ENVIRONMENTAL-EFFECTS OF LAND-USE CHANGE, AS IDENTIFIED BY HABITAT RECORDING - A CASE-STUDY IN THE LLYN PENINSULA, WALES

A base-line environmental survey in 1972 was repeated in 1987 to test the effectiveness of the methodology in detecting environmental change and in predicting future change. In both cases, the habitats were recorded in a 30 m radius "quadrat" in each of Llŷn's 410 constituent km2 squares. Fifteen per cent of the area had changed. Improved grassland showed the greatest gain (6·3% of Llŷn), the greatest losses being in arable (1·6%) and marsh (1·9% of Llŷn or 27% of its 1972 cover) habitats. Habitat change was significantly greater at lower altitudes, lesser slopes, gley soils and near the centre of population. In 1972 Llŷn could be divided, by its habitat associations, into upland grassland, improved grassland and wetland groups. By 1987 these became polarized towards an upland and a lowland group only. Agricultural census data showed a marked increase in grassland and in stock rearing, but a decrease in crops. Farm size had increased and farm numbers decreased. This agricultural improvement of economically suitable areas had, by the consequent loss of habitats, increased the uniformity of Llŷn; thus, the two main habitat associations. If land management practices remain the same, it is predicted that there will be a loss, mainly to improved grassland, of 43% of the marshland present in 1987 by the year 2002. There will also be increased losses in other semi-natural vegetation. However, the designation of Llŷn as an Environmentally Sensitive Area should ensure a slowing down of such losses: the method described here provides a means of testing the effectiveness of such a designation. It also demonstrates the importance to nature-conservation of examining changes in large areas rather than in designated sites only. © 1992 Academic Press Limited.