Saturday, 11 April 2009

A Fallowfield Peat Bog

Last year, at about this time, Richard Gardner, Julian Robinson, and I took a walk along the Fallowfield Loop – the cycle track which follows the old Midland railway line from Chorlton, through Fallowfield, to East Manchester.
In Fallowfield the line of the track is interrupted by Wilmslow Road, and just before we reached this break point I noted that one of the embankments was covered in moss. The species was Hair Moss (Polytrichum commune) which is the largest British moss species and about the only one that I can recognise on sight. Hair Moss is a characteristic plant of some of my favourite sites in the Mersey Valley – so I climbed up the bank to investigate further. To my amazement, nestling among the Hair Moss was what appeared to be a species of glistening red Sphagnum Moss. To explain why this find was so striking and unexpected it’s necessary to recall what was once a common landscape feature in the North West – a feature which has now been almost completely lost.
If you look at a detailed map of the North West you will see the word ‘Moss’ everywhere: Carrington Moss, Chat Moss, Red Moss, White Moss, Ashton Moss, Barton Moss and Lindow Moss are just a few examples. In addition there are dozens of ‘Moss Sides’, Moss Lanes’, ‘Moss Nooks’ etc.
Confusingly, the word ‘Moss’, in the sense of a landscape feature, does not refer to small, flowerless plants like Sphagnum or Polytrichum but is thought to be a contraction of the word ‘morass’. Many of the old Mosses were, in fact peat bogs; although not all were - and the name seems to have been applied to any tract of marshy ground (e.g. Jackson’s Moss- which is now Whalley Range, and Turn Moss at Stretford).
Having said all that, peat bogs are (coincidentally) composed mainly of living and dead moss plants, in particular Sphagnum mosses. Bogs tend to form in areas of high rainfall and in places where water gets trapped by the local geology or topography and can’t run away fast enough. Such areas provide an ideal habitat for Sphagnum species and other plants. As the plants die off they form horizontal layers, and within these layers conditions are acidic and lacking in oxygen. The process of decay is slowed down and the detritus of dead plants (i.e. ‘peat’) accumulates. Bogs are very slow growing and can take many centuries to become significant landscape features.
There are several different types of peat bog but the two which appear to have been commonest in North West England were ‘blanket’ bogs and ‘raised’ bogs. The former were commonest in the hills of the Pennines whilst the latter tended to occur at lower levels in areas like river valleys.
It would seem that raised bogs were remarkable phenomena; here is an account (1), by the 19th Century Manchester botanist Leo Grindon, of Ashton Moss:

“Owing to their immense capacity for absorption, many mosses swell into mounds higher than the surrounding country, ... and after heavy rains this enlargement is so much increased that distant objects are concealed from view until evaporation and drainage have caused subsidence to the ordinary level. Before Ashton Moss (between Droylesden and Ashton-under-Lyne) was drained, trees and houses were often lost to view for many days, by persons residing on the opposite side.”

This passage suggests that, by acting like giant sponges, the Mosses may well have played an important role in the control of flooding. And we now know that peat bogs are also important repositories for carbon.
Nevertheless, however remarkable the Mosses were, and however useful they may have been at absorbing water and carbon, the Industrial Revolution saw their wholesale destruction. The first to go were the blanket bogs of the Pennines. After 1780 the peat layers (which are dateable) are full of soot (2). This soot was, of course, from factory chimneys in Manchester, Sheffield, Leeds, Bradford, and other industrial centres, and it was full of sulphur compounds - which are poisonous to Sphagnum.
The raised bogs met a different fate: they were drained, ploughed up and turned into agricultural land to feed the growing populations of the industrial cities. In 1839 Leo Grindon visited White Moss, near Blackley, with the doyen of local naturalists, George Crozier, who showed him such floral gems as the Bog Rosemary and the Cranberry and such spectacular insects as the Fox and Emperor Moths (3). But within 20 years both White and Ashton Mosses had been drained and converted to agriculture.
In a book published in 1922 (4) the Altrincham naturalist Thomas Coward (who was, incidentally, the first Guardian Country Diarist) described the Carrington Moss of his boyhood – a place full of plants, insects, reptiles and birds now considered scarce or rare. He then went on to relate how, in 1886, the Moss was purchased by Manchester City Council who drained it, ploughed it and dumped Manchester’s ‘night soil’ (i.e. sewage) on it to fertilise it. By the First World War it was more or less converted to farmland.
In the 20th Century the remaining Mosses met a different fate; they were ‘mined’ and stripped of their peat which was sold as garden compost (peat bogs are still being lost to this type of commercial exploitation to this day). In 1984 commercial peat diggers found a 2000 year old body preserved in the peat of Lindow Moss near Wilmslow (5). ‘Lindow Man’, as he was named, may have been the victim of a ritual sacrifice – although some authorities dispute this. The body had been preserved by the acidic, anaerobic conditions typically found in bogs.
So what of my Fallowfield Sphagnum? My limited reference works on moss plants suggested that it might be the species Sphagnum capillifolium (frankly, this was something of a guess on my part). I sent a specimen to John Lowell, who is treasurer of the Manchester Field Club and one of the Club’s authorities on mosses. John was intrigued and agreed to meet me at the site. He thought that it probably was S. capillifolium but felt that this was so unlikely for such a site that he needed confirmation. He took another specimen and sent it to Des Callaghan, local recorder for the Bryological Society of the British Isles. Mr Callaghan confirmed the S. capillifolium identity – but, as John said to me, it was a most unusual find for an urban site and would normally be a species that he would expect to find on the West Pennine Moors. And if that weren’t enough he found a second species of Sphagnum (S. falax) with the first and 22 other moss species in the same area (none of them as unusual as the Sphagnums).
Is it an exaggeration, I wonder, to say that what I had found on that early spring day, last year, was a tiny peat bog, just a few inches across – a miniature version of the mighty Mosses that once dominated the landscapes of the North West (and probably formed, like them, by restricted drainage)? A strange thing to find within two or three miles of the centre of Manchester!

Dave Bishop, April 2009


1.‘Country Rambles and Manchester Walks and Wild Flowers’ by Leo Grindon, Palmer & Howe, 1882.

2.‘Wild Flowers and Other Plants of the Peak District’ by P. Anderson and D. Shimwell, Moorland Publishing, 1981.

3.‘Country Rambles etc.’ by Leo Grindon

4.‘Bird Haunts and Nature Memories’ by T.A. Coward, Frederick Warne, 1922.

5.‘Wikipedia Article on Lindow Man’: http://en.wikipedia.org/wiki/Lindow_Man

No comments: