Meres and Mosslands

Whilst some of Cheshire's meres have originated as a result of subsidence in the area of the underlying salt beds (this is believed to be a factor in the origin of such important sites as Rostherne Mere, Wybunbury Moss and Oakmere), many of the basins were formed as 'kettle holes'. Such sites were created when ice blocks from the retreating ice face were buried in the glacial outwash of clays and sand some 10,000 years ago. The Cheshire meres form a part of the internationally important North West Midland Meres.

Some of the meres, such as Hatch Mere, Budworth Mere, Combermere, Tabley Mere, Barmere, Quoisley Mere and Chapel Mere at Cholmondeley, receive nutrient-rich water and have remained open with fen margins. Only the most secluded of these have escaped human interference.

Hydrosere succession is the ultimate, natural, fate of a mere. Meres are Britain's natural mesotrophic and eutrophic lakes which often have associated endangered wetland habitats such as alder/willow carr, fen and swamp.

Mosslands have developed in wet sites colonised by the Sphagnum mosses with some habitats forming deposits of peat. These include numerous kettle holes where catchments are small and waters are acidic. The succession of vegetation has developed as a raft community or 'Schwingmoor', over a water lens with the finest examples being in Wybunbury Moss and Abbots Moss.
Where moss grows and accumulates dead plant material, peat is formed, sometimes forming extensive raised bogs. These Peatlands support rare plant and animal communities.

Fenland
Fens are peatlands that receive water and nutrients from the soil, rock and ground water as well as from rainfall: they are minerotrophic. Fens are dynamic semi-natural systems requiring appropriate management in order to maintain the open fen communities and associated species richness. Two main types of fen occur: Topogenous fens where water movement in the peat or soil is generally vertical (e.g. basin fens and floodplain fens) and Soligenous fens where water movements are lateral (e.g. mires associated with springs, rills and flushes and valley mires). Fens can also be described as poor fens and rich fens dependent on the chemical properties of the water that feeds them.

In the Cheshire region fens are often found in a complex of habitat types associated with the meres and mosses as part of the hydrosere succession, e.g. at Hatch Mere or as fen woodland or fen pasture. Petty Pool valley SSSI contains an extensive mosaic of poor and rich fen and is considered as the best example of these communties in Cheshire. Locally rare species are often associated with fens, such as tufted sedge Carex elata at Chapel Mere and the small pearl-bordered fritillary Bolaria selene at Bagmere.