Monitoring and Assessment of EU Habitats Directive Annex I Priority Habitat Petrifying Springs, 2025

Denyer, Joanne

Publication

Monitoring and Assessment of EU Habitats Directive Annex I Priority Habitat Petrifying Springs, 2025

Denyer, Joanne

Citation

Denyer, J. (2025). Monitoring and Assessment of EU Habitats Directive Annex I Priority Habitat Petrifying Springs, 2025. Irish Wildlife Manuals, No. 160. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage, Ireland.

Abstract

This project involved the survey, review and Conservation Status Assessment of petrifying springs in Ireland. Petrifying springs with tufa formation (Cratoneurion) (EU Habitat code *7220) are listed as a priority habitat in Annex I of the EU Habitats Directive (92/43/EEC). A field survey of 42 petrifying springs sites was undertaken in 2023-2024, of which 39 were located in SACs. The sites were selected to be a representative sample of petrifying springs in Ireland. They were located in 21 counties with 14 coastal sites and 28 inland sites. At each site, petrifying spring locations were mapped and detailed plots undertaken in a selection of petrifying springs. Data were collected on indicator species (vascular plants and bryophytes), water chemistry, tufa formation, water flow and potential impacts such as trampling, grazing and modifications to water flow. A review of recent literature, reports and other data sources was also undertaken to obtain additional data on new and existing petrifying spring sites in Ireland. The data included new locations for petrifying springs, updated information on known sites and data on petrifying spring condition. Data from the project (field surveys and data review) added 237 new spring points to the database. This resulted in a dataset with 679 petrifying spring points, from 190 sites in Ireland. In the field survey, a total of 176 plots were recorded in petrifying spring flushes, seepages, springheads and streams. The most frequently recorded petrifying spring vegetation communities were Group 1 Eucladium verticillatum-Pellia endiviifolia tufa cascades, which have high tufa formation and low species diversity, and Group 6 Carex lepidocarpa small sedge springs, which have low tufa formation and high species diversity. The High conservation value community, Group 8 Saxifraga aizoides-Seligeria oelandica springs, was recorded from three sites. A total of 10,4158 m2 of petrifying spring habitat was recorded from the 42 field survey sites. The sites were ranked according to the Conservation scores of the petrifying springs present. Three sites have Outstanding ranking, these are Arroo Mountain SAC, Ben Bulben, Gleniff and Glenade Complex SAC and Black Head-Poulsallagh Complex SAC. Area, Structure and Functions and Future Prospects were assessed for each field survey site. Water pollution was a major factor determining site condition, leading to low numbers of positive indicator species. Twenty-one sites (50%) had a Favourable overall conservation assessment; 14 sites (33%) had an Unfavourable-Inadequate assessment and seven sites (17%) had an ‘Unfavourable-Bad’ overall site assessment. The western sites tended to have higher petrifying spring area than the eastern sites (particularly in upland areas). Therefore although only 50% of sites were in Favourable condition, 77.38% (0.08km2) of the total surveyed area was in Favourable condition. 0.02 km2 (18.42%) of the area was in Unfavourable-Inadequate condition and 0.004 km2 (4.2%) of the area in Unfavourable-Bad condition. A National Conservation Assessment (NCA) was undertaken in 2024, using the 2023 field survey data and data from the petrifying spring data review. The overall NCA for petrifying springs is Unfavourable-Inadequate, with a Stable trend. Range and Area were assessed as being Favourable. Both have increased since the last assessment (2019), but this is due to more complete data being available. Whilst there have been small losses of habitat area within the reporting period, these are small in comparison to the overall Range and Area and the trend is reporting as ‘Stable’ for both. Structure and Functions are considered to be Unfavourable-Inadequate, with poor Future Prospects, as 33% of petrifying spring area was in Unfavourable condition. The most frequent criteria which failed the Structure and Functions assessment were: positive indicator species (10% plots); nitrate (8% plots); and, negative bryophyte species (6% plots). These are frequently linked, as elevated nitrate levels can cause an increase in negative bryophyte species and a decrease in positive indicator species. The key pressures recorded in the current assessment relate to water quality and changes to hydrology (groundwater pollution, groundwater abstraction, drainage and modification of hydrological flow). Another key pressure is lack of management, leading to petrifying springs becoming overgrown with tall vegetation. Recommendations include hydrogeological investigations, further site surveys and the undertaking of conservation measures.