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Invasive Species on Irish Peatlands

Peatland as a potential habitat for colonisation by invasive species is restricted due to its characteristics. The high moisture content of the peat soil promotes a very acidic substrate, of low nutritional value which acts as a natural control for many invasive species. However if this habitat is altered, particularly by human activity such as drainage, it becomes a highly suitable environment for rapid colonisation by certain invasive species. To date, the main species that have caused problems for peatland conservation include Rhododendron (Rhododendron ponticum), Pitcher plant (Sarracenia purpurea) and a number of conifer species. Both Rhododendron and Pitcher plant can exclude the native bogland flora by competing for space. Once established both species can spread quickly. Conifer trees that become established on a bog surface have the additional effects of causing drying out and increased shading which transforms the bog surface into an unsuitable habitat for peatland flora, and ultimately creates conditions suitable for woodland. Boggy ground which has been reclaimed for agricultural purposes and subsequently abandoned provides an ideal habitat for Gunnera tinctoria. This species has become a particular problem on Achill Island, Co. Mayo.

The table below shows the number of peatland sites of conservation importance that are known to be impacted by invasive plant species. IPCC's sites database indicates that 84 conservation worthy peatland sites are affected by alien species. The overall trend is likely to be an increase in invasive species on peatlands, in part as a result of the on-going drying out process caused by drainage associated with turf cutting and the spreading of pines from adjacent plantations. A survey by Fernandez et al, (2005) found invasive species on 35 out of 48 raised bogs surveyed in the Irish midlands. The most common invasive species surveyed were Pinus contorta, Rhododendron ponticum and Sarracenia purpurea.

The table shows the number of conservation worthy peatlands in the Republic of Ireland threatened by invasive species. Source: IPCC'S Peatland Sites Database 2009.

Invasive Species	Fen	Raised Bog	Blanket Bog
Gunnera tinctoria	-	-	3
Picea abies	1	-	-
Picea sitchensis	3	6	1
Pinus contorta	-	5	1
Pinus sylvestris	9	29	-
Sarracenia purpurea	2	8	1
Sarracenia flava	-	1	-
Rhododendron ponticum	10	7	10

The priority actions for tackling the issue of invasive species on peatlands in the Republic of Ireland are set out in the table below:

Actions Needed to Control Invasive Species on Peatlands	Priority	Timescale On-going Short (0-3 years) Medium (3-5 years) Long (5-10 years)
Take an all Ireland approach to controlling invasive species on peatlands.	High	On-going
Incorporate measures for the eradication of alien plant species in all peatland management.	High	Medium
Assess the ecological and economic impact of invasive species in Ireland in order to plan and execute cost-effective strategies for their control and eradication.	Medium	Medium
Raise awareness through education and public awareness programmes of the effects of invasive species on our natural environment. In particular attention should be drawn to preventing spread and the means of control.	High	Long
Incorporate measures for the prevention and eradication of invasive species into agri-environment schemes and into Local Biodiversity Action Plans.	High	Medium
Use only native flora in all publicly funded planting including infrastructure projects and in public places.	High	On-going
Ban the sale of known invasive plant species such as Gunnera tinctoria and Rhododendron ponticum for horticultural purposes nationwide.	High	Short
Determine the distribution of established invasive species on peatlands and monitor their expansion.	Medium	Medium
Report all sightings of invasive species to Invasive Species Ireland.	High	On-going
Prevent the spread and new introduction of invasive species through collaboration with government, academic, NGO and industry groups.	High	On-going
Provide an early warning system to notify site managers of range expansion or new introductions of invasive species.	High	Short

Source Citation
Malone, S. and O'Connell, C. (2009) Ireland's Peatland Conservation Action Plan 2020 - halting the loss of peatland biodiversity. Irish Peatland Conservation Council, Kildare.

Expanding on the content of the IPCC Action Plan 2020
Please follow the links below to further information from the IPCC Action Plan 2020.

Peatlands 2020 IPCC Conservation Action Plan Summary

Extent and Utilisation of Irish Peatlands

Designation of Peatlands of Conservation Importance

Halting the Loss of Biodiversity

Peatland Site List of Conservation Importance in Ireland

Peatland Habitat Loss

Over-Exploitation of Peatlands for Peat

Peatlands and Climate Change

Nutrient Pollution of Peatlands

Invasive Species and Peatlands

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