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Commoge Marsh














Habitat Map | Management Plan Summary





 
Scarce Flowering Plants of Commoge Marsh

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Yellow Bartsia (Parentucellia viscosa)
















 

In the south-eastern corner of the marsh, the direct contact between a freshwater inflow and the brackish water of the lagoon provides habitat for a species-rich plant community of high botanical interest. Three nationally scarce plant species occur in this area: Dotted Sedge (Carex punctata) and Yellow Bartsia in a narrow belt of wet grassland in a transitional brackish/freshwater zone; and Chaffweed (Anagallis minima) on adjacent areas of bare mud.

 

Dotted Sedge was recorded in 15 10km squares in Ireland between 1987 and 1999 and is largely restricted to West Cork (from Glandore westwards) and South Kerry. The population at Commoge Marsh represents the most easterly known extant population in Ireland. Dotted Sedge was first recorded at Commoge in 1891, and this population has been surveyed several times in recent years. It has always been scarce at Commoge, occurring in just a few scattered clumps, and is  very sensitive to hydrological conditions in the marsh. During a sustained period of high water levels in 2003 only one clump was found.

 

Yellow Bartsia is not as restricted in its distribution as Dotted Sedge, and was recorded from 49 10km squares in Ireland between 1987 and 1999. At Commoge, Yellow Bartsia grows in areas where the sward is short, avoiding areas where the sward is longer. As an annual plant species, it can respond quickly to changes in water levels. When water levels are low, it can be very abundant at Commoge, but during the sustained high water levels in 2003, it was restricted to a small area of shoreline.

 

Chaffweed was recorded in 29 10km squares in Ireland between 1987 and 1999. Chaffweed was found on exposed mud at  Commoge in 1997 but has not been looked for subsequently. No suitable habitat for this species was present at Commoge Marsh throughout most of 2003 due to high water levels within the marsh.

 

It is likely that the plant communities of Commoge Marsh have undergone substantial changes in recent decades due to changes in the hydrological regime associated with the operational condition of the sluices. A nationally protected plant species, Borrer’s Saltmarsh-grass (Puccinellia fasciculate) was recorded from Commoge Marsh in the 1950s. However, this species was not recorded in recent surveys and conditions are no longer suitable for it. In recent years, Sea Club-rush (Bolboschoenus maritimus) and Grey Club-rush (Scirpus lacustris tabernaemontani) appear to have been invading the northern sections of the lagoon.

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Dotted Sedge (Carex punctata)

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