Bryn Marsh and Ince Moss, situated 3 km south-east of Wigan, are Sites of Special Scientific Interest (SSSI), which means they have been designated as protected areas for conservation purposes.
They form two of a series of wetlands that run partly along the Hey Brook valley, stretching for some 10 km between Wigan and Leigh, known as the Wigan Flashes. Both lie adjacent to, but are separated by, the Leeds and Liverpool Canal and the Preston to Liverpool railway line. The Ince Moss area is underlain by tills and Late-glacial flood gravels overlying Triassic sandstones of the Sherwood Sandstones Group.
Agricultural and industrial activity have had a profound effect on the vegetation of the area, resulting in a complex system of habitats dominated by open water and swamp but still retaining fragments of the original mossland. This site supports the best example of swamp and tall fen vegetation in Greater Manchester and Merseyside as well as important populations of dragonflies and breeding birds.
Key habitats
- Open water
- Fen and swamp
- Mire
- Woodland
- Acidic and neutral grassland
- Ruderal communities.
The extent of open water has increased due to flooding caused by subsidence and ash extraction. This has led to a rise in alkalinity with pH levels ranging from 4 to 8, or acidic to mildly alkaline.
Ecology of the area
- The sparse flora of the open water includes species such as broad-leaved pondweed Potamogeton natans and spiked water-milfoil Myriophyllum spicatum.
- In fen and swamp communities, single-species swamps of reeds Phragmites australis, water horsetail Equisetum fluviatile and common spike-rush Eleocharis palustris occur, but more unusual are the extensive stands of lesser bulrush Typha angustifolia and glaucous bulrush Schoenoplectus lacustris spp. tabernaemontani - species more commonly found in coastal locations.
- Smaller areas of greater bulrush Typha latifolia, reed sweet-grass Glyceria maxima, sweet flag Acorus calamus and another coastal species sea clubrush Scirpus maritimus are also present.
- More diverse areas of fen support a rich assemblage of species such as hop sedge Carex pseudocyperus, false fox sedge Carex otrubae, gipsywort Lycopus europaeus, water forget-menot Myosotis scorpioides, marsh bedstraw Galium palustre, trifid bur-marigold Bidens tripartite and marsh pennywort Hydrocotyle vulgaris.
- Hydroseral succession from the swamp and fen into the mire and also into carr woodland is well represented.
- The mire or mossland areas exhibit a range of communities from the wetter areas of common cottongrass Eriophorum angustifolium with bog mosses Sphagnum palustre, S. squarrosum and S. fimbriatum, to drier areas dominated by purple moor-grass Molinia caerulea and then bracken Pteridium aquilinum. Relict species such as royal fern Osmunda regalis and narrow buckler-fern Dryopteris carthusiana occur.
- The carr woodland is dominated by goat willow Salix caprea and grey willow Salix cinerea often with a sparse understorey, though locally, greater pond sedge Carex riparia is found. Woodland and scrub of both silver Betula pendula and downy B. pubescens birch is also found in the drier areas.
- Acidic grassland is represented by areas of purple moor-grass and wavy hair-grass Deschampsia flexuosa and neutral grassland by more species rich swards of bents Agrostis spp., fescues Festuca spp. with a variety of herbs such as hardhead Centaurea nigra and birdsfoot trefoil Lotus corniculatus.
- Industrial activity has led to a number of lime-loving and locally rare species such as yellow-wort Blackstonia perfoliata, marsh helleborine Epipactis palustris and marsh orchids Dactylorhiza praetermissa and D. incarnata.
Birdlife
The breeding bird community support a characteristic range of wetland species such as little grebe, great crested grebe, mute swan, tufted duck, snipe, redshank, reed and sedge warblers.
Roosts of migrant swallows and wagtails, and passerines (especially warblers), use the reedbeds for roosting or on passage in autumn, and the site is also used by raptors such as sparrowhawk and long-eared owls, especially in winter.
Insects
The area is important for dragonfly and damselfly populations. Ten species are present, some of which, such as the four-spotted chaser Libellula quadrimaculata and the blacker darter Sympetrum scoticum, are locally rare, but there are large populations of more common species such as the brown hawker Aeshna grandis and common darter Sympetrum striolatum.