Efficacy of sod removal in regenerating fen vegetation

Common Sundew (Drosera rotundifolia)

Project code 

QU08-10

Contact

Dr. Neil Reid

Project staff

& Tommy McDermott

Client

NIEA

Funding

NHRP

Client Officer(s)

Paul Corbett

Start date

01/08/2008

End date

31/10/2008

Fens support a high biodiversity but are threatened by agricultural and urban development, habitat fragmentation and hydrologic changes and are frequently mismanaged. The majority of Northern Ireland Fen ASSIs are classed as being in poor condition, suffering from a lack of positive management.
 
 Previous studies demonstrated that removal of thatch and high density grass root stocks by sod removal can be an effective management practice in encouraging the regeneration of the historical seed bank and reducing the density of invasive species such as purple moor-grass (Molinia caerulea).

Montiaghs Moss Nature Reserve is still a stronghold for the Marsh Fritillary Butterfly

The main aim of this project was to test the efficacy of ‘sod removal’ as a fenland restoration technique using an experimental approach at Montiaghs Moss Nature Reserve from 2006 to 2008. The site suffered from rank purple moor-grass coverage which out-competed herbaceous species.
 
Sod removal dramatically reduced purple moor-grass cover from 78-79% on control plots to 9-11% on sod removal plots. The cover of other grass species was also significantly negatively affected including sweet vernal grass (Anthoxanthum odoratum), meadowsweet (Filipendula ulmaria) and Yorkshire fog (Holcus lanatus).
 
 
Sod removal significantly increased the cover of species characteristic of fenlands including sedges (Carex spp.), rushes (Juncus spp.) and marsh pennywort (Hydrocotyle vulgaris and lesser spearwort (Ranunculus flammula). The removal of competition, persistence of bare peat, exposure of the historical seed bank and establishment of pioneer species resulted in sod removal plots having greater species richness than control plots.
 
It seems likely that sod removal lowered the surface of the peat restoring minerotrophic conditions, exposed the historical seed bank and stimulated the regeneration of fenland specialists.
 
There was no demonstrable effect of sod removal on devil’s-bit scabious (Succisa pratensis); the larval food plant of the Annex II listed marsh fritillary butterfly (Euphydryas aurinia). Devil’s-bit scabious was maintained at similar densities on experimental and control plots. Cconsideration should be given to artificially seeding devil’s-bit scabious to increase plant abundance.
 
Restoring minerotrophic conditions, reducing purple moor-grass dominance and increasing species richness are essential to restore fen plant communities to favourable condition. Sod removal appears to be an efficacious means by which to achieve this provided small areas are targeted in a ‘patchy’ fashion to ensure heterogeneity of habitat structure and species composition.
 
This project was funded by the Northern Ireland Environment Agency (NIEA) via the Natural Heritage Research Partnership (NHRP).

This project was funded by the Northern Ireland Environment Agency (NIEA) via the Natural Heritage Research Partnership (NHRP)

This study was published in the peer-reviewed open access journal Conservation Evidence as:
 
Reid N., McEvoy P.M. & Preston J.S. (2009) Efficacy of sod removal in regenerating fen vegetation for the conservation of the marsh fritillary butterfly Euphydryas aurinia, Montiaghs Moss Nature Reserve, County Antrim, Northern Ireland. Conservation Evidence, 6; 31-38. 
 
You can also view the final project report here:
 
Preston, J.S. & Reid, N. (2008) Efficacy of sod removal in regenerating fen vegetation. Report prepared by the Natural Heritage Research Partnership, Quercus for the Northern Ireland Environment Agency, Northern Ireland, UK.