Ecosystem Accounts - Peatlands and Heathlands 2018

This CSO frontier publication is part of a series of thematic publications that the CSO plans to publish under Ecosystem Accounts. It aims to provide preliminary information on Irish peatlands and heathlands regarding (i) spatial extent; (ii) aspects of condition; and (iii) spatial extent under restoration and rehabilitation programmes. These accounts are provisional. More detailed ecosystem accounts on Irish peatlands and heathlands will be compiled in future editions of this publication, pending data availability and methodological developments.

What are peatlands?

Peatlands are freshwater wetland areas where peat soil occurs naturally¹. Peat soil is soil characterised by the accumulation of organic matter called peat over a depth of at least 45cm on undrained land and 30cm on drained land². Peat derives from dead or decaying plant material under high water saturation conditions¹. In Ireland, peatlands can be divide into two main categories: bogs and fens^2,3. Based on the Heritage Council Classification (Fossitt, 2000)³, each category can be further divided as follows:

Categories of peatlands	Sub-categories of peatlands	Description
Bogs	Raised bogs	Location: Keelogues Bog; Taken by: Peter Foss	Bogs shaped like a dome or elevated above the surrounding land receiving water from rainfall. Raised bogs have an average peat depth of 7m and are mainly located in the midlands2.
	Blanket bogs	Rain-fed bogs with an average peat depth of 2.5m. Blanket bogs are restricted to oceanic areas of high levels of rainfall throughout the year and no distinctly dry summer period2. They are divided into:
		Location: Owenirragh; Taken by:Florence Renou-Wilson; Source: BOGLAND final report2	Atlantic (or lowland) Blanket bogs: Found on flat or gently sloping ground in wetter regions along the western seaboard below 150m altitude, where the annual rainfall exceeds 1250 mm3.
		Location: Fiddandary; Taken by: Florence Renou-Wilson	Mountain (or upland) Blanket bogs: Found on flat or gently sloping ground in Irish hills and mountains above 150m altitude3.
Fens	Rich Fens	Location: Sumerhill Lough; Taken by: Peter Foss	Usually found over areas of limestone bedrock, this peat-forming habitat is fed by groundwater or flowing surface waters that are at least mildly base-rich or calcareous3.
	Poor Fens	Location: Windy Gap; Taken by: Peter Foss	Peat-forming habitats fed by groundwater and flowing surface waters that are acidic. Poor fens have a very limited spatial extent in Ireland3.
	Transition mires and quacking bogs	Location: Faltagh; Taken by: Peter Foss	Extremely wet peat-forming systems with characteristics lying between poor and rich fens3.

What are heathlands?

Heathlands are defined as habitats covered with open low-growing vegetation composed of at least 25% dwarf-shrubs, such as heather, or where mosses dominate in the case of montane heath³. Based on the Heritage Council Classification (Fossitt, 2000)³, Irish heathlands can be divided into three categories:

Categories of heathlands	Description
Dry heaths	Location: Raheenkyle; Taken by: Thomas Gorman	Irish dry heaths can occur on drained, nutrient-poor and acidic mineral soils or shallow peat soil (typically <50cm deep) on sloping ground4. They can be divided into dry siliceous and dry calcareous heaths3. The difference lies in the presence of lime-loving plants in dry calcareous heaths. They are absent in dry siliceous heaths3.
Wet heaths	Location: Knockroe; Taken by: Thomas Gorman	Heathlands occurring on peaty soils and shallow wet peats of 15-50 cm depth in average3,4. They are intermediate habitat between dry heaths and blanket bogs4. As such, wet heaths can be found closely associated with both habitats4 and are also considered as peatlands1 .
Montane heaths	Location: Slievenaglogh; Taken by: Peter Foss	Montane heaths occur at high altitudes on mountains and other very exposed locations in the uplands or on the coast. They are usually associated with shallow mineral or peat soils4.

Peatlands, heathlands and mosaics?

Although classified here as heathlands, by definition wet heaths are also peatlands (e.g. with wet conditions and presence of peat soil). With dry heaths and blanket bogs, they generally form intimate mosaics (i.e. areas with multiple types of habitats)^2,3. Distinguishing between them can sometimes be difficult.

Peatland and heathland ecosystems therefore have a complex relationship which is also reflected in the similarity of the services they provide. Climate regulation, habitats of importance for biodiversity, flood regulation, recreational experiences and exceptional conservation conditions for archaeology are all examples of services on which the well-being of society and people rely. These will be explored in future editions of this publication.

To acknowledge the connection of structure and functions between both ecosystems, we report on them together in this publication. 

The first step in compiling information on Irish peatlands and heathlands is to determine their spatial extent: Where are they? How much is there? Answering these questions presents a significant challenge.

Spatial data on peatlands and heathlands in Ireland have been collected by a number of organisations for a variety of purposes, at a range of different spatial scales, and over different time periods. Compiling these data to produce a consistent map at a national level is not straightforward. Given this difficulty, and in the absence of a national ecosystem map, two data sources have been used in this publication: the CORINE Land Cover dataset and the data reported by the National Parks and Wildlife Service (of the Department of Housing, Local Government and Heritage) under Article 17 of the EU Directive on the Conservation of Habitats, Flora and Fauna (92/43/EEC) (hereafter Article 17 - EU Habitats Directive).

