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In the Nordic Taiga, a river marked by logging undergoes ecological restoration with sediments transported by helicopter, bed recomposition, and scientific monitoring to track the return of aquatic habitats.
The Abramsån River, a tributary of the Råneälven located about 45 kilometers south of the Arctic Circle in northern Sweden, has become one of the most visible examples of river restoration in the Nordic Taiga region.
After decades of modifications made to facilitate timber transport, Rewilding Sweden has been conducting a project since 2023 to restore part of the lost natural structure to the watercourse.
The initiative combines the repositioning of stones, sand, gravel, and dead wood, along with scientific monitoring to assess the response of organisms living at the riverbed.
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In 2024, one of the most unusual stages of the project involved the aerial transport of 180 tons of sand and gravel to already restored sections of the Abramsån.
The material was dropped by helicopter to accelerate the recomposition of micro-habitats that, according to the project, could take centuries to form again through natural processes.
Restoration of the Abramsån River recovers area affected by logging
The intervention seeks to recover sections of the upper Abramsån that were simplified by old works related to logging.
According to Rewilding Sweden, the modifications began before the 1880s and included the removal of stones, gravel, dead wood, and other natural structures that helped slow down the water.
These elements also created pools, rapids, spawning areas, and shelters used by fish, aquatic insects, and freshwater mussels.
In some areas, the impact was even more intense.
Wooden structures were installed at the riverbed to allow logs to slide more easily during river transport.
As a result, the channel became straighter, faster, and poorer in ecological variation.
The change reduced curves, backwaters, shallow areas, rapids, and zones of contact between the water and the banks.
What was once a more dynamic river began to function, in several sections, as a more simplified and faster channel.
Channelization reduced habitats in the Abramsån riverbed
The removal of large stones and the straightening of the watercourse altered the natural shape of the Abramsån.
This process, known as channeling, increased the speed of the current and reduced the diversity of environments in the riverbed.
Instead of bends, pools, shallow areas, and rapids distributed irregularly, the river began to flow more linearly.
The alteration met the logic of timber transport but changed essential conditions for part of the aquatic fauna.
With the faster current, much of the fine sediment that would be trapped between rocks, cavities, and areas of lower speed was carried downstream.
The loss of sand and gravel reduced the available sites for organisms living on the bottom.
It also affected areas used by fish for reproduction and habitats associated with freshwater mussels.
Rewilding Sweden began in 2023 a multi-year effort to restore sections of the upper Abramsån.
The work includes restoring the natural shape and flow of the river, with measures such as repositioning stones in the bed, returning deadwood, and reversing some of the changes made in the past.
The replenishment of sand and gravel was added as a complementary step because the natural replenishment of this material could take a long time.
Sand and gravel recreate aquatic habitats
The material transported by helicopter was distributed at various points of an already restored section of the Abramsån.
The intention was to fill cavities between larger stones and form environments similar to those found in rivers less altered by human action.
By occupying crevices, holes, and small areas of lower current, the sand and gravel help rebuild an important physical base for aquatic life.
According to Vebjørn Kveberg Opsanger, a Norwegian doctoral student associated with the Norwegian Institute for Nature Research, NINA, the recomposition of this sediment can mainly favor the benthic fauna.
Some species also help in water filtration.
By reconstructing part of this physical base of the ecosystem, the project aims to improve conditions for the benthic fauna.
Scientific monitoring accompanies the river restoration
The action in the Abramsån is also accompanied as an ecological restoration experiment.
Interventions with gravel replenishment have already been carried out in rivers in northern Sweden.
Before the release of the material, samples were collected from the river to record the composition of the benthic fauna.
The monitoring was planned to continue in 2025 and 2026.
A restored section, but without the addition of sand and gravel, should function as a control area.
This comparison allows for the evaluation of whether any changes are related to sediment replenishment or other channel restoration measures.
The effects do not tend to appear immediately.
Recolonization depends on the arrival of organisms from other sections or nearby rivers.
It also depends on the permanence of the material in suitable areas of the bed.
Part of the sand and gravel may be redistributed by the current itself, a process expected in the river’s natural dynamics.
Volume of sediments spreads across the restored bed
Although 180 tons represent a significant volume, the amount is distributed along the bed when used to fill gaps, cavities, and spaces between stones.
For this reason, the material was released at different points, rather than concentrated in a single area.
The operation had financial support from EKOenergy, according to Rewilding Europe.
If monitoring indicates positive results, Rewilding Sweden states that it may consider using the same technique in other sections of the Abramsån and in parts of other restored rivers in the future.
The initiative is part of an approach called by the organization “waterscape”, or aquatic landscape.
The proposal is to improve corridors formed by rivers, banks, wetlands, and forests, enhancing the connection between the water flow and the surrounding terrestrial environments.
In Abramsån, the measures aim to recover ecological functions affected by human interventions made for forestry exploitation.
Among the objectives cited by Rewilding Europe are the expansion of habitats for aquatic insects, the improvement of spawning areas, the favoring of filter-feeding mollusks, and the resumption of natural processes in the riverbed.
The goal, according to Rewilding Sweden, is not to reconstruct the Abramsån as it was at a specific date in the past.
The proposal is to return to the river its natural tools: structure, dynamics, and connection with the surrounding landscape.
With the water once again able to shape its own course, the project aims to favor the gradual recovery of the Råneälven valley.
The operation shows a recurring characteristic in environmental restoration projects: the use of equipment and technical planning to try to reestablish physical conditions that allow the ecosystem to resume natural processes.
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