Increasing the biodiversity of forests one step at a time: towards regenerative forestry

Have you already heard about regenerative forestry? Its objective is the management and use of commercial forests in a way that increases their vitality, biodiversity and climate resilience before they are passed on to the next generation. In practice, the aim is to increase both the growing stock and the number of species in forests managed in accordance with the principles of regenerative forestry.

“For example, an abundance of species increases competition between species, which in turn reduces the risk of dominance by destructive insect species,” says Timo Lehesvirta, Metsä Group’s leading nature expert.

Aiming for at least 10,000 measures

Metsä Group has set the goal of improving the state of forest nature by 2030. By that time, it intends to take measures in the owner-members' forests in line with regenerative forestry, with the aim of increasing the forests’ biodiversity. This work contributes to the company’s sustainability goals.

Measures that strengthen the state of nature include water protection measures, management measures for herb-rich forests and ridges, members' new Metso sites, and groups of burned retention trees.

The members of Metsäliitto Cooperative, Metsä Group’s parent company, own over half of Finland’s privately-owned forests. The measures that are carried out in these forests are therefore of great importance for the entire Finnish forest environment.

"Forestry is a long-term activity, and we want our members' forests to be in good condition not only in five years’ time but also fifty and a hundred years from now. This creates the basis for the utilisation of renewable natural resources: we can have profitable forestry and a forest industry based on it, as well as healthy forests with high biodiversity,” says Silja Pitkänen-Arte, Sustainability Manager at Metsä Forest.

Clear steps forward

Regenerative forestry follows goal-oriented principles aimed at strengthening the state of nature. Good forest management has existed in the past, but increased research data and better understanding have now broadened the range of available measures.

The principles are put into practice through the Metsä Group Plus forest management model, for example. It is available to all members of the cooperative specifically for each wood sale. Under this management model, more retention trees and high biodiversity stumps are left in the forest than usual, and buffer zones for waterways are wider.

At its simplest, the following principles apply:

1. Making the most of our native tree species

Our use of forests will continue to be based on naturally occurring tree species, i.e. spruce, pine, silver birch, white birch and aspen. They all spread to Finland after the Ice Age. Other native tree species are grown alongside commercial trees, although they are not industrially exploited. Naturally occurring trees also provide living conditions for native species such as tree root fungi, mosses and lichens growing on tree trunks, insect larvae, and organisms decaying forest litter.

2. Aiming for high-biodiversity mixed forests

The diversity of tree species in forests is increased by aiming for mixed forests consisting of several tree species: spruce and pine are cultivated alongside each other, and the share of birch trees in coniferous forests is increased. Rarer tree species such as the great sallow, bird cherry, grey alder, black alder and the sturdy aspen are left in the forest to support biodiversity and climate resilience instead of being harvested for energy production. This policy is very important, as more than half the approximately 25,000 species living in Finnish forests directly depend on certain tree species. Birds, mammals and other species also prefer mixed forests.

3. Increasing decaying wood in various forms

Decaying wood is important, as up to 5,000 of our forest species depend on it. These species include enemies of pest insects. Decaying sturdy trunk wood is relatively rare in commercial forests. For example, it is increased by high biodiversity stumps and retention trees, which decay over time, and by retaining trees that have died earlier. Unmanaged protective thickets are left in the forests, which can also produce decayed wood in the long term.

4. Protecting valuable habitats

The forest is like a mosaic of different habitat types, some of which are considered to be particularly valuable. These include, in particular, the wettest and driest and the lowest and highest places: brook dells, marsh patches, spring complexes, herb-rich forests, rocky sites and forests lying directly underneath bluffs. They are managed in a way that strengthens their characteristics, or they are protected and completely excluded from utilisation.

5. On guard near waterways

Buffer zones are left on the shores of waterways, and their width depends on the site. Some of the sites are also protected under the Forest Act. For example, springs or streams in a natural state require a buffer zone at least the length of a tree, which protects the microclimate of the site from heat.

The purpose of the buffer zone is also to protect waterways from water load, while preserving the biodiversity of species in unique habitats.

Forestry in peatlands also has impacts on water systems. These are mitigated by favouring continuous cover forestry on suitable sites and by avoiding drainage, for example. These measures also prevent greenhouse gas emissions from peatlands.

Measures and verification

The objective of regenerative forestry is to strengthen the state of nature, and the achievement of this objective is also verified with measurements. This entails a significant investment in the development of forest biodiversity indicators and monitoring methods.

"Finnish nationwide monitoring data is unique internationally. However, monitoring as a whole is being further developed, both within Metsä Group and as part of the joint biodiversity roadmap for the wood processing industry, in which we are actively involved,” says Timo Lehesvirta.

The impacts of the measures on the species are also investigated in separate monitoring projects. These provide interesting information about the insects found in groups of burned retention trees, for example.

“It’s important that the whole industry uses common science-based indicators and monitoring methods. The more advanced our national monitoring system is, the stronger our position in the transition to sustainability will be,” Lehesvirta points out.