Summary: 1. Forest reserves are established to preserve biodiversity, and to maintain natural functions and processes. Today there is heightened focus on old‐growth stages, with less attention given to early successional stages. The biodiversity potential of younger forests has been overlooked, and the cost‐effectiveness of incorporating different age classes in reserve networks has not yet been studied.2. We performed a reserve selection analysis in boreal Sweden using the Swedish National Forest Inventory plots. Seventeen structural variables were used as biodiversity indicators, and the cost of protecting each plot as a reserve was assessed using the Heureka system. A goal programming approach was applied, which allowed inclusion of several objectives and avoided a situation in which common indicators affected the result more than rare ones. The model was limited either by budget or area.3. All biodiversity indicators were found in all age classes, with more than half having the highest values in ages ≥ 100 years. Several large‐tree indicators and all deadwood indicators had higher values in forests 0–14 years than in forests 15–69 years.4. It was most cost‐effective to protect a large proportion of young forests since they generally have a lower net present value compared to older forests, but still contain structures of importance for biodiversity. However, it was more area‐effective to protect a large proportion of old forests since they have a higher biodiversity potential per area.5. The geographical distribution of reserves selected with the budget‐constrained model was strongly biassed towards the north‐western section of boreal Sweden, with a large proportion of young forest, whereas the area‐constrained model focussed on the south‐eastern section, with dominance by the oldest age class.6. Synthesis and applications.We show that young forests with large amounts of structures important to biodiversity such as dead wood and remnant trees are cheap and cost‐efficient to protect. This suggests that reserve networks should incorporate sites with high habitat quality of different forest ages. Since young forests are generally neglected in conservation, our approach is of interest also to other forest biomes where biodiversity is adapted to disturbance regimes resulting in open, early successional stages.

Improving productivity in forest logging operations while reducing negative impact on soil and streams has gained increasing attention. Positioning primary extraction routes is crucial in these efforts, as it has a huge impact on efficient and sustainable forwarder passages. To minimize the total forwarding distance and avoid steep terrain and impact on soil and water, we developed a decision support system, including a detailed optimization model and solution method. The main source of information consisted of a detailed digital terrain model, depth-to-water maps, and forest volume density. The information was supplemented with the extent of the stand, position of the landing(s), nature and culture conservation sites, and any known unavoidable crossings in the terrain (e.g., streams). Because fast solution time was a critical requirement, we developed a decomposition method based on Lagrangian relaxation. The system was evaluated in two case studies in Sweden. In the first case, the optimization model performance was analyzed at 30 final harvesting sites. In the second case, experienced forest company staff evaluated the primary extraction routes at 19 harvest sites in operational conditions. The results indicated that the model allowed for faster planning, shorter driving distances, and the potential to reduce negative impact on soil and water.