The first day of the Anglesey and Llyn fens LIFE conference saw a group of newly acquainted Wetland Science MSc students visit Cors Goch on their inaugural field trip...before I begin, let me get you acquainted with some interesting Wetland facts!
Looking across the fen from the top of the limestone scarp to the South West
Geological origins of the landscape and fen hydrology and statigraphy
Situated on the eastern side of Anglesey in North Wales, Cors Goch lies in a glacial eroded valley fed by lime rich springs from the limestone escarpment surrounding the fen. During the last ice-age, this part of Anglesey was covered by a thick ice sheet from the Irish Sea. A lake, Llyn Cadarn, subsequently formed in the hollowed out basin left by the glaciation.
Limestone protrudes from soil at the top of the scarp
and alters the pH of the water running into the fen
Cors Goch has been in the ownership and management of the North Wales Wildlife Trust (NWWT) since 1963 and is
designated as a Special Area of Conservation (SAC), owing the site special protection from the European Commission; the site is also protected under the ramsar convention. It was rescued from being turned into
a landfill site due to its unique conservation interests.
Over thousands of years the lake began to infill with peat,
from its margins towards the deeper water in the centre (termed
terrestrialisation). The terrestrialisation of the lake was triggered by a deposition of till from the
valley sides during the last glaciation. The resultant clay and silt
run-off from the valley sides lead to a reduction in the wave-action of the lake. As a result, conditions around the lake margins became waterlogged due to the colonisation of peat forming fen vegetation.
Looking toward the south west limestone scarp with
typical fen vegetation in the foreground
A workers millstone (plus two students) carved into the bedrock of millstone grit
on the sandstone dominated central ridge - the highest point of the basin at 3.5 meters!
Heather was frequent on the higher sandstone ridge
as the influence of the spring water had dropped quite dramatically.
The fen is divided into north-east and south-west basins by the sandstone and millstone ridge, . A change in plant community demarcates the acidic characteristics of the sandstone from the calcium influences of the limestone springs flushes. The calcium-rich water now percolating through the limestone beds serves to irrigate the fen, producing a rich variety of alkaline and calcareous fen plant communities within the basin.
Fen management and vegetation communities
The main management issues expressed by NWWT warden was;- scrub encroachment drying up the fen
- ecological succession due to scrub
- fears of the fen drying out from water loss
Peat cutting was also prevalent
until the 1920’s, but is no longer a threat to the fen. Drainage, though it
has been attempted, has not been effective, and the water level is kept high by
the restriction of the outlet. There is some surface flooding in the South
–western basin, this is thought to be a result of the natural topography exacerbated by the legacy of peat cutting.
Localised high watertable due to a natural depression and
localised historical peat cutting
The scrub encroachment witnessed on the site is a
product the natural succession being affected by the legacy of draining operations. The major
management effort within the fen involves reversing the reduction in biodiversity
that has resulted from draining activities, thus restoring early successional
habitats such as Alkaline fens and Calcareous fens with Cladium mariscus and
species of the Caricion davallianae which are defined and protected under current EU legislation as
Annex 1 habitats of the "Habitats Directive". The fen supports a matrix of plant communities of particular
importance to nature conservation and there is a pattern of Annex 1 habitat in areas that have survived historical peat cutting and non protected habitat in the former cuttings. Should this be redressed at Cors Goch?
Prunus spinosa (Blackthorn) occurs around the drier edges of the fen
Myrica gale (Bog Myrtle) also as a succession species in Wetland plant communities
Crataegus monogyna (Hawthorn) also occurs on the dry edges of the fen
Here you can see Bracken encroaching on the fen....a product of past draining!
The current management on the fen was that of mowing, strimming
and grazing at different times of the year. Area's of the fen previously under-grazed and derelict due to the absence of any wild herbivores in Britain and the resource
constraints of the land managers are now being actively managed due to The LIFE project and its large LIFE+ grant.
New heavy duty cutting and mowing machinery was purchased in order to remove the dense stands of Cladium mariscus and allow grazing livestock such as Belted Galloway and
Highland cattle to graze the new seasons’ growth and open up the
stand to sunlight and develop a richer biodiversity.
Research on the Fen
The two pictures immediately below show a research project comparing a cut plot of vegetation and a control plot left to go go derelict. This experiment will test the effects of active management on biodiversity. (Early results have shown a significant increase in biodiversity in the cut plot by the second growing season!)
Here is a plot that was cut by a Wetland Harvester...(pristine)
....and here is a control plot receiving no management (degraded)
Bryophytes submerged in the surface water on the cut vegetation.
A good indicator that sunlight is penetrating the canopy!
Pinguicola (Butterwort) species are carnivorous! the ultimate adaptation to
life in a low nutrient environment. they also have thick waxy cuticles to store nutrients and
keep their leaves they do not have to re-cycle their nutrients after winter.
Other features of the site
Another important habitat feature of Cors Goch is the limestone pavement.
Pond creation for educational purposes. I wonder how long that one will last?
The visit ended back where it had started at the top of the limestone scarp but no before passing some ponds that have been created for educational purposes which is why we are here in the first place I guess...my next trip is to Cors Erddreiniog fen and includes some large-scale fen restoration works.
The Boring Bit
Location: Cors Goch, Isle of Anglesey, Wales
Grid Ref: SH494811
Date: Wednesday 9th October 2013
Weather: Dry but cloudy (80% cover)
Weather: Dry but cloudy (80% cover)
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