soil Organic Carbon Change
Avoided Emissions
Project Emissions
Leakage
Net GHG Reductions/Removals

The Monitoring Report must provide a narrative explaining the trends observed, any ecological or hydrological factors that influenced results, and any deviations from projections made in earlier reports.

10.11 Documentation and GIS Requirements

All geospatial data used to define project boundaries, monitoring strata, hydrological features, vegetation changes, and shoreline movements must be submitted in digital GIS formats. The report must include updated maps and descriptions of the methods used for imagery classification and accuracy assessment. Shapefiles must be archived and made available to the VVB for verification.

10.12 Transparency and Accessibility

The Monitoring Report must ensure transparency by presenting all methods, assumptions, data, and calculations in a manner that allows replication. All supporting documents, including raw field data, lab reports, hydrological measurements, community consultation records, and remote sensing analyses, must be retained and provided to the VVB upon request.

Annex A - Carbon Pool Measurement Equations (Mangrove-Specific)

A.1 Overview

This annex presents the equations and methodological principles required to estimate carbon stocks and carbon stock changes in mangrove ecosystems. Mangrove carbon accounting differs from terrestrial forests because of deep organic soils, extensive below-ground root networks, and sediment-driven carbon burial. The equations provided here must be applied consistently during each monitoring cycle and must be supported by field measurements, soil analyses, and species-appropriate allometric models.

The equations integrate above-ground biomass, below-ground biomass, deadwood, litter where material, and soil organic carbon. They also account for hydrological and sediment processes unique to coastal wetlands.

A.2 Above-Ground Biomass (AGB)

AGB in mangroves is estimated using species-specific or regionally calibrated allometric equations that relate diameter at breast height and, when required, tree height to tree biomass. Because mangroves often exhibit specialized growth forms such as prop roots and pneumatophores, general forest allometric models must not be used unless validated for mangrove species under similar ecological conditions.

The general structure of mangrove AGB equations is expressed as:

AGB_tree = a × (DBH)^b × (ρ)^c

where

• a, b, and c are coefficients derived from mangrove-specific destructive sampling studies,

• DBH is tree diameter at breast height (cm), and

• ρ is species wood density (g/cm³).

AGB per plot is determined by summing tree-level estimates and dividing by plot area.

Table A-1. Examples of Mangrove Allometric Equation Forms

Species Group	Equation Structure	Notes
Rhizophora spp.	AGB = a × DBH^b	Height often unnecessary
Avicennia spp.	AGB = ρ × exp(a + b ln(DBH))	Wood density-driven
Mixed mangrove stands	AGB = 0.251 × ρ × DBH² × H	Requires tree height

Allometric models must remain consistent across monitoring cycles.

A.3 Below-Ground Biomass (BGB)

Mangrove species develop extensive below-ground systems that often exceed above-ground biomass. BGB must be estimated using mangrove-specific root-to-shoot ratios or validated allometric equations that reflect species adaptation to tidal and sediment conditions.

The general BGB estimation is expressed as:

BGB = AGB × R

where R is the mangrove-specific root-to-shoot ratio.

Table A-2. Representative Mangrove Root-to-Shoot Ratios

Species Type	R Value
Rhizophora	0.50–0.65
Avicennia	0.40–0.55
Mixed stands	0.45–0.60

Ratios must be applied conservatively when species composition shows substantial variability.

A.4 Deadwood Carbon

Deadwood in mangroves includes standing dead trees, fallen stems, and woody debris embedded in sediment. Deadwood biomass must be estimated through field measurement of diameter and length, classification by decay class, and application of mangrove-appropriate density values.

Deadwood biomass is estimated using:

Biomass_deadwood = Volume × Density

Volume for cylindrical pieces is based on diameter and length; irregular shapes may require adaptations using geometric approximations.

Carbon is then estimated using a carbon fraction.

A.5 Litter Carbon

Although typically a smaller component of mangrove carbon stocks, litter may be measured through destructive sampling within quadrats. Litter biomass is calculated as the dry mass per unit area and converted to carbon using a default carbon fraction.

A.6 Soil Organic Carbon (SOC)

SOC is the dominant carbon pool in mangrove ecosystems. Estimating SOC requires measurements of bulk density, carbon concentration, and depth increments. Sediment cores must be sectioned into depth intervals and analyzed individually.