CORINE Land Cover

The best available data for mapping peatlands and heathlands at national level is the CORINE (Co-ORdinated INformation on the Environment) Land Cover (CLC) dataset from the Environmental Protection Agency (EPA). CLC provides national maps of land cover and change in land cover for five different years starting from 1990 onwards. It is based on the interpretation of satellite imagery data which the EPA enhanced using in situ national land use data obtained from different organisations such as the Department of Agriculture, Food and the Marine, the Forest Service and Coillte. Since its 2012 version, CLC has been embedded in the European Union’s Earth observation programme Copernicus.

Two land cover classes of CLC are relevant for mapping peatlands and heathlands: “Peat bogs” and “Moors & Heathlands”. Although moors and heathlands are mapped together in CLC, moors is not a term commonly used in Ireland. “Peat bogs” encompasses raised bogs, blanket bogs and quaking bogs while “Moors & Heathlands” includes wet heaths, dry heaths and montane heaths (Table 1.1). Fens and transitional mires are part of another CLC class called “Inland Marshes”. As this category also includes habitats that are not considered as peatlands and heathlands (e.g. humid meadows, inland saline marshes), they will not be reported in this publication when using CLC dataset (Table 1.1). Note however that natural fens are rare in Ireland as 97% have been drained for agriculture⁵.

The use of the CLC dataset presents several advantages, including the ability to map the distribution of Peat bogs and Moors & Heathlands at a national level; examine change over time; compare with other land cover types; and even comparisons across European countries. To examine these ecosystems in more detail, however, more granular data are needed.

Article 17 – EU Habitats Directive data reported by the National Parks and Wildlife Service

Under Article 17 of the EU Directive on the Conservation of Habitats, Flora and Fauna (92/43/EEC), the National Parks and Wildlife Service (NPWS) report the conservation status of specific habitats to the European Commission. These habitats are known as Annex I habitats as they are listed under Annex I of the Directive. A lot of data on habitats is reported under Article 17, including their geographical range, spatial area, structure and functions, and conservation status.

Annex I habitats include the types of peatlands and heathlands described earlier: raised bogs, blanket bogs, transition mires and quaking bogs, rich fens, wet heaths, dry heaths and montane heaths (Table 1.1). Article 17 - EU Habitats Directive data provide a more detailed breakdown of the spatial extent than the CORINE Land Cover (CLC). However, these data are derived from scientific surveys directly commissioned by NPWS and also other sources. Therefore, the absence of a habitat at a given location can be due to either the absence of the habitat at this location or the lack of sampling and/or other data sources for this location. Moreover, these data do not cover the highly drained, cutover and cutaway bogs⁶. Hence the additional use of CLC to supplement Article 17 - EU Habitats Directive data.

Summary: what data to analyse peatlands and heathlands?

In this publication, we report the spatial extent and condition of peatlands and heathlands based on two different datasets:

1. CORINE Land Cover (CLC) which offers a broad national distribution of peatlands and heathlands based on “Peat bogs” and “Moors & Heathlands” classes.
2. Article 17 - EU Habitats Directive data reported by the National Parks and Wildlife Service to map Annex I peatland and heathland habitats.

Table 1.1 below summarises what is included in each of the CLC and Article 17 - EU Habitats Directive data that are used in this publication:

The statistics in this report have been produced in line with the System of Environmental Economic Accounting - Ecosystem Accounting framework (SEEA-EA). The SEEA-EA aims at mainstreaming environment into economics taking an ecosystem approach. This framework proposes standards for the compilation of ecosystem accounts to record the stocks and flows of ecosystem services, as well as tracking their changes over time.

Ecosystem accounting is a relatively new area which raises a number of questions: What are ecosystems? Why are they important? What is Ecosystem Accounting? Answers to these questions, along with an introduction to the concepts behind Ecosystem Accounting, can be found in the CSO Information Note on Ecosystem Accounting.

1. National Peatlands Strategy. (National Parks and Wildlife Service. Department of Arts, Heritage and the Gaeltacht, 2015).

2. Renou-Wilson, F. et al. BOGLAND: sustainable management of peatlands in Ireland - final report. (Environmental Protection Agency, 2011).

3. Fossitt, J. A. A guide to habitats in Ireland. (The Heritage Council, 2000).

4. The Status of EU Protected Habitats and Species in Ireland - Volume 1. (National Parks and Wildlife Service, 2019).

5. Foss, P. Study of the Extent and Conservation Status of Springs, Fens and Flushes in Ireland 2007. (National Parks and Wildlife Service, 2007).

6. The Status of EU Protected Habitats and Species in Ireland - Volume 2. (National Parks and Wildlife Service, 2019).

Go to the next chapter: Spatial Extent and Condition based on CORINE Land Cover