Putting back an essential missing component of a healthy river system.
Healthy river catchments have lots of wood in the water from trees falling into the river. In Scotland, which has lost much of its woodland cover, the supply of deadwood has reduced and this important natural process has been lost.
After restoration
Large Woody Debris has been installed, creating a dynamic and biodiverse ecosystem.
- Large root plates divert flow, creating pools behind them with deep, cool water for fish to escape from warmer temperatures and fierce floodwaters. Roots and branches shelter young fish from predators.
- The structures trap organic matter like twigs and leaves – an important source of nutrients for the aquatic food chain. They also provide habitat for algae and invertebrates, boosting food availability.
- Obstacles create friction, reducing the water’s speed and helping to mitigate flooding downstream.
- By forcing water to divert around them, woody debris encourages horizontal erosion and natural meandering. This creates a more complex channel structure with a greater diversity of habitats, such as sediment bars, deep pools, and shallow gravel riffles.
CASE STUDY: Large woody structures were installed into the River Calder, near Newtonmore, in 2022. Whole conifer trees from a nearby plantation were installed in the river, while trees were planted along the banks to provide a future supply of deadwood.