The Wildlife of Floodplain Meadows Emma Rothero and Sophie Lake
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Open Research Online The Open University’s repository of research publications and other research outputs Floodplain Meadows: Beauty and Utility - A Technical Handbook Book How to cite: Rothero, Emma; Lake, Sophie and Gowing, David (2016). Floodplain Meadows: Beauty and Utility - A Technical Handbook. Milton Keynes: Open University. For guidance on citations see FAQs. c 2016 The Open University https://creativecommons.org/licenses/by-nc-nd/4.0/ Version: Version of Record Link(s) to article on publisher’s website: http://www.floodplainmeadows.org.uk/floodplain-meadow-technical-handbook Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyright owners. For more information on Open Research Online’s data policy on reuse of materials please consult the policies page. oro.open.ac.uk Chapter 1 Introduction Emma Rothero “By flow’ry meads on each side of its banks The Ouse, well stocked with fish, runs through the town” (from Eboracum by Alcuin, 8th century) Floodplain meadows are beautiful, ancient and fascinating Floodplain meadows: places rich in wildlife and history. Throughout the spring and · generate a sustainable and prized hay crop; early summer, they are awash with wildflowers and waving · provide an important nectar source for pollinating grasses, humming with insects and the birds that depend insects such as bumblebees and hoverflies; on them. They provide a vibrant and beautiful spectacle that · support rare plant communities and are vital sources of has now all but disappeared from the UK. seed for the restoration of meadows; · provide flood-storage areas, trap sediment and store Floodplain meadows evolved over many hundreds of years carbon, and will be increasingly valued for these through the need to store the summer grass crop as hay to functions as the climate changes; and sustain cattle, sheep and especially horses over the winter · provide a link with the past, a living reminder of the months. The system of allowing the vegetation to grow up traditional, rural landscapes and the ways of life that in the spring, taking a hay crop in midsummer and then created them. grazing the re-growth prevented taller, coarser species from becoming dominant and created the diverse flower- A more detailed discussion of the value and history rich sward we see today. Once valued primarily for their of floodplain meadows is found in Chapter 3. More key role in commercial agriculture, the few remaining information on the distribution and conservation of species-rich floodplain meadows are now valued for a floodplain meadows in the UK can be found in wider set of attributes. Chapter 4. Floodplain meadows are often older than parish churches, and were so important in medieval times to rural communities that they were valued many times more highly than arable land (Brian and Thompson 2002). © Mike Dodd FloodplainFloodplainFloodplain Meadows Meadows Meadows – Beauty– –beauty Beauty and and and Utility. utility: Utility. A a ATechnical technical Technical Handbookhandbook Handbook 1 Chapter 1 Introduction The Oxford Meadows in flood. © Mike Dodd Floodplains are defined as low-lying ground bordering a river, formed mainly from sediment deposited during flooding. Where natural flooding still occurs, floodplains may be managed as pasture (used for livestock grazing) or as meadows (cut for hay or silage and then grazed). Most floodplains have been greatly altered by drainage and the creation of flood defences and, where flooding is prevented, floodplains are often used for arable crops or have even been developed. What are floodplain meadows? In cases where the river has been embanked, floodwater may sometimes still enter the site from the back drain. Floodplain meadows are areas of grassland used for hay Water regimes can therefore vary across a meadow, and making (and after the hay is cut, for a range of other this variation differs between sites depending on the main activities including grazing, horse racing, fairs or ice skating) source of floodwater. This results in very different patterns that are periodically flooded by an adjacent river or stream, in the bands of vegetation that develop. Chapter 8 provides or have a plentiful groundwater supply through gravel or descriptions of different vegetation communities found and sand aquifers. their hydrological requirements. Figure 1.1 Most floodplain meadows are bounded by Floodplain grasslands developed under an agricultural watercourses as they usually lie between the river or stream and management that included an efficient surface drainage a back drain often historically dug to help drain the meadow. system. Many sites also rely on subsurface drainage provided Wheldrake Ings, part of the Derwent Ings SSSI and Lower by shallow seams of underlying sand or gravel (Gowing, Derwent Valley SAC. © Crown Copyright and Database Right [December 2015]. Ordnance Survey (Digimap Licence). Lawson et al. 2002). This is important in allowing floodwater to drain away rapidly. Chapter 7 explores the water requirements of floodplain