Vegetation (Floating River Vegetation) - Office of Public Works

iver diversity. Under REPS 3, measure 5 option 3b new hedgerow replanting is encouraged. To
prevent excessive shading of watercourses and provision of access for maintenance machinery,
unplanted sections should be left in the proposed hedgerow rather than planting a continuous
hedgerow. Hedgerow management should include coppicing to provide variation in hedgerow
density shape and height. Management of trees during watercourse maintenance would be
beneficial to floating river vegetation.
5.2 Influence of current Environmental Drainage Maintenance work practices
The current drainage maintenance under the guidance of the Environmental Drainage
Maintenance Programme is and will be beneficial for floating river vegetation. For the most part the
10 step recommendations for fish species are also applicable to floating river vegetation. To benefit
floating river vegetation the following adjustments to the current Environmental Drainage
Maintenance Programme should be considered.
•Removal of vegetation should not be restricted to instream vegetation. Marginal vegetation may
need to be removed especially if there is encroachment by terrestrial plant species from the river
bank. Plant species such as watercress and fools watercress may also require controlling.
•Phragmites, Bulrush, Bur-reed, Water celery and large marginal grasses need to be contained or
removed during maintenance. Excessive growth of these plants will lead to a greater rate of
siltation, reducing the aquatic environment for floating river vegetation.
•Riparian woodland on wide rivers was not found to interfere with the colonisation and growth
of floating river vegetation. Dense sections of Willow and overgrown hedgerows on channels of
less than three metres wide did reduce the level of sunlight reaching the watercourse floor.
Without sunlight plants cannot produce food through photosynthesis to sustain growth.
Appropriate tree management should allow sunlight penetrate the riverbed.
•Development of two stage channels could be beneficial to floating river vegetation. A fast
flowing slightly deeper section of gravel base would favour water crowfoot species. Deep
sections of river would facilitate some species of pondweed. Shallow areas of slow flow prone
to sedimentation would be ideal for the water parsnip.
•Placement of boulders in channels following maintenance will also be beneficial for the
propagation and colonisation of floating river vegetation especially if there is evidence of
floating river vegetation species upstream.
•There would be an element of concern regarding the loosening of channel bed gravel between
mid June to mid August. Seeds associated with floating river vegetation would be present on the
channel bed and or may be in the process of germination for the following year. Loosening
gravel may cause the seed to be buried beneath a gravel layer or be washed away. Should the
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