Coastal Change in Poole Harbour: Realignment of Tidal Banks, Supporting Transitions and Creating Enhancements

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An article from the CIEEM Ecological Restoration & Habitat Creation SIG

Matthew Bowell from Atkins, international infrastructure consultants, used the ERHC SIG’s EcoWorks service regarding a managed realignment project at The Moors at Arne. This site is situated on the edge of Poole Harbour, Dorset. The project is designed to provide more coastal and intertidal habitats to benefit a wider coastal ecosystem.

The proposed realignment of tidal embankments will result in a designated coastal grazing area transitioning to into intertidal habitat. The local environment on site include transitions of habitats between M23 (Juncus effusus/acutiflorus–Galium palustre rush-pasture), M24 (Molinia caerulea–Cirsium dissectum fen-meadow), and M25 (Molinia caerulea – Potentilla erecta mire).  Some of these habitats will be retained, but others of which will be lost or will transition to intertidal zones. The design includes retained terrestrial habitats to which it is hoped might be saved or recreated. A key requisite of the proposal was to maintain as much area of M24 habitat as it possible. It also aspires to achieve no net loss (or better) in area of this habitat type.

M24 fen-meadow is known to be hydrology, soil and pH dependant. The SIG were asked about the practicalities of translocating or creating M24 fen-meadow habitat in areas of retained M23 rush-pasture and other more species poor rush pasture. The SIG provided some useful steering information about the complexities and considerations of such work including hydrology, soil type, pH and inundation/salinity.

This information was helpful in designing the strategy for these habitats in proposals, which has been developed (as part of a wider ecological design) to include elements of translocation, habitat management and interplanting along with a strategy of monitoring and adaptive management to maximise the success of the key habitats.

Photos in this article of the M24 habitat including Devils-bit Scabious were by Kate Townend; Atkins, a member of the SNC-Lavalin Group.