SOC per depth layer is estimated as:

SOC_layer = Bulk density × Carbon concentration × Depth interval × Area conversion factor

SOC for the soil profile is then the sum of all depth intervals.

Table A-3. SOC Calculation Inputs

Parameter	Description
Bulk density	Measured in g/cm³
Carbon concentration	Percentage of carbon by weight
Depth interval	Depth represented by each soil section
Area conversion factor	Converts g/cm² to tonnes carbon per hectare

SOC changes may include avoided loss and new accumulation.

A.7 Carbon Conversion Factors

All biomass and soil carbon calculations must use scientifically credible conversion factors. These include carbon fraction of biomass, wood density values, and sediment carbon characteristics specific to mangroves.

Table A-4. Carbon Conversion Values

Material	Carbon Fraction
Woody biomass	0.47
Mangrove roots	0.48 (preferred)
Deadwood	0.47
Litter	0.40–0.45

A.8 Aggregation Across Plots, Strata, and the Project Area

Final carbon stocks for each pool must be aggregated first at the plot level, then at the stratum level, and finally across the project area. Aggregation follows the structure:

C_stratum = Mean C_per_plot × Area_stratum

C_project = Σ C_stratum

These aggregated values feed into the GHG accounting procedures described in Chapters 6 and 10.

Annex B - Allometric Models And Parameters For Mangroves

B.1 Overview

Allometric models convert measurable tree characteristics into biomass estimates. Mangroves require specialized allometric equations because their structural forms, rooting systems, salinity tolerance, and growth patterns differ significantly from terrestrial forest species. This annex provides scientifically supported equations and parameters used to calculate above-ground and below-ground biomass in mangrove ecosystems across different species groups and geomorphological settings. These models must be selected and applied consistently throughout the project’s lifetime to maintain continuity and accuracy of carbon estimates.

Mangrove biomass models must be based on destructive sampling studies conducted in environments similar to the project area. Where species-specific equations are unavailable, regionally calibrated or mixed-species equations may be used, provided they are appropriate for the ecological and hydrological context.

B.2 Principles for Selecting Mangrove Allometric Models

The selection of allometric models must reflect ecological similarity between the original study and the project area, including species composition, tree size distribution, salinity regimes, sediment type, hydrological patterns, and forest structure. Mangrove wood densities and growth forms vary widely between genera such as Rhizophora, Avicennia, and Bruguiera. Therefore, generic tropical forest models must not be used unless validated against mangrove data.

When multiple applicable equations exist, the project must select the equation most representative of local species and conditions. Consistency across monitoring cycles is critical; any change in model selection must be justified with strong ecological evidence.

B.3 Allometric Models for Above-Ground Biomass

Several equations have been developed specifically for mangroves. These typically rely on diameter at breast height (DBH) and wood density, with some requiring tree height. The following table presents representative forms only; projects must specify the exact coefficients and equations used.

Table B-1. Representative Mangrove Above-Ground Biomass Equations

Species Group	General Equation Structure	Ecological Notes
Rhizophora spp.	AGB = a × DBH^b	Suitable for stilt-rooted species in high-salinity zones
Avicennia spp.	AGB = ρ × exp(a + b ln(DBH))	Performs well in dynamic sediment environments
Bruguiera spp.	AGB = a × DBH^b × ρ	Used in basin and riverine mangroves
Mixed stands	AGB = 0.251 × ρ × DBH² × H	Height-inclusive equation for heterogeneous forests

These structures illustrate the types of models used; the exact forms depend on field calibration data approved during validation.

B.4 Wood Density Values for Mangrove Species

Wood density is a key parameter in many mangrove allometric models. It varies substantially by species and must be measured or sourced from credible global or regional databases. Mangrove wood tends to increase in density in environments with higher salinity and slower growth.

Table B-2. Representative Wood Density Values for Mangrove Species

Species	Wood Density (g/cm³)	Notes
Rhizophora apiculata	0.88	High-density timber species
Rhizophora mucronata	0.85	Common in estuarine settings
Avicennia marina	0.60	Fast-growing pioneer species
Bruguiera gymnorhiza	0.70	Found in river-dominated forests
Mixed mangrove group	0.65 (default)	Used when species identification is incomplete

Wood density values directly influence carbon estimates and must be selected conservatively when uncertainty exists.

