A naturalist found an unusual species in a forest in southern Finland – no one knows how it got there

Rähelökäpa grows on the trunk of the tree, forming a dense and spectacular growth. — Knotweed is a highly endangered species that requires decaying wood as a growing medium.

A highly endangered ruffed lemur was found in a protected forest in Kymenlaakso. For some reason, the species, which used to occur only in northern Finland, has started to spread to southern Finland.

Metsäkoulu’s forest is an exceptionally old and natural forest area, because it has been protected and was once used for teaching by Sippola’s forest school. There is little human footprint in the forest and there is a lot of rotting wood on the ground.

A moldy orange dwarf fungus grows on the trunk of a tree. — The spore mother of the tufted rabbit, which grew in the forest protected by Metsäkoulu in Sippola, was already at the end of her life when she was found.

Röyhelökäävä's observations in map graphics. Twenty or so near Helsinki and a few sightings in Kymenlaakso. — The map shows the number of sightings of frilled pygmies in southern Finland. In the capital region, observations are from Vantaa and Helsinki. Sippola is located halfway between Kouvola and Kotka.

Unlike many snakes, the above-ground part of the frilled snake, or spore queen, only lives for about a week.

A surprising migration of dwarves

In 2018, there were still no sightings of the ruffed grouse in southern Finland.

Now more than twenty sightings have been accumulated in Uusimaa.

The ruffed grouse requires a stump or tree trunk that has been pre-digested by the trunk grouse to live.

Forest, fabric forest, forest inventory. — The tufted dwarf thrives in old spruce-dominant forests with rotting wood.

Roundworms spread by releasing millions of spores into the air. Usually, the spore spreads only about 10–100 meters away from the spore base.

– With good air flow, some of the spores may end up even higher and fly very far. But it’s a different matter if the spore lands on the right kind of rotting tree trunk where it could grow, says Junninen.

Junninen has a suspicion that the frilled pigeon may have spread to the forests of southern Finland from Estonia.

A printer’s fellow

According to the researchers, it is possible that in addition to warm air currents, some insects spread dwarf spores. Insects may eat dwarf spore embryos and then carry the spores directly to suitable rotting tree trunks.

– It is possible that even the beetles that dig into the trunk will take the spore to a really good place to grow there at the same time, says Junninen.

An orange, whistle-like dwarf grows on the trunk of a tree. — The tufted dwarf grows on the surface of the tree and its attention-grabbing orange whistles are 1–3 millimeters in diameter.

From the point of view of biodiversity and dwarfs, the firs felled by the book printer is not a bad thing.

– The fir trees eaten by the bookworm have been allowed to stand up and fall over in the Sippola nature reserve, and thanks to that, the frilled dwarf is now growing there.

The bookworm is a species of beetle that kills spruces by burrowing under the bark layer of the tree.

According to Junninen, the letterpress destructions that occurred in nature reserves are an excellent opportunity to observe the forest’s rotting tree continuum and its consequences. Many ducks, such as the lemon duck and the enchanted duck, thrive on the trunks of decaying spruce trees.

Tragic cycle of life

The surveyors are not immediately going to the tufted rabbit found in the Sippola forest again. There are many nature sites to be mapped, as Metsähallitus examines, among other things, how the monitored species included in the EU’s habitat directive are succeeding in Finland.

According to Junninen, kāvai have a tragic life cycle.

– They decompose their own growth medium and sooner or later when it is completely decomposed, the specific individual also disappears, says Junninen.

Paloheinä's natural forest. — Fallen trees in the nature reserve remain on the forest floor as so-called ground trees. The picture is from Paloheina in Helsinki.

The story uses the interview of Kaisa Junninen, a special expert in the nature protection of Metsähallitus’s Nature Services, who specializes in mushrooms and dwarfs, as a source.