News and updates

News and updates from the project, writings about kelo trees

23.3.2023 – Kaisa Junninen: Polypore life in Koitajoki

Antrodia crassa

I found my very first Antrodia crassa in the year of 1999 from Tapionaho in Koitajoki. It was a significant event, not just for me, but for the survey of threatened polypore species in general, as by then, few A. crassa occurrences were known in the whole of Finland.

A. crassa grows only on fallen, well-decayed pine kelo trees, often by a mire. The sporocarp of the polypore hides under the pine trunk and resembles a white piece of soap.

For A. crassa to be found, the forest must have lived in peace and quiet for several hundred years. First, a pine seedling needs to sprout in a suitable location. Next, the tree must be able to grow several centuries into an elderly pine tree, and after its death, the tree must develop into a silverly kelo. Finally, after falling, the tree has to lie on the forest floor for decades until the wood material is decayed enough to host A. crassa.

Although the habitat might be suitable, the specialist might not find it. For the population of A. crassa to prosper, a fallen kelo needs to be surrounded by an extensive kelo pine forest. In this forest, the A. crassa spores will make their way to a new kelo trunk when the previous one becomes too decomposed. If there are not enough suitable kelo trees in the forest stand and other stands are not nearby, A. crassa likely disappears from the area.

After that one observation, no further A. crassa was found in Koitajoki. Outside conservation areas, where the forest is under 400 years old, the species cannot survive. In addition, the old-growth forest stands of conservation areas are very fragmented in the landscape and located far away from one another. If A. crassa becomes extinct in one forest stand, it is unlikely to be able to disperse there again, although old kelo logs might be there to give it a home.

This is why A. crassa has become an endangered species.

Luckily, there are still many other polypore species that inhabit Koitajoki area.

Fallen spruces are decorated by Fomitopsis rosea and Amylocystis lapponica. A bright yellow Antrodiella citrinella may succeed on the trunks decomposed by Fomitopsis pinicola, and after Phellinus ferrugineofuscus, Skeletocutis brevispora and S. exilis may inhabit a spruce log. Under the trunk, you might even find a Skeletocutis stellae hiding.

Kelo logs in Koitajoki are still inhabited by Antrodia albobrunnea, Postia lateritia and Antrodia infirma. In addition, restoration burns and burning of logging sites have created suitable habitats for Dichomitus squalens and Erastia aurantiaca. Moreover, Gloeophyllum protractum, in turn, settles especially on the human-made duckboards.

Fallen aspen logs provide a home for Antrodia pulvinascens and A. mellita. After an Inonotus obliquus, the Chaga, has decayed a birch trunk, Antrodiella pallescens, Aporpium canescens and Gloeoporus dichrous can follow.

Polypores release nutrients from tree trunks for the use of other organisms. A well-decomposed log is a perfect seedbed for a tree seedling, and so the story starts from the beginning again.

Text is written by the Kelo-project’s Kaisa Junninen. The text was originally published in Pogostan Sanomat 2.2.2023.

28.2.2023 – Kelo trees in Finland prior to modern forestry

How kelo trees are formed is still poorly understood, but the evidence so far points to a long chain of events for a pine seedling to develop into a kelo. However, after a kelo forms, it may remain standing for centuries and hence with time, natural forests may gradually accrue large numbers of kelo trees in different stages of their development. Due to the long time spans involved, even a small human influence either directly on existing kelo trees, or to pine trees – the candidates for future kelo trees – may have an impact on the presence of kelo trees in a forest landscape.

Modern forestry with rotation times up to 100 years or shorter is largely incompatible with the formation of kelo trees. However, in many regions kelo trees disappeared from the forested landscapes already prior to the onset of currently dominant forest management regime in Finland, which occurred in the 1950s. Using measurements from the national forest inventories, Kalliola (1966) studied the changes in the numbers kelo trees from the 1930s to 1960s, which encompasses this transitional period. His aim was to examine the naturalness of the Finnish forests for which the presence of kelo trees is one credible indicator (it should be noted that Kalliola uses measurements of all hard standing dead trees over 20 cm to estimate the density of kelo trees. He argues that other species than pine fall over relatively rapidly and represent only a minor share of the whole). The findings demonstrate clearly how kelo trees had disappeared from the southern and western parts of Finland already prior to modern forestry, but how they were a prominent structure in the forests of the Suomenselkä water divide in Central Finland, in the East, and in the North all the way to the subarctic treeline.

Kelo densities started to decline also in these regions, when forest management based on clearcutting reached these previously relatively untouched forests. While kelo trees were earlier used as firewood, the intensification of forest industries meant that kelo trees were also harvested for the pulp industries, which is visible especially well in the reduction the numbers of kelo trees in the southern Lapland.

