Mixed cultivation of spruce and pine is the best way to ensure a full-density seedling stand

When establishing a new forest in Finland, you can order mixed cultivation of pine and spruce from Metsä Group. This means planting spruce and either planting or sowing pine in the regeneration area. The method is particularly suitable for areas where there is a risk of moose damage, and it also reduces the risk of other damage.

You do not need to figure out whether mixed cultivation is suitable for the area where you plan to establish a new forest. Metsä Group’s forest specialist will help you choose the right tree species.

The cultivation method offered by Metsä Group starts with soil preparation in the regeneration area, followed by the planting of spruce and the planting or sowing of pine. For example, for every 1,000 to 1,200 spruce seedlings planted per hectare, around 150 grams of pine seeds will be sown.

The person in charge of the procedure is equipped with a basket for seedlings and a seed bottle. They plant seedlings in some of the mounds and sow seeds in the rest. Pine has traditionally been sown in harrowed or scalped soil, but an inverted mound also offers a suitable bed for pine seeds. In cost terms, mixed cultivation is somewhat less expensive than planting only spruce seedlings on the site.

Young stand management is the same for mixed cultivation and traditional cultivation. The most important task is to remove deciduous tree sprouts, which are harmful to the planted and sown trees. The number of spruce and pine per hectare ranges from 1,800 to 2,000, and deciduous trees are left in the area to the extent possible.

Spruce and pine grow at the same rate

Previously, interest in mixed cultivation was hampered by the fear of different tree species growing at such a different rate that it would make mixed cultivation impossible. However, recent research results by Natural Resources Institute Finland indicate that spruce and pine grow at an equal rate on mixed cultivation sites, provided that the forest is well managed.

The growth site’s nutrient content often varies within a single regeneration area. Mixed cultivation helps make full use of the soil’s growth potential if pine is favoured in the more barren parts, and spruce in the more nutrient-rich areas. Good tree growth is beneficial to both forestry and the climate.

Less damage, more biodiversity

The mixed cultivation of spruce and pine can facilitate forest regeneration in areas where a dense moose population makes it difficult to cultivate pine alone, even if the nutrient content of the soil is perfect for pine.

By cultivating spruce and pine side by side, forest owners can ensure successful regeneration, even if some of the pine seedlings are eaten by moose. Single-species cultivation with pine would not produce a sufficiently dense forest, while a pure spruce forest would not grow as much as a mixed forest.

In addition to mitigating moose damage, mixed cultivation reduces other risks. Forests of a single tree species are more vulnerable to damage than mixed forests. During particularly dry summers like those experienced in recent years, spruce is more prone than pine to suffer from a lack of water, which hinders its growth. In such circumstances, spruce is also more prone to damage caused by insects, and this risk is increasing with climate change.

Mixed cultivation increases biodiversity, as long as the forest is established as a mixed forest from the outset, and a sufficient number of silver birches and other deciduous trees is left on the site in addition to pines and spruces during young stand management.