B.5 Height–Diameter Relationships for Mangroves

Some allometric equations require tree height as an input. When height is not measured for every tree, height–diameter models may be developed from local data. Mangroves often show nonlinear height responses due to salinity, hydrology, and nutrient availability. These models must be calibrated using site-specific measurements collected across representative species and size classes.

Table B-3. Example Structure of Height–Diameter Models

Model Form	Explanation
H = a + b ln(DBH)	Suitable for fringe mangroves influenced by wave action
H = exp(a + b DBH)	Used in tall, riverine mangroves
H = a DBH^b	Used in uniform-aged stands or plantations

Exact coefficients depend on empirical analysis and must be documented in the Monitoring Report.

B.6 Allometric Models for Below-Ground Biomass

Below-ground biomass represents a substantial portion of mangrove carbon stocks. Mangrove root systems can be extensive and vary by species group. They include fine roots, coarse roots, and specialized structures such as pneumatophores or prop roots.

Because direct measurement is impractical, BGB is estimated using either mangrove-specific root biomass equations or root-to-shoot ratios calibrated from destructive sampling. These ratios generally exceed those found in terrestrial forests.

Table B-4. Example BGB Calculation Approaches

Approach	Typical Ratio or Structure
Species-specific R/S ratio for Rhizophora	0.50–0.65
Species-specific R/S ratio for Avicennia	0.40–0.55
Combined mixed mangrove ratio	0.45–0.60
BGB = a × DBH^b × ρ	Used where root biomass models exist

The selected model or ratio must reflect the ecological conditions of the site and remain consistent across monitoring periods.

B.7 Mangrove Allometry for Young or Regenerating Forests

Newly restored mangrove stands often contain young trees and dense propagule recruitment. The allometric equations used must be appropriate for smaller diameter classes. Models calibrated only on large, mature trees must not be applied to regenerating stands.

Young-mangrove allometry often uses simplified equations based on stem diameter and height relationships. Field teams must ensure that monitoring captures height data reliably during early stages, as DBH may not yet be measurable for a large proportion of seedlings.

B.8 Validation and Justification of Allometric Model Selection

The Monitoring Report must include a clear justification for the chosen allometric models and parameters. This justification must describe the ecological similarity between the project site and the original equation development context. Factors such as tidal regime, salinity gradients, sediment type, stand age, and species dominance must be considered.

Where multiple models are available, the justification must explain why the selected model provides the most appropriate representation of biomass conditions. If uncertainties cannot be resolved through literature or local data, the more conservative equation must be adopted.

B.9 Documentation Requirements

Documentation must include a full description of the equation form, coefficient values, source reference, species coverage, diameter range, and any limitations. The project must also provide field evidence supporting the applicability of the selected model and must ensure that all equations remain unchanged unless ecological conditions shift so substantially that recalibration becomes necessary.

Table B-5. Documentation Template for Allometric Models

Element	Required Description
Equation	Full mathematical expression
Coefficients	Values of a, b, c, and any species-specific terms
Source reference	Peer-reviewed study or validated dataset
Species applicability	Genus or species group represented
DBH range	Minimum and maximum diameters covered
Ecological conditions	Notes on salinity, sediment, hydrology
Justification	Explanation for model selection
Limitations	Any known constraints or uncertainties

Annex C - Default Values For Mangrove Carbon Estimation

C.1 Purpose of Default Values

Mangrove ecosystems vary widely in their structure, species composition, sediment conditions, and hydrological regimes. While project-specific measurements are preferred, certain parameters may require the use of default values when direct measurement is not feasible, when species-specific models are unavailable, or when conservative assumptions must be applied. Default values help ensure consistency and transparency while maintaining environmental integrity. They must always be used cautiously, and only when they provide a conservative representation of local ecological conditions.

Default values in this annex are derived from global mangrove carbon literature, IPCC Wetlands Supplement datasets, and peer-reviewed ecological studies from tropical and subtropical mangrove systems.

C.2 Default Carbon Fraction Values

The carbon fraction represents the proportion of biomass composed of carbon. Mangroves typically show carbon fractions similar to terrestrial hardwoods but with greater variability in younger stands and saline environments. Default carbon fractions may be applied when direct species-specific measurements are unavailable.

