The ecological status of grasslands on lowland farmlands in western Ireland and implications for grassland classification and nature value assessment

The identification and protection of High Nature Value (HNV) farmland is an objective of the European Rural Development policy which has yet to be met by Member States. Remote sensing and models based on farm statistics are commonly used to identify HNV farmland. Use of datasets such as Corine Landcover Classes is widespread but it has been acknowledged that such datasets can significantly overlook fine-scale biodiversity features. In countries where farmland is predominantly grass-based, there is an added difficulty in distinguishing between grassland types without undertaking field-scale survey work. This study was conducted to improve our knowledge of grassland biodiversity on lowland farms with a view to helping assess their potential conservation value in a High Nature Value farmland context. We analysed the grassland species composition of 603 fields on 32 lowland farms and investigated their relationship to management, ecological and spatial descriptors. Non-metric Multidimensional Scaling (NMS) and Multi-Response Permutation Procedure (MRPP) analyses of the grasslands and their ecology on these farms revealed a continuum between semi-natural and improved agricultural grasslands, including an intermediate Semi-Improved Grassland type. This gradation from improved to semi-natural grassland highlights the biodiversity variation that occurs on farms that are frequently considered to be of low nature value. Statistical analyses showed that management practices, and especially soil fertility, were most strongly associated with grassland type. The detailed description of the grasslands that occur on these lowland farms has the potential to provide a better assessment of the overall nature value of a farm, potentially aiding the identification of Type 2 High Nature Value farmland. Before this can be achieved, however, there is a need to amend the grassland classification system used in Ireland in order that intermediate semi-natural grassland assemblages can be identified at the field level. Field surveys are necessary for this level of detail.