Interest in mixed cultivation among Finnish forest owners has grown rapidly. Metsä Group began offering mixed cultivation of pine and spruce to forest owners in autumn 2019, five years before mixed cultivation was incorporated into best practices for sustainable forest management in Finland. In recent years, mixed cultivation has grown to account for approximately one fifth of all forest regeneration projects carried out by Metsä Group.
Mixed cultivation means establishing a forest with more than one tree species on the same regeneration area from the outset. In mixed cultivation of pine and spruce, spruce is planted, and pine is either sown or planted at the same time. The method is best suited to fresh heath forest, where both spruce and pine grow at a similar rate.
“Mixed cultivation has quickly established its place among Finnish forest owners. Less than half of Finland’s forests grow on fresh heath forest sites, where mixed cultivation of pine and spruce is best suited. Therefore, a 20% share of all regeneration projects is a clear indication of change in Finnish forests,” says Tiina Laine, Forest Management Manager at Metsä Group.
Alongside the growing popularity of mixed cultivation, the share of spruce-only forest regeneration has declined significantly. Back in 2008, spruce was the sole tree species on approximately 80% of Metsä Group’s planting sites. By 2026, the corresponding figure had fallen to just 36%.
“Many forest owners are wondering how their forests will withstand climate change, which brings not only rising temperatures but also a greater risk of various types of damage. Forest owners are already preparing for the impacts of climate change and for bark beetle outbreaks seen in Central Europe, for example, by reducing spruce planting. At the same time, mixed cultivation has become a more common way to spread the risks associated with forest regeneration,” Laine says.
Selecting the right tree species always starts with the characteristics of the regeneration site. Factors such as soil fertility, moisture conditions and site-specific damage risks determine which tree species are best suited to a particular site.
More reliable forest regeneration
On fresh heath forest sites, mixed cultivation provides forest owners with greater economic security and supports successful forest regeneration and growth. Forests consisting of a single tree species are generally more vulnerable to different types of damage than mixed forests. A diverse tree species composition is therefore one way to improve resilience and adaptability to a changing climate. Spruce is more susceptible to drought stress than pine, which can increase the risk of insect damage in spruce-dominated forests. Mixed cultivation of pine and spruce can also reduce the impact of moose damage, as spruce helps secure seedling stand development even in areas prone to moose damage.
When a forest is established as a mixed forest from the beginning and naturally regenerated deciduous trees are retained during young stand management, the result is a more diverse tree species composition. This strengthens forest vitality and biodiversity while improving the forest’s ability to adapt to changing conditions of growing.
“The right tree species choice is influenced by factors such as soil fertility and moisture conditions. Forest owners do not need to assess on their own whether mixed cultivation is suitable for a particular regeneration area. Metsä Group’s forest specialists help assess the site and select the regeneration method that best supports the forest owner’s objectives. A shared long-term goal for Metsä Group and our owner-members is to keep Finnish forests healthy, productive and growing well,” Laine notes.
Benefits of mixed cultivation for forest owners
• More reliable forest regeneration: The combination of pine and spruce helps secure a successful seedling stand, even in areas prone to moose damage.
• Improved risk management: Growing more than one tree species reduces the risks associated with single-species forests.
• Full use of site potential: Mixed cultivation makes full use of the soil’s growth potential, even where site fertility varies.
• Enhanced biodiversity: A more diverse tree species composition creates habitats for a wider range of plants, insects and other organisms.
• Site type matters: Mixed cultivation of pine and spruce is particularly well-suited fresh heath forest sites.