Natural Heritage Areas (NHAs) for Calaminarian Grassland: Selection Criteria

Abstract

Calaminarian Grassland vegetation is characterised by the presence of metallophyte plants, i.e. plants that can tolerate high levels of heavy metals. In Ireland, metallophyte vegetation no longer occurs naturally, but it may develop locally in habitats created by past mining activities, particularly on old copper or lead mine spoils. Survey work in 2006, 2008 and 2018 has found that such vegetation can support some very rare bryophyte species (mosses and liverworts), several of which are threatened with extinction in Europe, and has concluded that only 6.2 ha of Calaminarian Grassland habitat remains in Ireland. Calaminarian Grassland is listed under Annex I of the EU Habitats Directive and five Special Areas of Conservation (SACs) in Ireland are selected for this habitat as a qualifying interest. This report aims to identify and rank the most important mine sites that should be considered for protection as Natural Heritage Areas (NHAs). It uses four selection criteria (rare bryophytes, area of Calaminarian Grassland, structure and functions of vegetation and occurrence within existing designated areas) and applied these criteria to 29 mine sites. Results show that seven of the 12 top- ranked mine sites occur within SACs and that one is within a Special Protection Area (SPA). Another mine site, ranked further down the list, is also within an SAC for which Calaminarian Grassland is a qualifying interest. These nine mine sites are recommended for designation as biological NHAs under habitat Theme ‘Grassland and Marsh’, based on the presence of Calaminarian Grassland. A further four mine sites, with no other site protection status, would also benefit for consideration as biological NHAs.