10. River and reedbed restoration at Duck Trap Wood
Theme: Water Quality, Habitats and Wildlife
- That whatever the flow level, the river and its associated habitats, including banks and floodplains, are managed to support chalk stream species
- That water quality, temperature and river bed quality are such that they support chalk stream ecology
This project has several aims: to reverse natural succession in marsh and fen habitat, to create a new 2 hectare reed bed, to repair damage to the river from dredging in the 1980s, and to restore 700m to a classical shallow, gravel bedded, fast flowing chalk stream.
Duck Trap Wood is a strip of wet woodland extending for 700m along the east bank of the river Mimram, midway between Whitwell and Codicote Bottom. Tall fen vegetation (reed/sedge/rush) occurs in the flood plain, beneath a mixed wood canopy of cricket bat willow, poplar plantation and hazel coppice. In the mid-1980s, the river was dredged, leaving deep holes in the bed.
The project would have a number of parts:
• A boundary line will be negotiated with the owners to define land reserved for commercial forestry and for reed bed construction.
• A botanical survey will be done to further define areas suitable for reed bed restoration/creation.
• Reed bed will be created by removing all encroaching willow scrub, and then by river bed lowering and the creation of channels to encourage reed to spread from existing locations.
• A fish and invertebrate survey will be carried out before river restoration work starts.
• The river bed depth profile will be surveyed to determine the quantity of silt to be removed and/or dispersed and the necessary quantity of gravel required to recreate good chalk stream bed conditions.
• Gravel will be used to replace silt and raise the bed to its former profile before dredging.