Mosses and Mires
Cumbria contains some of the best remaining examples of mosses and mires in the UK, they all have one thing in common, Peat.
Peat forms where there is a combination of Waterlogging, mineral leaching and low temperatures. As the peat soil becomes more and more acidic a plant community dominated by Heathers, Cotton grass and sphagnum mosses forms.
Within this environment, Bilberry, Bog Asphodel, Cranberry and Bog Rosemary are commonly found, as well as some specialised plants such as the carnivorous Sundews and Butterwort that obtain nutrients by catching small insects.
There are three different types of bog found in the county, these are:
True Blanket Bog is only found on wide, flat or gently sloping ground above 1500ft altitude. The thick mantle of peat covers all features of the original surface and within it the remains of trees that originally grew on the fells can frequently be found where erosion of the peat occurs.
The peat is Ombrogenous, that is built up above the ground water level so that plants growing on its surface derive their mineral content only from rain.
A good example of this habitat is Poukes Moss located on Lank Rigg in the western fells (grid reference NY082115) and shown in Figure 1
Another type of Ombrogenous peat body is found around the coast where impermeable clays were deposited after the last ice age. The peat forms great raised domes and is many feet thick.
For centuries, Foulshaw, Meathop and other mosses on the north shore of Morecambe bay blocked coastal communication routes and caused traffic between Furness and the rest of Lancashire to use tidal routes across the sands.
This type of bog is found around the coast of Cumbria from the Kent to the Duddon esturaries in the south, and again along the Solway coast in the north.
As the name suggests these mires are found where peat has developed within low lying wet hollows.
There are numerous examples of this habitat in almost all the valleys. A particularly interesting variant occurs where peat forms below the water table in a glacial hollow called a ‘kettle hole’. Here the layer of peat floats on water forming a ‘schwingmoor’ that readily bounces underfoot!
Groundwater brings in a certain amount of nutrients and the peat is also less acidic so a more varied floral community is present.
The Best example of a basin mire in Cumbria is Hallsenna moor NNR in West Cumbria Grid reference NY 006007 shown in figure 3
This habitat is the home of the LARGE HEATH, the subspecies ‘Davus’ being found on the Morecambe bay mosses and ‘Polydama’ on the Solway Mosses.
The Larval foodplant of this butterfly is Cotton Grass, which forms white carpets across many of our mosses in the spring, just look on a good map and see how many places are called ‘White Moss’ !
The largest colonies of Green hairstreak are also found where the larval foodplant Bilberry is abundant.