Of all the actions we undertake, restoring the habitat of smaller sized rivers and tributaries seems to be the most controversial and least well understood.
Habitat degradation in rivers is usually caused by overgrazing of bank side vegetation and the trampling of riverbanks by sheep and cattle. This results in the destabilisation of the banks, which cause streams to become wider and shallower. It also leads to more silt in rivers.
Starting in 1996, the Foundation’s surveys found large parts of the Wye and Usk catchments were no longer in a sufficiently good state to support the densities of fish of former years. Two things had changed in rural areas:
- A huge increase in stocking densities of farm animals has occurred since the early 1980s
- The historic practice of coppicing had ceased decades earlier.
In combination, these had led to fish densities in the majority of tributary streams being only 20% of their potential.
The Foundation’s ‘habitat prescription’
This has three main elements.
- We fence out grazing animals to allow bankside vegetation to regenerate in a natural way. This gives the banks the protection against excessive erosion in high flows.
- We also manage the tree cover to produce dappled shade and, at the same time, cut back multi-stemmed trees back to single stems. This allows enough light into the river channel to enable plants and algae to grow, kick-starting the ecosystem. Of increasing importance, this also gives just enough shade to give a stream a degree of ‘climate proofing.’
- Finally, we have also found that laying or pleaching-in hazel or willow and smaller stems horizontally with the flow creates cover and protection for juvenile salmonids. Severe erosion is also corrected by grading the banks and protecting their base with alder stems pinned to the bed.
Many of the Foundation’s projects have involved some sort of habitat restoration.
Many of the Foundation’s projects have involved some sort of habitat restoration.
