Report Number 692 Re-creation options for River Severn/Avon floodplain wetlands English Nature Research Reports working today for nature tomorrow English Nature Research Reports Number 692 Re-creation options for River Severn/Avon floodplain wetlands Ecoscope Applied Ecologists and Silsoe College, Cranfield University with Aspinwall Clouston Ltd For: The Environment Agency (Midlands region, Lower Severn Area) English Nature (Three Counties Team) The Royal Society for the Protection of Birds (Central England Region) January 1999 You may reproduce as many additional copies of this report as you like for non-commercial purposes, provided such copies stipulate that copyright remains with English Nature, Northminster House, Peterborough PE1 1UA. However, if you wish to use all or part of this report for commercial purposes, including publishing, you will need to apply for a licence by contacting the Enquiry Service at the above address. Please note this report may also contain third party copyright material. ISSN 0967-876X © Copyright English Nature 2006 Cover note Project officer Dr Peter Holmes based at English Nature’s Three Counties Team office, Bronsil House, Eastnor, Ledbury, Herefordshire HR8 1EP. tel 01531 638500 [email protected] Contractor(s) (where appropriate) Ecoscope Applied Ecologists 9 Bennell Court Comberton Cambridge CB3 7DS and Silsoe College, Cranfield University Silsoe Bedford MK45 4DT with Aspinwall Clouston Ltd Sanderson House Station Rd Horsforth Leeds LS18 5NT The views in this report are those of the author(s) and do not necessarily represent those of English Nature This report should be cited as: ECOSCOPE APPLIED ECOLOGISTS, SILSOE COLLEGE, & ASPINWALL CLOUSTON LTD. 1999. Re-creation options for River Severs/Avon floodplain wetlands. English Nature Research Reports, No 692. Contributors, consultees and acknowledgements The project was carried out by Dr Graham Tucker (project manager), Matthew Fasham, Duncan Watson and Alison Bennett of Ecoscope Applied Ecologists, Dr David Gowing, Joanne Gilbert and Tim Hess of Silsoe College and Dr Shaun Salmon of Aspinwall & Co. The project was managed by Peter Holmes (English Nature), Alan Churchward and Cathy Beeching (Environment Agency) and Ian Barber (RSPB). We wish to thank the following organisations who provided data and helpful advice during the course of the project. Landowners and Internal Drainage Board representatives Robin Smith (Longdon and Eldersfield IDB), Noel Baker and Colin Evers (Trustees for Walmore Common), Mr Hyslop (West Gloucestershire IDB) and Larry Howells (South Gloucestershire IDB). Utilities Transco (gas), Severn Trent Water (water and sewerage), Midlands Electricity (MEB) (electricity and oil), Malvern Hills District Council, Forest of Dean District Council, Tewkesbury District Council, Wychavon District Council (sewerage). Archaeology Gloucestershire County Council and Worcestershire County Council. Nature Conservation Dr Colin Studholme (Gloucestershire Wildlife Trust), Andrew Thompson (Warwickshire Wildlife Trust) and Andrew Fraser and Andy Graham (Worcestershire Wildlife Trust). Executive summary The aim of this project has been to identify and assess areas that are suitable for the re- creation of floodplain wetland habitats within the Severn and Avon Vale Natural Area, as defined by English Nature. Although historic data on habitats within the Natural Area are scattered and incomplete, it is clear that a large proportion of the River Severn and Avon floodplains formerly consisted of wetlands. Before widespread human influence, such wetlands would probably have been predominantly natural marshland and wet woodland communities. These natural habitats were then gradually replaced by wet grasslands for hay production and grazing. Such traditionally managed semi-natural grasslands had rich plant communities and often held substantial numbers of breeding and wintering birds. However, the majority of wetlands within the Natural Area have been lost as a result of centuries of river impoundments and other navigational improvements, flood prevention measures and drainage schemes. Furthermore, in recent years, many of the remaining wet grasslands have been lost or degraded through agricultural improvements including ditching, field drainage, re-seeding and the use of fertilisers. As a result, only small remnants of semi- natural grassland remain and fens, reedbeds and wet woodlands are now relatively rare. In turn, many associated species, including some nationally rare and scare wetland plants and breeding waders, have also declined. Consequently, an English Nature objective for the Natural Area is to “‘Prevent deterioration of wetland habitats and where appropriate reverse past degradation and re-create wetland habitats