Restoring Calderdale’s Sphagnum Moss: Nature’s Water and Carbon Sponge

Guest blog by Gill Wrigley, Sphagnum project officer, Calderdale Council

Sphagnum moss holds twenty times its weight in water.   Once it was the most abundant plant on the hill tops of Calderdale, soaking up the water as soon as it falls, keeping the peat wet and slowing the flow of water into our steep sided valleys.  

The Calderdale sphagnum project is a four-year project funded by The National Lottery.  As part of the project, we have developed a way of growing ten local species of sphagnum.  These are grown from samples of sphagnum moss that have been collected locally.   We are educating other conservation organisations about how to grow sphagnum so that they too can repair their peat bogs.

The history of Calderdale sphagnum

For 2000 years the moors of Calderdale looked very different from how they do today.  The tussocky purple moor grass and heather that we associate with our moors are drought tolerant species which are there in such abundance because our sphagnum moss has been outcompeted due to land management practices.

4000 years ago, the hillsides of Calderdale were covered in mixed woodland, then our predecessors deforested the land for charcoal burning and farming.  This resulted in leaching of the nutrients from the soils and clay pans developing.  The only plants that could survive this harsh nutrient poor, waterlogged soil were bog plants. Over 2000 years blanket bog was formed.  

Blanket bog is made up of a myriad of plant species but all of these rely on plants that build up the peat depth and maintain the wetness of the peat.  Sphagnum moss is the primary plant with this role.  Sphagnum does not have roots; water does not have to penetrate the ground for it to be taken up.  Instead, sphagnum absorbs water through its leaves.   It also produces an acid like vinegar which pickles all of the other plants in the bog, so that they do not rot.  This wet, pickled plant matter is peat.

Fortunately, Blanket bog holds more carbon and more water than any forest could.    All living things have carbon in their bodies.  When they die in a peat bog the carbon in their bodies stays there.  30% land stored carbon is held in peat bogs which make up only 3 % worlds land area, so healthy peat bogs are one of the keys to keeping Carbon out of the atmosphere.

Unfortunately, 250 years ago the industrial revolution produced chemicals which rained on the blanket bog and killed off a lot of the sphagnum moss.  Next the bogs were drained to create a mixture of upland pasture and heather moorland. Then there’s controlled burns, and burns that occur due to the peat being so dry.  All of these factors and overgrazing has meant that the bog building sphagnum moss has almost died out on our hills so our peat is not as efficient at storing water or carbon.  When the peat dries out it releases carbon that has been stored for thousands of years.

How can I help?

Calderdale Council has a Sphagnum project officer, Gill Wrigley who works 18.5 hours per week but most of the sphagnum growing is done by volunteers at Manor Heath Park in Halifax and Cromwell Bottom Nature Reserve in Brighouse.  They are currently also undertaking vegetation surveys of sites that they hope to rewet.

If you would like to get involved contact countryside@calderdale.gov.uk or for regular updates check out the Calderdale Countryside and Woodlands Team Facebook page. Calderdale Countryside and Woodlands Team.