Research call on continuity forests as carbon sink

Old-growth forests in Sweden serve as major carbon stocks and store significantly more carbon than managed forests. Pascual et al. (2026) indicate that the carbon stock in old-growth forests may be 78 to 89 percent higher than in forests that have been actively managed over long periods and that the difference is several times greater than previous assessments based on more limited datasets. A key explanation is that large amounts of carbon are stored in the soil, not only in tree biomass. In old-growth forests, soil carbon stocks can be as large as the total carbon content of managed forests, including living trees, dead wood, and soil. This means that old-growth forests function as long-term carbon reservoirs where carbon can remain stored for hundreds of years if forests are left undisturbed (e.g. Luyssaert, et al., 2008). When forests with high carbon stocks are logged, the loss of stored carbon is greater than in forests that have been managed, and it therefore takes a long time to compensate for the reduction in carbon stocks caused by forestry activities.

Pascual et al. (2026) compare two extremes of forest conditions: old-growth forest (largely unaffected) and intensively managed forest (clear-cutting forestry). Forests with a long ecological continuity include both old-growth forests and forests with varying degrees of low-extensive management, including natural and semi-natural forests. and they represent a substantial proportion of forest area in Sweden. Consequently, further study is needed to identify how and to what extent other forests with long ecological continuity share the characteristics of old-growth forest and their capacity to store carbon in soils. Additional knowledge is also required on how soil carbon sequestration varies across different types of these forests, which factors drive this variation, and how these factors interact with one another.

To what extent may the results and conclusions from existing studies in Swedish/Nordic old-growth forest comply to other Swedish forests with long ecological continuity, and in which types of forests are the conditions particularly favourable for carbon sequestration? Results and conclusions may be important for the implementation of the Nature Restoration Regulation.

We request a project that:

• Apply and further develop methods from existing studies that have compared carbon stocks between old-growth forests and production forests managed under clear-cutting adapting them to a Swedish study on forests with long ecological continuity using available geospatial data. What needs to be developed to assess carbon storage in Swedish forests with long ecological continuity? To what extent can the results and conclusions of existing studies be transferred to continuity forests in Sweden with different ecological characteristics?
• Develop a methodology for assessing the potential of continuity forests as carbon sinks in relation to the objectives of the LULUCF regulation and the Nature Restoration Regulation.
• Provide recommendations on how data and methodologies can be improved to generate representative datasets for assessing the carbon sink potential in different forests with long ecological continuity. 

Funded projects must consult with the Swedish Environmental Protection Agency regarding the data sources to be used from the Swedish National Forest Inventory conducted by the Swedish University of Agricultural Sciences (SLU) as well as other relevant data sources. 

The relevance of the project to the mandates of the Swedish Environmental Protection Agency and the Swedish Agency for Marine and Water Management must be clearly stated. 

The principal investigator must hold a PhD and be employed by a university, university college, research institute or authority that conducts research as part of its mandate. The host organisation must have a Swedish corporate identity number. Final reports from previous projects funded by the Swedish EPA, where the project period has ended, must have been submitted and approved before new funding can be granted.

Researchers who are granted funding are expected to have regular check-ins with the relevant officers at the Swedish Environmental Protection Agency to ensure input and relevance, write a final report, and communicate the results in appropriate ways.