ISO 13391-2:2025

Overview

ISO 13391-2:2025 - "Wood and wood-based products - Greenhouse gas dynamics - Part 2: Forest carbon balance" provides a standardized methodology for calculating the forest carbon balance of one or more forest management units (FMUs). It explains how to quantify whether carbon pools in an FMU act as a net greenhouse gas (GHG) sink or source, supporting consistent carbon accounting for organizations involved in forestry and wood supply chains.

Key topics and technical requirements

• Scope and purpose: Methodology for FMU-level carbon balance intended for organizational or aggregated product-level use. Applicable to public or private organizations of any size and position in the value chain.
• System boundaries: Rules for defining the FMU, geographic scale, land ownership arrangements and time periods used in calculations.
• Carbon pools covered: Changes in carbon reservoirs for living biomass (above- and below-ground), dead biomass and soil organic matter are addressed; non‑CO2 greenhouse gases are also considered. (Harvested wood products and emissions from forestry-related fossil fuels/industrial processes are excluded - see Related Standards.)
• Data and methods: Use of forest inventory data and other data sources, requirements for data quality and time series, and stock change approaches. The standard outlines a tiered approach (different methodological tiers) to estimating emissions and removals depending on data availability and accuracy.
• Allocation rules: Guidance on allocating forest carbon balance to the portion of wood sourced from FMU(s).
• Reporting considerations: Recommendations for transparency, data sources, and treatment of exceptional events (e.g., wildfire, storms, pests) that affect carbon stocks.

Applications and who should use it

• Forest owners and managers calculating forest carbon sequestration and GHG balances.
• Companies sourcing timber and wood-based products seeking consistent carbon accounting for supply-chain or product footprint reporting.
• Cooperatives, regional authorities and aggregated FMU groups performing landscape-level carbon assessments.
• Certification bodies, auditors and consultants supporting climate mitigation claims.
• Policymakers and NGOs evaluating forest-based mitigation, resilience and adaptation strategies.

Benefits include improved comparability across organizations, more transparent FMU-level carbon reporting, and support for corporate and public climate‑change mitigation planning.

Related standards

• ISO 13391-1 - covers greenhouse gas dynamics for wood-based products related to harvested wood products and forestry operations (fossil fuel and industrial process emissions).
• ISO 13391 series - other parts addressing broader GHG dynamics for wood and wood-based products.