Managed realignment in the UK – the first 5 years of colonization by birds
Abstract:With current losses of saltmarsh running at > 100 ha per year in the UK, creation of new intertidal habitats through managed realignment is likely to be increasingly used. Potentially, this has biodiversity as well as engineering benefits. However, assessing the conservation value of many of the current UK schemes is difficult as the biological monitoring has been generally poor, with a few notable exceptions. At the Tollesbury and Orplands realignment sites, Essex, bird communities were dominated by terrestrial species during the first year of inundation and waterbird communities rapidly developed during the second and third years. Five years after the initial breach in the sea wall, communities were similar to surrounding mudflats but with some notable exceptions. Dunlin Calidris alpina and Common Redshank Tringa totanus that prey on the early colonizing Nereis and Hydrobia used the sites in the first 2 years. Eurasian Oystercatcher Haematopus ostralegus did not occur on the realignment site as there were no large bivalves, whereas Red Knot Calidris canutus used the site after 4–5 years coincidentally with the appearance of Macoma balthica. The differences in the bird communities occurred because UK sites are often small, enclosed and poorly drained. If at a suitable height in the tidal frame, UK managed realignment sites are successful in that they have developed saltmarsh and biologically active mudflats but they may lack the full range of biodiversity found in surrounding natural intertidal habitats, even decades after inundation.
Document Type: Research Article
Affiliations: 1: Centre for Ecology, Evolution and Conservation, School of Environmental Sciences, University of East Anglia, Norwich, Norfolk NR4 7TJ, UK 2: English Nature, Northminster House, Peterborough PE1 1UA, UK 3: British Trust for Ornithology, The Nunnery, Thetford, Norfolk IP24 2PU, UK 4: Royal Society for the Protection of Birds, Stalham House, 65 Thorpe Road, Norwich NR1 1UD, UK 5: Royal Society for the Protection of Birds, Old Hall Marshes, 1 Old Hall Lane, Tolleshunt D’Arcy, Maldon, Essex CM9 8TP, UK
Publication date: 2004-09-01