Trees Bear Fruit!

December 03, 2020

Three years ago, we began introducing Large Woody Structures (LWS) into the upper catchment. We have been very pleased with their performance so far, creating diverse instream habitats for fish and other aquatic wildlife, providing shelter and catching nutrients.

This autumn, 40 large wood structures were installed on the upper Muick, from the loch outlet downstream for over 4km. Each structure made up of 4 large wind-blown trees, which were transported from surrounding forests, manoeuvred and fixed into the river at carefully chosen locations in a bid to boost habitats for salmon. These latest large wood structures take the total installed in the catchment over the last three years to 104, comprising 400 trees, all of which have been firmly locked into the riverbed.

River Operations Manager, Edwin Third, said.

“Salmon have a very complex life cycle, requiring different types of habitat at different stages. By adding large wood structures to the river, we can help to re-create complex and diverse habitats for them. Sites for LWS's are chosen carefully usually where the river is trying to create some complexity by itself, where shingle has been deposited by the river and is beginning to make small islands or gravel bars. The added wood then gives the river the ability to deposit more material to accentuate those gravel bars and islands. In this way the trees are like the building blocks of the river structure – we just lend a hand by adding the wood.

While we wouldn’t normally expect to see significant improvements in the river until a few years’ after installation, we’ve already seen the benefits of the structures installed on the Gairn last year and the Muick earlier this year. They have proved attractive for spawning salmon. A significant number of the newly installed structures have created excellent areas of spawning habitat and salmon redds have been recorded on these gravels in the Gairn and Muick this year. To me all this is really encouraging, and a clear sign that this type of restoration can make a difference to our salmon and the overall health of the river and the catchment.”

The restoration was funded by the Biodiversity Challenge Fund.