Nobody knows how large a part of biodiversity we can afford to lose before the ecosystem crashes. The situation is alarming in Finnish forests, as more and more species are becoming endangered. Researchers are trying to find ways to prevent different species from disappearing.
Coarse woody debris (CWD) is an inseparable part of biodiversity in forests. It is estimated that some 4,000 to 5,000 species, i.e. approximately one-fourth of all species living in our forests, need CWD to live.
“CWD sustains an incredible number of species. A single stem can be home to dozens of fungal species alone”, says Raisa Mäkipää, research professor at the Natural Resources Institute Finland (Luke).
According to studies, the low amount of CWD is the main reason why the number of species is decreasing in our forests.
Updated information about the conservation status of Finnish species is expected to be released on 8 March. The red book of Finnish species, produced by a group of some 180 specialists, includes assessments of the conservation status and future of nearly 22,500 species. Mäkipää expects the conclusions and recommendations of the assessments to steer future actions.
Steps in the right way
Mäkipää studies the functioning of forest ecosystems and one of her recent projects was focused on CWD and fungus species that live on it.
“It is exciting how diverse processes have evolved in nature. For example, some species that live on CWD have evolved to only live on stems of a specific size or species or on stems that are in a specific stage of decay. Extremely specialised species are only able to live on burnt wood or on wood decayed by a specific fungus species.”
The importance of biodiversity is now understood better than before. The most significant nature sites are protected by the Forest Act and the Nature Conservation Act, certification criteria require to leave retention trees in forests, and private forest owners can voluntarily protect their forests for compensation through the METSO programme and many of them have chosen to leave artificial snags, i.e. stumps of 2 to 5 metres in height, in their stands during felling.
“We are heading in the right direction, and all actions that slow down the disappearance of species are necessary. However, there is still a lot of work ahead of us before we can stop species from disappearing”, Mäkipää says.
An ambitious biodiversity strategy
Mikko Mönkkönen, professor in applied ecology at the University of Jyväskylä, leads a research project that aims to identify how forests could be used and protected so as to maintain their biodiversity.
“Forests may lose a large part of their biodiversity before any consequences can be identified. Forests keep on growing, even though species disappear”, Mönkkönen says.
Like Mäkipää, Mönkkönen also believes that too efficient a commercial use of forests presents a risk to biodiversity, and that we should do everything in our power to maintain it.
“Ecosystems rely on biodiversity. Nobody can say how much or what part can be lost before the system crashes.”
The significance of biodiversity is also identified at an EU level. One of the goals of the EU Biodiversity Strategy is to stop biodiversity from decreasing by 2020. This is an ambitious goal, and most likely it cannot be achieved in Finland.
Mönkkönen’s research group is currently studying what is needed to stop biodiversity from decreasing in forests.
“As our research is still in progress, I cannot give any straight answer. However, my educated guess is that we need to significantly increase the conservation level, particularly in Southern and Central Finland, and to withhold from increasing felling volumes.”
Extra boost from comprehensive planning
According to Mönkkönen, we could decelerate this negative trend by means of forest planning at a landscape level.
“Sites that are important in terms of biodiversity should be examined not at the level of individual farms, but at the level of individual municipalities or, say, whole catchment areas. Depending on the outlines, sites can be hundreds, thousands or even tens of thousands of hectares in size”, Mönkkönen says.
If the conservation methodology is like a machine that maintains biodiversity, forest planning at a landscape level is like a turbo boost that gives extra power from the machine.
“When forests are examined more broadly than from inside the boundaries of a single farm and over a timespan of the rotation age, we can identify the most significant sites in terms of biodiversity and target conservation actions to areas where they produce the highest benefits. Correspondingly, felling can be carried out in areas where it causes the least adverse impact on biodiversity”, says Mönkkönen.
In this way, the volume of wood needed by the industries could be harvested from a smaller area and, correspondingly, conservation measures could be increased.
Diversity also in forest management
According to Mönkkönen, protecting biodiversity does not mean that forests should be left in their natural state. Full protection is needed regarding species that cannot withstand human intervention. However, outside these areas, diverse forest management methods should be used.
“Unfortunately, we consider rotation based forestry and continuous cover forestry to be opposites of each other, even though a combination of these would be the best option for biodiversity.
In the future, decreases in the most endangered species could be decelerated by returning species to their most ideal living environments in areas from which they have disappeared”, Mäkipää says. In Luke’s project, rare fungi living on CWD are transplanted in forests where they originally lived.
Researchers continue to work to secure biodiversity. According to Mönkkönen’s words: Biodiversity is like insurance. It is like an unnecessary cost, until something unexpected happens.
Text: Maria Latokartano
Published in Finnish on 18 February 2019 in Maaseudun Tulevaisuus newspaper.
Four ways to increase biodiversity in your forest
1) Save groups of retention trees
“The significance of retention trees would be greater if they were actually left in forests. Unfortunately, some forest owners use them as firewood when they die and fall. At this stage, they would start to produce the most benefits for biodiversity”, Raisa Mäkipää says.
2) Leave storm damaged trees in forests, if possible
““If the link between a tree canopy and its roots is cut, the stem will dry during the winter, and it will not be troubled by the European spruce bark beetle the next summer. Numerous competing insects and parasites live in dead trees. This means that if you remove all dead trees, you also remove all natural enemies of the European bark beetle”, Mäkipää says.”, Mäkipää says.
3) Leave CWD in your forest, already at the thinning stage
“While some CWD species survive clearcutting by living in stumps and logging residues, their populations will collapse after 20 to 30 years. If CWD was left in forests, already at the thinning stage, it would help certain species to survive. Trees of a low commercial value could be felled to decay and dead or dying standing trees could be left as retention trees”, Mäkipää says.
4) Use a combination of all forest management methods
“A large group of forest management methods is needed to maintain biodiversity. In addition to periodic and continuous cover forestry, the rotation age can be extended by 10 to 30 years, and the number of retention trees, as well as the timing and intensity of thinning, can be changed”, Mikko Mönkkönen says.