A. Relevance and sustainability context
A.1 Policy relevance
The net stock change indicator measures the change in forest growing stock over time and reflects whether forest biomass resources are increasing, stable or declining. It is highly relevant for forest policy, climate policy and national greenhouse gas reporting, as it provides information on the long-term development of forest carbon stocks and the sustainability of forest utilization.
A.2 Sustainability and / or comparative evaluation options
Sustainability perspective: Net stock change can be compared with climate-policy benchmarks, forest reference levels and mitigation pathways to assess whether forests continue to function as a carbon sink. It can also be evaluated against national and European LULUCF (Land Use, Land Use-Change, and Forestry) accounting targets.
Bioeconomy perspective: The indicator can be related to harvest levels and wood consumption to assess whether increasing biomass use for the bioeconomy is associated with declining, stable or increasing forest stocks. It therefore helps evaluate trade-offs between biomass utilization and the maintenance of forest resources.
B. Data availability
B.1 Stage of development
Established indicator: The indicator is already used in existing forest monitoring and greenhouse gas reporting systems.
B.2 Data sources
Historical data: National Forest Inventory (Bundeswaldinventur) and National Greenhouse Gas Reporting (Thünen Institute).
Future projections: German Projection Report and forest-related scenario studies such as the DIFENs project (Dealing with Impacts on Forests under changing End-use demand, climate change, Natural disturbances and Policy goals). Model-based evaluation and interpretation of future developments may be required.
B.3 Coverage over time and replicability
Historical observations are available approximately every five years (from NFI (national forest inventory) and CI (carbon inventory) in 2002, 2007, 2012, 2017 and 2022). Future projections may be available at annual or five-year intervals up to 2050. The indicator can be consistently replicated using established inventory and reporting methodologies.
B.4 Coverage across scales and sectors; compatibility
The indicator is available for the German forestry sector at national level and can potentially be disaggregated to federal-state level. It is fully compatible with forest inventory systems, national greenhouse gas reporting and international climate reporting frameworks.
C. Considerations for operationalization
C.1 Feasibility: Fit for monitoring
Robustness ranking: very robust. Historical estimates are based on established inventory and reporting systems. Future projections are subject to uncertainty due to assumptions regarding forest management, disturbances and climate change impacts.
C.2 Institutions
Historical monitoring is conducted primarily by the Thünen Institute. Future projections may involve the Thünen Institute, Öko-Institut and other research institutions depending on the selected modelling framework and scenario approach
C.3 Future prospects
The indicator is expected to remain available and highly relevant for future monitoring. It is already used within established forest and climate reporting frameworks and therefore has strong prospects for continued application.
C.4 Costs, considerations and reproducibility
Costs mainly arise from the collection and processing of inventory data, greenhouse gas reporting, scenario development and graphical presentation. Reproducibility is high because the indicator relies on well-established methodologies and data sources.
C.5 Potential for automation
Data processing, indicator calculation and visualization can be partly automated. However, expert interpretation remains necessary, particularly when assessing the drivers of stock changes and evaluating future scenarios.
C.6 Presentation options and breakdown / sub-indicator needs
The indicator can be presented as:
- Long-term trends in stock accumulation or depletion;
- Net stock changes expressed in m³, carbon or CO₂ equivalents;
- Breakdown by coniferous and broadleaved species, or finer species aggregation levels;
- Comparison of historical observations and future scenario projections;
- Integration with harvest and gross increment indicators to illustrate forest resource 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 demand pathways and climate change on forest carbon stocks.
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;
- National Forest Inventory activities;
- Forest carbon monitoring;
- Bioeconomy monitoring related to biomass supply and resource sustainability.
Further Comments:
The net stock change indicator should be interpreted alongside growing stock, gross increment, harvest and tree mortality indicators. Together, these indicators provide a comprehensive picture of forest resource dynamics and help assess whether forest utilization remains within sustainable limits. Reliable assessment requires consistent time series of growing stock, increment, harvest and disturbance-related losses, aligned with greenhouse gas reporting methodologies and future scenario assumptions.