Finland's commercial forests have surprised researchers with their species diversity, according to a report by Metsähallitus, which compiled and recorded more than seven thousand observations of different species, 1700 of which relate to endangered species. In total, 133 species were identified, 101 of them endangered or near-threatened. The report focused on commercial forests and examined species of lichen, polypore and moss inhabiting both living trees and deadwood.
"The results were a pleasant surprise. We identified a large number of species. Of every one of them we can say that they were observed more often than we had expected. There is a great deal of new information about species and their occurrence in commercial forests," says Tuomas Kallio (Tuomas Kallio), a species expert at Metsähallitus.
The report was made public on 15 May at a webinar hosted by Metsähallitus. The range of species found is used as an indicator of forest and nature conservation values. According to Kallio, these species make up a substantial share of the species (biodiversity) found in the forest, whose condition was assumed to have deteriorated as a result of forest use.
Metsähallitus, Finland's state forest management enterprise, spent two years (up to 2023) surveying the ranges of endangered species and carrying out counts at 230 sites in Lapland, Kainuu and the Finnish Lakeland.
"No extensive surveys of endangered species have been carried out in commercial forests until now. The data obtained is important for assessing, for example, which species can be conserved in commercial forests, as well as the success of nature management," says Kallio, noting that endangered species and others included on the so-called Red List occur in many forest types, even in very ordinary commercial forests.
"Commercial forests do not create a so-called species vacuum. Through nature management it is possible to preserve a suitable environment for them in commercial forests and thereby support protected areas. For particular species to be found in commercial forests, it is important that the conditions those species need are present, such as decaying wood, old trees or broadleaved trees," Kallio says. He explains that most of the species on the Red List occur in many places, although in most cases the number of individuals is small.
"Not all species are highly demanding; they can grow in various forest types. Species that need serious protection are quite definitely more common in old forests, and we will see them relatively rarely in commercial forests."
Survey sites chosen at random (the randomisation principle)
The forest compartments were selected at random. In more than half of them (64%) the trees were younger than 80 years, and in roughly a fifth (22%) they were between 20 and 80 years old. In fourteen percent of the compartments the trees were older than 120 years.
"Most of the stands were what are known as ordinary commercial forests, that is, the usual regeneration and thinning work had been carried out in them," Kallio explains. According to him, the species surveyed can be found in any forest regardless of its age, but it was found that the number of species increases as the age of the dominant trees in an area rises.
"A wide range of species was identified at nature sites located within commercial forests, and these are highly important for protecting biodiversity. The nature sites had more species, and more unusual ones, than sites located in ordinary commercial forests," Kallio says.
Most of the observations relate to epiphytic lichens growing on tree trunks and branches. There were fewer observations of species inhabiting decaying wood. The presence of old trees and broadleaved trees was a pleasant surprise.
"On the whole there is little damaged wood in commercial forests, so there were fewer observations of species inhabiting deadwood than of species inhabiting the trunks and branches of living trees. Endangered polypore species, for example, were found at only a few sites," Kallio explains.
Lessons for forest management
The report has prompted Tuomas Kallio to stress once again that one of the things to pay attention to in felling areas is the number and type of retention trees.
"It is especially important to spare old trees. Broadleaved trees should be spared at every stage of forest management, and unnecessary felling should be avoided. Preserving existing deadwood is a cost-effective method of increasing forest biodiversity," Kallio lists.
The survey was a Metsähallitus Forestry Ltd project. The practical work was carried out by Metsähallitus forest biology specialists, with experts from other institutions brought in. The project recently received the Metsähallitus Environment and Innovation Award.