NPWS Study of the Extent and Conservation Status of Springs, Fens and Flushes in Ireland

Foss, P.J. (2007) National Parks and Wildlife Service Study of the Extent and Conservation Status of Springs, Fens and Flushes in Ireland 2007. Internal Report, Department of the Environment, Heritage and Local Government, Ireland.

Report cover

The aim of this NPWS Fen Study was to consolidate information on the Extent and Conservation Status of Irish Springs, Fens and Flushes on existing information held by the National Parks & Wildlife Service and by other interested parties nationally.а No systematic national survey of fens has yet been undertaken in Ireland, in contrast to the situation for raised and blanket bogs. This study aimed to ascertain our current understanding of the fen resource in Ireland, and what is currently known about this resource in terms of the number of sites present,а the various fen vegetation types that occur within these sites and and the extent of each fen type.аа

The study addressed the following research objectives:а

•ааа collect and amalgamate data on known fen sites of conservation importance in Ireland from within the NPWS and following consultation with external groups;а


The fen study focused on 6 fen habitat types of conservation importance (four of which are listed in Annex 1 of the EU Habitats Directive, two of which - denoted with an asterisk - are priority habitats) in Ireland:а

7140 Transition mires and quaking bogs (Fossitt category PF3)а

7210 *Calcareous fens with Cladium mariscus and species of the Caricion davallianae (Fossitt category PF1)а

7220 * Petrifying springs with tufa formation (Cratoneurion) (Fossitt category FP1)а

7230 Alkaline fens (Fossitt category PF1)а

Poor Fens - Caricion curto-nigrae (Fossitt category PF2)а

Non-Calcareous springs - Cardamino - Montion (Fossitt category FP2)аа

These fen habitat types can be found as discrete fen communities in their own right, or in association with (or within) blanket bog, raised bog, turlough, dune slack, machair, wet heathland, wet grassland, woodland, karst areas, lacustrine and riverine habitats and systems.

A variety of data sources (reports, publications, databases and inventory lists), groups and individuals were consulted in the compilation of information for the NPWS Fen Study database, over an eight month period in 2006, both within NPWS and from externalа sources.а

The past extent of fens in Ireland is presented.а The original area of fens in Ireland is estimated to have been at least 92,508 ha.а An estimated 19,660а haа of conservation worthy intact fens, occurring in 367 discrete sites were recognised in Ireland by IPCC in 2001.аа

The total area of estimated fen vegetation recorded in the NPWS Fen Study amounted to 22,180 ha within 681 discrete sites. In total the NPWS Fen Study database holds information on 808 sites, where fen habitats are known or believed to occur.аа

In relation to the fen habitat types classified within the present NPWS Fen Study, the following number of sites and estimated area (ha) of fen vegetation have been recorded:а

•ааа 7210 *Calcareous fens with Cladium mariscus: 122 sites with a fen area of 1,486 ha

•ааа 7230 Alkaline fens: 380 sites with a fen area of 6,830 ha

•ааа Poor Fens: 379 sites with a fen area of 11,841 ha

•ааа 7140 Transition mires and quaking bogs: 173 sites with a fen area of 1,955 ha

•ааа 7220 * Petrifying springs: 112 sites with a fen area of 36 ha

•ааа Non-Calcareous springs: 33 sites with a fen area of 32 ha


Annex 1 fens (i.e. Alkaline fen, Cladium fen, Transition mire, and Petrifying spring)а which more closely relates to the fen types identified in previous studies, was estimated to cover 10,307 ha or 46% of the total fen area estimated in the present study. This is an indication that Annex 1 fens are less widespread than previously estimated.аа

The most abundant fen type found in the course of this study was Poor fen with an estimated national cover of 11,841 ha or 53% of the total area estimated in the present fen study.а

12. These fens can be categorised, in terms of their current conservation designation, as follows:а

The number and area (ha) of fens which have been designated for Annex 1аarea of 2,190 ha of designated fen habitat; representing 10% of the totalаestimated fen resource in Ireland; or 21% of the total Annex 1 fen resource estimated for Ireland

The number and area (ha) of fen sites which are within designatedаNatural Heritage Areas (NHA) or proposed candidate Natural HeritageаAreas (cNHA): 363 sites with an area of 4,384 ha; representing 20% of theаtotal estimated Irish fen resource
The number and area (ha) of fen sites which are located within designatedаSpecial Areas of Conservation (SAC) or proposed candidate Special Areasаof Conservation (cSAC): 362 sites with an area of 14,086 ha; representing 64%аof the total estimated Irish fen resourcethe NPWS Fen Study and have no current conservation designationаat present: 88 sites with an area of 3,794 ha; representing 17% of theаtotal estimated Irish fen resource

It is very probable that sites with conservation worthy fen communities exist outside of the sites which have been identified in the present NPWS Fen Study.а

To identify zones and counties where potential new fens might occur, two analyses were undertaken as part of the NPWS Fen Study; a county wetland analysis and a digital fen soils analysis.а

The county wetland analysis was designed to identify those counties most likely to contain additional fen sites (from alkaline to more acid fen types). This analysis wasа based on the past and present fen and bog resource status within the county, soil type, geology and geomorphological land form suitability, past survey work on wetlands, the number and extent of lakes present, and the number of new fens notified to the present NPWS Fen Study. This revealed the following counties which had the highest probability that additional fens might be discovered: Galway, Leitrim, Limerick, Monaghan, Mayo, Offaly, Sligo and Westmeath.а

The digital fen soils analysis compared the original and known distribution of peat soils in each county with an overlay of the existing network of conserved areas (NHA and SAC) and the fen sites identified in this study. A series of regions were identified, where fen soils occur but fen sites are lacking. Assuming favourable environmental conditions are present, these zones might be likely to reveal additional fen sites of conservation value, following a detailed fen field survey, and merit further investigation.а The counties with the most significant potential fen zones included: Clare, Galway, Kildare, Leitrim, Laois, Mayo, Offaly, Tipperary and Westmeath.

Based on the results of these two analyses, this study recommends that the following counties should be prioritised as part of any future NPWS Fen Field Survey: Clare, Galway, Kildare, Leitrim, Limerick, Mayo, Offaly, Roscommon and Westmeath.

In relation to the 808 fen sites identified in the NPWS Study, one key result to emerge is that significant gaps exist in relation to our knowledge of this resource.а Specifically, the following issues have been identified:

ааааFen type identification: our knowledge in relation to the specific fen type(s) present, is considered wholly lacking or inadequate (confusion over one or more fen types) for 268 (33%) of sites identified in the present NPWS Fen Study database.

ааааExtent of fen types: our knowledge in relation to the extent of fen type(s) present on sites, is considered wholly lacking for 102 sites (13%), and inadequate for a some furtherа 600 sites (i.e. 74%, where only estimated data on fen extent is presently available) identified in the NPWS Fen Study database.

Our incomplete knowledge of many Irish fens makes a systematic survey of existing and newly reported sites a priority, if conservation worthy sites are to be identified and the best examples put forward for conservation under the Natural Heritage Area or European Habitats Directive Natura 2000 (SAC) network.а

ай Website design Peter Foss 2012