The Cambrian Wildwood site Bwlch Corog includes a range of habitats – rising from a river gorge, through ancient woodland, blanket bog and moorland to a minor summit. The hill is situated between two higher peaks: Pen Creigiau’r Llan and Pen Carreg Gopa. These hills dominate and give their name to Sites of Special Scientific Interest, both designated for blanket bog and upland heath. The degraded habitats of our property make an attractive proposition for restoration of blanket bog and upland heath. This will not only improve conditions for wildlife on our own land, but also provide habitat continuity across the landscape by linking these existing areas of good habitat.
Site surveys and analysis of aerial photography enabled ecologist Stuart Hedley to map out a network of 11 kilometres of drainage ditches, or ‘grips’. The dominance of purple moor grass (Molinia caerulea) across most of the site is likely to be the outcome of several factors: land drainage,
historic burning of the moorland vegetation,
nitrogen deposition from air pollution.
The significance of sheep is that they do not graze the tough Molinia grass, whereas cattle and horses can graze it and additionally the heavier animals are able to break up the large tussocks by trampling. We can influence all these factors in our management of the site except the nitrogen pollution. Fortunately, the recommended strategies are consistent with our overarching policy of enabling natural processes to take precedence.
Grazing with cattle and horses fits with introducing native large herbivores, a natural component of the ecosystem.
Reversing land drainage by blocking the grips is consistent with carrying out initial interventions to establish more natural conditions.
Desisting from burning the vegetation fits with the minimum intervention policy for ongoing site management.
With these factors in mind, blocking the grips is possibly the most significant restoration activity for the higher parts of the site. Entering the Welsh Government’s Glastir Advanced agri-environment scheme enabled us to receive capital funding for this work, along with annual payments for grazing at a suitable intensity.
We were fortunate to engage Peter Watkin, a highly experienced excavator operator with long experience of peatland and bog restoration. In partnership with scientists and land managers at Natural Resources Wales (and its previous incarnations), he has developed techniques for restoring the natural hydrology of these naturally water-logged habitats. Amongst the many sites where he has worked are Cors Caron National Nature Reserve and Cors Fochno in the Dyfi National Nature Reserve.
The work at Bwlch Corog involved blocking the drainage grips by digging out a small pond or scrape within the grip to provide the material (peat) to construct a dam at the lower side of the pond. These dams were spaced on average every 10 metres along the grips – on steeper ground they need to be closer, and on flatter ground they are more spaced. Because of the very wet ground conditions, the machinery is a specialised excavator, being lightweight and fitted with very wide tracks. Despite this, Peter had an awkward moment in the deepest part of the bog where the machine sunk in above the top of the tracks: by using the bucket he was able to pull the machine out of trouble, but it was a close call apparently.
Peter worked on this job off and on between April and September 2019. The result of the work is lines of ponds numbering about 1,200 in total, tracing the network of grips. A conveniently timed aerial photograph taken during the last week of work shows the ponds very clearly. The results on the ground are instantaneous, with the ponds filling with water as they are constructed, and the water flowing out to the sides of the grip, where the vegetation becomes water-logged. In the longer term, we expect to see the purple moor grass dying off and the water-logged ground being colonised by sphagnum moss, bog asphodel and other plants that thrive in wet conditions.