Table C-1. Default Carbon Fraction Values for Mangrove Biomass

Biomass Component	Carbon Fraction	Notes
Above-ground biomass	0.47	Widely accepted default across mangrove genera
Below-ground biomass	0.48	Accounts for root tissue composition
Deadwood	0.47	Assumed consistent with structural biomass
Litter	0.40–0.45	Variation reflects decomposition stage

C.3 Default Wood Density Values

Wood density is a critical parameter in mangrove allometry. It varies by species, sediment conditions, and growth stage. When species-specific wood density values are unavailable, the following representative values may be used.

Table C-2. Default Wood Density Values for Common Mangrove Species

Species	Wood Density (g/cm³)	Notes
Rhizophora apiculata	0.88	Dense, slow-growing timber species
Rhizophora mucronata	0.85	Common in estuarine conditions
Avicennia marina	0.60	Pioneer species with lighter wood
Bruguiera gymnorhiza	0.70	Typical of riverine mangroves
General mixed mangrove group	0.65	Conservative default where species mix is uncertain

These values should be used conservatively when species identification is incomplete or when stands exhibit mixed species with variable densities.

C.4 Default Root-to-Shoot Ratios for Mangrove Species

Mangroves allocate a significant proportion of biomass below ground, and root-to-shoot ratios are often higher than in terrestrial forests. When direct below-ground measurements are not available, the following ratios may be applied.

Table C-3. Default Root-to-Shoot Ratios

Species Group	Ratio (R)	Notes
Rhizophora spp.	0.50–0.65	Reflects extensive stilt-root architecture
Avicennia spp.	0.40–0.55	Pneumatophore-based rooting system
Mixed mangrove stands	0.45–0.60	Conservative range for heterogeneous forests

The lower bound of each range should be used when uncertainty exists regarding species composition.

C.5 Default Biomass Expansion Factors (BEFs)

Biomass Expansion Factors convert stem volume to total biomass when volume measurements are used. Mangrove BEFs differ from terrestrial forests because branch and prop-root biomass can be comparatively higher.

Table C-4. Mangrove Biomass Expansion Factors

Mangrove Type	BEF	Notes
Tall riverine mangroves	1.40–1.60	Higher branching structure
Basin mangroves	1.30–1.50	Moderate structural complexity
Fringe mangroves	1.20–1.40	Often exposed to wave and wind action

C.6 Default Soil Organic Carbon Values

Mangrove soils often store large quantities of carbon, with organic layers extending several meters deep. When SOC measurements are unavailable during initial assessments or in stratification exercises, the following conservative default values may be used. These values must be replaced by direct measurements during the first monitoring period unless otherwise justified.

Table C-5. Default SOC Stocks for Mangrove Sediments

Mangrove Setting	SOC Stock (0–1 m, tC/ha)	Notes
Riverine mangroves	300–500	Highest accumulation due to sediment supply
Basin mangroves	250–400	Stable hydrology, gradual accumulation
Fringe mangroves	150–300	Influenced by coastal dynamics
Degraded or impaired hydrology	80–200	SOC loss expected under baseline conditions

Defaults must always be applied conservatively, selecting the lower range unless ecological evidence supports higher values.

C.7 Default Sediment Accretion Rates

Mangrove SOC accumulation depends strongly on sediment accretion. When direct sedimentation monitoring is unavailable, conservative accretion rates may be applied.

Table C-6. Representative Sediment Accretion Rates

Mangrove Type	Accretion Rate (mm/year)	Notes
Riverine	4–6	High sediment input from upstream sources
Basin	2–4	Moderate but stable accretion
Fringe	1–3	Lower rates influenced by wave action
Degraded systems	0–1	Hydrological restriction often halts accretion

Accretion values influence SOC accumulation estimates and must be used cautiously.

C.8 Default Bulk Density Values

Bulk density affects SOC calculation and varies with moisture, sediment type, and decomposition stage. The following values may be used when laboratory measurements are not available.

Table C-7. Default Bulk Density for Mangrove Soils

Soil Condition	Bulk Density (g/cm³)
Organic-rich surface layers	0.30–0.45
Mid-depth sediments	0.45–0.70
Mineral-dominated sediments	0.70–1.20
Degraded compacted soils	1.00–1.30

Bulk density defaults must always be replaced by measured values when soil cores are collected.

