Monday, May 19, 2025
SCA has experimented with a novel approach to fire-mimicking techniques in pine woods. Targeted burning of pines for conservation can be accomplished with a so-called “portable fire,” which is produced by Retrå Resource Operations. “The portable fire causes damage that resembles what occurs to pines during controlled conservation burnings without the need to burn an entire area,” comments Lukas Holmström, nature conservation specialist at SCA.
The planned burns along the trunks of many trees in the Bjurholm region may appear a little odd to the untrained eye. But to produce a particular kind of pinewood that many species value, burning is a necessary conservation strategy. “For certain species to survive, the forest needs to burn occasionally. Conducting controlled conservation burnings is an excellent way to help these species. In this way, we develop vital habitats for species that rely on fire-adapted forests to survive,” remarks Lukas.
The fire-damaged pine protects itself by impregnating its trunk with tar-like substances to prevent decay. “Tar-impregnated pines become highly resistant to rot, allowing them to remain in the forest for a long time, both as living and dead trees,” Lukas stresses.
Easy to use with the portable fire
During the snow-free season, SCA carries out a lot of conservation burnings, although these actions are very weather-dependent in order to reduce the possibility of fire spreading. By using the portable fire, specific activities can be performed on specific pines rather than destroying a whole region. “A portable fire is easy to carry and convenient to use since you simply place it on the ground at the base of a pine to be burned. The entire box burns in just over an hour. By primarily using it when there’s snow on the ground, the process becomes both safe and easy to control.”
Retrå’s portable fire, carried by Lukas Holmströ. The fire is 18 cm deep, 32 cm high, and 30 cm broad. Wooden dowels hold it together. Retrå sources its lumber and scrap wood from Tegsnässkidan. Birch bark, wooden blocks, and a Firestarter bag are placed inside the completed portable fire.
Vindeln’s Retrå Resource Operations, a municipal project centered on long-term, work-oriented rehabilitation, manufactures portable fire. A few years ago, they started making portable flames and selling them in their used store to anyone searching for a basic, portable fire for camping or hunting excursions. “We don’t use nails or screws, so no remnants are left in the forest,” says Mats Byström Nuft, instructor and coordinator at Retrå.
Sveaskog introduced portable fire for conservation, reaching customers like SCA, Västerbotten County Board, and Mid Sweden University. “We’ve gone from producing a few hundred per year to about 3,000 this season. Additionally, we are working on developing a new model in collaboration with the county administrative board. The high level of interest is great, but we now need to carefully consider production to ensure it doesn’t escalate, given the nature of our operations,” says Mats.
Functions well
SCA has now burned about 130 trees in two locations in Bjurholm, where Lukas has utilised the portable fire. He is rather happy so far. “The portable fire works very well! We managed to partially burn off bark along the base of the trunks, and we could see resin flowing along the edges of the damaged area, which is good. This means the pine is sealing the damage, known as the fire scar, with resin-impregnated wood. However, it’s a little too early to say how the growth of the resinous wood will turn out – we can see that at the earliest this fall,” describes Lukas.
The bark of the pine is harmed as the portable fire burns against the trunk, resulting in what are known as fire scars. The tree uses tar-like compounds to saturate the wood and seal the injury. The damage response of pine to spot burning, partial debarking, and environment conservation burnings is examined in a 2024 thesis by Emma Munters, a student at the Swedish University of Agricultural Sciences (SLU). In order to encourage the pine to impregnate the wood with resin, part of the bark is removed.
Traditional burns showed widespread vertical resin impregnation, while spot burns led to deep radial resin concentration at the trunk base. “The effects of the three conservation methods differ, according to the study, but all three contribute to the formation of resin-impregnated wood. This is beneficial for biodiversity, as fire-marked pines are a scarce resource. At the same time, it’s important to remember that it takes a very long time for such substrates to develop, so we don’t know exactly how biodiversity is affected,” says Lukas.
A favourable compliment
For reindeer husbandry, portable flames are an excellent addition to conservation burnings. “By conducting these targeted burns, the presence of ground lichens is not negatively affected. The same applies to partial debarking of pine. There may also be other forests where we don’t want to burn an entire area but only selected pines.” Lukas intends to use the portable fires going forward. “We will purchase more for next winter. One idea is to try combining partial debarking of pine with portable fires to see if it results in more extensive damage.”
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