Forests play a critical role in achieving Sweden's climate goals. At the same time, there are many conflicting interests when it comes to forests, with opposing sides arguing for increased or decreased harvesting. As such, the Council for Evidence-based Environmental Analysis has tasked Formas with conducting an evidence synthesis that highlights how active forestry management can increase or decrease carbon sequestration and storage. This is a very broad and complex issue requiring clear delimitations in space and time and from adjacent systems. The long cycles in forestry pose a particular challenge. Since no studies have followed multiple cycles with today’s dominant system of even-aged forest management, there is limited empirical data showing the effects of forestry in the long term. Instead, much of our knowledge is based on simulation studies, where the results often depend on the applied assumptions. Meanwhile, the climate crisis is becoming increasingly acute, and many argue that it is more important to consider what is happening in the short and medium terms.

In boreal and temperate forests, carbon is stored both in living biomass and in dead organic matter in and on soils. Soil carbon stocks are larger than those of living biomass and have been built up over a long timescale. Changes in forest carbon stocks can have significant impacts on Sweden’s ability to achieve the level of stored carbon required by EU regulations. Meanwhile, the impact of forestry on sequestered carbon is relatively unknown. For example, the Swedish Forest Agency (Report 2022/15) reports that its understanding of less damaging forms of soil preparation and from operating forestry equipment is currently too uncertain to quantify the effectiveness of any potential measures. The systematic evidence synthesis by Formas is intended to bring clarity to this question.