within areas of high water table or subject to winter flooding”. Four formerly widespread habitats of particular biodiversity importance were therefore identified as targets for this project: • semi-natural wet grasslands, in particular species-rich flood meadows (National Vegetation Classification community MG4) and inundation grasslands (NVC community MG13); • reedbed (NVC community S4); • tall herb fen (NVC community S25); • wet woodland (NVC community W5). The re-creation of such wetlands could make a significant contribution to the UK Biodiversity Strategy and implementation of its associated Habitat Action Plans, such as for reedbeds and grazing marshes, and Species Action Plans, such as for otters and water voles. The re-creation of these habitats also aims to contribute to biodiversity actions for other associated UK Species of conservation concern, including breeding waders (eg curlew, lapwing, redshank and snipe), wintering waterfowl (eg Bewick’s swans), as well as to regional, county and local biodiversity targets. The study has been carried out in a two-stage process using two levels of criteria. The first stage aimed to identify large areas of the Natural Area that are of general suitability for wetland re-creation in terms of their topography, current land-use, general soil suitability and water availability (eg groundwater sources and flooding frequency). This initial broad assessment revealed that there is a large area of land that could feasibly be used for wetland re-creation in the Natural Area. However, 18 large candidate areas (with preliminary boundaries) were identified for further detailed investigation and evaluation against a second set of criteria. Firstly, each candidate area was assessed in terms of potential constraining factors, including land-use (eg housing, commercial use or presence of high grade agricultural land under intensive farming), presence of transport and service infrastructures, presence of important archaeological features and flood defence considerations. Each area was also evaluated in relation to the requirements of each target habitat type. In particular, assessments were made of the suitability of the soils, potential water regime, quality of water supply and the existing habitat. Finally, each candidate area was assessed in terms of its suitability for target species groups, taking into account land-use and topography, linkage to other suitable habitats and populations, the potential habitat and water regime that may be re-created, available food resources and the potential impacts of disturbance. For each criterion, the area was ranked according to three levels of suitability for the creation of wetlands: low, medium or high. The project was primarily carried out as a desk-study of existing data, supplemented with information obtained during brief visits to some of the key candidate areas. Further information was also obtained by consultations with landowners and trustees, IDB representatives, Wildlife Trusts, the Environment Agency, English Nature and RSPB. The overall conclusion of the study is that there is considerable potential for re-creating a range of different wetland types in the Severn and Avon Vale Natural Area. Most of the candidate areas have the potential for the successful re-creation of one or more target habitat in at least part of their area. Furthermore, some areas are particularly suitable for wetland re- creation and have the potential for meeting multiple objectives. A subjective ranking of the sites in terms of their overall suitability indicates that two sites are highly suitable overall: Longdon Marsh (Site 8) and the River Severn floodplain from Tewkesbury to Longford (Site 9). Another four sites were ranked as Medium/High: Birch Green (Site 5), Upton-upon-Severn (Site 6), Walmore Common (Site 13) and the River Avon floodplain from Eckington Bridge to Tewkesbury (Site 17). Due to the broad nature of this study and current hydrological and other data limitations, it is suggested that further detailed investigations are made of the feasibility of re-creating wetlands on the most suitable candidate areas. This should include confirmation of each area’s historic, current and potential hydrology and habitats. Consultations with landowners and other interested parties must also be carried out to assess the socio-economic implications of various wetland re-creation options and to measure support or oppositions to potential schemes. This information could then be used to prepare practical costed proposals for phased wetland re-creation. Contents 1 Background and objectives ......................................................................................13 2 The past and current status of wetlands in the Severn and Avon Vale