Estimating hedgerow length and pattern characteristics in Great Britain using Countryside Survey data

A chequer-board pattern of fields is characteristic of much of lowland Britain and other parts of western Europe. The field boundaries are often composed of hedgerows which, by tradition, are regularly managed to provide a relatively compact, sustainable, stock-proof barrier. The management regimes of hedgerows are, however, extremely variable resulting in a range of features, from low, compact, dense lines of shrubs through to tall, open rows of small trees. As well as providing an agronomic benefit, this network of several hundred thousand kilometres, has been shown to be a valuable resource to wildlife and is important as an aesthetic contribution to the British landscape. Therefore, the maintenance of the British hedgerow network is important and survey is essential to monitor its continuity. The Countryside Surveys have been used as means of achieving this, as well as providing a rich source of information, for example, about landscape pattern and changes in this over time. Hedgerow data have been collected during sample-based field surveys in 1978, 1984, 1990 and 1993. National estimates of the length of managed hedgerow derived from these data showed a 23% reduction in the resource between 1984 and 1990. Much of this 'loss' appeared to be due to management regimes which have led to more overgrown hedgerows and rows of scattered shrubs. The proportion of mixed-species hedgerows increased between the two dates and there was a reduction in stockproof hedgerows but most other characteristics (e.g. height and management) remained constant. Landscape-pattern measures applied to the hedgerow network showed broad similarity across a range of landscape types in Britain although the density of hedges was greater in the pastural landscapes of the south and west. Measurement of 'connectedness', a feature of potential value in aiding species movement through the landscape, suggested that the British landscape is less-well connected in 1990 than previously. Hedgerows were found next to linear features, such as roads, as frequently as they were to any other land use. One of the most significant findings from analysis of 1984 and 1990 data was that there has been an increase in larger and more overgrown hedgerows, often to the point where they could no longer be defined as hedgerows. Overgrown hedgerows do have wildlife and other value but, to remain sustainable, hedgerows do require some degree of management. There is potential for using the Countryside Survey data further to provided better advice on the sustainable and sympathetic management of hedgerows. This is necessary to provide a rich and diverse network within a landscape or management unit. Countryside Survey hedgerow results have already been used to inform rural policy in Britain and have helped to underpin the introduction of policies and incentives which protect and enhance this landscape resource. These data are also being used to measure indicators of sustainable development and to provide a baseline against which changes in ancient and/or species-rich hedgerows can be assessed, as required in the UK Biodiversity Action Plan. The surveys have proved useful in gathering information on the hedgerows and other linear features in the British landscape. The approach could well be adapted to the needs of other countries where, for example, fencerows and roadside vegetation also provide an important ecological and landscape resource. (C) 2000 Academic Press.