meadows. The nature of the drainage also depends on soil type. The classic soil profile of floodplain meadows is one of alluvium (silt deposited by floods) lying over a coarser deposit such as gravel. Less often, floodplain meadows are found on peat soils where drainage is governed by a system of shallow gutters connected to drains surrounding each field. Peat sites tend to have a higher summer water table and are more likely to support the plant communities typical of damper conditions. Where mineral and peat soils meet, a different pattern of plant communities may be found, as at Moorlinch and Wet Moor on the Somerset Levels where the peat has a clay topping. The nutrient dynamics of floodplain meadows are also important in shaping the vegetation. The removal of the hay crop results in a loss of fertility, which is then balanced by the sediment deposition and nutrients from floodwaters. Chapter 6 provides more information about floodplain-meadow nutrient cycles. Evolution and historic management Woodland clearance during the Neolithic period (c. 4,000 to 2,500 BC) probably resulted in a rise in floodplain water levels. The intensification of cultivation in upper catchments during the Iron Age (c. 800 BC–50 AD) and the Roman period (c. 50–AD 410) may have increased silt and water run-off and led to greater deposition of alluvium on land adjacent to rivers. This may have accelerated the development of large expanses of flat floodplain through the infilling of old river channels and stream beds with silt (McDonald 2007a). 2 Floodplain Meadows – Beauty and Utility. A Technical Handbook Chapter 1 Introduction Floodplain meadows differ greatly in size, ranging from just a few hectares (e.g. often those adjacent to a small stream that still receives floodwaters) to several hundred hectares (e.g. those associated with major river systems). Left: North Meadow, a medium- sized floodplain meadow (44 ha) and National Nature Reserve in Wiltshire. © Rob Wolstenholme Right: Yarnton Meadow, a larger floodplain meadow (86 ha), Oxfordshire. © Mike Dodd Once riparian woodland had been cleared, mire vegetation probably dominated on floodplains. Increased silt deposition and the development of active farming, including drainage and the introduction of mowing and grazing, led to the development of floodplain grassland. It is thought that typical floodplain meadows are around 1,000 years old. Since then, a long history of traditional management has resulted in the distinctive character of floodplain meadows as we know them today. This historical management is described in Chapter 3. Management, restoration, creation and monitoring One of the objectives of this handbook is to raise awareness of the sensitivity of floodplain-meadow plant communities to changes in water level, management and soil fertility to help conserve the few remaining species-rich floodplain meadows. The handbook is also a call to arms to prevent further fragmentation of this habitat and encourage restoration and creation where possible. In addition to providing new habitat, this will increase the resilience of the existing areas. Chapter 9 and Chapter 10 provide information on these aspects and include relevant case studies. Monitoring of sites and new projects is necessary to increase understanding, determine success and identify Monitoring soil: measuring water levels in a dipwell using a problems. Chapter 11 provides guidance on how to go about buzzing stick. © Emma Rothero monitoring and interpreting the data collected. Floodplain Meadows – Beauty and Utility. A Technical Handbook 3 Chapter 1 Introduction Using this handbook Nomenclature The plant nomenclature used in this handbook follows the This handbook provides practical information about third edition of the New Flora of the British Isles (Stace 2010). managing and restoring floodplain meadows, with an Vernacular names are used in the text, with scientific names emphasis on case studies and examples. This is combined given in the Nomenclature. Vernacular names are also used with relevant technical information to facilitate background for NVC communities (see box). These are based on those understanding of the issues involved. The information has developed by John Rodwell for the Countryside Council for been collated through many years of scientific study carried Wales (now Natural Resources Wales). out by the Floodplain Meadow Partnership and through its links to restoration and community-based projects across the UK. It is intended to be accessible and informative for anyone managing or restoring floodplain meadows, or with an interest in the many other important aspects of floodplain meadows that are touched upon. The National Vegetation Classification (NVC) In this handbook, the NVC is used to help describe plant Within the NVC, the definition of communities and sub- communities in terms of their typical species composition, communities is based on the species content of a very large management history and environmental requirements. number of samples. The samples are analysed and grouped However, the value of floodplain meadows lies in the mix (e.g.