C.9 Default Methane and Nitrous Oxide Treatment

Mangrove systems typically produce minimal methane when salinity is sufficiently high, as saline conditions inhibit methanogenesis. Freshwater-influenced mangroves may produce higher methane or nitrous oxide emissions. Where non-CO₂ gases are material and direct measurements are unavailable, conservative emission factors may be applied based on IPCC Wetlands Supplement.

However, project developers must demonstrate the relevance of these factors to local hydrological conditions. Projects may assume negligible methane flux only when salinity, tidal flushing, and organic matter decomposition patterns clearly support this assumption.

C.10 Conditions for Using Default Values

Default values may be used only when they produce conservative estimates and do not overstate carbon benefits. They must not replace direct measurement when measurement is feasible or required by the methodology. All uses of default values must be explicitly justified in the Monitoring Report, including references to literature sources, ecological similarity, and reasons why more site-specific data were not available.

Annex D - Sampling Guidelines And Plot Design For Mangrove Systems

D.1 Purpose of Sampling Guidelines

Sampling in mangrove ecosystems presents unique challenges due to their tidal dynamics, variable soil conditions, irregular stand structures, and accessibility constraints. The purpose of these guidelines is to ensure that all field measurements for biomass and soil carbon estimation are reliable, reproducible, and representative of site conditions. Proper sampling design ensures that project estimates of carbon stocks and changes meet PCS accuracy thresholds and accommodate ecological heterogeneity across the project area.

D.2 Stratification Principles

Stratification divides the project area into zones with relatively homogeneous characteristics. In mangrove systems, stratification must reflect differences in species composition, tidal inundation frequency, stand age, hydrological condition, degradation state, and geomorphology such as fringe, basin, riverine, or scrub mangroves. A well-designed stratification allows sampling intensity to be allocated where it is most needed and improves precision by reducing variability within each stratum.

Stratification boundaries must be mapped using remote sensing, hydrological surveys, field reconnaissance, or a combination of these methods. Boundaries must remain consistent across monitoring periods unless ecological conditions change substantially. When changes occur, the Monitoring Report must document the updated stratification and justify how it improves representativeness of sampling.

D.3 Sampling Design for Above-Ground Biomass

Permanent sample plots must be established within each stratum to measure tree growth, mortality, recruitment, and overall biomass. Plots must be located to represent the ecological and structural variation within each stratum. The placement of plots may be random, systematic, or stratified-random, depending on accessibility and tidal conditions. Plot size must balance the need for representativeness with practical field constraints; commonly used sizes range from 100 to 500 square meters.

Field teams must measure tree diameter at breast height or at an alternative standardized height if buttressing or prop roots prevent DBH measurement. Tree height must be measured where required by the selected allometric equation. Species identification must be recorded for all trees, and saplings or seedlings may be monitored separately if relevant to stand development.

All plots must be permanently marked using durable materials suitable for tidal environments. Where markers may be lost due to erosion, sedimentation, or tidal movement, GPS coordinates must be recorded with sufficient accuracy to allow relocation.

Table D-1. Example Plot Structure for AGB Monitoring

Plot Attribute	Description
Plot size	10 × 10 m or 20 × 20 m depending on stand density
Minimum tree size	DBH threshold established in methodology
Measurements	DBH, height (if required), species, tree status
Frequency	Every 5 years unless otherwise justified

D.4 Sampling Design for Below-Ground Biomass

Below-ground biomass is estimated indirectly using root-to-shoot ratios or species-specific equations. Therefore, below-ground sampling does not require destructive measurement but depends entirely on accurate above-ground measurement. Consistency in plot measurement protocols is essential to ensure that below-ground biomass estimates remain stable and comparable across monitoring cycles.

D.5 Soil Organic Carbon (SOC) Sampling Design

SOC represents the majority of carbon in mangrove ecosystems and requires careful sampling. Soil cores must be taken to a depth consistent with the baseline, typically at least one meter or until an impermeable or mineral substrate is reached. Cores must be taken from representative points within each stratum and must avoid atypical features such as recently disturbed areas, tree depressions, or locations affected by erosion channels unless such features are common across the stratum.

SOC samples must be sectioned into discrete depth intervals, with each interval analyzed separately for carbon concentration and bulk density. When tidal conditions limit access, sampling must be timed to low tide periods or conducted using elevated platforms to avoid disturbance.

