Six ways in which forest companies improve forest biodiversity

30.5.2024 / Article
Nature management of commercial forests is crucial for protecting the overall biodiversity of forests, since most forests in Finland are commercial forests. Kuva: Harri Silvennoinen

We listed six concrete actions by Metsä Group, UPM and Stora Enso to improve the state of forests.

Nature management of commercial forests is crucial for protecting the overall biodiversity of forests, since most forests in Finland are commercial forests. Here are six concrete actions to benefit nature that are used by the listed companies Metsä Group, UPM and Stora Enso.

1. Biodiversity bonus to forest owners

For a year now, Stora Enso has provided a special service to improve biodiversity in connection with timber trades. In a number of regions situated about the middle of Finland, forest owners are paid a biodiversity bonus on top of the timber price.

The biodiversity bonus is based on a decision by the forest owner to leave more retention trees and high stumps on the felling site than are required by the PEFC certification, which is based on sustainable forestry. – Retention trees are trees left permanently in the forest. High stumps are created by felling a tree at a height of about 2–3 metres and leaving the stump to decay.

According to Stora Enso, the biodiversity bonus requires that a minimum of 20 living retention trees per hectare are left on the site, while the minimum number of high stumps is ten per hectare. This is twice the number required by the PEFC. Moreover, all decayed wood is left untouched.

The biodiversity bonus is EUR 0.5 per cubic metre of timber. If, for example, the timber deal is for 600 cubic metres, the forest owner would gain an extra EUR 300 as bonus.

2. Threatened species proliferated on clear-cut sites

Many species of polypores and beetles thriving on decayed wood were found on UPM’s regeneration sites, as reported by the company.

The reason behind the favourable development is that in recent decades, the volume of stout decayed wood has increased on regeneration sites in forests owned by UPM. This helps to support the diversity of forest species. The matter was studied by Natural Resources Institute Finland (Luke) in the northern parts of Uusimaa and in Kanta-Häme, both in southern Finland.

Researcher Juha Siitonen from Luke says that a total of 18 species mentioned in Finland’s Red List of Threatened Species were found and were observed a total of 65 times.

’This may be considered encouraging. On more recent sites, where fellings were carried out in 2012–2018, both the total number of species and the number of species mentioned in the Red List were significantly higher than on older sites, and the numbers were strongly dependent on the presence of stout decayed wood,’ Siitonen reports.

Especially important hosts for species in the Red List were found to be retention aspens that had died either during or after the felling, as well as dead spruces that were left standing at the felling and had later fallen.

3. More high stumps and retention trees

In connection with timber deals, Metsä Group pays a bonus to forest owners who apply a forest management model that spares more than the required number of retention and decayed trees and more protective thickets at various stages of tending the forest. The model includes increasing the volume of retention trees and decayed wood, carrying out controlled burning to benefit species that favour fire sites, and sparing protective thickets and forests bordering waterways.

In an interview by Metsä Group, forest owner Ville Hirvonen from Rääkkylä speaks about the regeneration felling he commissioned from the company. After the felling, the seven-hectare site boasts clearly more high stumps and retention trees than usually: their total number is about 250.

’When I first saw this, I was a bit surprised by the number of high stumps. But it didn’t take me long to get used to it, and I’d say it looks pretty good,’ Hirvonen says.

In the short term, supporting forest biodiversity affects the forest owner’s earnings, Hirvonen says. There is, however, a silver lining.

’Supporting biodiversity in connection with fellings doesn’t give you the best possible financial result, but in the long run, it helps combat the risks in forest management,’ Hirvonen says.

 4. Successful translocation of threatened polypore

According to UPM, over half of the translocations of the threatened Perenniporia tenuis polypore were successful in inoculating the fallen aspens on felling sites of the company with polypore mycelium. This was established in a study by Natural Resources Institute Finland and the University of Helsinki, which looked at the reinstitution of species living in decayed wood by means of translocations.

In 2019 and 2020, UPM started a collaboration with the two research institutes, and threatened saprophytes were translocated to the company’s forests with plentiful decayed wood in Janakkala.

In 2019 and 2020, polypores living on spruce (9 different species), goat willow (Haploporus odorus) and aspen (Perenniporia tenuis) were translocated to UPM’s forests. With the species living in spruce, the success rate is 5–60 percent. With Perenniporia tenuis, over half of the operations were successful on fallen aspens on felling sites.

UPM is also financing a further study by Luke, which studies the translocations of seven threatened polypore species in Scots pine, Norway spruce, goat willow and aspen.

5. More attention paid to birds’ nesting period

For a few years now, Stora Enso has taken the birds’ nesting period into account more carefully.

According to a media release by the company, scheduling fellings when birds were nesting was actually avoided even earlier, as per recommendations, but the instruction is now confirmed by means of information systems. No fellings are undertaken in eutrophic, predominantly broad-leaved forests during the principal nesting period between 15 April and 15 July. In the north of Finland, the restriction begins on 1 May.

Numerous small birds, in particular, like to nest in forests dominated by broadleaves, thanks to the shelter and food they provide.

In addition, the company also takes account of trees where predators are known to nest, as well as the vicinity. Owls, grouse, hawks and falcons also have specific periods of nesting.

6. Mixed cultivation improves forest biodiversity

Metsä Group reports that it provides the service of setting up a new forest of mixed Scots pine and Norway spruce. The regeneration area is planted with 1,000–1,200 spruces and sown with 150 grams of pine seed per hectare. The method is particularly suitable for areas with a risk of elk damage, and it also reduces other forest damage.

Forests dominated by one species are more susceptible to damage than mixed ones. During dry summers, spruce suffers more than pine does from lack of water. It is then also more susceptible to insect damage, for example, a risk that increases with climate change.

The company says that, according to new research results from Natural Resources Institute Finland, spruce and pine will grow equally rapidly in well-managed mixed stands. The good growth of trees is of benefit to both climate and forestry.

Mixed cultivation improves biodiversity when a mixed forest is set up directly after felling. When tending young stands, enough broadleaves will be left to grow among the spruce and pine.

Read more: Wood to replace plastics, polystyrene, oil… Six important new products from Finnish bioeconomy

Read more: Natural enemies may prevent damage by spruce bark beetle – researcher explains how

Tero Karjalainen | English translation: Heli Mäntyranta

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