Stop 13: Canal margins

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The rich assemblage of emergent plants that thrive in the shallows are dominated by reeds, rushes and sedges alongside characteristic species like yellow flag iris, purple loosestrife and water mint. These aquatic fringes act as a vital refuge for birds, amphibians, reptiles, small mammals, aquatic invertebrates and fish. They provide:

• shelter and protection from predators
• a safe haven to breed, build nests and bear young
• a rich resource of food.

In turn, these areas provide excellent hunting grounds for the larger predators such as otters which are known to frequent this canal. Their importance for wildlife contributes significantly to the biodiversity richness of the Montgomery Canal, with12 species of dragonflies and damselflies known to breed here including scarce species such as club-tailed dragonfly, red-eyed damselfly and white legged damselfly.

Buffer zone

Along the navigable lengths these linear margins hold an additional function of protecting the soft earth banks from boat wash and wave action; helping to trap sediment and dissipate energy which in turn reduces bank erosion. They also play a key role in:

• protecting and improving the water quality of the aquatic environment
• providing a natural filtration buffer from sedimentation, erosion and diffuse run-off from the surrounding hillsides.

This is integral to the functioning of the aquatic ecosystem and the survival of the more sensitive aquatic plants, notably the European protected Floating water-plantain. 

Severn Uplands Project

The aims of the Severn Uplands project were to improve the habitats and water quality of this special environment through a number of initiatives, to protect macrophyte populations including floating water-plantain and the rare Grass-wrack pondweed, whilst bringing wider benefits to the ecology and wildlife of the canal. These were focused around enhancing riparian habitats and reducing impacts from sediment and pollutants from surrounding land.

However, as a man-made feature the canal is also a continually changing ecosystem. With a lack of fast flow and little or no boat traffic there is often a continual accumulation of silt on the canal bed. Without intervention or management this would lead to the gradual extension of the margins, eventual succession to terrestrial habitat, and the loss of the characteristic aquatic species. The key to sustaining this dynamic environment is retaining the fundamental balance between the margins and open water habitat.