Maps showing the
Presence and density of hard, standing dead wood over 20 cm in diameter across Finland as measured in the 2nd and 4th national forest inventories (redrawn from Kalliola 1966), in 1936-38 and 1960-1963. Color and topography of the map describe regional average of kelo densities. Already in the 1930s these trees were rare in the South and in the West, but still abundant in the East and the North, and the Suomenselkä water divide in Central Finland. Kalliola’s research well shows how kelo densities declined by mid-1960s, after which greater densities were confined to the Northeastern Wilderness and the Inari region in the far North.

Although kelo trees are considered a feature typical to the North, this geographical distribution is largely due to human influence on forests. Kelo trees have earlier been an important part of forests throughout Finland, and they are still found wherever untouched forests still remain. This includes the Bialowieza forest in temperate Europe, much further South than their distribution in Finland.

Reference: Kalliola, R. 1966. The reduction of the area of forests in natural condition in Finland in the light of some maps based upon national forest inventories. Annales Botanici Fennici 3: 442-448.

Text is written and map is made by Tuomas Aakala, Kelo-project coordinator.

19.1.2023 – From a seedling to a kelo and from a kelo to decayed woody debris – Lifecycle of a kelo tree takes breathtakingly long

Drawings of a Scots pine turning
Scots pine turning slowly into a kelo tree

Would you like a short and sweet introduction into what we know about kelo trees so far? In this post, I would like to present you an online booklet that I made, called “Lifecycle of a kelo tree”. With illustrations and texts you get to follow the lifecycle of one Scots pine tree, from seedling to a fallen kelo log. You can access booklet by clicking here.

I was prompted to make this booklet after reading all kinds of texts about kelos. Texts online and in books often state things about kelos, that are not based on research, but seem to be passed on from text to text without any idea of the original source and its accuracy. So in this booklet I made, I wanted to use only published scientific articles, to tell you what we know about Scots pine and its kelo form based on research so far. I can tell you right now, that there are only a handful of articles on kelo trees! The aim is to update this booklet as we get our own study results which hopefully will fill the knowledge gaps of kelo trees and their formation.

Best regards, Tilla

11.1.2023 – When a journalist accompanied us in the field last autumn

Tuomas coring a kelo in Cajander forest
Tuomas coring a kelo from one of our study plots in North Carelia in October

Last October, journalist Sampsa Oinaala joined us – Tuomas, Pem and Tilla – as we went to two of our study plots in the Cajander old-growth forest in Northern Carelia. We wanted to take some samples for preliminary analysis before the actual sample collection next summer, and Tilla and Pem also took the opportunity to practise their tree coring skills.

Sampsa followed our work and interviewed us as we travelled two hours from Joensuu. Based on that day and its discussions, Sampsa wrote a fine article about our research and kelo trees. It is now published in the Kone Foundation website, and you may read it by clicking here.

22.11.2022 – Aleksi Nirhamo: Kelos are important for lichen biodiversity

Calicium tigillare on an old fencepost. This species does not have pin-like fruiting bodies, but it forms a spore mass the same way as other calicioids. A similar-looking species called Calicium pinicola is known from Sweden and Norway, but unfortunately it does not occur in Finland. Photo: A. Nirhamo

Lichens are omnipresent in Finnish nature but taking notice of the full range of their diversity requires careful and detailed observation. Kelo trees, especially long-lasting ones, are also often full of diverse lichens.

In the summer of 2022, I surveyed a group of kelo trees in Patvinsuo national park in eastern Finland. I collected similar data from snags (standing dead trees) on logging sites formed from retained pines. The lichen communities on the kelo trees were highly species-rich: on average, 23 lichen species were found on the kelo trees, and one bore as many as 39 lichen species. Species richness was also rather high on snags on logging sites (avg. 18 species), but the species composition was distinctively different. Nearly all lichen species that specialize in growing on deadwood are small crustose lichens (also known as microlichens). In addition, larger generalist species and crustose lichens that also occur on bark may be found deadwood. The species assemblage on snags on logging sites consisted in a much larger extent of generalists, whereas the assemblages on kelo trees consisted of more specialized species. This is reflected for example in the occurrence of red-listed species: snags had, on average, 0,6 red-listed species, while kelo trees had on average 3,7 red-listed species, with 8 red-listed species on one kelo at the highest. Red-listed species often observed on kelo trees included Micarea elachista, Ramboldia elabens and Calicium denigratum. These numbers demonstrate the high importance of kelo trees to lichen diversity.

Calicium viride on the bark of Picea abies. The “pins” are the apothecia i.e. the fruiting bodies of the mycobiont, and they have developed an exceptionally long stalk. Another exceptional feature of these lichens is that the apothecia do not “shoot” the spores to be carried by the wind, instead the spores remain on top of the apothecium as a spherical spore mass. This way, the spores may be attached to woodpeckers or other birds and thus be dispersed to other trees with the birds. Photo: A. Nirhamo

However, at least in Patvinsuo the situation is worrisome, since it is evident that the kelo continuity of the areas, where I collected the data, is being disrupted. Because of logging operations completed before the founding of the national park, there are almost no large, old pines from which long-lasting kelo trees could form in the next decades. Scarce kelo trees may still be found in the area, and surveying these trees made me feel like an archaeologist studying ancient relics. These kelo trees may have originated from trees that were left as seed trees in previous loggings, or perhaps they were already dead at the time of the loggings. When the current kelo trees are eventually decomposed, it appears that there will be no new kelo trees for the lichens to colonize, which would mean local extinctions of the species dependent on kelo trees. There is likely a similar situation in many other Finnish protection areas. Loggings that cause disruptions of kelo continuities are also completed today especially in northern Finland. The continuing decline of kelo trees leads to the decline of lichens and other species dependent on kelo trees.