Table D-2. SOC Sampling Requirements

Parameter	Requirement
Minimum depth	1 meter unless otherwise justified
Depth intervals	Consistent across all monitoring periods
Number of cores	Determined by variability within each stratum
Laboratory standards	Must follow dry combustion or equivalent
Bulk density	Required for each depth interval

D.6 Sampling Design for Hydrological and Geomorphological Conditions

Hydrology must be monitored using fixed stations or repeated measurements, depending on site conditions. Sampling points must capture the tidal gradient influencing the project area. Water depth, salinity, and inundation duration must be recorded during representative tidal cycles.

Shoreline and sediment dynamics require repeated surveys using GPS, drone imagery, or sediment pins. These measurements must capture erosion or deposition patterns that may influence carbon stocks. Sampling points should be located along transects perpendicular to the shoreline or across areas subject to hydrological intervention.

D.7 Ensuring Representativeness and Reducing Bias

Sampling locations must be selected to minimize bias. Field teams must avoid choosing sites based on convenience or accessibility alone, as this may underrepresent key ecological conditions. If accessibility poses challenges, field planners may use a stratified-random approach that ensures representative coverage while accommodating practical constraints.

Monitoring teams must also ensure that plots remain undisturbed except for measurement activities. Any disturbance to sampling plots must be recorded, and the implications for data quality must be assessed.

D.8 Re-Measurement Protocols

Permanent plots must be re-measured at consistent intervals. Field crews must apply the same measurement protocols used during plot establishment. When trees grow to exceed measurement thresholds or when new species appear due to ecological regeneration, these changes must be incorporated into the measurement protocol.

SOC samples must be re-collected according to the schedule established in the methodology. Hydrological and geomorphological measurements must follow the timing described in Chapter 7. All re-measurement activities must be documented in field logs and supported by photographs, GPS tracks, and metadata on field conditions.

D.9 Quality Assurance and Quality Control (QA/QC)

All field measurements must adhere to a QA/QC framework that ensures reliability and reproducibility. Field teams must undergo training to ensure consistent measurement techniques. Equipment used for DBH, height, and soil sampling must be calibrated regularly. SOC laboratory analyses must follow certified analytical procedures that include blanks, duplicates, and standard reference materials. Any anomalies in field or laboratory results must be investigated and resolved before finalizing monitoring results.

D.10 Sample Size Determination

The number of sample plots or soil cores required depends on the variability within each stratum. Projects may perform a preliminary assessment of variance using pilot plots or historical data to estimate the number of samples needed to meet PCS uncertainty thresholds. If high variability exists due to species diversity, structural complexity, or hydrological heterogeneity, additional plots may be required to achieve acceptable precision.

Strata with relatively uniform conditions may require fewer plots, while degraded or transitioning strata may require higher sampling intensity. All sample size decisions must be explained and justified in the Monitoring Report.

Table D-3. Example Variance-Based Sampling Guidelines

Variance Level	Recommended Sampling Intensity
Low variability	Fewer plots or cores
Moderate variability	Standard number of plots
High variability	Increased sampling intensity

D.11 Archiving of Sampling Data

All field and laboratory data must be archived in a secure and accessible digital format. Metadata on sampling dates, field conditions, equipment used, laboratory procedures, and personnel must accompany the raw data. Photos, GPS coordinates and tracks, and plot maps must be retained as supporting evidence. These records are essential for verification and may be requested during subsequent monitoring periods or re-validation cycles.

Annex E - Leakage Calculation Examples For Mangrove Projects

E.1 Purpose of the Annex

Leakage occurs when project activities unintentionally cause greenhouse gas emissions outside the project boundary. Mangrove restoration and conservation projects may influence local resource use, land-use patterns, or economic activities that shift elsewhere as a result of the project. This annex provides structured examples demonstrating how leakage must be identified, quantified, and incorporated into the project’s GHG accounting. The examples illustrate the principles described in Chapter 5 and guide project developers and verifiers in applying these principles consistently.

E.2 Leakage Scenarios Relevant to Mangrove Systems

Leakage in mangrove landscapes commonly arises from displaced fuelwood harvesting, grazing, aquaculture expansion, or small-scale coastal development. The examples in this annex illustrate these scenarios using simplified numerical values. They are intended to demonstrate methodological steps rather than prescribe specific emission factors or datasets. Projects must adapt the underlying logic of these examples to the ecological and socio-economic conditions of their site.

