What is ‘special’ about Cae Gwyn SSSI?

Cae Gwyn has 1 special feature:

As well as the features listed above, Cae Gwyn has other habitats that contribute to the special interest. These include areas of willow scrub and common reed. There is also an area of grassy heathland with outcropping rock.. This mixture of habitats is important for much of the wildlife including sphagnum (bogmoss) and a profusion of common wetland herbs such as bogbean and marsh cinquefoil and locally uncommon plants including Royal fern, cranberry and bog sedge. Unless specified below, management of this site should aim to look after these habitats and species as well as the listed features of interest.

What do we want Cae Gwyn to look like?

The site should consist of two acid wetland basins, separated by an area of heathland with outcropping rock. The southern wetland confined by the rock basin should include a 'lawn' of sphagnum (bogmoss) and common wetland herbs such as bogbean and marsh cinquefoil. There should be an abundance of royal fern varying from very large old plants to young plants. Bog sedge should fringe small pools and runnels while cranberry threads its way over the sphagnum hummocks. The northern wetland should continue to include patches of grey willow but it should not be permitted to exceed 20% of the wetland area. A few scattered patches of European gorse will be tolerated. There should be limited areas of common reed and royal fern should be abundant. Overall water levels and quality should be maintained to support these communities.

What management is needed on Cae Gwyn SSSI and why?

Although Cae Gwyn is an excellent place for wildlife, it will only remain so if the necessary management continues. CCW’s aim is to work with you to ensure that this management is carried out.

What does this mean in practice?

There are many factors that could damage the special features at Cae Gwyn if they are not properly managed. These are the ones we regard as most important:

Water level and movement: A high water table is essential for the survival of wetland plants and animals. It is therefore important that no work is carried out which would lower water levels on the site – for example by widening or deepening ditches. Some wetland plants and animals require very shallow surface water or moving groundwater, but deep or prolonged flooding can destroy these. Raising water levels should not be undertaken without careful assessment. Equally important is the need to maintain the current water supply to the site through springs, groundwater seepage, ditches and surface run off. Any reduction in the amount of water entering Cae Gwyn would be damaging to the site.

Water quality: Good water quality is essential for maintenance of the characteristic assemblage of wetland plants and animals at Cae Gwyn. Nutrients such as nitrogen and phosphorous encourage competitive plants such as floating sweet-grass and common reed which can smother the less common (and more desirable) species at Cae Gwyn. This in turn would have a negative effect upon the animals that depend on these plants. Measures to enhance soil fertility, including fertiliser, slurry or waste applications within the catchment of the site are therefore likely to be harmful to the special interest features of Cae Gwyn.

Grazing: Light grazing of the bog removes excess plant material. The most appropriate grazers here are cattle or ponies as they can maintain open areas in wetland by browsing scrub and by light poaching of the ground. Up to 6 ponies (and no less than 3) should be used to graze both areas of wetland throughout the year. It may be necessary to restrict them to the wetland areas at certain times to encourage removal of excess plant material. Animal dung also provides an important food resource for some invertebrates. There should be no supplementary feeding with silage as this increases soil nutrient levels. Hay may be fed in severe weather, mineral licks used to enable the animals to digest coarse material and small quantities of concentrates to keep livestock tame.

Scrub control: Scrub (including willow and gorse) provides nesting places for birds and shelter for other animals. However too much scrub can alter the special qualities of the wetland site, shading and smothering the sphagnum lawns. Grazing alone may not be enough to prevent scrub expansion and manual control may sometimes be necessary .

Fire: Fire was regularly used in the past to clear land, promote new growth and attract grazing animals. However uncontrolled fires can damage some plant and animal communities, particularly acidic sphagnum hummocks, and its use should be very strictly limited on wetland. Small, controlled fires in winter may be used to rejuvenate the patches of heathland with excess leaf litter and to create more diversity of structure.


Our knowledge of wildlife is far from complete. It is possible that new features of value may appear and new management issues may arise in the future, whilst other issues may disappear. This statement is written with the best information we have now, but may have to change in the future as our understanding improves. Any information you can provide on the wildlife of your site, its management and its conservation would be much appreciated.

If you would like to discuss any aspect of your SSSI, or have any concerns about your SSSI, please contact your local CCW office.

Your local office is;

Cyngor Cefn Gwlad Cymru/Countryside Council for Wales

Llys y Bont,

Ffordd y Parc,

Parc Menai,


Gwynedd, LL57 4BN,

Telephone: 01248 672500

Fax: 01248 679259