A. Relevance and sustainability context
A.1 Policy relevance
The Change of Soil Carbon Pool indicator measures changes in carbon stocks stored in forest soils over time. Forest soils represent one of the largest terrestrial carbon reservoirs and therefore play a crucial role in climate change mitigation and the long-term sustainability of forest ecosystems. The indicator is highly relevant for climate policy, forest policy and national greenhouse gas reporting, as changes in soil carbon stocks directly influence net carbon sequestration and emissions from the land-use sector.
A.2 Sustainability and / or comparative evaluation options
Sustainability perspective: Changes in soil carbon stocks can be assessed in relation to overall forest carbon balances, carbon sequestration targets and climate mitigation pathways. The indicator can also be compared against reference conditions that support soil functioning, ecosystem resilience and long-term forest productivity.
Bioeconomy perspective: The indicator can be used to assess the effects of forest biomass utilization on belowground carbon stocks. Comparisons between alternative forest management and bioeconomy pathways can help evaluate the potential long-term carbon implications of increased biomass mobilization, residue extraction or intensified harvest practices.
B. Data availability
B.1 Stage of development
It is considered an established indicator. The indicator is already used within national greenhouse gas reporting frameworks and is supported by established monitoring and modelling approaches.
B.2 Data sources
Historical data: National Greenhouse Gas Inventory and associated reporting conducted by the Thünen Institute.
Future projections: German Projection Report and scenario studies, supplemented by forest and soil carbon modelling approaches. Future estimates may require additional scenario evaluation and model development as well as interpretation.
B.3 Coverage over time and replicability
Historical data are available annually from 1990 to 2023 through national greenhouse gas reporting. Future projections may extend to 2050 with annual resolution depending on the available modelling framework and scenario assumptions. Replicability is generally high, although uncertainties remain associated with soil carbon dynamics and modelling assumptions.
B.4 Coverage across scales and sectors; compatibility
The indicator is available for the German forestry sector at the national level and is fully compatible with national greenhouse gas reporting and international climate reporting frameworks. Spatial disaggregation may be possible depending on the availability of forest soil data and modelling approaches.
C. Considerations for operationalization
C.1 Feasibility: Fit for monitoring
Robustness ranking: Robust. While the indicator is well established and included in greenhouse gas reporting, considerable uncertainties remain regarding the estimation of soil carbon dynamics, implementation of soil carbon modelling, and future developments under changing environmental conditions.
C.2 Institutions
Historical monitoring and reporting are primarily conducted by the Thünen Institute within Germany's greenhouse gas inventory system. Future projections may involve the Thünen Institute, Öko-Institut and other institutions contributing to forest and climate scenario modelling.
C.3 Future prospects
The continuation of monitoring is considered highly likely due to the importance of soil carbon dynamics for climate reporting and mitigation policies. The indicator is already established and expected to remain a core component of climate-related monitoring systems.
C.4 Costs, considerations and reproducibility
Costs are associated with soil monitoring, data processing, modelling activities and the preparation of reporting outputs. While the indicator relies on established reporting systems, uncertainties related to soil processes and model assumptions should be clearly communicated. Reproducibility is generally high when consistent methodologies are applied.
C.5 Potential for automation
Data processing, calculation and visualization can be partly automated. However, expert input remains necessary for model development, interpretation of soil carbon dynamics and assessment of future scenarios.
C.6 Presentation options and breakdown / sub-indicator needs
The indicator can be presented as:
- Time series of annual soil carbon stock changes;
- Carbon stock changes expressed in tonnes of carbon (C) or CO₂ equivalents;
- Historical trends and future projections;
- Comparison across alternative management and bioeconomy scenarios;
- Integration with other forest carbon pool indicators to illustrate overall forest carbon dynamics.
C.7 Potential for scenario integration
The indicator has high potential for integration into forest, climate and bioeconomy scenarios. It is particularly useful for assessing long-term impacts of alternative management strategies, biomass extraction levels and climate change on forest carbon balances.
C.8 Interlinkages and alignment with other monitoring activities
The indicator is closely linked to:
- National greenhouse gas reporting;
- LULUCF (Land Use, Land Use-Change, and Forestry) accounting;
- Forest carbon monitoring;
- Climate mitigation monitoring;
- Forest ecosystem assessments;
- Bioeconomy monitoring related to sustainable biomass utilization and carbon neutrality claims.
Further Comments:
The "Change of soil carbon pool" indicator should be interpreted together with other forest carbon pool indicators, including growing stock, net stock change and harvested wood products. A comprehensive assessment requires harmonised soil monitoring or model-based estimates that are consistent with greenhouse gas inventory methodologies. For bioeconomy assessments, the indicator provides valuable information on the long-term carbon consequences of alternative biomass utilization pathways and forest management practices. Consistent assumptions across forest growth, carbon accounting and scenario modelling frameworks are essential to ensure comparability and policy relevance.