ENVIRONMENTAL SURVEY OF HEDGEROWS
A hedgerow is defined as ‘a line of one or more woody species, which may contain gaps, and includes associated vegetation of adjacent banks, ditches and/or field margins’ (http://www.hedgelink.org.uk). Hedgerows are one of the most characteristic features of the British countryside. Of great importance visually, culturally and historically, they provide a rich habitat for many of our native species of plants and animals. Over the years hedgerows have suffered as farming and land use practices have changed. The total length of hedgerows decreased by 28% in Britain between 1945 and 1974 (Vincent, 1990). This was followed by a net loss of 23% hedgerows (about 130,000 km) between 1984 and 1990. Between 1978 and 1990 on average one plant species was lost from each 10 metres of hedge, an 8% loss of plant species diversity (Department of Environment, 1994). Hence, ancient and species-rich hedgerows have now been identified as ‘priority habitats’ (The UK Biodiversity Steering Group, 1995). Research and action to protect these features of great importance is now a national priority. Many of the wildlife organisations are at present actively involved in species recording and drawing up action plans for the protection and preservation of hedgerows. Walmgate Stray is a remnant of York's historic landscape. It covers the marshy area of Low Moor and two sections either side of The Retreat. Walmgate Stray is an area of around 32 hectares (79 acres) of open pasture, of which part is the ancient common of Low Moor, which was enclosed in 1757 but probably has its origins in the 13th century or earlier. Following the abandonment of small, isolated parcels of common land elsewhere in Walmgate Ward, additions were made to the area of Walmgate Stray during the 1820s. Walmgate Stray contains a range of archaeological features surviving as earthworks dating from the medieval period to the Second World War (http://www.pastscape.org.uk/hob.aspx?hob_id=1403469). The aim of this report is to assess the status of the hedgerows on Walmgate Stray, in particular in terms of their value for biodiversity and the variation in hedgerows with respect to hedge types, condition and management, and in relation to natural area. And also to evaluate the strengths and weaknesses of the OPAL Biodiversity survey methods and the Defra Hedgerow survey methods. Comparing the results for hedgerow status and condition obtained using two different survey methods.
In this survey two different methods were used to assess the value of a specific 30 meters length of hedgerow on Walmgate Stray. The survey followed the methodology described in the OPAL and DEFRA Hedgerow Survey Guides. The OPAL Biodiversity survey was designed to engage people with no previous experience in a simple assessment of the biodiversity of the hedgerows. There are four sections of the OPAL Biodiversity survey. Further details of the survey method can be found on OPAL website http://www.opalexplorenature.org/BiodiversitySurvey. The Defra Hedgerow survey was designed for use by more experienced observers either those who have done this sort of assessment before, or people who would have received at least half a day of training before taking records. Further details of the survey method can be found on: https://vle.york.ac.uk/@@/D16D814A694A2579E51D7FF844BFA750/courses/1/YOPEN-000797/content/_587477_1/hedgerow-survey-handbook.pdf.
The hedgerow field surveys were undertaken on the 27th October 2011. 30m section of the hedgerow were surveyed.
Four people have assessed the whole 30 meters length of hedgerow using sections from the Defra Hedgerow survey methods and five pairs of students have selected a 3meters section of this 30 meters hedgerow and assess it using the OPAL survey methods. Those five section (3 meters) within the whole 30 meters have been equally spaced along the 30 meters length.
There was a wide range...
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