An ecological study of grassland field margins in Northern Ireland

Abstract

The plant diversity of agricultural grassland field margins in Northern Ireland is assessed to provide an ecological basis for agri-environmental management. Approximately 70 per cent of the land area of Northern Ireland (NI) is used for agriculture, of which grassland, typically with hedged boundaries, comprises most. Improved grasslands are predominant, with less semi-improved grassland and a much smaller area of species-rich semi-natural grassland.

The thesis aims were to model: a) the regional ecological influence of agricultural management factors on the plant species composition of grassland field margins and b) vegetation composition along the field boundary, field margin, managed grass field spatial gradient.

The methodology was through statistically structured quadrat sampling. Multivariate ordination was carried out by detrended correspondence analysis and canonical correspondence analysis to assess the main regional and spatial explanatory environmental gradients influencing plant species composition. A hierarchical typology of Neutral grassland field margins was created with two-way indicator species analysis, to facilitate the implementation of agri-environment scheme management.

A soil fertility gradient inferred from weighted vegetation indicators for nitrogen and pH was the main regional environment gradient influencing the species composition of field margins. This gradient was related to grassland management intensity and field boundary structure. A spatial composition gradient between the field margin, field boundary and grass field was also related to field boundary structure and grassland management intensity. This highlights the spatial and temporal variability of the field margin zone as a habitat to be targeted by agri-environment schemes.

Date of Award	May 2012
Original language	English
Sponsors	Department of Agriculture and Rural Development (DARD) PhD studentship
Supervisor	Paul McKenzie (Supervisor)