The brash is pinned in to stop erosion of the bank but will also provide homes for invertebrates and cover for fish.
Willow is included, this will sprout into new trees to make the structure alive and permenant.
Source: https://x.com/powell_peter/status/1738873845841346644?t=OcEENuLM_OcIx-CKI5AxFA&s=09
UK River Protection by Peter Powell – https://twitter.com/powell_peter/status/1729084663321481685
Further reading https://www2.ca.uky.edu/agcomm/pubs/AEN/AEN124/AEN124.pdf
Raincentre's Blog 