The Calder is a large upland tributary of the Spey running through beautiful Glen Banchor above the village of Newtonmore. Recent concerns that, compared to other similar tributaries, the Calder was under-performing in terms of producing juvenile salmon were thought to be linked to the lack of riparian woodland along the river and the relatively uniform nature of the river bed, which lacked features such as the gravel deposits needed for fish spawning. To try to tackle these issues, SCI embarked on two large scale projects with much wider aims for improving habitats, biodiversity and climate change resilience on the Calder.
With funding from SEPA, our first intervention was completed in August 2020. There was virtually no dead wood in the river channel, so whole trees from a nearby plantation were harvested and secured into the bed and banks at strategically chosen locations along 1.6km of the river to form 29 Large Wood Structures (LWS). These are designed to mimic natural dead wood, creating more diverse flow patterns and sediment deposition features which provide much more diversity of habitats for fish, invertebrates and other river life. As the trees slowly break down nutrients will be added to the water, giving a further boost to productivity. By November we have already seen salmon redds around the structures and increased amounts of gravelly substrate – early proof that the LWS are doing their job.
To achieve sustainable long term restoration, we are working with landowners Glenbanchor and Cluny Estates to create extensive riparian woodland in three blocks along about 4.5km of the river. The new woodland will cover 22.5 ha and over 15,000 native broadleaf trees will be planted in spring 2021, with further natural regeneration expected. Funding for this project is from NatureScot’s Biodiversity Challenge Fund, with trees donated by the Woodland Trust. The new woodland will not only provide a future source of dead wood for the Calder, but also shading to control rising peak water temperatures and natural flood risk mitigation – more on this in our next blog!
Source: Spey Catchment Initiative