E.3 Example 1: Displacement of Fuelwood Collection

In the baseline scenario, local communities harvested dead and living mangrove wood from within the project area. After restoration begins, access restrictions are imposed to protect regenerating stands. As a result, communities begin collecting wood from a nearby coastal forest outside the project boundary.

To estimate leakage, the project must first determine the quantity of wood displaced. Monitoring data indicate that 20 tonnes of wood per year were harvested from the project area under baseline conditions. After project implementation, households continue to consume a similar amount of wood but now collect it from an adjacent coastal forest.

The displaced wood volume is converted to carbon using appropriate biomass-to-carbon factors. If, for example, the adjacent forest has a wood density and carbon fraction resulting in an emission factor of 1.8 tCO₂ per tonne of wood removed, the total leakage would be calculated as:

Leakage emissions = Displaced wood volume × Emission factor

Leakage emissions = 20 t × 1.8 tCO₂/t

Leakage emissions = 36 tCO₂ per year

This value must be deducted from project benefits.

E.4 Example 2: Grazing Displacement From Restored Mangrove Flats

Prior to restoration, degraded mangrove flats were used seasonally for goat and cattle grazing. Restoration activities reintroduce tidal flow, submerging these flats and making them unsuitable for grazing. Livestock owners subsequently move grazing activities to inland shrublands. If this shift leads to measurable biomass loss in the shrublands, the difference must be considered leakage.

Assume monitoring data show that 10 hectares of shrubland experienced increased grazing pressure, reducing above-ground biomass by 2 tonnes per hectare annually compared to baseline conditions. The total biomass loss is converted to tCO₂ using a carbon fraction and conversion factor.

Annual leakage = 10 ha × 2 t biomass/ha × 0.47 carbon fraction × 3.67 conversion

Annual leakage = 34.5 tCO₂

This value must be deducted from net project removals or avoided emissions.

E.5 Example 3: Displaced Aquaculture Development

In the baseline scenario, part of the project area faced credible risk of conversion to aquaculture ponds. The conservation project successfully prevents conversion in the project area. However, monitoring and land-use assessments reveal that aquaculture development subsequently shifts to a nearby mangrove fringe outside the project boundary.

To quantify leakage, the project must estimate emissions caused by this displaced conversion. If baseline-emissions analysis indicates that converting one hectare of mangroves for aquaculture typically generates 1,000 tCO₂ through biomass removal and long-term soil carbon oxidation, and if monitoring reveals that 3 hectares were cleared outside the boundary as a result of redirected development pressure, the leakage would be:

Leakage = 3 ha × 1,000 tCO₂/ha

Leakage = 3,000 tCO₂

Clear evidence of causal linkage must be provided to justify applying this calculation. If conversion outside the boundary is unrelated to project activities, no leakage must be assigned.

E.6 Example 4: Leakage Assessment When No Displacement Is Observed

In some mangrove projects, baseline activities such as fishing, honey collection, or non-timber gathering continue at the same level after project implementation and do not shift to other areas. In such cases, no displacement occurs, and no leakage must be applied. The project must provide a narrative explaining the absence of displacement supported by monitoring data, stakeholder consultations, and observations of land-use patterns. This example demonstrates that leakage is not automatic and should only be applied when displacement clearly results from the project.

E.7 Incorporating Leakage Into Net GHG Benefits

Leakage emissions must be deducted directly from the gross project benefits. The Monitoring Report must present the data, calculations, and assumptions used in estimating leakage. Where ranges of possible leakage values exist, the most conservative credible estimate must be applied. The following table structure is recommended for reporting leakage values.

Table E-1. Structure for Reporting Calculated Leakage

Leakage Source	Description	Calculation Basis	Annual Leakage (tCO₂)	Notes

Each leakage source must be listed in a separate row to allow transparent review and verification.

E.8 Documentation Requirements

All leakage analyses must be documented with supporting evidence. This may include household surveys, grazing maps, land-use permits, remote sensing imagery, or interviews with local authorities and community leaders. Documentation must demonstrate that displacement is a direct result of the project rather than an unrelated trend. All assumptions related to leakage estimation must be conservative and must withstand independent verification.

