Fen Management Handbook - Scottish Natural Heritage

78
An example of the consequences of unmanaged fen succession
Aughnadarragh Lough in County Down, Northern Ireland, has been
designated as an ASSI for its fen vegetation communities and its marsh
fritillary butterfly population. The diagram below shows the degree of
successional change from 1953 to 1996. Even in this relatively short
period of time, the area of open water has significantly decreased, the
fen communities around the open water have changed in extent and
distribution and the amount of scrub within the ASSI boundary has
increased from 32% to 47%. If left unmanaged, the entire area will
eventually become wet woodland and the important fen communities
that support the rare marsh fritillary butterfly will be lost.
1953
32.2%
1996
46.7%
Diagrammatic maps of habitat change at Aughnadarragh Lough, Co. Down
Kebble Fen on Rathlin
Island just off the north
coast of Northern
Ireland is a transitional
basin fen. The coloured
lines show how part of
the fen vegetation has
risen above the level of
ground water influence
where specialised
bog plant species
are colonising the
ombrotrophic peats that
are fed by rain water
alone. (B. Hamill)