Identification and quality assessment of high nature value (HNV) farmland in the North-West of Ireland.

Abstract

High Nature Value (HNV) farmland is farmland that is managed at low intensity and which supports a high diversity of flora and fauna. HNV farmland has been acknowledged as being essential to the conservation of biodiversity in Europe. In recent years, as agricultural support payments have progressively incorporated measures to support farmland biodiversity, the identification and enhancement of HNV farmland has become increasingly important. To date methods of identifying HNV farmland have been highly variable amongst E.U. Member States or even within countries. Additionally, methods of measuring the quality of HNV regions have been limited and have had variable successes. This provides the incentive for this study which examined the habitat composition of 60 farms in the Counties Mayo, Sligo and Leitrim in the north-west of Ireland. This data was used to aid the identification of HNV farmland in Ireland and development of HNV grassland quality assessment. The first part of this study works towards developing a nature value index for pastoral farmland in a Northern Atlantic biogeographic region. Using data from 30 farms, a simple 10 point nature value index was developed following a five step statistical process. The benefit of this index is that it is based on three easily measured variables i.e. (i) proportion of improved agricultural grassland on a farm, (ii) stocking density and (iii) length of linear habitats per hectare on a farm. These values are combined to assign a nature value score to a farm. This score has the potential to be used as an identification tool for HNV farmland and could also be used to inform targeting of agri-environment supports and monitoring of the success (or failures) of measures within such schemes. The second part of this study aims to increase the understanding of the farm types that are associated with HNV landscapes. Using farm biodiversity values and farm management values, four distinct farm types within a HNV landscape have been identified. These farm types represent the gradient of management intensities in a HNV landscape. This information can be used to inform the development of future agri-environment schemes and highlights those areas which may benefit from targeted supports to enhance and maintain biodiversity levels. The final section of this study examines the vegetation groupings associated with HNV farmland and investigates the potential of assessing the floristic quality of fields in HNV landscapes. Four primary vegetation groups associated with HNV farmland were identified and described using cluster analysis and indicator species analysis. Additionally, a measure of the quality of fields within this landscape was developed based on HNV grassland indicator species. This measure of quality was found to relate to the nature value index developed in part one of this study. The use of the quality score in combination with the nature value index provides a holistic measure of the biodiversity value of HNV farmland in pastoral regions. These measures have the potential to be used as part of targeted agri-environmental schemes.