LAUSR

Abstract High Nature Value farmland (HNVf) is managed farmland that has high biodiversity and often supports species of conservation concern. Assessing the distribution and extent of such farmlands is useful for appropriate targeting of conservation measures and supporting associated rural communities. The conservation of species and habitats within HNVf is also among the aims of the EU’s (European Union) Biodiversity Strategy and is a focus of the Common Agricultural Policy (CAP) Rural Development Programme. Data on HNVf distribution and extent is required for both policy implementations under the CAP for income support payments and reporting within the EU Biodiversity strategy. Here, we extend the scope of the methodology from a previous study by presenting a finer spatial resolution to map the likely distribution of HNVf in the Republic of Ireland using indicators adapted for the Irish context and weighted based on expert knowledge and literature. The indicators (and weighting) used were: semi-natural habitat cover (40%, from CORINE land cover), stocking density (30%, from Land Parcel Information System; LPIS), hedgerow/scrub cover (10%), river and stream density (10%), and soil diversity (10%). Indicators were included in a weighted sum model (WSM) that combined raster indicator inputs, representing relative weights and the output had a tetrad-scale (2 km × 2 km) resolution. We used various datasets (national nature designations, Irish semi-natural grasslands survey, intensive farmland points and field points with semi-natural habitats) to validate the final HNVf map. To do this, all datasets were converted from polygon to point data format by considering the centroid of the polygon as the data point and overlaid on the HNVf map to assess the possible incidence. Of the 13,660 tetrads defined as farmland in the analysis, 4602 (33.7%) had a high or very high likelihood of being HNVf. About 54% of the latter set of tetrads partly or wholly coincided with Natura 2000 sites; about 84% partly or wholly coincided with NPWS priority areas for conservation of biodiversity in agri-environment schemes, and about 53% were in upland areas (>150 m a.s.l.). Validation data representing extensive farmland systems had an increasing incidence in tetrads with higher values (HNVf likelihood); the opposite was true for validation data representing intensive farmland. The final output was combined with the NPWS priority areas for farmland biodiversity conservation because the latter represented Type 3 HNV that is poorly represented by our method (which best represents Type 1 HNV). To our knowledge, this study represents the most comprehensive method to estimate and validate the extent and distribution of HNVf in the Republic of Ireland. It indicates that a substantially higher proportion of the country is likely to comprise HNVf than previously estimated, and large areas of HNVf occur outside the Natura 2000 network, and in lowland areas. Improved knowledge of the distribution and extent of HNVf provides a valuable tool to help improve the decision-making process for policy targeting, implementation and monitoring of HNVf. The methodology presented here could be adapted by other EU countries that have relevant national-scale datasets.