Annex F - Example Monitoring Tables For Mangrove Projects

F.1 Purpose of Monitoring Tables

Monitoring tables provide standardized formats for presenting field measurements, analytical results, and carbon calculations across monitoring periods. These formats ensure consistency, transparency, and comparability across projects and facilitate independent verification. Mangrove projects require tables tailored to their unique carbon pools, hydrological processes, and ecological characteristics. The tables in this annex illustrate the preferred structure for presenting biomass, soil organic carbon, hydrological conditions, leakage, and net GHG calculations.

F.2 Example Table for Above-Ground Biomass Monitoring

Above-ground biomass monitoring requires recording the characteristics of all measured trees within permanent plots. The following structure consolidates data at the plot and stratum level.

Table F-1. Above-Ground Biomass Monitoring Summary

Stratum	Plot ID	Number of Trees	Mean DBH (cm)	Mean Height (m)	AGB per Plot (t)	AGB per Hectare (t/ha)

This table must be completed for each monitoring cycle. Supporting worksheets should contain raw tree-level measurements.

F.3 Example Table for Below-Ground Biomass Calculation

Below-ground biomass is estimated from above-ground biomass using root-to-shoot ratios or species-specific equations. The following table provides a format for presenting results.

Table F-2. Below-Ground Biomass Calculation

Stratum	AGB (t/ha)	Ratio Used	BGB (t/ha)

The table must specify the ratio applied and the rationale for its selection.

F.4 Example Table for Deadwood and Litter Carbon

For projects where deadwood or litter pooling is material, the following format can be used to document changes.

Table F-3. Deadwood and Litter Carbon Monitoring

Stratum	Deadwood Biomass (t/ha)	Litter Biomass (t/ha)	Total Carbon from Detrital Pools (tC/ha)

F.5 Example Table for Soil Organic Carbon Monitoring

SOC monitoring involves presenting detailed analytical results for each soil depth interval. The following table structure must be used.

Table F-4. Soil Organic Carbon Monitoring Summary

Stratum	Core ID	Depth Interval (cm)	Bulk Density (g/cm³)	Carbon (%)	SOC per Layer (tC/ha)	SOC Total (tC/ha)

Projects must attach laboratory certificates and raw data files to the Monitoring Report.

F.6 Example Table for Hydrological Monitoring

Hydrological monitoring includes recording tidal amplitude, salinity, water depth, and inundation frequency. These values influence carbon dynamics and restoration success.

Table F-5. Hydrological Monitoring Summary

Monitoring Point	Parameter	Measurement Value	Date	Notes

Typical parameters include tidal height, salinity, dissolved oxygen, inundation duration, and water flow velocity.

F.7 Example Table for Vegetation Regeneration

Vegetation regeneration is critical to restoration outcomes. This table supports documenting natural recruitment and survival.

Table F-6. Vegetation Regeneration and Stand Development

Stratum	Seedling Density (per m²)	Sapling Density (per ha)	Species Composition (%)	Survival Rate (%)

F.8 Example Table for Erosion and Sedimentation Monitoring

Shoreline stability and sediment dynamics influence SOC permanence and hydrological outcomes.

Table F-7. Sedimentation and Shoreline Change Monitoring

Measurement Point	Elevation Change (cm)	Sedimentation Rate (mm/year)	Erosion Indicator	Notes

F.9 Example Table for Leakage Reporting

Leakage calculations must be presented clearly and separately from project emissions.

Table F-8. Leakage Reporting Summary

Leakage Source	Description	Affected Area	Emission Factor	Leakage Emissions (tCO₂e)

F.10 Example Table for Project Emissions

Project emissions are deducted from gross benefits and must be reported transparently.

Table F-9. Project Emissions Summary

Source	Activity Description	Fuel or Material Used	Emissions (tCO₂e)

F.11 Example Table for Net GHG Benefit Calculation

The Monitoring Report must conclude with a consolidated summary of GHG benefits.

Table F-10. Net GHG Benefit Summary

Component	Value (tCO₂e)
Above-Ground Biomass Change
Below-Ground Biomass Change
Soil Organic Carbon Change
Avoided Emissions
Subtotal Gross Benefits
Project Emissions
Leakage
Net GHG Reductions/Removals

F.12 Archiving and Verification Requirements

All monitoring tables must be archived in digital format, ideally with linked raw datasets, GIS layers, soil lab certificates, hydrological measurements, and metadata files. These tables serve as core evidence for verification and must be consistent with narrative sections of the Monitoring Report.