“Scarce kelo trees may still be found in the area, and surveying these trees made me feel like an archaeologist studying ancient relics.”

The research on the lichens on kelo trees will continue next summer. With the data we will collect then, we may look into the development of the lichen communities on kelo trees over time after their death. Previous studies have strongly suggested that the value of kelo trees for lichens increases with the time after their death, but the studies so far have been insufficient. In addition, we may look into how the lichen communities are affected by the chemical features of the wood. For example, lichen communities on bark and rock substrates are known to be strongly affected by the chemical variation of the substrate. This could also be the case for deadwood substrates, but it has not been studied.

Micarea hedlundii requires moister conditions, and thus it is not found on kelo trees in (sub)xeric pine forests. It may, however, be found at the base of kelo trees or fallen kelo trees in spruce-dominated forests, where the moisture of the substrate and the immediate surroundings is higher. Photo: A. Nirhamo

What kind of lichens do we find on kelos?

  • About 1 700 species of lichens are known from Finland
    • About one-third of them are epiphytic i.e. growing on trees
    • About 10 % of epiphytes are found only on (dead)wood
  • In addition several species grow primarily on wood, and facultatively on bark
  • Out of the red-listed epiphytic lichen species, one-fourth (78 species) occur primarily on wood
  • The lichens that grow on wood may coarsely be divided into species found on decaying and moist wood and species found on decay-resistant, dry wood
    • For the latter, kelo trees are the most important substrate
  • “Kelo species” may also be found on fences, the walls of sheds or barns, piers and other wooden structures

Out of the lichens found on deadwood, perhaps the most startling are the calicioids, which include for example the species from the genera Chaenotheca and Calicium. Calicioids are a taxonomically disparate group, but they share similar morphological and often also ecological features. There are also non-lichenized fungi that are also referred to as calicioids, which share a similar morphology with calicioid lichens. Many calicioids (both lichenized and non-lichenized) are specialized to deadwood, and they are also characteristic for kelo trees. For example, Chaenotheca ferruginea, Calicium viride, the rare Calicium tigillare, or the non-lichenized Chaenothecopsis fennica may be found on kelo trees.

This article was written and photos were taken by Aleksi Nirhamo, our lichen specialist (you can read more about him in the People-tab)

19.10.2022 – Kelo-project in the Cold Forests-conference

Pem presenting in the conference
Pem presenting in the conference

Tilla, Pem and Aleksi from the Kelo-project held presentations of their PhD-projects in the “International Research Network on Cold Forests”-conference, which was held in Joensuu this year, in the beginning of October. From down below you can watch the five minute presentations uploaded in Youtube.

Tilla’s presentation
Pem’s presentation
Aleksi’s presentation

12.9.2022 – Project kicked-off properly, and the first post

Salamanperä forest and an old charred stump
Salamanperä forest and an old charred stump

Hello, this is Pem and Tilla, working on our doctoral disserations in the Kelo-project and managing this website. We started just at the beginning of the summer. Tilla will be diving into the chemical composition of kelo trees and Pem will be focusing on the dynamics of kelo trees – how often and where they form and how long do they remain standing.  Together, we aim to answer how and why some pines become kelo trees, and what are the factors responsible for creating this one-of-a-kind forest structure.  

In this September evening, we have just finished our first summer of field work. Yay! We started it in the cloudberry-rich Kuusamo in northeastern Finland, continued in the steep hills and eskers of Northern Karelia, and have now wrapped up the establishment of our sample plot network in the rocky forests of Salamanperä just as autumn colours are starting to bloom in the birches and mires.  

With help from Romain Bergeret (visiting us from AgroParisTech in Nancy, France), and the kelo-project’s lichen specialist Aleksi Nirhamo, we mapped  kelo trees, their characteristics and peculiarities in circular sample plots inside some of the best remnants of old-growth forests still remaining in Finland. This network of field plots forms the backbone of next summer’s fieldwork, where we will sample the trees for their growth history, chemical composition, and the species that dwell on them. You can get to know all the people involved in this project through this link

We saw some very old and remarkable kelos, in addition to multiple cut stumps and trees that had died young. It is surprising how far human influence reaches even in the most distant forests of Finland! Fires had been present in the history of most stands, and we were able to observe trees with multiple fire scars and charred surfaces. The fire history of the trees is of interest for both of our studies.  

Now we will continue to develop our research methods through the winter and do some preliminary analysis from the collected data. What might we find?