Recovery of the vegetation of a cutover raised bog in Ireland following rewetting measures

Abstract

Abstract:Restoration works involving the blocking of drains with peat dams and the construction of a marginal berm along the edge of the cutover on Killyconny Bog in Co. Cavan, Ireland were carried out in the mid to late 2000s. Vegetation change between a pre-restoration baseline and surveys carried out 7–13 years post-restoration are assessed and demonstrate that 5.0ha of Sphagnum-rich regenerating bog vegetation has developed across the 26.9ha study site since restoration works were implemented. Although the restoration measures have triggered Sphagnum regeneration, increased the number of positive indicators species of Active Raised Bog (ARB) and initiated the process of peat-formation, the vegetation still lacks the presence and/or abundance of some critical ARB indicators. Moreover, 56% of the site is still dominated by vegetation with a low Sphagnum cover; 44% by Calluna vulgaris dominated vegetation and 12% by Molinia caerulea dominated vegetation. The key importance of topography in determining restoration potential is highlighted as extremely fine variations in topography appear to have resulted in significant differences in the vegetation that has developed. Any further increase in the area of regenerating bog on the cutover is likely to require enhanced restoration works such as cell bunding and additional marginal berms, the design of which will be informed using the modelling techniques outlined. Although not yet considered ARB habitat, the 19% of the Killyconny cutover that is classed as regenerating is clearly of conservation significance as a peat-forming habitat that supports assemblages of several specialist species and demonstrates how restoration works that raise water levels can initiate Sphagnum regeneration in a relatively short period of time.