Impact of Livestock on Hill Environment

Abstract

The hill and mountain landscape of western Ireland is an area of high scenic value as well as contributing to the livelihood of local farmers mainly through extensive grazing. Measures that were intended to support lamb prices led to increased ewe numbers. Public concern attributed this increase to an apparent deterioration in the status of the semi-natural vegetation and to an increase in the rate of soil erosion. In the absence of an existing databank, Teagasc undertook a research programme to quantify the impact of hill sheep on the semi-natural vegetation, the progress of soil erosion and changes in certain weather elements e.g. ‘driving rain’. A detailed database of the physical background (physiography and soils) of the Teagasc hill sheep farm, Leenaun, was compiled on the basis of a grid, 100 m x 100 m. Changes in the frequency of vegetation on the unimproved hill were monitored, 1995-2002, by point quadrat. Ten permanent exclosures representing the main vegetation types and a controlled grazing experiment on the upper steep slope were established. Sequential aerial photography (1973/7-1996/8) for selected sites in western counties and wind and rain data (1957-2000) for five western synoptic stations were obtained. The classification of the peatland and heathland habitats was considered. Analysis of data highlighted a range of issues among which were the physical complexity and fragility of the landscape, the sustainability of the hill sheep system on the Teagasc hill sheep farm, the beneficial effects of controlled grazing, the progressive erosion of hill soils and an increase in high intensity levels of ‘driving rain’. The classification of the habitats, peatland and heathland, should encompass other forms of biodiversity as well as flora. The sustainable use of this landscape requires a deep knowledge of the of the grazing management system, which increasingly involves part-time farming, and its impact on the soils and semi-natural vegetation.