Results of a monitoring survey of the Annex II species Saxifraga hirculus (Marsh Saxifrage) in Ireland 2015?2018

• Main Authors: O'Neill, Fionnuala, Hodd, Rory, Long, Maria
• Format: Report
• Language: English
• Published: National Parks and Wildlife Service. Department of Culture, Heritage and the Gaeltacht 2019
• Subjects: Saxifraga hirculus; Marsh saxifrage; Monitoring; Annex II; EU Habitats Directive; Ecology; Conservation status; Article 17; Field survey; Lockhart; Marsh Saxifrage
• Online Access: http://hdl.handle.net/2262/89914

This report presents details of a monitoring survey conducted between 2015 and 2018 to assess the conservation status of the Annex II species Saxifraga hirculus (Marsh Saxifrage) (EU code 1528). The aims of the survey were to assess the species in terms of three parameters: Population, Habitat for the Speciesand Future prospects. Nineteen sites were surveyed, comprising 16 in Co.Mayo and three in Co. Sligo. A review of the previous baseline and monitoring surveys was undertaken as part of the project remit. The assessment criteria were generally found to be suitable. However, following population surveys a number of points were noted: absence of Sagina nodosa did not necessarily signify unfavourable habitat condition, so expert judgement was applied on a site-by-site basis; the general target for vegetation height had been set too low at ?15cm and was adjusted upwards to ?20cm; and for water level, or hydrology, to pass, a pass rate of 40% of stops was applied in the current survey, with expert judgement the final decider of whether the site?s overall hydrology was suitable or not. Population extents were determined by extensive walkover surveys and recording GPS waypoints at the outer limits of the population. These points were used to map polygon envelopes in GIS. Assessment data were recorded within monitoring plots measuring 1 m2, which were placed at several locations throughout the population. Count data from monitoring plots were extrapolated up to the population level by multiplying the values in the 1m2 plots by the area in square metres of occupied habitat mapped in GIS. Population was assessed at each site by three criteria: total number of rosettes estimated for the population, density of rosettes (average of counts from 1m2 monitoring plots), and estimated number of flowering heads in the population. Habitat for the Species was assessed by seven criteria: area of S. hirculus (target to match or exceed that measured in the baseline survey), water level, cover of Sagina nodosa (positive indicator species), cover of Molinia caerulea (negative indicator species), cover of Holcus lanatus (negative indicator species), vegetation height, and grazing (recorded on a four-category scale). Positive and negative activities were recorded at sites where they occurred. Grazing was usually seen as a positive where it occurred, although grazing by cattle was regarded as negative and sheep grazing is generally preferable for fragile S. hirculus habitat. Most of the negative pressures recorded were of a low intensity or affected less than half of the habitat at a site. However, undergrazing was regarded as a serious pressure at three sites. Drainage was a direct problem at four sites, although the effect was recorded as low intensity. Water levels at two sites were regarded as too low for S. hirculus, with vegetation tolerant of drier conditions becoming tall and rank as a consequence and out-competing S. hirculus. Climate change may become an important negative impact in the future but its intensity is currently unknown and the length of time over which a measurable impact will be seen is likewise unknown. The Population, Habitat for the Species and Future prospects assessment results were combined to produce a single overall site-level assessment for each site. Thirteen sites received a Favourable assessment, four sites were assessed as Unfavourable-Inadequate, and two sites were Unfavourable-Bad. The report concludes with a discussion of the results and recommendations for monitoring the species in the future and improving the conservation status of less favourably scored sites. The NPWS Project Officer for this report was: Deirdre Lynn; [e-mail] This IWM was edited by Deirdre Lynn & Neil Lockhart